March 2006 Archives

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."