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stackblur.go
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stackblur.go
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// Go implementation of StackBlur algorithm described here:
// http://incubator.quasimondo.com/processing/fast_blur_deluxe.php
package caire
import (
"image"
)
type blurstack struct {
r, g, b, a uint32
next *blurstack
}
var mul_table []uint32 = []uint32{
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 []uint32 = []uint32{
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,
}
func (bs *blurstack) NewBlurStack() *blurstack {
return &blurstack{bs.r, bs.g, bs.b, bs.a, bs.next}
}
func Stackblur(img *image.NRGBA, width, height, radius uint32) *image.NRGBA {
var stackEnd, stackIn, stackOut *blurstack
var (
div, widthMinus1, heightMinus1, radiusPlus1, sumFactor uint32
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 uint32
)
div = radius + radius + 1
widthMinus1 = width - 1
heightMinus1 = height - 1
radiusPlus1 = radius + 1
sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2
bs := blurstack{}
stackStart := bs.NewBlurStack()
stack := stackStart
for i = 1; i < div; i++ {
stack.next = bs.NewBlurStack()
stack = stack.next
if i == radiusPlus1 {
stackEnd = stack
}
}
stack.next = stackStart
mul_sum := mul_table[radius]
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, 0, 0, 0, 0, 0, 0, 0
pr = uint32(img.Pix[yi])
pg = uint32(img.Pix[yi+1])
pb = uint32(img.Pix[yi+2])
pa = uint32(img.Pix[yi+3])
r_out_sum = radiusPlus1 * pr
g_out_sum = radiusPlus1 * pg
b_out_sum = radiusPlus1 * pb
a_out_sum = radiusPlus1 * pa
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++ {
var diff uint32
if widthMinus1 < i {
diff = widthMinus1
} else {
diff = i
}
p = yi + (diff << 2)
pr = uint32(img.Pix[p])
pg = uint32(img.Pix[p+1])
pb = uint32(img.Pix[p+2])
pa = uint32(img.Pix[p+3])
stack.r = pr
stack.g = pg
stack.b = pb
stack.a = pa
r_sum += stack.r * (radiusPlus1 - i)
g_sum += stack.g * (radiusPlus1 - i)
b_sum += stack.b * (radiusPlus1 - i)
a_sum += stack.a * (radiusPlus1 - i)
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++ {
pa = (a_sum * mul_sum) >> shg_sum
img.Pix[yi+3] = uint8(pa)
if pa != 0 {
pa = 255 / pa
img.Pix[yi] = uint8((r_sum * mul_sum) >> shg_sum)
img.Pix[yi+1] = uint8((g_sum * mul_sum) >> shg_sum)
img.Pix[yi+2] = uint8((b_sum * mul_sum) >> shg_sum)
} else {
img.Pix[yi] = 0
img.Pix[yi+1] = 0
img.Pix[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 = x + radius + 1
if p > widthMinus1 {
p = widthMinus1
}
p = (yw + p) << 2
stackIn.r = uint32(img.Pix[p])
stackIn.g = uint32(img.Pix[p+1])
stackIn.b = uint32(img.Pix[p+2])
stackIn.a = uint32(img.Pix[p+3])
r_in_sum += stackIn.r
g_in_sum += stackIn.g
b_in_sum += stackIn.b
a_in_sum += stackIn.a
r_sum += r_in_sum
g_sum += g_in_sum
b_sum += b_in_sum
a_sum += a_in_sum
stackIn = stackIn.next
pr = stackOut.r
pg = stackOut.g
pb = stackOut.b
pa = stackOut.a
r_out_sum += pr
g_out_sum += pg
b_out_sum += pb
a_out_sum += pa
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++ {
r_in_sum, g_in_sum, b_in_sum, a_in_sum, r_sum, g_sum, b_sum, a_sum = 0, 0, 0, 0, 0, 0, 0, 0
yi = x << 2
pr = uint32(img.Pix[yi])
pg = uint32(img.Pix[yi+1])
pb = uint32(img.Pix[yi+2])
pa = uint32(img.Pix[yi+3])
r_out_sum = radiusPlus1 * pr
g_out_sum = radiusPlus1 * pg
b_out_sum = radiusPlus1 * pb
a_out_sum = radiusPlus1 * pa
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
pr = uint32(img.Pix[yi])
pg = uint32(img.Pix[yi+1])
pb = uint32(img.Pix[yi+2])
pa = uint32(img.Pix[yi+3])
stack.r = pr
stack.g = pg
stack.b = pb
stack.a = pa
r_sum += stack.r * (radiusPlus1 - i)
g_sum += stack.g * (radiusPlus1 - i)
b_sum += stack.b * (radiusPlus1 - i)
a_sum += stack.a * (radiusPlus1 - i)
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
pa = (a_sum * mul_sum) >> shg_sum
img.Pix[p+3] = uint8(pa)
if pa > 0 {
pa = 255 / pa
img.Pix[p] = uint8((r_sum * mul_sum) >> shg_sum)
img.Pix[p+1] = uint8((g_sum * mul_sum) >> shg_sum)
img.Pix[p+2] = uint8((b_sum * mul_sum) >> shg_sum)
} else {
img.Pix[p] = 0
img.Pix[p+1] = 0
img.Pix[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 = y + radiusPlus1
if p > heightMinus1 {
p = heightMinus1
}
p = (x + (p * width)) << 2
stackIn.r = uint32(img.Pix[p])
stackIn.g = uint32(img.Pix[p+1])
stackIn.b = uint32(img.Pix[p+2])
stackIn.a = uint32(img.Pix[p+3])
r_in_sum += stackIn.r
g_in_sum += stackIn.g
b_in_sum += stackIn.b
a_in_sum += stackIn.a
r_sum += r_in_sum
g_sum += g_in_sum
b_sum += b_in_sum
a_sum += a_in_sum
stackIn = stackIn.next
pr = stackOut.r
pg = stackOut.g
pb = stackOut.b
pa = stackOut.a
r_out_sum += pr
g_out_sum += pg
b_out_sum += pb
a_out_sum += pa
r_in_sum -= pr
g_in_sum -= pg
b_in_sum -= pb
a_in_sum -= pa
stackOut = stackOut.next
yi += width
}
}
return img
}