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-rw-r--r--integralimg.go40
-rw-r--r--integralimg_test.go5
2 files changed, 36 insertions, 9 deletions
diff --git a/integralimg.go b/integralimg.go
index 17d3332..a0cb565 100644
--- a/integralimg.go
+++ b/integralimg.go
@@ -28,22 +28,50 @@ func (i I) At(x, y int) color.Color {
return color.Gray{}
}
- var oldx, oldy, oldxy uint64
- oldx, oldy, oldxy = 0, 0, 0
+ var prevx, prevy, prevxy uint64
+ prevx, prevy, prevxy = 0, 0, 0
if x > 0 {
- oldx = i[y][x-1]
+ prevx = i[y][x-1]
}
if y > 0 {
- oldy = i[y-1][x]
+ prevy = i[y-1][x]
}
if x > 0 && y > 0 {
- oldxy = i[y-1][x-1]
+ prevxy = i[y-1][x-1]
}
- orig := i[y][x] + oldxy - oldx - oldy
+ orig := i[y][x] + prevxy - prevx - prevy
return color.Gray{uint8(orig)}
}
+func (i I) Set(x, y int, c color.Color) {
+ var prevx, prevy, prevxy uint64
+ prevx, prevy, prevxy = 0, 0, 0
+ if x > 0 {
+ prevx = i[y][x-1]
+ }
+ if y > 0 {
+ prevy = i[y-1][x]
+ }
+ if x > 0 && y > 0 {
+ prevxy = i[y-1][x-1]
+ }
+ gray := color.GrayModel.Convert(c).(color.Gray).Y
+ final := uint64(gray) + prevx + prevy - prevxy
+ i[y][x] = final
+}
+
+// NewImage returns a new Integral Image with the given bounds.
+func NewImage(r image.Rectangle) *I {
+ w, h := r.Dx(), r.Dy()
+ var rows I
+ for i := 0; i < h; i++ {
+ col := make([]uint64, w)
+ rows = append(rows, col)
+ }
+ return &rows
+}
+
// Sq contains an Integral Image and its Square
type WithSq struct {
Img I
diff --git a/integralimg_test.go b/integralimg_test.go
index 3bc8dd6..df97caa 100644
--- a/integralimg_test.go
+++ b/integralimg_test.go
@@ -23,10 +23,9 @@ func TestFromPNG(t *testing.T) {
t.Fatalf("Could not decode image: %v\n", err)
}
b := img.Bounds()
- gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
- draw.Draw(gray, b, img, b.Min, draw.Src)
- integral := ToIntegralImg(gray)
+ integral := NewImage(image.Rect(0, 0, b.Dx(), b.Dy()))
+ draw.Draw(integral, b, img, b.Min, draw.Src)
if !imgsequal(img, integral) {
t.Errorf("Read png image differs to integral\n")