Best algorithm for matching colours.

Question

Hi, I got array of some (about 200) colours in RGB format. I want to write program that taking any RGB colour and trying to match colour from my array that is most "similar".

Of course I need better definition for "similar". Unfortunately I don't have any. It want it to act like a parson asked the same question.

I want to show some infos about matching accuracy. For example black-white -100% and for the same colour but little different hue -4%.

So maybe I should use neural network? But I think it must be easer way.

Answer 1

Convert all of the colors to the CIE Lab color space and compute the distance in that space

deltaE = sqrt(deltaL^2 + deltaA^2 + deltaB^2)

Colors with the lowest deltaE are the most perceptually similar to each other.

Answer 2

No, you do not need neural networks here! Simply consider an HSL color value a vector and define a weighted modulus function for the vector like this:

modulus = sqrt(a*H1*H1 + b*S1*S1 + c*L1*L1);

where a,b,c are weights you should decide based on your visual definition of what
creates a bigger difference in perceived color - a 1% change in Hue or a 1%
change in Saturation

I would suggest you use a = b = 0.5 and c = 1

Finally, find out the range your modulus would take and define similar colors to be those which have their moduli very close to each other (say 5%)

Answer 3

I'd also point out the least squares method, just as something slightly simpler. That is, you take the difference of a number, square it, then sum all these squared differences.