Web Front-endJS TutorialImage blur algorithm code sharing implemented in JavaScript_javascript skillsImage blur algorithm code sharing implemented in JavaScript_javascript skills
HTML5 blurred images need to be used in the project. In the past, GDI was used. There are ready-made components in GDI to implement it. How to implement it in HTML5?
1.createImageData()
2.getImageData()
3.putImageData()
The above three functions can be implemented. For usage and secrets, please go to Baidu yourself. I will not repeat the description. Doesn't make much sense.
The following is the JS that implements the fuzzy algorithm. In fact, there is another 2B level algorithm which is the distribution matrix, which increases the efficiency many times, but the effect is very poor and the feathering effect is not strong.
Implementation code:
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 ];
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
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 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) {
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 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 {
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 {
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 {
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack.a = pa;
stack = stack.next;
}
for( i = 1; i {
p = yi (( widthMinus1 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 {
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 )
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 {
g_in_sum = b_in_sum = a_in_sum = r_in_sum = g_sum = b_sum = a_sum = r_sum = 0;
yi = x 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 {
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack.a = pa;
stack = stack.next;
}
yp = width;
for( i = 1; i {
yi = ( yp x )
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 {
yp = width;
}
}
yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y {
p = yi 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)
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 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) {
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 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 {
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 {
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 {
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack = stack.next;
}
for( i = 1; i {
p = yi + (( widthMinus1 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 {
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 )
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 {
g_in_sum = b_in_sum = r_in_sum = g_sum = b_sum = r_sum = 0;
yi = x 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 {
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack = stack.next;
}
yp = width;
for( i = 1; i {
yi = ( yp x )
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 {
yp = width;
}
}
yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y {
p = yi 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)
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;
}
使用方法：
stackBlurCanvasRGBA( targetCanvasID, top_x, top_y, width, height, radius );
stackBlurCanvasRGB( targetCanvasID, top_x, top_y, width, height, radius );
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