topical media & game development
graphic-canvas-util-pixastic-actions-laplace.js / js
/*
* Pixastic Lib - Laplace filter - v0.1.0
* Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
* MIT License [http://www.opensource.org/licenses/mit-license.php]
*/
Pixastic.Actions.laplace = {
process : function(params) {
var strength = 1.0;
var invert = !!(params.options.invert);
var contrast = parseFloat(params.options.edgeStrength)||0;
var greyLevel = parseInt(params.options.greyLevel)||0;
contrast = -contrast;
if (Pixastic.Client.hasCanvasImageData()) {
var data = Pixastic.prepareData(params);
var dataCopy = Pixastic.prepareData(params, true)
var kernel = [
[-1, -1, -1],
[-1, 8, -1],
[-1, -1, -1]
];
var weight = 1/8;
var rect = params.options.rect;
var w = rect.width;
var h = rect.height;
var w4 = w*4;
var y = h;
do {
var offsetY = (y-1)*w4;
var nextY = (y == h) ? y - 1 : y;
var prevY = (y == 1) ? 0 : y-2;
var offsetYPrev = prevY*w*4;
var offsetYNext = nextY*w*4;
var x = w;
do {
var offset = offsetY + (x*4-4);
var offsetPrev = offsetYPrev + ((x == 1) ? 0 : x-2) * 4;
var offsetNext = offsetYNext + ((x == w) ? x-1 : x) * 4;
var r = ((-dataCopy[offsetPrev-4]
- dataCopy[offsetPrev]
- dataCopy[offsetPrev+4]
- dataCopy[offset-4]
- dataCopy[offset+4]
- dataCopy[offsetNext-4]
- dataCopy[offsetNext]
- dataCopy[offsetNext+4])
+ dataCopy[offset] * 8)
* weight;
var g = ((-dataCopy[offsetPrev-3]
- dataCopy[offsetPrev+1]
- dataCopy[offsetPrev+5]
- dataCopy[offset-3]
- dataCopy[offset+5]
- dataCopy[offsetNext-3]
- dataCopy[offsetNext+1]
- dataCopy[offsetNext+5])
+ dataCopy[offset+1] * 8)
* weight;
var b = ((-dataCopy[offsetPrev-2]
- dataCopy[offsetPrev+2]
- dataCopy[offsetPrev+6]
- dataCopy[offset-2]
- dataCopy[offset+6]
- dataCopy[offsetNext-2]
- dataCopy[offsetNext+2]
- dataCopy[offsetNext+6])
+ dataCopy[offset+2] * 8)
* weight;
var brightness = ((r + g + b)/3) + greyLevel;
if (contrast != 0) {
if (brightness > 127) {
brightness += ((brightness + 1) - 128) * contrast;
} else if (brightness < 127) {
brightness -= (brightness + 1) * contrast;
}
}
if (invert) {
brightness = 255 - brightness;
}
if (brightness < 0 ) brightness = 0;
if (brightness > 255 ) brightness = 255;
data[offset] = data[offset+1] = data[offset+2] = brightness;
} while (--x);
} while (--y);
return true;
}
},
checkSupport : function() {
return Pixastic.Client.hasCanvasImageData();
}
}
(C) Æliens
20/2/2008
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.