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rewrote sepia filter from scratch

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Anton Lavrenov
2019-02-20 14:04:58 -05:00
parent 033dbc57cd
commit b251fe3f57
3 changed files with 23 additions and 58 deletions
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46
src/filters/Sepia.ts
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@@ -1,51 +1,29 @@
// based on https://stackoverflow.com/questions/1061093/how-is-a-sepia-tone-created
/**
* 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]);
*/
export const Sepia = function(imageData) {
var data = imageData.data,
w = imageData.width,
y = imageData.height,
w4 = w * 4,
offsetY,
x,
offset,
or,
og,
ob,
nPixels = data.length,
i,
r,
g,
b;
do {
offsetY = (y - 1) * w4;
x = w;
do {
offset = offsetY + (x - 1) * 4;
for (i = 0; i < nPixels; i += 4) {
r = data[i + 0];
g = data[i + 1];
b = data[i + 2];
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);
data[i + 0] = Math.min(255, r * 0.393 + g * 0.769 + b * 0.189);
data[i + 1] = Math.min(255, r * 0.349 + g * 0.686 + b * 0.168);
data[i + 2] = Math.min(255, r * 0.272 + g * 0.534 + b * 0.131);
}
};