1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
package imaging
import (
"image"
"math"
)
func gaussianBlurKernel(x, sigma float64) float64 {
return math.Exp(-(x*x)/(2*sigma*sigma)) / (sigma * math.Sqrt(2*math.Pi))
}
// Blur produces a blurred version of the image using a Gaussian function.
// Sigma parameter must be positive and indicates how much the image will be blurred.
//
// Usage example:
//
// dstImage := imaging.Blur(srcImage, 3.5)
//
func Blur(img image.Image, sigma float64) *image.NRGBA {
if sigma <= 0 {
// sigma parameter must be positive!
return Clone(img)
}
src := toNRGBA(img)
radius := int(math.Ceil(sigma * 3.0))
kernel := make([]float64, radius+1)
for i := 0; i <= radius; i++ {
kernel[i] = gaussianBlurKernel(float64(i), sigma)
}
var dst *image.NRGBA
dst = blurHorizontal(src, kernel)
dst = blurVertical(dst, kernel)
return dst
}
func blurHorizontal(src *image.NRGBA, kernel []float64) *image.NRGBA {
radius := len(kernel) - 1
width := src.Bounds().Max.X
height := src.Bounds().Max.Y
dst := image.NewNRGBA(image.Rect(0, 0, width, height))
parallel(width, func(partStart, partEnd int) {
for x := partStart; x < partEnd; x++ {
start := x - radius
if start < 0 {
start = 0
}
end := x + radius
if end > width-1 {
end = width - 1
}
weightSum := 0.0
for ix := start; ix <= end; ix++ {
weightSum += kernel[absint(x-ix)]
}
for y := 0; y < height; y++ {
r, g, b, a := 0.0, 0.0, 0.0, 0.0
for ix := start; ix <= end; ix++ {
weight := kernel[absint(x-ix)]
i := y*src.Stride + ix*4
wa := float64(src.Pix[i+3]) * weight
r += float64(src.Pix[i+0]) * wa
g += float64(src.Pix[i+1]) * wa
b += float64(src.Pix[i+2]) * wa
a += wa
}
r = math.Min(math.Max(r/a, 0.0), 255.0)
g = math.Min(math.Max(g/a, 0.0), 255.0)
b = math.Min(math.Max(b/a, 0.0), 255.0)
a = math.Min(math.Max(a/weightSum, 0.0), 255.0)
j := y*dst.Stride + x*4
dst.Pix[j+0] = uint8(r + 0.5)
dst.Pix[j+1] = uint8(g + 0.5)
dst.Pix[j+2] = uint8(b + 0.5)
dst.Pix[j+3] = uint8(a + 0.5)
}
}
})
return dst
}
func blurVertical(src *image.NRGBA, kernel []float64) *image.NRGBA {
radius := len(kernel) - 1
width := src.Bounds().Max.X
height := src.Bounds().Max.Y
dst := image.NewNRGBA(image.Rect(0, 0, width, height))
parallel(height, func(partStart, partEnd int) {
for y := partStart; y < partEnd; y++ {
start := y - radius
if start < 0 {
start = 0
}
end := y + radius
if end > height-1 {
end = height - 1
}
weightSum := 0.0
for iy := start; iy <= end; iy++ {
weightSum += kernel[absint(y-iy)]
}
for x := 0; x < width; x++ {
r, g, b, a := 0.0, 0.0, 0.0, 0.0
for iy := start; iy <= end; iy++ {
weight := kernel[absint(y-iy)]
i := iy*src.Stride + x*4
wa := float64(src.Pix[i+3]) * weight
r += float64(src.Pix[i+0]) * wa
g += float64(src.Pix[i+1]) * wa
b += float64(src.Pix[i+2]) * wa
a += wa
}
r = math.Min(math.Max(r/a, 0.0), 255.0)
g = math.Min(math.Max(g/a, 0.0), 255.0)
b = math.Min(math.Max(b/a, 0.0), 255.0)
a = math.Min(math.Max(a/weightSum, 0.0), 255.0)
j := y*dst.Stride + x*4
dst.Pix[j+0] = uint8(r + 0.5)
dst.Pix[j+1] = uint8(g + 0.5)
dst.Pix[j+2] = uint8(b + 0.5)
dst.Pix[j+3] = uint8(a + 0.5)
}
}
})
return dst
}
// Sharpen produces a sharpened version of the image.
// Sigma parameter must be positive and indicates how much the image will be sharpened.
//
// Usage example:
//
// dstImage := imaging.Sharpen(srcImage, 3.5)
//
func Sharpen(img image.Image, sigma float64) *image.NRGBA {
if sigma <= 0 {
// sigma parameter must be positive!
return Clone(img)
}
src := toNRGBA(img)
blurred := Blur(img, sigma)
width := src.Bounds().Max.X
height := src.Bounds().Max.Y
dst := image.NewNRGBA(image.Rect(0, 0, width, height))
parallel(height, func(partStart, partEnd int) {
for y := partStart; y < partEnd; y++ {
for x := 0; x < width; x++ {
i := y*src.Stride + x*4
for j := 0; j < 4; j++ {
k := i + j
val := int(src.Pix[k]) + (int(src.Pix[k]) - int(blurred.Pix[k]))
if val < 0 {
val = 0
} else if val > 255 {
val = 255
}
dst.Pix[k] = uint8(val)
}
}
}
})
return dst
}
|
