Recently in Digital Photography Category

Painters often create what they call a hierarchy of edges. Bright important edges are usually sharp, but darker, less important edges become lost edges.

This effect is easy enough to simulate in Photoshop, but I wonder how common it is. Most people use selective, luminance-based lens blur to simulate shallow depth of field. I'm talking about guiding the eye more in the painterly, less optics-based sense. This post is mainly about analyzing what painters do and incorporating those ideas into photography, although it is also interesting to see the efforts of artists who are approaching photographic ideas from the painterly side.

One could argue, I suppose, that creating a hierarchy of edges is only necessary for painters, and that photographers needn't worry about this issue (aside from DOF) because most of the edges are produced by the camera already suitably hard or soft. I'm not so sure about that. I think further manipulation might be warranted and beneficial.

UPDATE 3/8/2010

MM Forum Discussion

You never see a flat rollercoaster track go into a perfectly circular loop-the-loop because while that track is continuous in the first derivative, it is not continuous in the second derivative, and would make for a very jarring ride.

Entering the circular loop from a horizontal track would imply an instant onset of the maximum g-force (as would a direct transition a circular path with smaller radius of curvature). An immediate transition from one radius of curvature to another would give a continuous, smooth track, but with discontinuous second derivatives. Clearly, a function with continuous higher derivatives would be preferable.
Roller Coaster Loop Shapes

So is there a special curve with which to make the optimal photo studio wall?

This is why car surface designers, who are in many ways reflection pattern designers, worry about continuity and smoothness in the higher derivatives.

- A Periodic Table of Form: The secret language of surface and meaning in product design by Gray Holland

A little Valentine's Day image featuring the super cool Nekromistress.

I wanted to try and make a strong color statement - something along the lines of the work of Brian DeMint / Eyeworks of Joplin, Missouri.

I'm interested in trying to simulate things like tintypes using digital techniques.

I think the best way to do it is not to just use Photoshop tricks, nut to model and tecture a surface and render it in Maxwell, paying special attention to surface textures and materials and reflectivity.

Before I can do that, however, I need t have a good look at a few of these things. I want to hold them in my hand, flex them, scratch them, see how they reflect light.

I bought a few on eBay. Surprisingly cheap for small ones. I am scanning them on flickr in this set: Tintypes

I'll update this blog entry as my experiments in this area progress...

UPDATE 2/15/2010

model: Nekromistress

This is a straight Photoshop composite using some textures from some scanned tintypes I bought on eBay. To really do it up, I want to bring Maxwell and ZBrush into the mix. I haven't done so, yet.

For my daughter's 6th grade Science Fair experiment she chose to explore the Inverse Square Law as it relates to light falloff. Technically the ISL only relates to point light sources, and it will 'fail' when the lights are not point light sources, but just how badly does it fail?

Any light is approximately a point light if you get far away from it. So how accurate is the ISL in real world cases? I was actually pretty curious to find out, myself.

So without further ado, here are the results of our experiments, courtesy of my 12-year-old daughter...

Mannequin. Ridiculously underexposed with a Nikon D200. Brightened greatly in Lightroom 3 (beta). I thought it looked interesting.

Sometimes I find it necessary to copy a Photoshop color channel into the layers palette.

The standard workflow for this is to select the channel which interests you, ctl-A, ctl-C (on a PC) to select all and copy, then return to the layeres palette, make a new layer, and ctl-V paste.

If you do that, however, your channel will not be color managed. That matters if you plan to reconstruct those channels later as done here in RGB or here in CMY and hope to form an image that matches the original.

The way to use the Black & White Adjustment Layer to derive, say, a green channel, is to set all sliders containing green to 100. (That means the green, cyan, and yellow sliders) Then set all other sliders to 0.

You can save that set of sliders as a preset for convenience later.

The fifth image in my Nothing is Real but the Girl series.

Hokusai's Great Wave off Kanagawa is so iconic that I think it works well magnified and made somewhat more abstract - somewhat similar to the way Landor Associates handled the corporate ID program and signage for General Electric. Large and cropped.

Selective desaturation has a bad name but I am liking the effect of applying desaturation through a luminosity mask.

I think this could be a great effect for an austere, painterly look, or maybe even as a basis on which to build a pale pinup look.

To get the luminosity mask I go to the channels palette and control-click on the RGB composite channel.

To desaturate I use the Black and White Adjustment Layer. Never Hue/Saturation.

Hue/Saturation-based desaturation turns all additive and subtractive primaries to the identical 50% middle gray. Yuck.

I've been playing around with Polaroid, Cross Processing and Vintage Photography looks. Much of which from off-the-shelf sources. Above is an image of mine of Apnea as The Knife Thrower's Assistant, after having been treated to the Polaroin process. Polaroid heroin - it really is addictive. Lots of fun.

Other online Polaroid simulators include the Polaroid site, itself. (Justin Timberlake demonstrates)

Alien Skin also provides some Polaroid and Cross Processing settings for its Exposure 2 plugin.

Some good online tutorials on the matter include this one from photoshopsupport.com on cross processing.

Lot 8 Studios discusses some of his popular vintage look workflow here:

Vintage Feel Basics
Vintage Feel - Additional Effects (The Multiply Layer)
Vintage Feel - Additional Effect - The Hard Light Layer

And popular photographer mojokiss reveals some of his color secrets here

Here is a great discussion on feature film color grading and why exactly so many films these days have cyan-green shadows.

Creating a Summer Blockbuster Film Look

...and I'm looking forward to reading If It's Purple, Someone's Gonna Die: The Power of Color in Visual Storytelling

Love Conquers All, originally uploaded by jfrancis.

I tried a mild version of a curves-based cross-processing recipe here. I'm interested in treating the CG as if it were photography. That means lighting it moodily or throwing it out of focus regardless of how much work it took to model and texture - and it also means trying the same kinds of color treatments on the CG/photo hybrids that I would use on a straight photo.

UPDATE 1/18/2010

This Japanese site does an interesting job of turning modern photos old looking.

http://labs.wanokoto.jp/olds

UPDATE 1/29/2010

Messing around with the free tinting Photoshop plugin from Colormancer. I like the interface and the looks. Here as an experiment I put a heavy sepia layer on top of a green layer on top of a blue layer and used Photoshop blend-if sliders to control how much of each layer is seen.

Artist and model Jasmine Worth avoids Cupid's arrow for the last time in Love Conquers All, the fourth in my Nothing is Real but the Girl series of images.

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Love Conquers All, originally uploaded by jfrancis.

Trendy green faux cross-processed version. Which do you prefer?

click photo to enlarge

Pompeii: AD 79, in the shadow of the volcano Vesuvius.

In this third image in my Nothing is Real but the Girl series, model and singer Lisbeth Boada Phelps poses on a set designed to evoke the Lares Shrine at the House of the Vettii in Pompeii -- the same Lares Shrine mentioned in the Siouxie and the Banshees song, Cities in Dust.

The second in my 'Nothing is Real but the Girl' series. Jennifer Anne Black a/k/a Jenny Chaos poses in a 3D set designed after the now defunct Pussycat Theaters and rendered in the Maxwell Renderer.

scan-13, originally uploaded by jfrancis.

I bought a vintage Chinese newspaper so that I could scan it for interesting textures.

I have no idea what it says, or what it is called, but the eBay seller told me it was from Hong Kong, 1946.

The peachy paper is actually browner and more subtle in person. I should have toned it down a bit.

Click through to the flickr set for more.

A 2 foot by 3 foot softbox facing a parallel wall 9 feet distant - simulated in Maxwell Renderer v 1.7

Softbox with 1" deep egg crate grid - a Maxwell Render simulation

Softbox with 2" deep egg crate grid - a Maxwell Render simulation

Softbox with 4" deep egg crate grid - a Maxwell Render simulation

Softbox with 8" deep egg crate grid - a Maxwell Render simulation

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Here is a 30 minute render of a CG model using Maxwell Render 1.7 to simulate a softbox gridded deeply, shallowly, and not at all.

The three frames were all of quite different exposures. The deeper the grid, the more light was lost. Maxwell images are 32-bit HDR files, so I equalized them in Photoshop. You can see how much noise remains in the deep grid image after a half hour of rendering.

As the grid gets deeper, the light rays become more parallel, and the shadow on the wall becomes sharper, as if from a harder light. I find it hard to see much difference in softness or hardness on the figure itself, although with more light on the wall there is more bounce fill and less contrast.

I mulled over some of the conclusions I came to in the previous post about film being binary. I'm mainly just looking for a Photoshop recipe that approximates the idea of the grain using off-the-rack filters.

NOTE:

These are not finished 'recipes' for digital film grain. They are not meant to look good at this stage. They are 'amped up' for the purpose of discussion, and for getting a good, close look.

Stochastic halftones have a nice random distribution of points.

Using the Crystallize filter makes them clump into irregular shards that seem to resemble film grain at some magnifications.

The reticulation filter has a nice organic look. I applied it to middle gray, then hard mixed it with a black and white photo and blurred the results.

The Crystallize filter makes some nice chunky 'silver halide crystals,' but the reticulation filter seems worth a closer look, as well.

