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
|
package preproc
// TODO: add minimum size variable (default ~30%?)
// TODO: switch to an interface rather than integralimg.I
import (
"errors"
"fmt"
"image"
"image/color"
"image/draw"
_ "image/jpeg"
"image/png"
"os"
"rescribe.xyz/go.git/integralimg"
)
// returns the proportion of the given window that is black pixels
func proportion(i integralimg.I, x int, size int) float64 {
w := i.GetVerticalWindow(x, size)
return w.Proportion()
}
// findbestedge goes through every vertical line from x to x+w to
// find the one with the lowest proportion of black pixels.
func findbestedge(img integralimg.I, x int, w int) int {
var bestx int
var best float64
if w == 1 {
return x
}
right := x + w
for ; x < right; x++ {
prop := proportion(img, x, 1)
if prop > best {
best = prop
bestx = x
}
}
return bestx
}
// findedges finds the edges of the main content, by moving a window of wsize
// from near the middle of the image to the left and right, stopping when it reaches
// a point at which there is a lower proportion of black pixels than thresh.
func findedges(img integralimg.I, wsize int, thresh float64) (int, int) {
maxx := len(img[0]) - 1
var lowedge, highedge int = 0, maxx
// don't start at the middle, as this will fail for 2 column layouts,
// start 10% left or right of the middle
notcentre := maxx / 10
for x := maxx / 2 + notcentre; x < maxx-wsize; x++ {
if proportion(img, x, wsize) <= thresh {
highedge = findbestedge(img, x, wsize)
break
}
}
for x := maxx / 2 - notcentre; x > 0; x-- {
if proportion(img, x, wsize) <= thresh {
lowedge = findbestedge(img, x, wsize)
break
}
}
return lowedge, highedge
}
// wipesides fills the sections of image not within the boundaries
// of lowedge and highedge with white
func wipesides(img *image.Gray, lowedge int, highedge int) *image.Gray {
b := img.Bounds()
new := image.NewGray(b)
// set left edge white
for x := b.Min.X; x < lowedge; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
new.SetGray(x, y, color.Gray{255})
}
}
// copy middle
for x := lowedge; x < highedge; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
new.SetGray(x, y, img.GrayAt(x, y))
}
}
// set right edge white
for x := highedge; x < b.Max.X; x++ {
for y := b.Min.Y; y < b.Max.Y; y++ {
new.SetGray(x, y, color.Gray{255})
}
}
return new
}
// toonarrow checks whether the area between lowedge and highedge is
// less than min % of the total image width
func toonarrow(img *image.Gray, lowedge int, highedge int, min int) bool {
b := img.Bounds()
imgw := b.Max.X - b.Min.X
wipew := highedge - lowedge
if float64(wipew) / float64(imgw) * 100 < float64(min) {
return true
}
return false
}
// Wipe fills the sections of image which fall outside the content
// area with white, providing the content area is above min %
func Wipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray {
integral := integralimg.ToIntegralImg(img)
lowedge, highedge := findedges(integral, wsize, thresh)
if toonarrow(img, lowedge, highedge, min) {
return img
}
return wipesides(img, lowedge, highedge)
}
// WipeFile wipes an image file, filling the sections of the image
// which fall outside the content area with white, providing the
// content area is above min %.
// inPath: path of the input image.
// outPath: path to save the output image.
// wsize: window size for wipe algorithm.
// thresh: threshold for wipe algorithm.
// min: minimum % of content area width to consider valid.
func WipeFile(inPath string, outPath string, wsize int, thresh float64, min int) error {
f, err := os.Open(inPath)
defer f.Close()
if err != nil {
return errors.New(fmt.Sprintf("Could not open file %s: %v", inPath, err))
}
img, _, err := image.Decode(f)
if err != nil {
return errors.New(fmt.Sprintf("Could not decode image: %v", err))
}
b := img.Bounds()
gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
draw.Draw(gray, b, img, b.Min, draw.Src)
clean := Wipe(gray, wsize, thresh, min)
f, err = os.Create(outPath)
if err != nil {
return errors.New(fmt.Sprintf("Could not create file %s: %v", outPath, err))
}
defer f.Close()
err = png.Encode(f, clean)
if err != nil {
return errors.New(fmt.Sprintf("Could not encode image: %v", err))
}
return nil
}
|
