Usage: stackBlurImage( sourceImageID, targetCanvasID, radius, blurAlphaChannel );
or: stackBlurCanvasRGBA( targetCanvasID, top_x, top_y, width, height, radius );
or: stackBlurCanvasRGB( targetCanvasID, top_x, top_y, width, height, radius );
Thank you to Mike Shaver
for fixing my first slider implementation.
Thanks to Michael Deal for noticing and fixing the ARGB/RGBA mixup and the pre-multiplied alpha bug.
For some slightly faster box blurs which do not look as good though check out my Superfast Blur
, StackBox Blur
and Integral Image Blur
For a speed comparison of all 4 blur algorithms check this jsPerf test