The trick is to get the scales and strengths right. For color I'll do each channel separately and combine them RGB additive style or CMY multiplicative / subtractive style. Not sure it matters which.

UPDATE 10/21/2009

Adobe Photoshop Lightroom 3 public beta promises a

• Film grain simulation tool for enhancing your images to look as gritty as you want

I think film grain is binary. Why do I think that? I learned it here:
Photo Utopia: Clumps and Chumps (or why film isn't binary)

The author meant to have the opposite effect, but after I read his explanation for why film is not binary, I formed a differnt impression.

I have been thinking a lot about film grain recently. I'm interested in mimicking its look in the digital domain.

I don't like the usual 'soft light or overlay some gray-centered noise' approach to making digital film grain, because I feel it doesn't really model what film grain actually is. That technique does not cause edge breakup, for example.

So What Exactly is Going On?

I needed to know if film grain got more or less gray (true analog), larger and smaller (like a traditional halftone, but with jittered cell placement), or denser and sparser (like a stochastic frequency-modulated halftone. In researching my questions I learned that this is apparently a point of some contention.

After mulling it over for a while, I decided I would go with this guy:
Clumps and Chumps or Why Bumble Bees Can't Fly and not just because he knows about bumble bee wing vortex shedding, although that did give me some added confidence :D

So here is how I think it goes, based on what I've read here on teh internets.

I think after development it's little black crystals of reasonably similar size that scatter and overlap. The more light a region gets, the more numerous the crystals become.

I think a negative image (or 3 color separations combined as here) would make a good start. Maybe stochastic halftones would form a good basis. Could the halftone be 'crystallized' using, maybe, the median filter? I wasn't thrilled with the results, but another method for crystallizing the halftone might be good.

I saw a quote on one of the preceding links from a Kodak scientist who flat out said film is analog, but Kodak needs to hold to the line that film is superior to digital, so I don't put that much weight on that statement. (Film is superior to digital in many ways, btw, and what's motivating me in this post is my desire to make digital seem to be more filmic). Plus at the right scale an FM screen will seem analog.

That same link concludes (ironically) with this quote:

So next time some 'expert' spouts off about bumblebees and how grain is binary tell them it's about "the energy of an electron being raised into the conduction band from the valence band"

I say 'ironic' because in quantum mechanics there is no continuous analog scale. Things are quantized. There are only certain bands at certain energy levels. There's the Valence Band. There's the Conduction Band. (And in between there's the Gap Band) That's why it's called Quantum Mechanics.

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In my next post I'm going to propose a recipe for digital grain. No guarantee that it will be the best. Feedback welcome.

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UPDATE 7/15/2009

I got this illustration from the photo.net argument thread. I'm adding in as a partial response to the first comment below about film grain being crystals vs filaments. If I follow it, (at least some) crystals (somehow) look like filaments at the right magnification. I'm including this filament idea mainly because as of my posting of this blog item it was the strongest argument I could find for film being analog. I still think of film grain as being composed of random areas of black or clear crystals.

Comments referring to the "Gurney-Mott development model" (causing the silver speck to grow like a traditional AM halftone?) or "plate disc theory" (not seeing this on Google) are new information for me. Thank you for that. I'll investigate further.

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THE GOAL

I should add that I don't particularly care whether film is one thing or another. My goal is to get an understanding of whatever it is - a mental model - that will help me come up with some sort of recipe for trying to copy it in something like Photoshop. And if it turns out that existing recipes for faking grain are as good as it gets, then so be it. But I want to take a closer look.

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UPDATE

I'm looking at this page (reprinted from an old Kodak source) discussing latent images and the Gurney-Mott Theory, and it looks to be a pretty good explanation.

Here's what I read:

• The dark spots on the negative are metallic silver. They are essentially opaque. This suggests two states: dark and clear.

• The numbers of dark spots on a grain increases with exposure, but the number of grains doesn't increase. This suggests something like an FM screen.

• The dark spots tend to cluster at favored formation points on the grains. This means the dark regions grow with exposure, more like an AM halftone with jittered placement of halftone cells.

So I think after reading this material that we are talking about a 'binary' state black/white process that functions like an analog process (like a newspaper halftone), especially at the scales at which we use it.

If you are willing to call a traditional newspaper halftone an analog process, since those dots can be any size and don't take discreet size change steps, (and I see that traditional halftoning is indeed considered analog) then I guess I have changed my mind.

I still consider film to be akin to a halftone, but over the course of this posting my opinion of halftones has changed. If a black circle can be any size on a white field then I'm comfortable saying that the area of the black circle is an analog function. But is the 'gray' analog? There is no gray. But I guess the perceived gray is analog, continuously variable, too.

Okay. Fine grained film, like coarse newspaper ads, is analog.

Although this guy has taken a patent out on the notion of space-filling curves (like the filaments in the photo at the top of this blog?) as a form of digital, not analog halftone. If the coils can be arbitrarily dense then shouldn't his process be considered a form of analog halftone?

...Now how best to simulate artificial 'film' grain in a digitally-originated image?

I recently upgraded to Adobe Creative Suite CS4 Production Premium and I started getting this error message every time I opened Photoshop:

Owl Orphanage - photoshop.exe Entry Point Not Found...

The problem turned out to be connected to image file formats or filters or plugins I passed along from Photoshop CS3. When I got rid of them all, the problem went away. Now I have to reintroduce the ones I still care about and see who the troublemaker is...

More info from others with similar issues here: http://forums.adobe.com/thread/373471

Blend Mode Killer Apps

I'm compiling a list of blend mode tutorials. It is incomplete for now. I'll add to it over time.

I'm particularly interested in the 'killer app' for each blend mode, and the best way to demonstrate it. I think that any collection of tutorials that uses the same pair of images and only varies the blend mode combining them is not demonstrating each mode in the best possible way.
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The Normal Blend Modes

• Normal

Additive RGB Color Mixing using Photoshop Normal Blend Mode

Subtractive CMY Color Mixing using Photoshop Normal Blend Mode

• Dissolve

I used dissolve to create the chalky white line in this illustration

A Simulation of Additive RGB Color Mixing using the Dissolve Blend Mode

The Darken Blend Modes

• Darken
• Multiply

Multiply Blend Mode | What it is and why you need itSome Thoughts on Photoshop Multiply,

Soft Light, Overlay Blend Modes

Photoshop Screen and Multiply Blend Modes as Logic Gates

Additive Color vs Subtractive Color

Color Transparency in Computer Graphics

Colorize Black & White Art by Keymixing

Creating an Outline

Subtractive Color Mixing using Multiply, Difference and Exclusion

• Color Burn
• Darker Color

The Lighten Blend Modes

• Lighten

• Screen

Screen Blend Mode | What it is and why you need it

Photoshop Screen and Multiply Blend Modes as Logic Gates

Additive Color vs Subtractive Color

• Color Dodge
• Linear Dodge (Add)

Additive Color vs Subtractive Color

Simulating 2D Metaball Blobbies with Photoshop

Compositing Premultiplied 3D CG in Photoshop

Colorize Black & White Art by Keymixing

• Lighter Color

The Contrast Blend Modes

• Overlay

Some Thoughts on Photoshop Multiply, Soft Light, Overlay Blend Modes

Overlay and Softlight are good for non-destructive dodging and burning. Float a gray layer above your image and 'carve' it with lighter and darker grays

• Soft Light

Overlay and Softlight are good for non-destructive dodging and burning. Float a gray layer above your image and 'carve' it with lighter and darker grays

Some Thoughts on Photoshop Multiply, Soft Light, Overlay Blend Modes

• Hard Light
• Vivid Light
• Linear Light
• Pin Light
• Hard Mix

Custom Halftone Pattern in Photoshop

Hard Mix Photoshop Blend Mode Killer App

Photoshop 'hard Mix' Dual Brush

The Inversion Blend Modes

• Difference

Difference vs Exclusion Photoshop Blend Mode Killer App

Subtractive Color Mixing using Multiply, Difference and Exclusion

• Exclusion

Difference vs Exclusion Photoshop Blend Mode Killer App

Subtractive Color Mixing using Multiply, Difference and Exclusion

The Component Blend Modes

• Hue
• Saturation
• Color
• Luminosity

The Miscellaneous Blend Modes

• Divide

Transparency Mapping and Matte Lines
Compositing Premultiplied 3D CG in Photoshop

• Unmult

Transparency Mapping and Matte Lines
Compositing Premultiplied 3D CG in Photoshop

Alpha Channels
Alpha Channels | premultiplied, straight and uncorrelated
Alpha Channel as a Clipping Channel
Alpha Channel as a Holdback Matte
Image Arithmetic
Blend Modes
Compositing Premultiplied 3D CG in Photoshop

Other Web Sites

SimpelFilter - Blending Modes of Photoshop & Co

You can simulate the halftone process in Photoshop by using the hard mix blend mode.

Create a custom halftone screen pattern of any kind you like. Use continuous tone grays from black to white. When you combine it with a black and white photograph using the hard mix blend mode, the grays will interact to force each other to black or white in the appropriate proportions.

A blurred checkerboard makes a nice basis for a halftone screen pattern.

I used twirl on the halftone screen before hard mixing it with the photo.

