1 | var utils = require('../utils')
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2 | , nodes = require('../nodes');
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24 | function luminosity(color){
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25 | utils.assertColor(color);
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26 | color = color.rgba;
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27 | function processChannel(channel) {
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28 | channel = channel / 255;
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29 | return (0.03928 > channel)
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30 | ? channel / 12.92
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31 | : Math.pow(((channel + 0.055) / 1.055), 2.4);
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32 | }
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33 | return new nodes.Unit(
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34 | 0.2126 * processChannel(color.r)
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35 | + 0.7152 * processChannel(color.g)
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36 | + 0.0722 * processChannel(color.b)
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37 | );
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38 | };
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39 | luminosity.params = ['color'];
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40 | module.exports = luminosity;
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