Thursday, June 10, 2010

What’s the true color of this scene?


There’s no way of knowing, certainly not for you, as – I assume – you weren’t there that day. But not for me either, but not only because I don’t remember the scene independently of the photograph. But because the notion of “true color” doesn’t make sense, not quite.

I did a post on this at The Valve some time ago, so I won’t repeat that in full. But, in brief, wavelength is physically real, but perceived color is not. The color you see is not a direct function of the wavelengths that enter your eye from (through and/or reflected by) an object. If it were, the color of objects would vary more widely than it does. Perceptual psychologists call that color constancy (which is one of several perceptual constancies). Perceived color is relatively constant because the eye/brain makes context sensitive adjustments. There isn’t anything such thing as non-perceived color; there’s wavelength, but that’s not color.

There are, for example, these demonstrations where a patch that reflects some wavelength will appear as color X in one context and color Y in a different context (see examples here). Same wavelength, different colors.

What this means, then, for the photographer sitting in front of a computer intent on “developing” a digital image, is that “true color” is rather evasive. To make things worse, neither the monitor nor any photographic paper is capable of displaying the dynamic range that the eye can see. The eye can see light brighter than any reflected off of paper or transmitted from a monitor and no monitor or paper can be as black as a room sealed from all light.

So, when you’re developing an image, you have considerable discretion about just how to render the colors so they look real. These colors are obviously not real:


But what about these?


Or these?


2 comments:

  1. Apart from the purple ground, the picture that is obviously not real reminded me of the most spectacular sunsets Ive had the pleasure to see.

    A somewhat tainted pleasure due to it's origin.

    I lived with one of the biggest chemical works in Western Europe on the distant horizon (Living to close was not a good option)

    Watching the sun set in summer through the toxic effluent was a thing of great beauty.

    A somewhat uncelebrated and potential dangerous beauty. But still a wonder.

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  2. Well, I'll tell you, Jeb, I live in New Jersey on the West Bank of the Hudson River off of lower Manhattan. This area is plagued with chemical plants. That photo looks west over the Meadowlands. There's a major power plant not a mile away and chemical plants and oil refineries all around. All that crap in the atmosphere does make for some spectacular sunsets.

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