A hard mix with 50% gray is pixel-identical to a threshold adjustment layer at 127. You can perfectly duplicate the behavior of the threshold adjustment layer by varying the gray value with which you hard mix a photo layer.

UPDATE 6/13/2009

Use the hard mix blend mode to combine a black and white rendering of a 3D object with the same object texture mapped in closely-spaced wrapping stripes or dots and you'd have a halfway decent stab at rudimentary non-photorealistic digital engraving.

UPDATE 6/21/2009

Stochastic Halftones using the Photoshop Dissolve Blend Mode

glass_DSC6428_crop, originally uploaded by jfrancis.

The Harmonious Art of Eric Dandurand by Natasha Dalton. Glassblowing photo by Joseph Francis issuu.com/journalplus/docs/may_09_journal_plus_web



While driving home to LA from a New Year's in San Francisco, we passed through the tiny town of Harmony, CA (pop 18) where I happened to photograph master glass artist Eric Dandurand. That photo was recently published in Journal Plus, Magazine of the Central Coast, May 2009, p 12

The Black and White Adjustment Layer has a nice ability to target and boost or suppress narrowly defined hues. For example, it can affect red without affecting yellow. That's something you can't do with curves.

In this video I'm experimenting not with what kinds of black and white images can be made from the Black and White Adjustment Layer, but what kinds of color images can be made using it.

related:
Technicolor 2-Strip Process in Photoshop

FOLLOWUP: An Experiment with Selective Color Adjustment Layer

I'm curious to see if all I did above was recreate Selective Color the hard way. It looks as though there is some overlap, but Selective Color is not as aggressive in being able to change the image.

UPDATE

Photoshop Black and White Adjustment Layer: A Closer Look

UPDATE 5/31/2009

The Black and White Adjustment Layer

reconstructs the red channel of an image as follows:

R 100% and its 2 red-containing companions, Y and M at 100% - all else at 0%

reconstructs the green channel of an image as follows:

G 100% and its 2 green-containing companions, Y and C at 100% - all else at 0%

reconstructs the blue channel of an image as follows:

B 100% and its 2 blue-containing companions, C and M at 100% - all else at 0%

UPDATE 5/31/2009

The color photography of Madame Yevonde

(A Maxwell Render simulation)

Depth of Light

When the figure and ground are almost the same distance from the light they will be of similar brightness.

To let falloff separate figure from ground, pull the model away from the background and place the light so that it is much closer to the model than to the background. Expose for the model.

see Violations of the Inverse Square Law

The Inverse Square Law is not an innate property of light. The ISL is a property of expanding spheres. When light does not expand spherically (as in a collimated beam) or when the source cannot be approximated by a point, then light seems to 'violate' the Inverse Square Law.

Cases where the ISL does not hold.

Umbrellas and softboxes will follow the law quite closely for distances greater than twice their diameter.

To see the Inverse Square Law in action, see Depth of Light

If you have a distortion filter that is reversible you can pre-distort an image, apply an 'art filter' to the distorted image, then un-distort the image. The result? The 'art filter' is distorted, while the image itself seems undistorted.

Unfortunately not enough Photoshop distortion filters are reversible, but I could probably back calculate an inverse displacement to a distortion by applying it to an image of absolute pixel addresses - an idea I partially present here:

Smear Now or Smear Later and
UV Map Now or UV Map Later

UPDATE 5/10/2009

I was reasonably successful in using channel calculations to compute displacement maps that undo other displacement maps. The quality is somewhat limited by things like Photoshop's refusal to displace in higher than 8-bits, but below is a test.

I used Perlin noise Photoshop 'clouds' to displace a photo, then I applied the mosaic filter. Finally I reversed the displacement so that the photo was normal, but made of rippled 'mosaic' tiles.

I reversed the displacement by applying the same displacement to an image of absolute pixel address (the yellow, red and green 'UV' image) and subtracting the undistorted version from the distorted version to get an image of relative displacements.

See Digital Heat Ripple to learn all about how the Photoshop displacement filter works.

UPDATE 5/12/2009

Here is a color version: a CMYK color halftone without using CMYK inks

Half brick offset mosaic. One level is offset, then mosaiced, then re-offset.

Full brick offset mosaic. One level is offset, then mosaiced, then re-offset.

I may do more elaborate work by uv mapping and warping reversible Maya meshes.

UPDATE 6/22/2009

More on Hexagonal / Triangular Grid Mosaics in Photoshop

I noticed that every time you apply certain filters to an image they run differently each time. I thought it might be fun to check out the image stacking in Photoshop's new 'extended' versions.

I chose coarse settings for the pixelate > crystallize filter - course enough to disguise the photo. Below is a stack of 8 such images averaged together. The more you use, the less the filter disguises the original.

Here is a (tedious) method for stacking images without the extended version of Photoshop

High ISO Noise Reduction by Image Averaging

UPDATE
I was playing around with this. For image averaging you don't actually need Photoshop Extended. You can do it in any version of Photoshop that supports 32-bits:

Stack the images in layers. Use the LINEAR DODGE (ADD) blend mode to sum all the layers. You will blow out the image way past white. No worries. Kick into 32-bit mode and dim the sum (no pun intended :D ) back into a usable range. For a true average, dim it by a factor of (1 / N layers)

(click on image to take a close look)

The obvious method: combine a blurry and sharp version of the same image using a layer mask. In most cases this is good enough, but look how the blur behaves through the transition.

(click on image to take a close look)

Blur through a selected alpha channel instead and the blur radius actually grows in proportion with the brightness of the alpha channel. Nice.

This 'ramping up the parameters' behavior is true in other Photoshop filters, as well.

UPDATE

Actually, Photoshop seems to be inconsistent on this issue.

Some filters, like Ocean Ripple, do not ramp up, while others, like Ripple, do ramp up their strength based on alpha.

What a mess.

An AND gate can be replaced by an OR gate with both inverted inputs and outputs. Correspondingly, the OR gate can be replaced with an AND gate with both inverted inputs and outputs.

To test De Morgan's transformation, and check out this nice Boolean logic gate applet.

In Photoshop, a MULTIPLY blend mode is equivalent to an AND logic gate. When two images are multiplied, both have to be bright to produce a bright result. If either one is dark, the result will be dark.

A SCREEN blend mode can be replicated exactly by inverting two layers, multiplying them, and inverting the result. De Morgan's rules. This means that if a MULTIPLY blend mode is analogous to an AND Boolean logic gate then a SCREEN blend mode must be an OR gate. And sure enough, it is analagous to one. In a SCREEN blend, if either layer is bright (or if both are bright) then the result will be bright. Since SCREEN mode is derived from MULTIPLY mode using essentially De Morgan's rule, it would seem that SCREEN is a 'better' description of an OR gate than Linear Dodge (Add) is.

It also turns out that the transformation between MULTIPLY and SCREEN works the other way, as well. A MULTIPLY blend mode can be created by SCREENING two negatives and inverting the reult, also as predicted by De Morgan.

DIFFERENCE blend mode acts like an EXCLUSIVE OR (XOR) gate. If either layer is bright the results will be bright. If both layers are bright the results will be dark.

UPDATE 5/4/2009

Josh Tynjala has a really great Flash-based logic gate circuit simulator.

This effect may remind you of Quicktime VR, or the Black Eyed Peas video for 'Lets Get it Started' (which makes me think Google Street View: The Movie)

I've written about this before, but never made a video, or gathered everything into one place.

More after the jump...

Here is a grayscale fractal Mandelbrot set image generated by Alex Calothis (he offers his generator for download)

Mandelbrot sets are graphs that describe the rate of a certain behavior of points in the complex plane. Colors are assigned to them arbitrarily.

One common method over the years for assigning color to Mandelbrot sets resembles the functionality of the Photoshop gradient map.

Above is what happens if you use a Photshop gradient map to colorize a grayscale Mandelbrot set fractal.

UPDATE 4/27/2009

In a way, everything gets 'gradient mapped' by our brains, since nothing is actually 'colored.' Things just reflect (combinations of) wavelengths on a scale from lower to higher.

Multiply by pure black and you will turn your image black. Screen with pure white and you will turn your image white. Obviously.

Soft Light by 100% black and 100% white and this is as far up or down asyou can push the image.

It looks a lot like what happens when you multiply the layer by itself (square it) or screen it over itself (kinda sorta like square-rooting it). I know the math is not the same between Soft Light and gamma correcting by 2 or (1/2) - but it looks pretty similar, don't you think?

At the moment, this is how I picture Soft Light acting when I want an approximate mental image.

Here is Overlay by 100% black and 100% white. This is as far as the Overlay blend mode can push an image.

It looks an awful lot like a self-multiply or a self-screen 3 layers deep. I know a gamma correction of 3 or (1/3) is not the mathematical definition of the Overlay blend mode, but it sure seems to approximate the look, no?

At least this experiment works at the black and white extremes. I haven't done enough testing to see if it falls apart significantly when the value of the channel being screened is a gray well between 0% and 100%

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A growing Blend Mode Killer App list is here.

The math, along with some pretty good interpretations of the math is here.

I noticed some interesting color at the edges of the type in this shallow focus photograph. I tried digitally blurring the sharp type using Photoshop lens blur and found (no surprise) that there was no such burst of saturation the the soft transitions at the edges of the letters.

