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.
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%
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.
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.
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:
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:
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
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
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
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
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.
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.
I was inspired by all of the previous posts to take a shot at simulating the Technicolor 2-Strip Process in Photoshop.
First, I am aware that apparently there was 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.
Second. I am also aware that there is a lot of discussion on the internet in one forum or another about how to do this, ever since it was done for The Aviator.
Third, what I've done above is likely not as good as one of the somewhat more complex implementations described elsewhere, but I threw this together as a quick 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)
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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.
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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.
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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 tem onto black layers.
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.
* 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.
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.
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.
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...
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.
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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 an SLR still camera
...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.
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Mini review: Photoshop Channels and Masks One-on-One. Deke McClelland.
I had some free time, so I watched the 30 hours Deke McClelland put together on Lynda.com on channels and masking. I figured I knew a lot of the material already, and 30 hours is a long time. It's more like 40+ when you really do it -- so it's a full time job for a week.
I made myself watch bit of every segment, though, even if I thought a particular segment would be a waste of time. For me it was worth the effort, and I'm glad I put in the time.
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.
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.
Scar arises. Latex by Syren.
Kumi Monster at repose in the darkness. Latex by Syren.
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 Porcile 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 Lyla 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.
I have a Model Mayhem portfolio now.
Here's a conversation I had at Nikonians about this.
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.
An experiment to see what differences exist between originating digital black and white photography using Nikon D200 in-camera settings vs shooting in color and converting to black and white as a post process.
From what I can see, 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.
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.
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
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
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.
Sometimes it's handy to turn black and white images into smooth outlines. Here's a little recipe for doing just that.
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.
