Rédigé par Whiteshoulders -

Glitch

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J'aime bien les glitch, j'aime le javascript. Donc j'ai mixé les deux, pour un résultat des plus approximatif. L'idée étant que ça ressemble à l'image d'une VHS qui a moisi trop longtemps.

Résultat : Choisissez une bien belle image sur votre disque dur (de préférence pas plus grande que 400x400, histoire que ça ne mouline pas trop) et déposez la sur le cadre gris ou choisissez-en une à droite, réglez le niveau de glitchiness, et glitchez moi ça.

<div id="glitch_wrapper">
    <canvas id="glitched" height="400" width="400"></canvas>
    <div id="imSelect">
        <img id="im1" src="/data/images/glitch/im1_t.png" /><br/>
        <img id="im2" src="/data/images/glitch/im2_t.png" /><br/>
        <img id="im3" src="/data/images/glitch/im3_t.png" /><br/>
        <img id="im4" src="/data/images/glitch/im4_t.png" />
    </div>
    <div id="controls">
        <p>GLITCHINESS: <input id="glitchiness" type="range" value="10" max="20" min="0"></input></p>
        <button id="glitch">Glitch !</button>
    </div>
</div>
<script type="text/javascript">
    var glitchness = 0.5;
    var canvas = document.getElementById("glitched");
    var context = canvas.getContext("2d");
    var img = document.createElement("img");
    var button = document.getElementById("glitch");
    var slider = document.getElementById('glitchiness')

    context.font = 'normal 20pt Calibri';
    context.fillText("Deposez une image", 100, 185);
    context.fillText("ou choisissez-en une", 95, 215);

    var im1 = document.getElementById("im1");
    var im2 = document.getElementById("im2");
    var im3 = document.getElementById("im3");
    var im4 = document.getElementById("im4");
    im1.onclick = function(){
        img.src = "/data/images/glitch/im1.png";
    }

    im2.onclick = function(){
        img.src = "/data/images/glitch/im2.png";
    }

    im3.onclick = function(){
        img.src = "/data/images/glitch/im3.png";
    }

    im4.onclick = function(){
        img.src = "/data/images/glitch/im4.png";
    }   

    canvas.addEventListener("dragover", function(evt){
        evt.preventDefault();
    }, false);

    canvas.addEventListener("drop", function(evt){
        var files = evt.dataTransfer.files;
        if(files.length>0){
            var file = files[0];
            if(typeof FileReader !== "undefined" &amp;&amp; file.type.indexOf("image" != -1)){
                var reader = new FileReader();
                reader.onload = function(evt){
                    img.src = evt.target.result;
                }
                reader.readAsDataURL(file);
            }
        }
        evt.preventDefault();
    }, false);

    img.addEventListener("load", function(){
        canvas.width = img.width;
        canvas.height = img.height;
        context.clearRect(0, 0, canvas.width, canvas.height);
        context.drawImage(img, 0, 0); 
        stackBlurCanvasRGB("glitched", 0, 0, canvas.width, canvas.height,1);
    })

    button.addEventListener("click", function(){
        glitchness = slider.value/20;
        var canvasWidth = canvas.width;
        var canvasHeight = canvas.height;
        context.drawImage(img, 0, 0); 
        var imData = context.getImageData(0, 0, canvasWidth, canvasHeight);
        var data = imData.data;
        var dataOriginal = JSON.parse(JSON.stringify(data));

        var aleat = Math.pow(0.9999, glitchness);
        var aleat1 = Math.pow(0.999, glitchness);

        var fact1 = 1;
        var fact2 = 1;
        var decalX = 0;
        var deform = false;
        var freq = 10;
        var amp = 0;
        var red = glitchness*Math.random()+1;
        var green = glitchness*Math.random()+1;
        var blue = glitchness*Math.random()+1;
        var reverseX = Math.random()>0.5;
        var reverseY = Math.random()>0.5;
        var minX = 0;
        var maxX = 0;
        var c1 = 1;
        var c2 = 1;
        var c3 = 1;

