smartblur convolution experiment

1 files changed, 138 insertions, 0 deletions

diff --git a/smartblur.js b/smartblur.js
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+
+// http://asserttrue.blogspot.ca/2010/08/implementing-smart-blur-in-java.html
+SmartBlurFilter = function () {
+  var SENSITIVITY = 10
+  var REGION_SIZE = 5
+  var edge_zero_fill = true
+
+	var kx = -((REGION_SIZE/2)|0), ky = -((REGION_SIZE/2)|0), klen = REGION_SIZE*REGION_SIZE
+
+  var kernelArray = [
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1,
+    1,1,1,1,1,1,1,1,1
+  ]
+
+  var kernel = new Kernel(9, 9, kernelArray)
+  kernel.normalize()
+
+  function lerp(a,b,amt) {
+    return a + amt * (b - a);
+  }
+
+  function rmsError(src, i, size) {
+    var ave = 0;
+
+		var len = size*size, data = src.data
+
+		var ix, iy
+		var r,g,b,a
+		var w = src.width, h = src.height
+		ix = i%w
+		iy = (i/w)|0
+		it = i * 4
+		r = g = b = a = 0
+		for (var j = 0; j < klen; j++) {
+			jx = ix +  j%size + kx
+			jy = iy + ((j/size)|0) + ky
+			jt = 4 * (jx + jy*w)
+			if (0 > jx || jx > w || 0 > jy || jy > h) {
+				if (edge_zero_fill) {
+					continue
+				}
+				jt = it
+			}
+			r += data[jt]
+// 			g += data[jt+1]
+// 			b += data[jt+2]
+// 			a += data[jt+3]
+		}
+    r /= klen
+//     g /= klen
+//     b /= klen
+//     a /= klen
+
+    var diff = 0
+    var accumulator = 0
+
+		for (var j = 0; j < klen; j++) {
+			jx = ix +  j%size + kx
+			jy = iy + ((j/size)|0) + ky
+			jt = 4 * (jx + jy*w)
+			if (0 > jx || jx > w || 0 > jy || jy > h) {
+				if (edge_zero_fill) {
+					continue
+				}
+				jt = it
+			}
+			diff = data[ jt ] - ave
+			diff *= diff
+			accumulator += diff
+    }
+
+    var rms = accumulator / klen
+    rms = Math.sqrt(rms) / 255
+    return rms
+  }
+
+  function lerpPixel( src, dest, blur, i, amt) {
+  	dest[i]   = lerp(src[i],   blur[i],   amt)
+  	dest[i+1] = lerp(src[i+1], blur[i+1], amt)
+  	dest[i+2] = lerp(src[i+2], blur[i+2], amt)
+  	dest[i+3] = lerp(src[i+3], blur[i+3], amt)
+  }
+
+  function blurImage( src, dest, blur, sensitivity ) {
+    var newPixel = 0
+    var amt = 0
+    var size = REGION_SIZE
+		var w = src.width, rms
+
+		var srcData = src.data
+		var destData = dest.data
+		var blurData = blur.data
+    for (var i = 0, len = srcData.length/4; i < len; i++) {
+
+			rms = rmsError(src, i, size)
+
+//			amt = rms < sensitivity ? rms/sensitivity : 1.0
+			lerpPixel( srcData, destData, blurData, i*4, rms)
+    }
+    
+    return dest
+  }
+
+  this.blur = function (src_canvas, dest_canvas) {
+    var convolver = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
+
+    // clone image into target
+    if (! dest_canvas) dest_canvas = document.createElement("canvas")
+    var w = dest_canvas.width = src_canvas.width
+    var h = dest_canvas.height = src_canvas.height
+    var srcctx = src_canvas.getContext('2d')
+    var destctx = dest_canvas.getContext('2d')
+
+    destctx.drawImage(src_canvas, 0, 0);
+
+    // get source pixels
+    var src = srcctx.getImageData(0,0,w,h)
+    var dest = destctx.getImageData(0,0,w,h)
+
+    // blur the cloned image
+    dest = convolver.filter(src, dest);
+
+		destctx.putImageData(dest, 0,0)
+    var blurred = destctx.getImageData(0,0,w,h)
+    var dest = srcctx.getImageData(0,0,w,h)
+    dest = blurImage(src, dest, blurred, SENSITIVITY)
+		destctx.putImageData(dest, 0,0)
+
+    return dest_canvas
+  }
+}
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