/
image.go
145 lines (114 loc) · 3.17 KB
/
image.go
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package imgdedup
import (
"errors"
"fmt"
"image"
"math"
"os"
)
type Pictable [][][3]uint64
func newPictable(dx int, dy int) Pictable {
pic := make([][][3]uint64, dx) /* type declaration */
for i := range pic {
pic[i] = make([][3]uint64, dy) /* again the type? */
for j := range pic[i] {
pic[i][j] = [3]uint64{0, 0, 0}
}
}
return pic
}
type ImageInfo struct {
Data Pictable
Format string
Bounds image.Rectangle
Path string
Filesize uint64
}
func NewImageInfo(imgpath string, subdivisions uint) (*ImageInfo, error) {
file, err := os.Open(imgpath)
defer file.Close()
if err != nil {
return nil, err
}
img, ifmt, err := image.Decode(file)
if err != nil {
return nil, err
}
pict, err := pictableFromImage(img, subdivisions)
if err != nil {
return nil, err
}
fi, err := file.Stat()
if err != nil {
return nil, err
}
imginfo := &ImageInfo{
Data: pict,
Format: ifmt,
Bounds: img.Bounds(),
Path: imgpath,
Filesize: uint64(fi.Size()),
}
return imginfo, nil
}
func pictableFromImage(m image.Image, usize uint) (Pictable, error) {
bounds := m.Bounds()
size := int(usize)
avgdata := newPictable(size, size)
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
for x := bounds.Min.X; x < bounds.Max.X; x++ {
rX := int64(math.Floor((float64(x) / float64(bounds.Max.X)) * float64(size)))
rY := int64(math.Floor((float64(y) / float64(bounds.Max.Y)) * float64(size)))
r, g, b, _ := m.At(x, y).RGBA()
avgdata[rX][rY][0] += uint64((float32(r) / 65535) * 255)
avgdata[rX][rY][1] += uint64((float32(g) / 65535) * 255)
avgdata[rX][rY][2] += uint64((float32(b) / 65535) * 255)
}
}
divisor := uint64((bounds.Max.X / size) * (bounds.Max.Y / size))
if divisor == 0 {
return nil, fmt.Errorf("Image dimensions %d x %d invalid", bounds.Max.X, bounds.Max.Y)
}
for rX := 0; rX < size; rX++ {
for rY := 0; rY < size; rY++ {
avgdata[rX][rY][0] = avgdata[rX][rY][0] / divisor
avgdata[rX][rY][1] = avgdata[rX][rY][1] / divisor
avgdata[rX][rY][2] = avgdata[rX][rY][2] / divisor
}
}
return avgdata, nil
}
// ErrorDissimilarSubdivisions is returned on trying to compare ImageInfo's of different sizes
var ErrorDissimilarSubdivisions = errors.New("diff: cannot compare dissimilar subdivisions")
func DiffImageInfos(left *ImageInfo, right *ImageInfo) (uint64, error) {
return diffPictables(left.Data, right.Data)
}
func diffPictables(left Pictable, right Pictable) (uint64, error) {
if len(left) != len(right) {
return 0, ErrorDissimilarSubdivisions
}
subdivisions := len(left)
var xdiff uint64
for rX := 0; rX < subdivisions; rX++ {
for rY := 0; rY < subdivisions; rY++ {
aa := left[rX][rY]
bb := right[rX][rY]
xdiff += absdiff(absdiff(absdiff(aa[0], bb[0]), absdiff(aa[1], bb[1])), absdiff(aa[2], bb[2]))
}
}
return xdiff, nil
}
func DiffImages(left image.Image, right image.Image, subdivisions uint) (uint64, error) {
lp, err := pictableFromImage(left, subdivisions)
if err != nil {
return 0, err
}
rp, err := pictableFromImage(right, subdivisions)
if err != nil {
return 0, err
}
return diffPictables(lp, rp)
}
func absdiff(a uint64, b uint64) uint64 {
return uint64(math.Abs(float64(a) - float64(b)))
}