Something to keep in mind when trying to use digital lens blur as a stand-in for real lens blur.

UPDATE 6/14/2009


click for larger view

Gaussian blur makes a poor substitute for lens blur.

via How a Lens Works

Real vignette caused by a camera on the left. A fake digital vignette using a simple 'multiply by gray' recipe on the right. Note the bland color in the corners on the right.

You can, of course, mimic a real photographic vignette more effectively - but you have do more than simply drop the luminosity at the corners.

surfBoards, originally uploaded by jfrancis.

I've been going through old hard drives and uploading to this Flickr set anything that seems worthwhile.



"You never know what you gonna get..."

A brief demonstration of how I use the Photoshop pen tool. My main points are:

• Use as few points as possible. 2 points can make an S-curve
• Put the points out there. You can always move them
• Fit the curves later. Not as-you-go

I'm finding DAZ Studio 2.3 more useful to me than Poser was. For one thing, DAZ handles the 'background reference image plane' issue better than Poser does. For another, the one character provided, Victoria, can assume all kinds of shapes - even male - with more variety and control than Poser provides. I understand there is a way to get a rigged Victoria from DAZ into Poser but I couldn't easily figure it out.

Anyhoo. To match AZ and Maya cameras and scales:..

click image to enlarge

Scale is easy. The native DAZ unit is the centimeter. Note in the image above that to make two 1-cm cubes kiss face-to-face I had to move one of them 1.00 DAZ slider units.

The translation sliders read out in centimeters. So import your .obj files into DAZ using the Maya option, or any other option that sets the scale to 100% (no change)

click image to enlarge

As with Poser, the DAZ Studio camera has an (undocumented) horizontal film aperture of 1 inch. I chose a 15mm lens crazy-close for this test, so if I were wrong, it would have shown immediately.

So all of that talk about film formats within DAZ is really just a fancy way of describing nothing more than aspect ratios. They seem to put no effort into matching those film formats to their actual film format sizes - a key ingredient in calculating accurate angles of view. Most users likely have no basis for comparison and so don't notice the difference.

click image to enlarge

In summation - to match Maya and DAZ Studio:

• Work in centimeters in DAZ Studio
• Set your Maya horizontal film aperture to 1.0

To match Poser to Maya, set Maya's film back to 1 inch and work in PNU's in Poser

I picked up the April, 2009 issue of Spin Magazine to pass the time on my flight back from Easter with the family. On page 37 I got a bit of a surprise: a campaign for the 60th anniversary of Onitsuka Tiger designed by Amsterdam Worldwide featuring a visually ambiguous model of a sneaker-slash-island (the island being Japan)

The image caught my eye because I'm currently working on an ambiguous island model of my own, only mine will have a tropical 'tiki' motif, complete with a volcano and small trees rendered in Maxwell. (don't go too much by the illustration above - it's for position only, at the moment)

One thing I noticed was the decision in the sneaker print ad to frame so loosely as to reveal the edges of the painted sky backdrop. The other thing that really stood out to me was the subtle, but visible electrical cord in the ad. The volcano in my image will be internally lit and I also plan to incorporate a visible (CG) electrical cord into the composition.

In the same way that I hung my Tiki Moon on unnecessary 'wires,' or built my CG hot rod flames within the limitations of 4' x 8' sheets of virtual plywood, I like to add these misleading cues to my computer graphics.

"My philosophy is to use 3D CG to 'fly under the audience's VFX radar.' No matter how well you render a robot, the viewer will evaluate the work as VFX. If you render a painted wooden wall and some throwing knives, hopefully the viewer will evaluate the work as an image -- one with nice production value and a healthy budget for props and styling, but an image nonetheless."
-- A quote from my cgsociety.org gallery

More on multi-plane theatrical backdrops and photography.

More un CG celestial bodies on unnecessary wires: Paper Moon (game)

I had originally assumed a Fresnel lens would be too hard to make work, but I decided to give it a shot, anyway. I grabbed a cross section from wikipedia and made a surface of revolution from it.

It functioned quite similarly to the plano-convex lens - exactly as advertised.

I nudged the light source closer and farther until the beam looked fairly parallel. No calculations involved.

Here is the Maya / Maxwell file

FresnelLens_test.mb

UPDATE 1/8/2010

Here is the lens in .obj format

FresnelLens-OBJ.obj

I had planed to model a Fresnel lens, and while searching for a good cross-section technical drawing of one I came across some interesting work from Adam Donovan from 2007 that is in many ways similar to explorations I'm making now.

I'm mainly interested in creating light modifiers for use in a Maxwell environment, so it doesn't matter to me what the lens looks like, only what kind of beam it throws.

The main advantage of a Fresnel lens is that it is thin and lightweight compared to a bulky, heavy plano-convex lens of equivalent power. [glass Nd = 1.51]

In CG I don't care about bulkiness or weight, so I opted to dispense with the Fresnel lens and use its plano-convex equivalent.

I used a portion of a sphere for a lens, and found the focal point by trial and error. A sphere doesn't have perfect focus, but a little spherical aberration is acceptable to me in a light source.

UPDATE

Changed my mind. I simulated a Fresnel lens after all.

When you use them as displacement maps (I used Mental Ray) you can really see the difference between 8- and 16-bit images. The 16-bit displacement maps creates a smooth surface. The 8-bit displacement map gives rise to lego-like terrace artifacts in the surface.

A lot of people say, 'I get it right in camera, so I don't need to push the images very far. Originating in 8 bits is fine for me.'

But what if you change your mind later and you need to create a key from a flesh colored arm against a not too different background. I think in that case you'll be glad to have the extra bits in between when you push one of those regions black and the other white.

(click for a closer look - note the artifacts)

(click for a closer look - smooth)

A parabolic reflector carefully modeled with a Maxwell Render emitter placed at the calculated focus point of the parabolic reflector. As expected, a strong beam of light emerges.

In this HD youtube video I use Photoshop's 'Blend if...' function to create split tones and rich-looking sepia photographs.

You could use the same technique to de-noise an image just in the shadow areas of a photograph all under interactive preview control.

UPDATE 4/20/2009

Read the comment below, then click me

UPDATE 7/1/2009

I put this blog entry together mainly to look at the blend-if sliders - not so much to make sepia images, per se. However...

I was looking at these images tonight

The Humphrey Winterton Collection of East AfricanPhotographs 1860-1960

and thought I'd put something quick together to mimic their antique sepia photography appearance using a gradient map.

UPDATE 1/29/2010

People often ask what the difference is between a silver and a white beauty dish. I have heard it said that beauty dishes are designed to be white, and that silver beauty dishes are a marketing department afterthought. Others say that silver dishes are more contrasty, and have more 'snap,' and so have their place in the photographer's studio.

The Maxwell Renderer is quite accurate at simulating the behavior of light. I thought it might be instructive to use the Maxwell Renderer to investigate the differences between a highly polished near perfect mirror-coated beauty dish (which as far as I know does not exist in the market), a typical silver beauty dish, and a white one.

To reveal the light paths, I ran a wall right through the center of the dishes, bisecting them in half like wall sconces. The virtual beauty dishes are ellipsoids - squashed hemispheres. They are not scientifically designed. The light is placed within the dish by eye, not at any special focal point, and no particular brand of beauty dish is being emulated here.

Remember: these are virtual tests. Not real ones. You may, nonetheless find them worthwhile to see.

click thumbnail above to enlarge

click thumbnail above to enlarge

click thumbnail above to enlarge

UPDATE 9/30/2009

Walter Melrose with mola-light.com on Silver Beauty Dishes

"A silver surface is much cooler in colour temperature and tends to add a cyan cast....The silver surface does not allow the light to follow the contours of the reflector as they were intended. Although the silver surface gives the impression of greater output it does not apply to function, our white surface is 90% reflectance and very efficient."

I remember this quote from the primary source, the Mola site, but right now I can only find secondary references to it on flickr and photo.net

Watch in Hi-Def at youtube

Folders are not just a place to stash messy piles of layers. Folders also help Photoshop users organize layer composites a bit more like what is possible in programs like Shake.

Watch it in Hi-Def on youtube

Watch it in widescreen HD at youtube.

This is a 16-bit Photoshop environment. Because I am summing two relatively bright layers, I have overexposed and clipped the photograph.

Once the values go over 65536 (256 in 8-bits), they are lost, and dimming them later cannot recover them.

If I drastically overexpose in a 32-bit composite, as I have above, I still seem to clip above white.

But I can still recover the 'lost' information.

Photoshop's 32-bit environment is different from its 16- and 8-bit versions. In 32-bits there are not simply more divisions between black and white, there are values far outside those limits.

I'm not sure why Photoshop doesn't do all its math at 32-bits internally and then just cast to 16- or 8-bits at output. I'd use the 32 bit environment more often, but for some reason not everything works in 32 bits.

UPDATE 5/11/2009

I was inspired by all of the previous posts to take a shot at simulating the Technicolor 2-Strip Process in Photoshop.

There was actually no such thing as a 'Technicolor 2-Strip Process.' The Technicolor two-component system used a single roll of black & white negative film that alternately recorded both the red and green color records. Multiple films were not used until the introduction of three-strip Technicolor in 1932.

