On Monday, June 9, 2003, at 10:16 AM, David Squance wrote:
Is there a simple way to randomize color of text and background of a field
without getting a combination which is unreadable?
One approach is to randomly choose two colors until you get a readable combination. You may want to return black & white if something goes wrong and after a hundred tries you don't get an readable combination.
One approach to readability is contrast.
If handling color blindness is a priority, then map the colors into an appropriate 2D or 1D space for contrast analysis. An easy 1D is brightness. Distance is also easy to calculate in 1D; no squares or square roots are involved.
You may want to map to a psychological space, but I think RGB space should work in most cases.
To calculate the distance sum the squares of the deltas in each dimension and take the square root of that. Consider a combination readable if the distance is above some threshold.
You may want a higher threshold if text is lighter than the background.
You can avoid the square root if you square your threshold and compare against that.
To randomly choose a color, randomly choose each of the RGB values.
Is this the direction you were thinking?
Dar Scott
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