Clive Walkden

PHP, MySQL, HTML5, CSS3, jQuery code and ideas.

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PHP Colour lightness function

PHP Colour lightness function

in PHP
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Following on from my other 2 useful functions I thought I would show you another one which I have found useful for determining if a colour background needs a white or black text colour over the top. 
I found this function a while back so can't take the credit for writing it myself, I have no idea to give the credit to but whoever you are thank you. 
[code lang="php"]
function get_brightness($hex) {
// returns brightness value from 0 to 255
// strip off any leading #
$hex = str_replace('#', '', $hex);
$c_r = hexdec(substr($hex, 0, 2));
$c_g = hexdec(substr($hex, 2, 2));
$c_b = hexdec(substr($hex, 4, 2));
return (($c_r * 299) + ($c_g * 587) + ($c_b * 114)) / 1000;
The function takes your hex colour input and returns a value between 0 and 255. 0 is the darkest and 255 is lightest. I find a value around 80-90 is a good place to change the text colour from white to black, but this figure is worth experimenting with.
I hope this function helps you as much as it has me.
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