There is a fair amount of discussion on the internet in one forum or another about how to do this, ever since it was done for The Aviator.

What follows is not as involved as one of the somewhat more complex implementations described elsewhere, but I put this together as an experiment.

The basic idea:

A) Multiply the Red Sep by RED

B) Make a group; set the group blend mode to Normal, not Pass Through (important) - In the group, screen the Green and Blue Seps together and multiply them by CYAN.

C) Add the results of (A) and (B) using LINEAR DODGE (or Screen, if you like. Same result in this particular case)

------------------
UPDATE:

I took another look at the process. I felt the skin tones were taking to great a loss in saturation, and the whole image was being dominated by the cyan contribution.

Instead of adding red to a cyan-tinted 'sum' of green and blue, I'm adding red to a cyan-tinted 'average' of green and blue.

------------------
UPDATE:

This is a work in progress. I re-jiggered the file one more time, replacing the 'sum of half red and half green' with the essentially equivalent 'half of the sum of the two' a/k/a the average of the two. To avoid clipping in the sum, I went to 32 bits. I like the exposure adjustment layer. I think the exposure plus the gamma provides nice control over the look.

If you'd like a more detailed explanation on why I thought 32 bits was necessary, check the next entry.

------------------
UPDATE:

In future I'll probably derive the channels by adding the channel mixer into the workflow instead of manually loading the channels as selections and pasting white through them onto black layers.

------------------
UPDATE 5/22/2009

I got some promising results using the black and white adjustment layer to build color images.

click image for a closer look

2-Strip-R-C.psd

2-Strip-R-C_2.psd

Here is the Photoshop file based on R G and B solid color filters and 3 B;ack and White Adjustment layers (pictured above)

2-Strip-R-C_4.psd

UPDATE 6/26/2009 (based on comment below)

Two Strip Technicolor (Subtractive Method)

Red record dyed cyan and combined 'subtractively' (muliplicatively) with a strict cyan record stained red. By 'strict' cyan I mean I used a black and white adjustment layer set to accept cyan, but reject green and blue.

Two Strip Technicolor (Subtractive Method)

Red record dyed cyan and combined 'subtractively' (muliplicatively) with a more 'permissive' cyan record stained red. By 'permissive' cyan I mean I used a black and white adjustment layer set to accept cyan, and green and blue in equal amounts.

UPDATE 6/30/2009

click photo to enlarge

This (what if) experiment in yellow-blue 2-strip technicolor made me think this was an error: The coral cake frosting rose is getting turned yellow, instead of surviving the yellow filter with much of its coral still intact (red should survive a yellow filter). This is because everything is getting turned gray before being filtered yellow. Interesting, but is it a mistake? Maybe not. These separations did get recorded to black and white film first. I wish I could see more examples of the real deal instead of digital recreations.

UPDATE 11/9/2009

Color Film of London in 1927

You can really see the effect of two colors on one strip in action here. Fast moving objects color fringe. Darks decompose into cyans and reds. Where the two overlap (are multiplied - if digital) darkness results in the positive image.

In 2006, the BBC ran a series of programmes called The Lost World of Friese-Greene. The series, presented by Dan Cruickshank included The Open Road Claude Friese-Greene's film of his 1920s road trip from Land's End to John o' Groats. The Open Road was filmed using the Biocolour process, and the British Film Institute had to use computer enhancement of the original print of the film to remove the flickering problem.

- wikipedia

I jumped briefly into CMYK to grab copies of the C, M, Y and K channels, before returning to RGB.

I created 4 'solid color' adjustment layers, one each for CMY and K.

I masked each layer with the negative of its alpha channel *

I multiplied them all together.

The layered .psd is here, if you'd like a closer look.

SubtractiveColor_3.psd

* To mask a layer with an alpha: go to the alpha channel you want. Click on it while pressing the 'control' key on a PC. That should load the alpha channel as a selection. Now with the selection still loaded, ask for a layer mask on the layer you wish to mask. It will materialize with the selection already punched into it. Finally, hit control-i on a PC to invert the layer mask, which is a necessary step in following along above.

So 'subtractive color' might be better called 'multiplicative color.'

If the color match in this example isn't perfect, I plead RGB <-> CMYK gamut and Photoshop color management and colorspace issues.

UPDATE 6/2/2009

According to Getting It Right in Print by Mark Gattner, the K in CMYK was not chosen because it disambiguates from the B in Blue. The K in CMYK stands for 'key,' as in 'key plate,' the plate (often with the text) to which the other colors are registered.

UPDATE 6/15/2009

An in depth look at the linear equations and non-linear lookup tables that more closely approximate the RGB to CMY conversion can be found in Digital Color Halftoning by Henry R. Kang

I've derived theoretical C, M and Y plates from the RGB channels in the previous entry on Additive Color Mixing.

To achieve the cyan plate, I took the red channel, negated it, multiplied it by full (255 0 0), then inverted (color negated) the result. I did the analogous steps with the green and blue channels to derive theoretical magenta and yellow color plates.

The blend mode between each derived color plate is MULTIPLY.

The layered .psd file is here if you'd like a closer look.

SubtractiveColor_1.psd

Now lets simplify the Photoshop file. I merge the layers in sets of 3 starting from the top so that we can get a plain look at these theoretical CMY plates.

Cyan, Magenta and Yellow color ink plates on white paper - with a multiply blend mode between each.

Here is the layered .psd file if you'd like a closer look.

SubtractiveColor_2.psd

So what is with this 'theoretical' word, anyway? And why only CMY? Where is the K?

Good questions. I'll try Photoshop-produced CMYK plates next...

UPDATE 6/1/2009

Actually CMY is not just theoretical, now that I think about it. Color motion picture film is 'subtractive' CMY - no K. So this mimics the behavior of color motion picture film.

Here is another variation on the Photoshop file.

Subtractive-Color.psd

By replacing the C, M, or Y 'emulsions' with faded, dirty, warped, misaligned or scratched versions I could mimic an aging film effect fairly well.

UPDATE 6/4/2009

A good description of the process of colorizing and assembling three black and white color separations. [pdf] I think today's Photoshop may automate the registration/alignment process better now.

Digital Tri-Color Photography

UPDATE 6/15/2009

An in depth look at the linear equations and non-linear lookup tables that more closely approximate the RGB to CMY conversion can be found in Digital Color Halftoning by Henry R. Kang

Here is an RGB image. RGB is additive color. Can you guess how to mix the RGB color separations to produce the image?

You add the three color separations together. In Photoshop, the blend mode for adding is LINEAR DODGE.

(You can also use SCREEN in this case, since the R, G and B channels are completely independent of each other, SCREEN and LINEAR DODGE produce identical results)

The layered .psd file is here if you want a look.

Next up: (so-called) subtractive color mixing. Can you guess which blend mode combines CMYK color separations?

Above images from tutorial Lenses and perspective, or distortion on a face for beauty are copyright Steven Eastwood

Inspired by an online conversation I had with photographer Steven Eastwood, I just wanted to record here a few remarks I had made on the nature of the '5-eye line.'

You can really see the 5-eye-line in the beauty shot above that was taken from a distance with a long lens. The sides of the model's head are evident.

In the wide-angle closup shot, the '5-eye line' is almost a '3-eye line,' and the side planes of the model's head are no longer visible.

A Nikon D200 uses a standard DX size sensor. (23.6 x 15.8 mm)

Maya's 'film' is described by two measurement: Horizontal Film Aperture and Vertical Film Aperture

According to Nikon's online documentation:

Horizontal Film Aperture and Vertical Film Aperture are the height and width of the camera's aperture or film back, measured in inches. The Camera Aperture attribute determines the relationship between the Focal Length attribute and the Angle of View attribute. The default values are 1.417 and 0.945.

---

Now, why Maya uses the word 'aperture' to describe this should have been my first clue that something was wrong, but I always assumed that Maya's default camera mimicked 4-perf movie film, just like most people shoot and project. It would have been the obvious thing for them to have done.

Turns out I was wrong.

All these years Maya masked its values by expressing them in inches, and all these years I never bothered to check the math, but it turns out that Maya's default width, the mysterious 1.417 works out to be 36mm.

All these years Maya has been modeling an 8-perf camera as its default. As if it were a 'full frame' still camera like a Nikon D700 or a Canon 5D Mark 2

...or as if it were Vistavision.

So to match a horizontal D200 to a Maya camera, set the

Horizontal Film Aperture = 0.929133858, which is 23.6 mm in inches

Vertical Film Aperture = 0.622047244, which is 15.8 mm in inches

Then your Nikon D200 lens should match your Maya lens.

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A 'full frame' Nikon D700 has a chip size of 36 mm x 23.9 mm.

At 1.417" x 0.945" Maya's default camera back equates to 36 mm x 24 mm. So Maya default cameras equate directly to Nikon D700 lenses.

I used the pen tool for most of the edges, but I couldn't capture the hair with either the pen or channel masks, so I made my own edge by stroking pen paths with a single pixel brush.

I cloned some of the artificial hairs around to get sufficient quantity.

Locking transparency, I even cloned in existing hair color and sheen, and modified the hair style a little bit.

Apnea poses as The Knife-thrower's Assistant. Part of my Nothing is Real but the Girl series of high production value images.

