konva/src/filters/Sepia.js

<p align="center"> <img src="https://raw.githubusercontent.com/konvajs/konvajs.github.io/master/apple-touch-icon-180x180.png" alt="Konva logo" height="180" /> </p>

(function() {
  'use strict';
  /**
     * Sepia Filter
     * Based on: Pixastic Lib - Sepia filter - v0.1.0
     * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
     * @function
     * @name Sepia
     * @memberof Konva.Filters
     * @param {Object} imageData
     * @author Jacob Seidelin <jseidelin@nihilogic.dk>
     * @license MPL v1.1 [http://www.pixastic.com/lib/license.txt]
     * @example
     * node.cache();
     * node.filters([Konva.Filters.Sepia]);
     */
  Konva.Filters.Sepia = function(imageData) {
    var data = imageData.data,
      w = imageData.width,
      y = imageData.height,
      w4 = w * 4,
      offsetY,
      x,
      offset,
      or,
      og,
      ob,
      r,
      g,
      b;

    do {
      offsetY = (y - 1) * w4;
      x = w;
      do {
        offset = offsetY + (x - 1) * 4;

        or = data[offset];
        og = data[offset + 1];
        ob = data[offset + 2];

        r = or * 0.393 + og * 0.769 + ob * 0.189;
        g = or * 0.349 + og * 0.686 + ob * 0.168;
        b = or * 0.272 + og * 0.534 + ob * 0.131;

        data[offset] = r > 255 ? 255 : r;
        data[offset + 1] = g > 255 ? 255 : g;
        data[offset + 2] = b > 255 ? 255 : b;
        data[offset + 3] = data[offset + 3];
      } while (--x);
    } while (--y);
  };
})();