colors.js

if(typeof module != 'undefined') {
	module.exports.getSkyColor = getSkyColor;
	module.exports.findNearest = findNearest;
	module.exports.hex = hex;
}

function getSkyColor(img, canvas) {
	var ctx = canvas.getContext("2d");
	canvas.width = img.width;
	canvas.height = img.height;
	ctx.drawImage( img, 0, 0 );

	// slice off the sky
	var padding = 1, cut = 0.6;
	var data = ctx.getImageData(
			padding, // top
			padding, // left
			img.width - 2 * padding, // width
			Math.round((img.height - 2 * padding) * cut) ).data;

	// calculate average color
	var color = [0, 0, 0];
	for(var i = 0; i < data.length; i += 4) {
		for(var j = 0; j < 3; j++) {
			color[j] += data[i + j];
		}
	}
	var count = data.length / 4;
	color = color.map(function(c) {
			return Math.round(c / count);
	});
	return color;
}

function hex(color) {
	return color.map(function(c) { return c.toString(16); }).join('');
}

function findNearest(rgb) {
	return colors
		.map(function(color) {
			return {
				d: colorDistance(rgb, color[1]),
				name: color[0]
			};
		})
		.sort(function(color1, color2) {
			return color1.d - color2.d;
		})[0].name;
}

function colorDistance(color1, color2) {
	return Math.sqrt(
			Math.pow(color1[0] - color2[0], 2)
		+ Math.pow(color1[1] - color2[1], 2)
		+ Math.pow(color1[2] - color2[2], 2)
	);
}

var colors = [
	["alice blue", [240,248,255]],
	["antique white", [250,235,215]],
	["aqua", [0,255,255]],
	["aquamarine", [127,255,212]],
	["azure", [240,255,255]],
	["beige", [245,245,220]],
	["bisque", [255,228,196]],
	["black", [0,0,0]],
	["blanched almond", [255,235,205]],
	["blue", [0,0,255]],
	["blue violet", [138,43,226]],
	["brown", [165,42,42]],
	["burlywood", [222,184,135]],
	["cadet blue", [95,158,160]],
	["chartreuse", [127,255,0]],
	["chocolate", [210,105,30]],
	["coral", [255,127,80]],
	["cornflower blue", [100,149,237]],
	["cornsilk", [255,248,220]],
	["crimson", [220,20,60]],
	["cyan", [0,255,255]],
	["dark blue", [0,0,139]],
	["dark cyan", [0,139,139]],
	["dark goldenrod", [184,134,11]],
	["dark gray", [169,169,169]],
	["dark green", [0,100,0]],
	["dark grey", [169,169,169]],
	["dark khaki", [189,183,107]],
	["dark magenta", [139,0,139]],
	["dark olivegreen", [85,107,47]],
	["dark orange", [255,140,0]],
	["dark orchid", [153,50,204]],
	["dark red", [139,0,0]],
	["dark salmon", [233,150,122]],
	["dark seagreen", [143,188,143]],
	["dark slate blue", [72,61,139]],
	["dark slate gray", [47,79,79]],
	["dark slate grey", [47,79,79]],
	["dark turquoise", [0,206,209]],
	["dark violet", [148,0,211]],
	["deep pink", [255,20,147]],
	["deep sky blue", [0,191,255]],
	["dim gray", [105,105,105]],
	["dim grey", [105,105,105]],
	["dodger blue", [30,144,255]],
	["firebrick", [178,34,34]],
	["floral white", [255,250,240]],
	["forest green", [34,139,34]],
	["fuchsia", [255,0,255]],
	["gainsboro", [220,220,220]],
	["ghost white", [248,248,255]],
	["gold", [255,215,0]],
	["golden rod", [218,165,32]],
	["gray", [128,128,128]],
	["green", [0,128,0]],
	["green yellow", [173,255,47]],
	["grey", [128,128,128]],
	["honeydew", [240,255,240]],
	["hot pink", [255,105,180]],
	["indian red", [205,92,92]],
	["indigo", [75,0,130]],
	["ivory", [255,255,240]],
	["khaki", [240,230,140]],
	["lavender", [230,230,250]],
	["lavender blush", [255,240,245]],
	["lawn green", [124,252,0]],
	["lemon chiffon", [255,250,205]],
	["light blue", [173,216,230]],
	["light coral", [240,128,128]],
	["light cyan", [224,255,255]],
	["light goldenrodyellow", [250,250,210]],
	["light gray", [211,211,211]],
	["light green", [144,238,144]],
	["light grey", [211,211,211]],
	["light pink", [255,182,193]],
	["light salmon", [255,160,122]],
	["light seagreen", [32,178,170]],
	["light skyblue", [135,206,250]],
	["light slategray", [119,136,153]],
	["light slategrey", [119,136,153]],
	["light steelblue", [176,196,222]],
	["light yellow", [255,255,224]],
	["lime", [0,255,0]],
	["lime green", [50,205,50]],
	["linen", [250,240,230]],
	["magenta", [255,0,255]],
	["maroon", [128,0,0]],
	["medium aquamarine", [102,205,170]],
	["medium blue", [0,0,205]],
	["medium orchid", [186,85,211]],
	["medium purple", [147,112,219]],
	["medium seagreen", [60,179,113]],
	["medium slateblue", [123,104,238]],
	["medium springgreen", [0,250,154]],
	["medium turquoise", [72,209,204]],
	["medium violetred", [199,21,133]],
	["midnight blue", [25,25,112]],
	["mint cream", [245,255,250]],
	["misty rose", [255,228,225]],
	["moccasin", [255,228,181]],
	["navajo white", [255,222,173]],
	["navy", [0,0,128]],
	["oldlace", [253,245,230]],
	["olive", [128,128,0]],
	["olive drab", [107,142,35]],
	["orange", [255,165,0]],
	["orange red", [255,69,0]],
	["orchid", [218,112,214]],
	["pale goldenrod", [238,232,170]],
	["pale green", [152,251,152]],
	["pale turquoise", [175,238,238]],
	["pale violetred", [219,112,147]],
	["papaya whip", [255,239,213]],
	["peach puff", [255,218,185]],
	["peru", [205,133,63]],
	["pink", [255,192,203]],
	["plum", [221,160,221]],
	["powder blue", [176,224,230]],
	["purple", [128,0,128]],
	["red", [255,0,0]],
	["rosy brown", [188,143,143]],
	["royal blue", [65,105,225]],
	["saddle brown", [139,69,19]],
	["salmon", [250,128,114]],
	["sandy brown", [244,164,96]],
	["sea green", [46,139,87]],
	["sea shell", [255,245,238]],
	["sienna", [160,82,45]],
	["silver", [192,192,192]],
	["sky blue", [135,206,235]],
	["slate blue", [106,90,205]],
	["slate gray", [112,128,144]],
	["slate grey", [112,128,144]],
	["snow", [255,250,250]],
	["spring green", [0,255,127]],
	["steel blue", [70,130,180]],
	["tan", [210,180,140]],
	["teal", [0,128,128]],
	["thistle", [216,191,216]],
	["tomato", [255,99,71]],
	["turquoise", [64,224,208]],
	["violet", [238,130,238]],
	["wheat", [245,222,179]],
	["white", [255,255,255]],
	["white smoke", [245,245,245]],
	["yellow", [255,255,0]],
	["yellow green", [154,205,50]]
];