        var d1 = 0.7+0.3*Math.random()*glitchness;
        var d2 = 0.7+0.3*Math.random()*glitchness;
        var d3 = 0.7+0.3*Math.random()*glitchness;

        var r = (glitchness === 0) ? 0 : Math.floor(Math.random()*3);
        var v = (glitchness === 0) ? 1 : Math.floor(Math.random()*3);
        var b = (glitchness === 0) ? 2 : Math.floor(Math.random()*3);

        for (var yd = 0; yd < canvasHeight; yd += 1) {
            for (var xd = 0; xd < canvasWidth; xd += 1) {
                if(reverseY){
                    y = canvasWidth-yd-1;
                }else{
                    y = yd;
                }

                if(reverseX){
                    x = canvasWidth-xd-1;
                }else{
                    x = xd;
                }

                var index1 = (y * canvasWidth + x) * 4;
                var variation = 0.000001*(Math.floor(Math.random()*2)*2-1);
                if(deform){
                    fact1 += variation*Math.random();
                    fact2 += variation*Math.random();
                }
                if(fact1>1 || !deform){
                    fact1 = 1;
                }
                if(fact2>1 || !deform){
                    fact2 = 1;
                }

                if(Math.random()>aleat){
                    decalX = (Math.floor(Math.random()*2)-1)*50*Math.random()*glitchness;
                    minX = Math.floor(canvasWidth/2*Math.random());
                    maxX = canvasWidth/2+Math.floor(canvasWidth/2*Math.random());
                }
                if(x>minX &amp;&amp; x<maxX){
                    x+=Math.floor(decalX);
                }

                var index2 = Math.floor((y*fact1 * canvasWidth + (x+decalX)*fact2) * 4);
                if(Math.random()>aleat1){
                    var freq = (Math.random())*100;
                    var amp = (Math.random())*50*glitchness;
                }
                index2 = index2 + Math.floor(Math.sin(y/freq)*amp);

                if(Math.random()>aleat){
                    deform = !deform;
                    fact1 = 1;
                    fact2 = 1;
                }

                index2 = Math.floor(index2*glitchness + (1-glitchness)*index1);
                index3 = Math.floor((y * canvasWidth + x+decalX) * 4);

                if(Math.random()>aleat){
                     c1 = Math.random()*glitchness;
                     c2 = Math.random()*glitchness;
                     c3 = Math.random()*glitchness;
                }
                data[index1+0] = Math.floor((dataOriginal[index2+0]*red + (1 + c1-glitchness)*dataOriginal[index3+0])/(2+c1) - Math.random()*50*glitchness);
                data[index1+1] = Math.floor((dataOriginal[index2+1]*green + (1 + c2-glitchness)*dataOriginal[index3+1])/(2+c1) - Math.random()*50*glitchness);
                data[index1+2] = Math.floor((dataOriginal[index2+2]*blue + (1 + c3-glitchness)*dataOriginal[index3+2] )/(2+c1) - Math.random()*50*glitchness);

                var blackBand = Math.pow(Math.sin(y),4)*2;
                data[index1+0] = (d1*data[index1+0] + (1-d1)*dataOriginal[index1+r])*Math.pow(blackBand,glitchness);
                data[index1+1] = (d2*data[index1+1] + (1-d2)*dataOriginal[index1+v])*Math.pow(blackBand,glitchness);
                data[index1+2] = (d3*data[index1+2] + (1-d3)*dataOriginal[index1+b])*Math.pow(blackBand,glitchness);
            }
        }
        context.putImageData(imData, 0, 0);
        stackBlurCanvasRGB("glitched", 0, 0, canvas.width, canvas.height,1+Math.pow(Math.random(),2)*4*glitchness);
    }, false);

/ StackBlur - a fast almost Gaussian Blur For Canvas

Version: 0.5 Author: Mario Klingemann Contact: mario@quasimondo.com Website: http://www.quasimondo.com/StackBlurForCanvas</a> Twitter: @quasimondo In case you find this class useful - especially in commercial projects - I am not totally unhappy for a small donation to my PayPal account mario@quasimondo.de Or support me on flattr: https://flattr.com/thing/72791/StackBlur-a-fast-almost-Gaussian-Blur-Effect-for-CanvasJavascript</a> Copyright (c) 2010 Mario Klingemann Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. / var mul_table = [512,512,456,512,328,456,335,512,405,328,271,456,388,335,292,512,

