Determining Color Difference Using the CIELAB Model?

Colour Blind asks: "I am working for a not-for-profit organization developing a website for kids. I am attempting to develop a method for testing if two colours (as defined by R, G, and B values [0-255]) are adequately different to be visible on top of each other. So far I have tried many things but this is the one that, by all accounts, should work: I have converted from RGB to (CIE)XYZ using a 3x3 matrix transformation. From here I have used three more equations to convert to CIELAB colour. I have then calculated the distance between the two colours in question in CIELAB colour space. The results are not correct: there are pairs of colours that are quite far from visible that yield the same difference as colours that are plainly acceptable for visibility. Any suggestions?"

Comments

Re:Try the Value in HSV instead

[sfraggle]

I have to agree with this. I am the author of Text Mode Doom and I hit a problem along these lines during development: the RGB value itself is not particularly useful when trying to find a numerical value for a particular "colour" that the human eye perceives. In text mode doom I was faced with the problem of mapping the particular colour value to a corresponding text colour, of which I was limited to a small value (under 16). I solved the problem by converting the RGB values into HSV and then assigning text colours to the real colours based on their hue. The results I found with this were quite impressive