-
Notifications
You must be signed in to change notification settings - Fork 0
/
histogram.go
55 lines (46 loc) · 1.02 KB
/
histogram.go
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
package main
import (
"fmt"
"image"
"image/jpeg"
"image/png"
"os"
"path/filepath"
)
const dimm = 16
type hist [dimm][dimm][dimm]int
type histrec struct {
h *hist
n string
}
func histogram(name string) (*histrec, error) {
fd, err := os.Open(name)
if err != nil {
return nil, fmt.Errorf("Cannot open file: %v", name)
}
defer fd.Close()
var img image.Image
switch filepath.Ext(name) {
case ".jpg", ".jpeg", ".JPG":
img, err = jpeg.Decode(fd)
if err != nil {
return nil, fmt.Errorf("Error at decoding: %v", name)
}
case ".png":
img, err = png.Decode(fd)
if err != nil {
return nil, fmt.Errorf("Error at decoding: %v", name)
}
default:
return nil, fmt.Errorf("Cannot process %v", name)
}
var histogram hist
boundaries := img.Bounds()
for i := boundaries.Min.X; i < boundaries.Max.X; i++ {
for j := boundaries.Min.Y; j < boundaries.Max.Y; j++ {
r, g, b, _ := img.At(i, j).RGBA()
histogram[r/(65536/dimm)][g/(65536/dimm)][b/(65536/dimm)]++
}
}
return &histrec{h: &histogram, n: name}, nil
}