454,405,364,328,298,271,496,456,420,388,360,335,312,292,273,512,
482,454,428,405,383,364,345,328,312,298,284,271,259,496,475,456,
437,420,404,388,374,360,347,335,323,312,302,292,282,273,265,512,
497,482,468,454,441,428,417,405,394,383,373,364,354,345,337,328,
320,312,305,298,291,284,278,271,265,259,507,496,485,475,465,456,
446,437,428,420,412,404,396,388,381,374,367,360,354,347,341,335,
329,323,318,312,307,302,297,292,287,282,278,273,269,265,261,512,
505,497,489,482,475,468,461,454,447,441,435,428,422,417,411,405,
399,394,389,383,378,373,368,364,359,354,350,345,341,337,332,328,
324,320,316,312,309,305,301,298,294,291,287,284,281,278,274,271,
268,265,262,259,257,507,501,496,491,485,480,475,470,465,460,456,
451,446,442,437,433,428,424,420,416,412,408,404,400,396,392,388,
385,381,377,374,370,367,363,360,357,354,350,347,344,341,338,335,
332,329,326,323,320,318,315,312,310,307,304,302,299,297,294,292,
289,287,285,282,280,278,275,273,271,269,267,265,263,261,259];

var shg_table = [9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,

17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19, 
19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23, 
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 
23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24 ];</code>

function stackBlurImage( imageID, canvasID, radius, blurAlphaChannel ) {

var img = document.getElementById( imageID ); var w = img.naturalWidth; var h = img.naturalHeight;

var canvas = document.getElementById( canvasID );

canvas.style.width = w + "px"; canvas.style.height = h + "px"; canvas.width = w; canvas.height = h;

var context = canvas.getContext("2d"); context.clearRect( 0, 0, w, h ); context.drawImage( img, 0, 0 );

if ( isNaN(radius) || radius < 1 ) return;

if ( blurAlphaChannel )

stackBlurCanvasRGBA( canvasID, 0, 0, w, h, radius );

else

stackBlurCanvasRGB( canvasID, 0, 0, w, h, radius );

}function stackBlurCanvasRGBA( id, top_x, top_y, width, height, radius ) {

if ( isNaN(radius) || radius < 1 ) return; radius |= 0;

var canvas = document.getElementById( id ); var context = canvas.getContext("2d"); var imageData;

try { try {

imageData = context.getImageData( top_x, top_y, width, height );

} catch(e) {

// NOTE: this part is supposedly only needed if you want to work with local files
// so it might be okay to remove the whole try/catch block and just use
// imageData = context.getImageData( top_x, top_y, width, height );
try {
    netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
    imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
    alert("Cannot access local image");
    throw new Error("unable to access local image data: " + e);
    return;
}

} } catch(e) { alert("Cannot access image"); throw new Error("unable to access image data: " + e); }

var pixels = imageData.data;

var x, y, i, p, yp, yi, yw, r_sum, g_sum, b_sum, a_sum, r_out_sum, g_out_sum, b_out_sum, a_out_sum, r_in_sum, g_in_sum, b_in_sum, a_in_sum, pr, pg, pb, pa, rbs;

var div = radius + radius + 1; var w4 = width << 2; var widthMinus1 = width - 1; var heightMinus1 = height - 1; var radiusPlus1 = radius + 1; var sumFactor = radiusPlus1 * ( radiusPlus1 + 1 ) / 2;

var stackStart = new BlurStack(); var stack = stackStart; for ( i = 1; i < div; i++ ) {

stack = stack.next = new BlurStack();
if ( i == radiusPlus1 ) var stackEnd = stack;