Apnea of Apneatic.com wears fake fur under an incandescent spot light.

Liz Ashley

Kumi poses with a Japanese Shamisen

An experiment in overexposure. The incomparable Liz Ashley in yellow vinyl back lit by a large frosted glass door.

The beautiful Apnea of Apneatic.com

10 degree grid and warm light on face. 20 degree grid and cold light on face and torso. Where they combine the light is relatively neutral. The falloff is cold.

On the left I placed a stobe at a high angle, fitted it with a 20 degree honeycomb grid from White Lightning, and aimed it at the face of my mannequin. As one would expect, a pool of light surrounds the face.

Next I tried feathering the light. I aimed the high angle 20 degree gridded strobe at the mannequin's chest. The result? Even illumination down the body.

Why?

The face receives dim edge light but is also closer to the source.

Courtney Cruz in the Mojave Desert under the shade of a red lace parasol.

Internationally famous latex fetish model Kumi Monster on a dry lake bed in the Mojave Desert.

I bounced light off a cinder block wall to make this portrait of Marissa Spokes. A white bounce card behind her provided some fill.

A portrait of Scar 13 [18+ NSFW]. Makeup by Chelsea Wildeye.

Internationally famous fetish model Kumi Monster unmasked. Fresnel hot lights. Nikon D200.

Jasmine Worth whispers to Natalie Addams by window light. Nikon D200.

I was playing with my Vagabond portable power supply in an alley.

A cinder block wall makes a nice large softbox.

UPDATE 2/10/2010

Same alley a few years later.

model: Kelly Polk

makeup test for piece based on the film Santa Sangre (1989)

Scar arises. Latex by Syren.

Kumi Monster at repose in the darkness. Latex by Syren.

Courtney Cruz captures Jasmine Worth

Scar of [NSFW 18+] Scar13.com under fresnel hotlights.

A photo I took of [18+ NSFW]Scar. Rocket Pack constructed for me by Mark Poutenis. Door panels by BJ Winslow of Dapper Cadaver. Photo by Joseph Francis.

Portrait of Jacqueline in evening gown. DeSisti lamps. Nikon D200. Hair and Makeup by Rocio Gonzalez and Ping Tan "Icey"

My first stab at using Fresnel hot lights.

I had this idea that cake frosting might make a novel model makeup effect. Model Amber Kendrella. Makeup by Geeta Dastyar. Frosting by Jennifer Orr. Mola beauty dish. Nikon D-200

Here are some more photos from the Cake Frosting Model Makeup shoot

http://img.photobucket.com/albums/v228/jfrancis/Amber/Amber_3177_c_600.jpg

http://img.photobucket.com/albums/v228/jfrancis/Betcee/Betcee_3124_600.jpg

http://img.photobucket.com/albums/v228/jfrancis/Betcee/Betcee_3127_600.jpg

http://img.photobucket.com/albums/v228/jfrancis/frosting/frosting_3242_600.jpg

http://img.photobucket.com/albums/v228/jfrancis/frosting/frosting_3288_600.jpg

As indicated by the meter. Lumisphere ball out on an overcast late afternoon.

1/3 stop brighter.

2/3 stop brighter.

1 full stop brighter.

It looks like a half stop at most is the adjustment in this test.

I've been using my Sekonic L-558R to set the exposure for my Nikon D200. So far I seem to be habitually underexposing the images more than I'd like. Above is a Gretagmacbeth grayscale card exposed as indicated by my meter in incident mode. I have included histograms in the images.

The same scene with the camera opened up 1/3 of an f-stop.

2/3 of an f-stop brighter.

At a full f-stop brighter the white on the card, which is supposed to be at something under 94% reflective, is off the histogram.

A portrait of Layla Jade with my new White Lightning beauty dish.

Another take from the set.

In preparation for some upcoming projects of mine involving photography and the Maxwell Renderer, I thought I'd try a visit to a photo shoot.

This was a group shoot, and I wasn't in control of either the lighting or the model direction, but I did gain some experience in exposing using photographers strobes.

The shoot itself presented certain challenges. The models were good at posing and mainly self directed, which placed the photographers more in the position of paparazzi, all competing to get a shot. It seemed to me that every time a model would strike a good pose, another photographer would either rise into my frame or beat me in sending his wireless radio signal from his camera to the strobe, causing me (since the light takes a moment to refresh) to miss the flash.

Not having ever worked with one before, I was concerned at first about how to best meter and expose for the strobe, but I soon figured out that the light wasn't going anywhere, and neither, for the most part, was the model, so the lighting conditions were fairly constant. Since we were shooting digital, I could just manually set the camera shutter speed to no higher than 1/250 - the synch speed of the Nikon D200, and just take a guess at the aperture. After a test shot or two, the lcd screen and histogram told me enough to make the necessary aperture adjustments.

Is that really all there is to it? Sure seemed that way.

UPDATE 8/3/2009

For quite a while Googling 'Model Photography' would return this image as the number one hit, which I got a kick out of. I checked today. It's no longer true; something changed in Google Images. Oh well.

The reason I even checked is I'm updating this image as part of my Nothing is Real but the Girl Series.
---
UPDATE 8/28/2009

I'm Hint. More to come...

After testing my Nikkor 85mm f/1.4 through Boujou 3 and getting a lens solve of around 50mm, I decided to test an actual 50mm lens.

I mounted a Nikkor 50mm f/1.8 lens on my Nikon D200 and moved it forward step by step toward a white board on which I had marked a few tracking crosshairs in erasable ink.

]

Boujou 3 appeared to perform well, reporting a point cloud revealing a push-in across a flat, vertical wall-like surface.

Maya 7 reported a camera focal length of a bit under the 50mm lens I had in fact used. Normally I'd be pleased at such a seemingly accurate answer, but I'm not quite sure how to interpret this data.

The problem is my Nikkor 85mm f/1.4 also solved out at around 50mm.

Further testing with other lenses is warranted.

I shot a few frames with my Nikon D200 using my new Nikkor 85mm f/1.4 AF-D lens and ran the images through Boujou 3 to see how it and Maya would see the lens.

I told Boujou that the lens focal length was 85mm, and that the film back was 23.6mm x 15.8mm which is, as far as I could research, the active area of the Nikon D200 APS-C chip.

The free move yielded a nice, well-defined point cloud -- you can easily see the curved chair back and flat wall beyond -- so I expected a lens solve close to 85mm.

Instead of an result close to 85mm, what I got from Boujou was a virtual lens with a focal length just under 50mm.

Maybe long lenses don't produce enough parallax for a closer solve.

Maybe more extensive testing on a longer sequence is required.

Since I intend to combine my Nikon D200 photography with rendered backgrounds from Maya and Maxwell, I'd like to get a good handle on how to best match lenses.

I plan to make some dramatically-lit photos (combined with Maxwell renders). As a prelude to this work, I an experimenting with some issues related to photographic exposure. My goal in this experiment is to create the illusion of a spotlight illuminating a figure on an otherwise dark stage without actually having a particularly dark stage. It's nothing new, but I want to try it myself.

The photograph above represents a human figure on a stage under subdued window lighting.

Here's the same set, but now I'm "whacking" the figure with an overpowered key light. This adds even more light to the set.

When I expose for the new bright key light, it's as if I've effectively "darkened the room."

By going from a one second exposure to a 1/250th second exposure (for a given aperture) I have darkened the scene by 8 f-stops. I even seem to have reversed the lighting; the window light is no longer apparent at all. What's more, I can have the depth of field and short shutter speeds not normally associated with low light photography - if I choose.

Photograph doesn't always have to "mimic" how you perceive the scene to be. I remember one day I visited a taping of The David Letterman Show. I was struck by how pale, washed out and desaturated the set and everyone on it looked in person, and how richly contrasty and lustrously saturated it looked on the monitors.

If you have a program like Photoshop, there is little difference, and little point in limiting yourself by using the in-camera black and white setting, unless you find it a convenience.

Original color image.

Original black and white image.

Black and White image derived from color in Photoshop using Image > Mode > Grayscale.

For sophisticated control in Photoshop over black and white images you are best served by shooting in color and using the new channel mixer.

UPDATE 5/14/2009

Better yet is the new Black & White adjustment layer. And for quality black and white conversions, the last thing you should use is Desaturate or the Hue / Saturation slider

UPDATE 5/24/2009
Don't miss this new less tedious method for Image Stacking / Averaging in 32 bits.
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If you are photographing a stationary subject with a stationary camera you can reduce grain or high ISO noise by averaging together multiple seemingly identical images.

I set up a still life under relatively low light conditions and photographed it eight times in a row at 1600 ISO with a Nikon D200 mounted on a tripod.

Here is a 100% crop of the 1600 ISO image. It's noisier than I'd like it to be.

I have now taken all 8 images and stacked them up in Photoshop CS2 in layers 0 through 7. Let's see what happens when we average them together.

First I set the opacity of layers 7, 5, 3, and 1 to 50% Next I merge them down in pairs -- 7 to 6, 5 to 4, 3 to 2, and 1 to 0. I now have 4 layers in a stack labelled 6, 4, 2, and 0

Here's what a pair of layers looks like when averaged together. You can already see a noise reduction.

