Created
October 3, 2013 07:38
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Get brightness from background color with jQuery
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| jQuery.fn.brightness = function() { | |
| var bg_color, rgba, y; | |
| bg_color = this.css('background-color'); | |
| if ((bg_color != null) && bg_color.length) { | |
| rgba = bg_color.match(/^rgb(?:a)?\(([0-9]{1,3}),\s([0-9]{1,3}),\s([0-9]{1,3})(?:,\s)?([0-9]{1,3})?\)$/); | |
| if (rgba != null) { | |
| if (rgba[4] === '0') { | |
| if (this.parent().length) return this.parent().brightness(); | |
| } else { | |
| y = 2.99 * rgba[1] + 5.87 * rgba[2] + 1.14 * rgba[3]; | |
| if (y >= 1275) { | |
| return 'light'; | |
| } else { | |
| return 'dark'; | |
| } | |
| } | |
| } | |
| } else { | |
| if (this.parent().length) return this.parent().brightness(); | |
| } | |
| }; |
Even its not the exact values it might be related to this http://en.wikipedia.org/wiki/Luminance_(relative). The general idea is that green impacts us the most on the perception of what is "bright".
The Y in YIQ.
Hi, may I use this gist in a project? I couldn't find any licensing information.
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Where do the numbers come from?