I had this in my notes, so I'd calculate the luma and sort by luma 

You probably want to shift hue, but not saturation or value.
So, convert your RGB value into HSV, add 180 degrees to H (modulo 360 
+degrees of course), and convert back to RGB.
function contrastingColor(color)
{
    return (luma(color) >= 165) ? '000' : 'fff';
}
function luma(color) // color can be a hx string or an array of RGB va
+lues 0-255
{
    var rgb = (typeof color === 'string') ? hexToRGBArray(color) : col
+or;
    return (0.2126 * rgb[0]) + (0.7152 * rgb[1]) + (0.0722 * rgb[2]); 
+// SMPTE C, Rec. 709 weightings
}

http://juicystudio.com/article/luminositycontrastratioalgorithm.php
http://www.splitbrain.org/blog/2008-09/18-calculating_color_contrast_w
+ith_php
http://stackoverflow.com/questions/301869/how-to-find-good-looking-fon
+t-color-if-background-color-is-known
http://search.cpan.org/~ian/Color-Scheme-1.02/lib/Color/Scheme.pm
    http://colorschemedesigner.com/
    http://stackoverflow.com/questions/97646/how-do-i-determine-darker
+-or-lighter-color-variant-of-a-given-color
    http://stackoverflow.com/questions/635022/calculating-contrasting-
+colours-in-javascript
    http://stackoverflow.com/questions/141855/programmatically-lighten
+-a-color
 http://www.mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-mod
+el-conversion-algorithms-in-javascript
 http://www.lighthouse.org/accessibility/effective-color-contrast
http://weblogtoolscollection.com/archives/2009/04/10/how-to-highlight-
+search-terms-with-jquery/
https://developer.mozilla.org/en/DOM/window.getComputedStyle

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In reply to Re: Ordering colors for contrast (luma) by Anonymous Monk
in thread [OT] Ordering colors by BrowserUk

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