Let's continue, repeating the process.

I'm now setting layers 6 and 2 to 50% and merging down in pairs -- 6 to 4, and 2 to 0. I now have 2 layers in a stack labelled 4 and 0.

Let's repeat the process one final time.

I set layer 4 to 50% and merge it down onto 0.

Look above. Look below. You can really see a difference.

Here's the original noise again -- just for comparison.

You can do grain reduction through image averaging on moving footage as well, just as long as the subject and camera are still. That may not sound useful, but the technique does have its place:

I had occasion to use this technique in the feature film Independence Day. There's a shot of The Empire State Building down at the end of an avenue waiting to explode. The model miniature footage was excessively grainy. I had the compositor replace every frame of the footage with a running average of the previous 20 frames. It made for a great grain removal technique. Once the model exploded, we returned to the grainy element, but it was so mixed with fire and flying debris that the grain wasn't objectionable.

Fun Idea

If you can steady the frames properly, you can use image averaging to get a better look at that flying saucer footage, or you can demosaic the identity- or nudity-obscuring blocky pixel mosaics sometimes placed on running video. The trick is to be able to get the frames to stack up in perfect register, which may not always be possible.

Additional Links

Image Stacker

Reindeer graphics Image Averaging

UPDATE 5/8/2009

It occurred to me here [Image Stack Fun - Photoshop Extended] that if you have 32-bit Photoshop you can average a stack of layers in a less tedious way without even needing Photoshop Extended. Sum all the layers using the LINEAR DODGE (ADD) blend mode, then dip into 32-bit mode and curve or exposure them back down out of the stacked, white hot 'blowout' look into something reasonable.

I'm curious to see what kind of dynamic range my new Nikon D200 has. As an experiment, I'm taking a series of exposures of a stucco wall as described in Ansel Adams's book, The Negative

The purpose of the exposure series is to place the stucco wall on various zones from Zone 0 to Zone X in order to see how the camera responds. Each "zone" represents one f-stop more or less exposure. Zone V is, by convention, the middle of the scale. It represents an 18% reflective gray card.

The basic idea of the Zone System can be stated as follows:

See something you wish to photograph. Pick a region in that scene. Meter it. the meter (by design) will tell you how to make that region fall in Zone V (middle gray). Decide for yourself onto which zone you would like that region to fall. Adjust your camera accordingly (ISO, shutter speed, aperture, or a combination of the three) so as to place the metered region onto the desired exposure zone. The other regions in the image will fall onto higher or lower zones accordingly, preserving their relative relationship to the metered area (unless you alter contrast in the developing process, in the case of film, or in the computer, in the case of digital photography).

My Results

I photographed a pinkish stucco wall in the shade of a building, taking care to place it on various zones. All photos were taken with a Nikkor 50mm 1.8 lens and a Nikon D200 in aperture priority mode. I set the aperture to f/11 and used exposure compensation to ramp the shutter speed up and down on one stop intervals.

The text that follows is what Ansel Adams expects in each zone. The photos are what I actually got. The images were shot in raw format and converted to jpeg using Photoshop CS2 set to a high (60%) -- but not very high -- quality setting.

Zone 0 - total black in print. My own Zone 0 test resulted in virtually total black. I'm not bothering to post it.

Zone I - effective threshold. Slight tonality. No visible texture - although in my test I do see texture, which tells me that on my Nikon D200, Zone I could be used as a dark Zone II -- a place to put subtle, dark, yet still somewhat discernable shadow detail.

Zone II - first suggestion of texture.

Zone III - average dark materials showing adequate texture.

Zone IV - average dark foliage or stone. Normal shadow value for caucasian skin in sunlight.

Zone V - middle 18% gray. Clear northern sky, dark skin, gray stone, weathered wood.

Zone VI - average caucasian skin in sunlight. Shadows on snow in sunny landscapes. Light stone.

Zone VII - very light skin. Light gray objects. Snow in acute sidelighting.

Zone VIII - whites with texture and delicate values. textured snow. Highlights on caucasian skin. If I wish to expose for highlights and still preserve some detail in them, then it would appear I can place them as high as Zone VIII, possibly as high as EV +3.0, but not much higher -- depending on the local range within the highlights.

Zone IX - white without texture approaching pure white.

Zone X - pure white -- as was my image. I didn't bother to upload it.

Conclusion

My results agree closely with Ansel Adam's expectations, with the exception that i got a little more texture than I expected in Zone I.

I'm pleased with the performance of the camera.

Some Nikonian Forum Interaction

D200 Dynamic Range Test per Ansel Adams

Exposing To The Left and Ansel Adams's Zones

The Zone System as it relates not to Photography, but to Painting

I see a natural crossover between the ideas of the Zone System and the approach master painter Craig Mullins uses in his approach to painting. He reveals his thought process on this forum (under the name spooge demon)

I excerpt his comments below:

"Decide what is in light and what is in shadow and don’t mix them up. Think like a comic artist. Two values, but if they are well thought out and designed and drawn they can look totally real. Think like that, but instead of making the light white and the shadow black, make the light a 7 and the shadow a 3. Then go ahead and use 5-10 in the light and 1-3 in the shadow to pull out sub forms. DO NOT use 1-5 in any part of the light, or use 5-10 in any areas of the dark. Keep you edges a little softer in the shadows, a little sharper in the light, you are done. (0 is black, 10 is white) Deciding what is in shadow and light for a particular object is pretty hard in words. I will leave that up to you and that is 99 percent of the struggle."

I'm concerned about this Nikon D200 banding artifact many (including me) are seeing. Some attribute this problem to blooming. It's not, as far as I can see, typical blooming. Many have taken to calling it banding, even though banding normally refers to posterization due to insufficient color bit depth. Silkypix calls it geometric noise, and provides a geometric noise NR utility.

There are discussions about the issue in several prominent places:

Nikonians.org - D200 and banding

Nikonians.org - D200 Banding II

Nikonians.org - D200 Banding III

Fredmiranda.com - D200 banding is real

DPReview.com - D200 banding noise issues

"I've done testing to confirm whether the reported "vertical banding" issue is for real, and can confirm it exists under given circumstances, the description of which is in the forthcoming review. (Expected around January 10, 2006)" - Bjørn Rørslett

KenRockwell.com Nikon D200 Striping, Vertical Stripe, Banding and Corduroy Effect
(If my camera's banding were as rare as Ken Rockwell's I wouldn't have sent it in.)

On an encouraging note:

This person Chris Maytag had a camera which exhibited the vertical noise "banding" problem, and I don't think you can attribute this particular example of it to blooming or poor exposure on his part, as is often the case with other photos.

http://flickr.com/photos/spincycle/74270369/

In this thread he claims that replacing the camera seems to have alleviated the problem:

http://www.flickr.com/groups/d200/discuss/141067/

If my own operator error is causing my problems, I hope I soon learn to avoid them. If this is a hardware or firmware problem, I may need to get my camera repaired or replaced.

UPDATE 1/5/2006

I contacted Nikon and uploaded the full resolution original .nef of this image:
http://img.photobucket.com/albums/v228/jfrancis/D200Banding/D200Banding_X1.jpg

After examining the image they requested I send my camera in for servicing.

I had a Return Authorization Number and a shipping label from B&H camera, and I could have sent it back to them for a refund and walked away, but I chose to send it to Nikon instead.

Why?

1) I believe in the camera and in Nikon.

2) I want a D200 sooner than later, and they are hard to come by.

3) Any new camera I might find in the near future could have the same issue.

4) This camera will get Nikon personal attention.

Call me crazy for opting for servicing over a refund from the retailer, but that's what I'm doing.

I'm confident that this problem will be ironed out soon.

UPDATE 1/7/2006

An opinion is emerging on the internet that D200 banding artifacts generally only occur in badly exposed pictures, and are therefore of no concern to "good" photographers. Anyone who has ever made a Paul Debevec HDR radiance map for computer graphics purposes will, however, recognize that some intentionally "bad" photography is a necessary part of the process of creating High Dynamic Range images, and will want their D200 to be corduroy-free.

UPDATE 1/10/2006

My camera arrived at Nikon in El Segundo today for evaluation and possible service. I expect it back in around 7 - 10 days. If it is serviced, I'll shoot a setup like the one above again and see to what extent the problem is solved.

UPDATE 1/13/2006

Here are some additional threads of interest:

A Discussion of Possible Hardware Fixes

A Preview of Bjorn Rorslett's Evaluation

UPDATE 1/15/2006

Nikon D200 Digital Camera Reviewed by Bjørn Rørslett

A Photoshop CS2 Action Script designed by M. C. Schuster to fix banding

UPDATE 1/18/2006
Thu Jan 5: FedEx D200 to Nikon El Segundo
Fri Jan 6: D200 arrives per FedEx
Tue Jan 10: D200 logged in "officially" arrived per Nikon
Wed Jan 18: (ongoing) waiting for parts.

Service Repair Rank B2 - "If Parts are Available"
Repair Category B2 - "Moderate Repair. Major Parts Replaced"

Thu Jan 19: Status now described as "In Shop"
Fri Jan 20: Status updated to "Bill" - Order Confirmed

Mon Jan 23: Camera has arrived back home - will begin testing tomorrow.

