guess complimentary color?

[michaellunsford]

This is probably a theory question. Is there a good way to determine whether text color should be white or black based on a provided background color? I can't figure out how to make PHP guess a good contrast.

Background colors are HTML colors -- could be something like #00b162 (which displays fine in black), or #2e2c29 (which is very difficult to read in black).

Thanks for any direction!

[Ninjakreborn]

unless I misunderstood, I would answer like this
Take all teh color's of hexes, and put them in a giant array, color name, hex number.

Then create a program to test the color, if it's a dark color generally white would look good, if it's a light color white would look good.  Then during testing you can take note of what looks bad and what doesn't and build onto the knowledge base overtime to make it smarter and smarter at discerning colors.

[michaellunsford]

Considering that there are over sixteen million possible color combinations. I'm thinking there's a way to convert to grayscale for purposes of detecting contrast.

[scotmcc]

Check this place out, it might be able to help you :)

[url=http://www.w3.org/TR/AERT#color-contrast]http://www.w3.org/TR/AERT#color-contrast[/url]

Scot

[michaellunsford]

HA! It might not be perfect in every situation, but it's working for me.
[code]<?php
function test_color($rgb) { //returns 0 if white, 1 if black.
$r=substr($rgb,0,2);
$g=substr($rgb,2,2);
$b=substr($rgb,4,2);
$detect=imagecreate(1,1);
imagecolorallocate($detect,0xFF,0xFF,0xFF);
imagecolorallocate($detect,0x00,0x00,0x00);
$detect_color=imagecolorclosest($detect,hexdec($r),hexdec($g),hexdec($b));
imagedestroy($detect);
return($detect_color);
}
?>[/code]