} stack.next = stackStart; var stackIn = null; var stackOut = null;

yw = yi = 0;

var mul_sum = mul_table[radius]; var shg_sum = shg_table[radius];

for ( y = 0; y < height; y++ ) {

r_in_sum = g_in_sum = b_in_sum = a_in_sum = r_sum = g_sum = b_sum = a_sum = 0;

r_out_sum = radiusPlus1 * ( pr = pixels[yi] );
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1] );
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2] );
a_out_sum = radiusPlus1 * ( pa = pixels[yi+3] );

r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
a_sum += sumFactor * pa;

stack = stackStart;

for( i = 0; i < radiusPlus1; i++ )
{
    stack.r = pr;
    stack.g = pg;
    stack.b = pb;
    stack.a = pa;
    stack = stack.next;
}

for( i = 1; i < radiusPlus1; i++ )
{
    p = yi + (( widthMinus1 < i ? widthMinus1 : i ) << 2 );
    r_sum += ( stack.r = ( pr = pixels[p])) * ( rbs = radiusPlus1 - i );
    g_sum += ( stack.g = ( pg = pixels[p+1])) * rbs;
    b_sum += ( stack.b = ( pb = pixels[p+2])) * rbs;
    a_sum += ( stack.a = ( pa = pixels[p+3])) * rbs;

    r_in_sum += pr;
    g_in_sum += pg;
    b_in_sum += pb;
    a_in_sum += pa;

    stack = stack.next;
}

stackIn = stackStart;
stackOut = stackEnd;
for ( x = 0; x < width; x++ )
{
    pixels[yi+3] = pa = (a_sum * mul_sum) >> shg_sum;
    if ( pa != 0 )
    {
        pa = 255 / pa;
        pixels[yi]   = ((r_sum * mul_sum) >> shg_sum) * pa;
        pixels[yi+1] = ((g_sum * mul_sum) >> shg_sum) * pa;
        pixels[yi+2] = ((b_sum * mul_sum) >> shg_sum) * pa;
    } else {
        pixels[yi] = pixels[yi+1] = pixels[yi+2] = 0;
    }

    r_sum -= r_out_sum;
    g_sum -= g_out_sum;
    b_sum -= b_out_sum;
    a_sum -= a_out_sum;

    r_out_sum -= stackIn.r;
    g_out_sum -= stackIn.g;
    b_out_sum -= stackIn.b;
    a_out_sum -= stackIn.a;

    p =  ( yw + ( ( p = x + radius + 1 ) < widthMinus1 ? p : widthMinus1 ) ) << 2;

    r_in_sum += ( stackIn.r = pixels[p]);
    g_in_sum += ( stackIn.g = pixels[p+1]);
    b_in_sum += ( stackIn.b = pixels[p+2]);
    a_in_sum += ( stackIn.a = pixels[p+3]);

    r_sum += r_in_sum;
    g_sum += g_in_sum;
    b_sum += b_in_sum;
    a_sum += a_in_sum;

    stackIn = stackIn.next;

    r_out_sum += ( pr = stackOut.r );
    g_out_sum += ( pg = stackOut.g );
    b_out_sum += ( pb = stackOut.b );
    a_out_sum += ( pa = stackOut.a );

    r_in_sum -= pr;
    g_in_sum -= pg;
    b_in_sum -= pb;
    a_in_sum -= pa;

    stackOut = stackOut.next;

    yi += 4;
}
yw += width;

}

for ( x = 0; x < width; x++ ) {

g_in_sum = b_in_sum = a_in_sum = r_in_sum = g_sum = b_sum = a_sum = r_sum = 0;

yi = x << 2;
r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1]);
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2]);
a_out_sum = radiusPlus1 * ( pa = pixels[yi+3]);

r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
a_sum += sumFactor * pa;

stack = stackStart;

for( i = 0; i < radiusPlus1; i++ )
{
    stack.r = pr;
    stack.g = pg;
    stack.b = pb;
    stack.a = pa;
    stack = stack.next;
}

yp = width;

for( i = 1; i <= radius; i++ )
{
    yi = ( yp + x ) << 2;

    r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
    g_sum += ( stack.g = ( pg = pixels[yi+1])) * rbs;
    b_sum += ( stack.b = ( pb = pixels[yi+2])) * rbs;
    a_sum += ( stack.a = ( pa = pixels[yi+3])) * rbs;

