Random colour

[Dar Scott]

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