/**
* Returns the image that is generated from the given disjoint set.
* If the randomColors parameter is true, a random color will be assigned
* to each segment of the image. If it's false, then the mean color of
* the pixels in the original image will be assigned to each segment.
*/
func imageFromDisjointSet(set *disjointset.DisjointSet,
originalimg image.Image, randomColors bool) image.Image {
resultimg := image.NewNRGBA(originalimg.Bounds())
width := originalimg.Bounds().Max.X
height := originalimg.Bounds().Max.Y
meanColors := make([]ImageColor, width*height, width*height)
if randomColors {
for u := 0; u < width*height; u++ {
meanColors[u] = randomColor()
}
} else {
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
c := set.Find(x + y*width)
r, g, b, _ := originalimg.At(x, y).RGBA()
meanColors[c].r += float32(r>>8) / float32(set.Size(c))
meanColors[c].g += float32(g>>8) / float32(set.Size(c))
meanColors[c].b += float32(b>>8) / float32(set.Size(c))
}
}
}
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
resultimg.Set(x, y, &meanColors[set.Find(x+y*width)])
}
}
return resultimg
}
/**
* Computes the threshold used by the GBS algorithm.
* T(c) = k/|c|
*/
func threshold(set *disjointset.DisjointSet, k float64, u int) float64 {
return k / float64(set.Size(u))
}