From 89cadbf468519782bc9c2396d6f3f7d75703d846 Mon Sep 17 00:00:00 2001 From: "(quasar) nebula" Date: Sun, 1 Nov 2020 10:51:09 -0400 Subject: initial commit --- color-conversion-algorithms.js | 138 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 color-conversion-algorithms.js (limited to 'color-conversion-algorithms.js') diff --git a/color-conversion-algorithms.js b/color-conversion-algorithms.js new file mode 100644 index 0000000..12a6fef --- /dev/null +++ b/color-conversion-algorithms.js @@ -0,0 +1,138 @@ +/** + * Converts an RGB color value to HSL. Conversion formula + * adapted from http://en.wikipedia.org/wiki/HSL_color_space. + * Assumes r, g, and b are contained in the set [0, 255] and + * returns h, s, and l in the set [0, 1]. + * + * @param Number r The red color value + * @param Number g The green color value + * @param Number b The blue color value + * @return Array The HSL representation + */ +function rgbToHsl(r, g, b) { + r /= 255, g /= 255, b /= 255; + + var max = Math.max(r, g, b), min = Math.min(r, g, b); + var h, s, l = (max + min) / 2; + + if (max == min) { + h = s = 0; // achromatic + } else { + var d = max - min; + s = l > 0.5 ? d / (2 - max - min) : d / (max + min); + + switch (max) { + case r: h = (g - b) / d + (g < b ? 6 : 0); break; + case g: h = (b - r) / d + 2; break; + case b: h = (r - g) / d + 4; break; + } + + h /= 6; + } + + return [ h, s, l ]; +} + +/** + * Converts an HSL color value to RGB. Conversion formula + * adapted from http://en.wikipedia.org/wiki/HSL_color_space. + * Assumes h, s, and l are contained in the set [0, 1] and + * returns r, g, and b in the set [0, 255]. + * + * @param Number h The hue + * @param Number s The saturation + * @param Number l The lightness + * @return Array The RGB representation + */ +function hslToRgb(h, s, l) { + var r, g, b; + + if (s == 0) { + r = g = b = l; // achromatic + } else { + function hue2rgb(p, q, t) { + if (t < 0) t += 1; + if (t > 1) t -= 1; + if (t < 1/6) return p + (q - p) * 6 * t; + if (t < 1/2) return q; + if (t < 2/3) return p + (q - p) * (2/3 - t) * 6; + return p; + } + + var q = l < 0.5 ? l * (1 + s) : l + s - l * s; + var p = 2 * l - q; + + r = hue2rgb(p, q, h + 1/3); + g = hue2rgb(p, q, h); + b = hue2rgb(p, q, h - 1/3); + } + + return [ r * 255, g * 255, b * 255 ]; +} + +/** + * Converts an RGB color value to HSV. Conversion formula + * adapted from http://en.wikipedia.org/wiki/HSV_color_space. + * Assumes r, g, and b are contained in the set [0, 255] and + * returns h, s, and v in the set [0, 1]. + * + * @param Number r The red color value + * @param Number g The green color value + * @param Number b The blue color value + * @return Array The HSV representation + */ +function rgbToHsv(r, g, b) { + r /= 255, g /= 255, b /= 255; + + var max = Math.max(r, g, b), min = Math.min(r, g, b); + var h, s, v = max; + + var d = max - min; + s = max == 0 ? 0 : d / max; + + if (max == min) { + h = 0; // achromatic + } else { + switch (max) { + case r: h = (g - b) / d + (g < b ? 6 : 0); break; + case g: h = (b - r) / d + 2; break; + case b: h = (r - g) / d + 4; break; + } + + h /= 6; + } + + return [ h, s, v ]; +} + +/** + * Converts an HSV color value to RGB. Conversion formula + * adapted from http://en.wikipedia.org/wiki/HSV_color_space. + * Assumes h, s, and v are contained in the set [0, 1] and + * returns r, g, and b in the set [0, 255]. + * + * @param Number h The hue + * @param Number s The saturation + * @param Number v The value + * @return Array The RGB representation + */ +function hsvToRgb(h, s, v) { + var r, g, b; + + var i = Math.floor(h * 6); + var f = h * 6 - i; + var p = v * (1 - s); + var q = v * (1 - f * s); + var t = v * (1 - (1 - f) * s); + + switch (i % 6) { + case 0: r = v, g = t, b = p; break; + case 1: r = q, g = v, b = p; break; + case 2: r = p, g = v, b = t; break; + case 3: r = p, g = q, b = v; break; + case 4: r = t, g = p, b = v; break; + case 5: r = v, g = p, b = q; break; + } + + return [ r * 255, g * 255, b * 255 ]; +} -- cgit 1.3.0-6-gf8a5