Tue Jan 24: I reproduced the setup that caused banding so easily for me before - a chair in front of an open window - and I would have to say I now consider the banding fixed. I'll repeat this at the bottom of this posting, and I'll elaborate in another posting.

*This work is covered under warranty, however. The bill amount is $0.00

According to the notes I got back from Nikon, nothing seems to have been replaced. The service was described as "ADJ IMAGE CONTROL"

UPDATE 1/20/2006

One individual reports Banding NOT fixed by Nikon El Segundo ... this is troubling news to me.

Imaging Resource - Nikon D200 User Report - scroll down to the section marked Footnote: What Causes This? for some speculation.

UPDATE 1/22/2006
Someone has a Nikon D200 Banding Fixed experience.

A responding commentor has no such luck himself.

UPDATE Tue Jan 24

I reproduced the setup that caused banding so easily for me before - a chair in front of an open window - and I would have to say based on my initial tests I now consider the banding fixed.

I couldn't resist trying some additional tests. The camera now passes just about every test it would have failed before, with this one exception . . .

It is possible under extreme circumstances to induce what Bjørn Rørslett calls Type I Banding.

UPDATE 2/5/2006
Nick Karpowicz provides a Fourier Analysis Image Processing solution to Nikon D200 Banding implemented in MATLAB. I havn't look at this in any detail yet, and I don't have MATLAB software either, but it looks interesting.

UPDATE 2/10/2006
Nikon USA acknowledges and discusses banding according to this forum post.

I had a discussion with someone unrelated to Nikon who shared with me his personal beliefs on the matter:

1) Readout on the D200 chip are in pairs of lines. The chip is made by Sony with an RGBE (Red-Green-Blue-Emerald) Bayer pattern and thus does a 2-line at a time serpentine readout.

Thus lines 0 & 1 read out together, lines 2 & 3 read out together, etc.

2) Readout alternates between the top and the bottom of the chip: 0&1 go UP, 2&3 go DOWN, 4&5 go UP, 6&7 go DOWN, etc. This means that blooming will have a tearing (or as you've guys called it a "Corduroy") pattern on horizontal or near horizontal edges, both on the tops and on the bottoms of those edges.

3) Noise in CCD cameras is always higher on the side of the chip that has the longest readout. Since half of the lines are reading out in the upwards direction and half are reading out in the downwards direction, unless you're looking at the middle of the image, the background noise between pairs of lines will not match. This is even more evident at high ISO values where there is higher amplification on the background noise.

4) CCD logic does NOT have an A/D on chip. Instead the CCD is connected (via solders & wires or traces) to a more standard Flash A/D. If there is a bad connection (or even a marginal one) you can get induced noise. If that is worse in the UP direction than the DOWN direction, you could see this as a preferential noise problem. If one of those traces was acting like an unshielded antenna (which can also happen sometimes) you might see a frequency pattern that could be removed by an FFT.

UPDATE 2/14/2006
DigitalReview.ca Nikon D200 Digital SLR Banding Issue FAQ

According to the info at the link above, Nikon says current production models don't exhibit (type II & type III) "long banding." The article (and the FAQ from Nikon) doesn't mention (type I) "short banding."

UPDATE 2/16/2006
According to this post on dpreview, in Croatia (at least) the fix involves a hardware replacement as well as a recalibration.

UPDATE 2/19/2006: The Other Side of Banding

I thought I'd dig up one of the many test pictures I took with my faulty camera - prior to its repair - that were intended to provoke Nikon D200 banding but failed to do so.

I put these images here to show "the other side of banding," and to try and lend some perspective to the issue.

Yes, you could say that the camera's performance was uneven, in that it often did not band, and that it was hard to predict when it would and when it would not, but I wanted to show that even a faulty, "banding" camera performed extremely well most of the time.

3/21/2006

A pretty good final word on the banding matter in this Nikon D200 Review by Thom Hogan

Photoshop CS2 contains a versatile tool for correction certain problems caused by camera lenses. You can find it under Filters > Distort > Lens Correction.

One option for this tool brightens and darkens the corners of images in order to compensate for lens vignetting.

The nice thing about this tool is that it acts as if all images are actually square. The lens vignette tool is not fooled by widescreen aspect ratios. Lenses are round, and so is the vignette correction.

You'd think Photoshop would adopt this outlook for the other related tools as well. Oddly enough, it does not.

The Canon 5D versus the Nikon D200. I know, I know. These cameras aren't intended to compete head-to-head in the marketplace. And yet this is how it seems to break down for me.

I'm looking for a good DSLR. I probably can't go wrong with either one.

I want sharp photography at a high resolution. I also think I'm going to be combining my photography with photorealistic 3D CG (probably from the Maxwell Renderer), so I think that as much as I like the look of shallow depth-of-field, I will, in practice, need deeper DOF. The smaller sensor of the Nikon lends itself to deeper DOF.

But I want to take some moody photographs in baroque, theatrical lighting conditions and combine them with 3D. For that reason, I like the low noise at high ISO characteristics of the Canon 5D.

But the Nikon D200 is half the price.

But the Canon shoots at over 12 megapixels, which is over the magic number (for me) of 4096 pixels wide. Why do I care about 4096 pixels? It's probably just a fetish, but when I used to create 8x10 transparencies of computer graphics for print, 4096 pixels was always the recommended resolution for the 10" dimension. 4096 pixels is also a minimum width for some large movie formats. As a visual effects practitioner I'm sometimes called upon to produce large format work, so for texture maps or backgrounds I like the megapixels.

But at 10.2 MP the Nikon d200 is pretty high resolution, too, and it's half the price. Plus it's got a sturdy build and better weather sealing from what I understand.

But the Canon 5D shoots full frame. Canon has great lenses, and Canon is a monster company on the rise. If they are pushing FF, it probably has a future. Plus the weather sealing is plenty good enough.

But the Nikon D200 has lighter lenses, and the smaller sensor uses the sweet spot of the lens, cropping off the dark, blurry corners.

But the Canon L glass is good, and Photoshop can correct the darkish corners of some pictures that will arise with some lenses at some apertures.

But the Nikon d200 has great lenses too, and more in development. And did I mention the D200 body is half the price?

But the Canon 5D is on shelves now.

But the Nikon D200 soon will be.

ADDITIONAL LINKS

dpreview.com compares the two

Ken Rockwell compares the two

Nikon D200 Review Roundup from Digital Camera Tracker

Canon EOS 5D Review Roundup from Digital Camera Tracker

Nikonians.org thread comparing the two (Nikon-oriented, of course)

Japanese site with similar (virtually side-by-side) photos taken first from the Nikon D200 and then the Canon 5D. It looks like the Canon performs with lower noise at high ISO's. Commentary on this comparison from a Nikon perspective here.

UPDATE 12/25/05

. . . and we have a winner.

UPDATE 1/15/2006

Nikon D200 Digital Camera Reviewed by Bjørn Rørslett

UPDATE 2/11/2006
Rumors are starting to emerge that the next Canon camera is the Canon EOS 35D

UPDATE 10/9/2006
The original math I did was this: Canon 5D at $3300? Or Nikon D200 at $1700? - 85% of the camera for half the price. The real question to ask - once you've spent a bunch on lenses and lights - is, "Do I want to spend $10000 on photography or $11700 on photography?"

Telephoto lenses don't "flatten" a scene, they merely crop it tighter. Wide angle lenses don't "distort" a scene, they merely crop it looser.

Here is a collection of photographs (copyright Ian Britton, FreeFoto.com) taken from the same camera position but with lens focal lengths of 300mm, 200mm, 100mm, 50mm, 35mm and 24mm.

Let's see what happens when we carefully compare one to the next.

If you work with pixel addresses instead of the pixels themselves, you can smear (or ray trace) now, and decide which image it was you were smearing (or refracting) later.

The 2D digital displacement map techniques in programs like Photoshop and Shake confuse many users. You need to supply these programs with separate red and green displacements, not just a gray displacement.

When you need to composite soft-edged or motion-blurred 3D CG (which has been rendered over black) over a background, and you don't want matte lines, you will get great results if you use the 3D element's alpha channel as a holdback matte

Many compositors think of an alpha channel as a "clipping channels" that trims a foreground element from its original context and places it over a background. When they get soft-edged 3D CG rendered over black, their composites always exhibit matte lines. Here's one way to avoid those matte lines.

UPDATE 6/17/2009

There are 3 basic methods for creating outlines around alpha channels and other hi contrast images:

A Well-planned Gradient Map
Simulating 2D Metaball Blobbies with Photoshop
The Exclusion Blend Mode
Exclusion Photoshop Blend Mode Killer App
The Multiply Blend Mode
(illustrated in detail below)

Sometimes it's handy to turn black and white images into smooth outlines. Here's a little recipe for doing just that.

UPDATE 6/22/2009

With later versions of Photoshop - simply let the black and white artwork be a layer mask between two colored layers.

/ UPDATE

A compositing technique called a key mix borrowed from the visual effects industry can turn a black and white alpha channel into 2-color artwork. What's more, it captures the subtleties of antialiasing and grays more easily than does Photoshop's magic wand tool.

The idea is to treat the black and white artwork as a key intended to mix two images of flat colors.