Dominant Image Color

dominant.go

package dominant

import (
	"fmt"
	"image"
	"image/color"

	"github.com/mdesenfants/gokmeans"
	"github.com/nfnt/resize"
)

func DominantImageColor(im image.Image, k int) color.NRGBA {
	im = resize.Thumbnail(64, 64, im, resize.Bilinear)
	rgba := imageToRGBA(im)
	size := rgba.Bounds().Size()
	w, h := size.X, size.Y
	var nodes []gokmeans.Node
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			c := rgba.RGBAAt(x, y)
			node := gokmeans.Node{float64(c.R), float64(c.G), float64(c.B)}
			nodes = append(nodes, node)
		}
	}
	ok, centroids := gokmeans.Train(nodes, k, 100)
	if !ok {
		return color.NRGBA{0, 0, 0, 255}
	}
	counts := make([]int, k)
	for _, node := range nodes {
		index := gokmeans.Nearest(node, centroids)
		counts[index]++
	}
	for i, centroid := range centroids {
		fmt.Println(centroid, counts[i])
	}
	bestIndex := 0
	bestCount := counts[0]
	for i, count := range counts {
		if count > bestCount {
			bestIndex = i
			bestCount = count
		}
	}
	centroid := centroids[bestIndex]
	r := uint8(centroid[0])
	g := uint8(centroid[1])
	b := uint8(centroid[2])
	return color.NRGBA{r, g, b, 255}
}