January 28, 2009

Obama poster in RGB space

This is a visualization of the color distribution in the Barack Obama HOPE poster.

I tried RGB space projection a bunch of different ways. At first I went with metaballs. Blender has a native metaball type, but it didn't like adding many thousands of points to it. The performance hit of my data size multiplied by my learning curve was slowing down my fun, so I moved on.

When I tried out my own metaballs in VPython I realized that influence wasn't really what I wanted to model ... I wanted to expose the scattering of rare colors as well as the magnitude of common colors. So I set opacity inversely proportional to frequency, and size = frequency. I like this much better.

Images that started out digitally, like this one, have quite different color distributions than photographs. I wonder how different kinds of image compression affect this. It might be neat to repeatedly re- and de-compress an image and animate the effect this has on color distribution.

Color representation is super-interesting. A 3d representation like this one feels more correct to me than a 2d histogram, but color physically is a scalar value: the frequency of the light. I wonder why there's no frequency representation among the other conventional color models: RGB, HSV, CMYK ... I suppose your eye rarely receives light at a specific frequency without many other similar colors clustered all around it.


  1. I'd guess frequency's left out of the discussion because as far as the tech is concerned it's an arbitrary abstraction layer... afaik there's no way to predictably manipulate color by frequency with any current color models, not to mention gamut limitations.

    Color space theory is pretty weird... eventually I suppose we could have better models based on eye biology, so far all we've got are more and more complicated phenomenologies like CIECAM02.

    You're on to something with the specific frequency comment though -- but it's not that the eye never receives single-frequency light, it's that there's so much overlap in the frequency response of the specialized cells there's no way to detect a single frequency.

    ...or maybe that's not what you meant. ?

  2. it's not that the eye never receives single-frequency light

    Great point about the limits of our sensory equipment, I hadn't thought of that. I was thinking more about real-world conditions: the constant movement of the eyes, of light sources and reflections, the physical composition of objects - excepting lasers, prisms, rainbows, and astronomic phenomena - I expect the frequencies of light we see are almost never isolated.