    r_in_sum += pr;
    g_in_sum += pg;
    b_in_sum += pb;
    a_in_sum += pa;

    stack = stack.next;

    if( i < heightMinus1 )
    {
        yp += width;
    }
}

yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y < height; y++ )
{
    p = yi << 2;
    pixels[p+3] = pa = (a_sum * mul_sum) >> shg_sum;
    if ( pa > 0 )
    {
        pa = 255 / pa;
        pixels[p]   = ((r_sum * mul_sum) >> shg_sum ) * pa;
        pixels[p+1] = ((g_sum * mul_sum) >> shg_sum ) * pa;
        pixels[p+2] = ((b_sum * mul_sum) >> shg_sum ) * pa;
    } else {
        pixels[p] = pixels[p+1] = pixels[p+2] = 0;
    }

    r_sum -= r_out_sum;
    g_sum -= g_out_sum;
    b_sum -= b_out_sum;
    a_sum -= a_out_sum;

    r_out_sum -= stackIn.r;
    g_out_sum -= stackIn.g;
    b_out_sum -= stackIn.b;
    a_out_sum -= stackIn.a;

    p = ( x + (( ( p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1 ) * width )) << 2;

    r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
    g_sum += ( g_in_sum += ( stackIn.g = pixels[p+1]));
    b_sum += ( b_in_sum += ( stackIn.b = pixels[p+2]));
    a_sum += ( a_in_sum += ( stackIn.a = pixels[p+3]));

    stackIn = stackIn.next;

    r_out_sum += ( pr = stackOut.r );
    g_out_sum += ( pg = stackOut.g );
    b_out_sum += ( pb = stackOut.b );
    a_out_sum += ( pa = stackOut.a );

    r_in_sum -= pr;
    g_in_sum -= pg;
    b_in_sum -= pb;
    a_in_sum -= pa;

    stackOut = stackOut.next;

    yi += width;
}

}

context.putImageData( imageData, top_x, top_y );

} function stackBlurCanvasRGB( id, top_x, top_y, width, height, radius ) { if ( isNaN(radius) || radius < 1 ) return; radius |= 0;

var canvas = document.getElementById( id ); var context = canvas.getContext("2d"); var imageData;

try { try {

imageData = context.getImageData( top_x, top_y, width, height );

} catch(e) {

// NOTE: this part is supposedly only needed if you want to work with local files
// so it might be okay to remove the whole try/catch block and just use
// imageData = context.getImageData( top_x, top_y, width, height );
try {
    netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
    imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
    alert("Cannot access local image");
    throw new Error("unable to access local image data: " + e);
    return;
}

} } catch(e) { alert("Cannot access image"); throw new Error("unable to access image data: " + e); }

var pixels = imageData.data;

var x, y, i, p, yp, yi, yw, r_sum, g_sum, b_sum, r_out_sum, g_out_sum, b_out_sum, r_in_sum, g_in_sum, b_in_sum, pr, pg, pb, rbs;

var div = radius + radius + 1; var w4 = width << 2; var widthMinus1 = width - 1; var heightMinus1 = height - 1; var radiusPlus1 = radius + 1; var sumFactor = radiusPlus1 * ( radiusPlus1 + 1 ) / 2;

var stackStart = new BlurStack(); var stack = stackStart; for ( i = 1; i < div; i++ ) {

stack = stack.next = new BlurStack();
if ( i == radiusPlus1 ) var stackEnd = stack;

} stack.next = stackStart; var stackIn = null; var stackOut = null;

yw = yi = 0;

var mul_sum = mul_table[radius]; var shg_sum = shg_table[radius];

for ( y = 0; y < height; y++ ) {

r_in_sum = g_in_sum = b_in_sum = r_sum = g_sum = b_sum = 0;

r_out_sum = radiusPlus1 * ( pr = pixels[yi] );
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1] );
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2] );

r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;

stack = stackStart;

for( i = 0; i < radiusPlus1; i++ )
{
    stack.r = pr;
    stack.g = pg;
    stack.b = pb;
    stack = stack.next;
}

