Sunday, March 14, 2010

3D Gamut Animations

First, let's have a look at a video. What you’ll see is a visualization of three different color schemes as 3D shapes floating within the RGB color space.



(If this embedded video doesn't play, try this link to YouTube). Each painting will be followed by an irregular shape that represents the range of colors used within that composition.

If you’ve read this blog for a while or dug back in the archives, you may remember seeing how we can chart a color scheme as a shape or gamut that takes up part of a color wheel. Everything outside the gamut is left out of the composition.

The painting Palace in the Clouds, above, has a gamut limited to intense blue, opposed by fairly dull reds and yellows, and some fairly dull dark greens.

To the right of that is a computer-generated image made by sampling all the pixels and charting them on a color wheel. The software was created by Phillipe Colantoni, and is available for Windows users at couleur.org.

We can also combine the value or lightness data to see the color scheme as a 3D representation inside an RGB cube. The RGB color space is created by graphing red, green, and blue as three separate vectors in XYZ space. (The green vector above is hidden by the gamut.)

Where the vectors intersect is pure black. At the opposite corner is pure white. In this configuration, the secondaries are cyan, magenta, and yellow, which would lie on the plane between each of the two vectors. A pure yellow, for example, would be on the plane formed by red and green (the horizontal plane in this view).

By comparing each of the paintings with its gamut in RGB color space, and then comparing the gamuts to each other, you can see how the gamuts vary. The gamut for Crocodile Swamp is narrower because the color scheme is more limited. There are hardly any blues.

The yellow windows in this scene show up as a scattering of yellow dots at the bottom of the gamut.
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Software by P. Colantoni at couleur.org.
Animation by Lester Yocum at lesteryocum.com
Previously on GurneyJourney: Color Wheel Masking Update

8 comments:

Tyler J said...

This is an interesting way to look at the colors in a piece. It put in mind the color sphere concept:
http://en.wikipedia.org/wiki/Munsell_color_system

James, how much thought goes into the selection of the palette colors for a piece and how much of it is intuition at this point for you?

Chris Jouan Illustration said...

I have been eagerly consuming every word from your recent and past posts about color. I wish I could have learned all of this 20 years ago instead of stumbling about like I have.

I feel like my paintings will only get better.

THANK YOU!

James Gurney said...

Chris--My pleasure, thanks for reading.

Tyler, I don't methodically plan every composition, but often will use the gamut planning method when I'm doing an important piece or planning the color script for a longer work. The biggest challenge for me is to move beyond color mixing and color arranging habits, and to try new schemes that are right for a given picture.

Justin M. said...

James, maybe I'm just old school (or missing the point) but I don't understand the worth of that 3D video. What do you gain from looking at the model that you couldn't take from just squinting at your picture?

James Gurney said...

Justin, I know what you mean. It's just a different way of looking at a color scheme. There's not necessarily much practical value in it. But I find it reveals things that I didn't see just looking at the painting directly: such as the first one of the skimmer had a lot of clipping in the lights--that is, the gamut was bunched into the white corner of the cube.

Jake said...

James,
The clipping you mentioned seems odd as there doesn't appear to be much pure white in the image. Maybe, the color space that the software is using is smaller than that of the scanned image.
Jake

BTW, my sister gave me a copy of Dinotopia from your online store for Christmas and we were all quite impressed with the personalized inscription and drawing. Very cool! Thanks!

Anonymous said...

are there any simplified explanations anywhere that shows how to use this? I have the book but would love to find a working process to understand it.

James Gurney said...

Anon, I find that it's a real conceptual challenge to think of gamuts in three dimensions. To make practical use of gamut mapping for designing color schemes, it helps me to reduce them to a regular two dimensional color wheel.