Most “stable” color representation : RGB? HSV? CIELAB?

Question

There are several color representations in computer science : the standard RGB, but also HSV, HSL, CIE XYZ, YCC, CIELAB, CIELUV, ... It seems to me that most of the times, t

Answer 1

I'm not aware of a colourspace that does what you want, but I do have some remarks:

RGB closely matches the way colours are displayed to us on monitors. It is one of the worst colourspaces available in terms of approximating human perception.

As for the other colourspaces: Some try to make sure colours that are perceptually close together are also close together in the colourspace. Others also try to ensure that perceptually similar differences in colour also produce similar differences in the colourspace, regardless of where in the colourspace you are.

The first means that if you think the difference in colour between blue A, and blue B is similar to the difference in colour between the blue A and blue C, then in the colourspace the distance between blue A and blue B will be similar to the distance between blue A and blue C, and they will all three be close together in the colourspace. I think this is called a perceptually smooth colourspace. CIE XYZ is an example of this.

The second means that if you think the difference in colour between blue A and blue B is similar to the difference in colour between red A and red B then in the colourspace the distance between blue A and blue B will be similar to the difference between red A and red B. This is called a perceptually uniform colourspace. CIE Lab is an example of this.

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[edit 2011-07-29] As for your problem: Any of HSV, HSL, CIE XYZ, YCC, CIELAB, CIELUV, YUV separate out the illumination from the colour info in some way, so those are the better options. They provide some immunity from illumination changes, but won't help you when the colour temperature changes drastically or coloured light is used. XYZ and YUV are computationally less expensive to get to from RGB (which is what most cameras give you) but also less "good" than HSV, HSL, or CIELAB (the latter is often considered one of the best, but it is also one of the most difficult).

Depending on what you are searching for you could calibrate the color balance of the images. For example: suppose you are matching coca cola logos: You know that the letters in the logo are always white. So if they are not in your image you can use the colour they have to correct that, which gives you information about the other colours.

Answer 2

You might want to check out http://www.cs.harvard.edu/~sjg/papers/cspace.pdf, which proposes a new colorspace apparently designed to address this precise question.

Answer 3

Our perception of the color of something is mostly determined by its hue; a colorspace such as HSV which gives a single value representing hue will work best.

The eye is a remarkable instrument though, and knowing the color of a single point is not enough. If the entire scene has a yellow or blue tint to it, the eye will compensate and your perception will be of a purer color - the orange Coke bottle will appear to be redder than it is. Likewise with darkness and brightness. If possible, you should try to compensate the image before taking the color sample.