for( i = 1; i < radiusPlus1; i++ )
{
    p = yi + (( widthMinus1 < i ? widthMinus1 : i ) << 2 );
    r_sum += ( stack.r = ( pr = pixels[p])) * ( rbs = radiusPlus1 - i );
    g_sum += ( stack.g = ( pg = pixels[p+1])) * rbs;
    b_sum += ( stack.b = ( pb = pixels[p+2])) * rbs;

    r_in_sum += pr;
    g_in_sum += pg;
    b_in_sum += pb;

    stack = stack.next;
}

stackIn = stackStart;
stackOut = stackEnd;
for ( x = 0; x < width; x++ )
{
    pixels[yi]   = (r_sum * mul_sum) >> shg_sum;
    pixels[yi+1] = (g_sum * mul_sum) >> shg_sum;
    pixels[yi+2] = (b_sum * mul_sum) >> shg_sum;

    r_sum -= r_out_sum;
    g_sum -= g_out_sum;
    b_sum -= b_out_sum;

    r_out_sum -= stackIn.r;
    g_out_sum -= stackIn.g;
    b_out_sum -= stackIn.b;

    p =  ( yw + ( ( p = x + radius + 1 ) < widthMinus1 ? p : widthMinus1 ) ) << 2;

    r_in_sum += ( stackIn.r = pixels[p]);
    g_in_sum += ( stackIn.g = pixels[p+1]);
    b_in_sum += ( stackIn.b = pixels[p+2]);

    r_sum += r_in_sum;
    g_sum += g_in_sum;
    b_sum += b_in_sum;

    stackIn = stackIn.next;

    r_out_sum += ( pr = stackOut.r );
    g_out_sum += ( pg = stackOut.g );
    b_out_sum += ( pb = stackOut.b );

    r_in_sum -= pr;
    g_in_sum -= pg;
    b_in_sum -= pb;

    stackOut = stackOut.next;

    yi += 4;
}
yw += width;

}

for ( x = 0; x < width; x++ ) {

g_in_sum = b_in_sum = r_in_sum = g_sum = b_sum = r_sum = 0;

yi = x << 2;
r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1]);
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2]);

r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;

stack = stackStart;

for( i = 0; i < radiusPlus1; i++ )
{
    stack.r = pr;
    stack.g = pg;
    stack.b = pb;
    stack = stack.next;
}

yp = width;

for( i = 1; i <= radius; i++ )
{
    yi = ( yp + x ) << 2;

    r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
    g_sum += ( stack.g = ( pg = pixels[yi+1])) * rbs;
    b_sum += ( stack.b = ( pb = pixels[yi+2])) * rbs;

    r_in_sum += pr;
    g_in_sum += pg;
    b_in_sum += pb;

    stack = stack.next;

    if( i < heightMinus1 )
    {
        yp += width;
    }
}

yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y < height; y++ )
{
    p = yi << 2;
    pixels[p]   = (r_sum * mul_sum) >> shg_sum;
    pixels[p+1] = (g_sum * mul_sum) >> shg_sum;
    pixels[p+2] = (b_sum * mul_sum) >> shg_sum;

    r_sum -= r_out_sum;
    g_sum -= g_out_sum;
    b_sum -= b_out_sum;

    r_out_sum -= stackIn.r;
    g_out_sum -= stackIn.g;
    b_out_sum -= stackIn.b;

    p = ( x + (( ( p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1 ) * width )) << 2;

    r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
    g_sum += ( g_in_sum += ( stackIn.g = pixels[p+1]));
    b_sum += ( b_in_sum += ( stackIn.b = pixels[p+2]));

    stackIn = stackIn.next;

    r_out_sum += ( pr = stackOut.r );
    g_out_sum += ( pg = stackOut.g );
    b_out_sum += ( pb = stackOut.b );

    r_in_sum -= pr;
    g_in_sum -= pg;
    b_in_sum -= pb;

    stackOut = stackOut.next;

    yi += width;
}

}

context.putImageData( imageData, top_x, top_y );

} function BlurStack() { this.r = 0; this.g = 0; this.b = 0; this.a = 0; this.next = null; }

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Quelle est la première lettre du mot lekk ?