1 files changed, 123 insertions, 0 deletions
diff --git a/distill.go b/distill.go
new file mode 100644
index 0000000..b998eca
--- /dev/null
+++ b/distill.go
@@ -0,0 +1,123 @@
+package main
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"math"
+	"os"
+
+	"github.com/EdlinOrg/prominentcolor"
+	"github.com/anthonynsimon/bild/clone"
+	"github.com/anthonynsimon/bild/imgio"
+	colorful "github.com/lucasb-eyer/go-colorful"
+)
+
+var (
+	blockSize          = 50
+	maxDominantColours = 8
+)
+
+func main() {
+	img, err := imgio.Open("starry-night.jpg")
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	source := clone.AsRGBA(img)
+
+	prominentColours, err := extractProminentColours(source)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	for x := 0; x < source.Bounds().Max.X; x += blockSize {
+		for y := 0; y < source.Bounds().Max.Y; y += blockSize {
+			var (
+				block          = source.SubImage(image.Rect(x, y, x+blockSize, y+blockSize))
+				avgBlockColour = calculateAverageBlockColour(block)
+				nearestColour  = nearestColour(avgBlockColour, prominentColours)
+			)
+			fillBlock(x, y, blockSize, nearestColour, source)
+		}
+	}
+
+	if err := imgio.Save("out.png", source, imgio.PNGEncoder()); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}
+
+func fillBlock(blockX, blockY, blockSize int, fillColour color.Color, image *image.RGBA) {
+	for x := blockX; x <= blockX+blockSize; x++ {
+		for y := blockY; y <= blockY+blockSize; y++ {
+			image.Set(x, y, fillColour)
+		}
+	}
+}
+
+func extractProminentColours(image image.Image) ([]colorful.Color, error) {
+	var prominentcolors []colorful.Color
+	sampleWidth := uint(image.Bounds().Max.X / 2)
+
+	colours, err := prominentcolor.KmeansWithAll(maxDominantColours, image, prominentcolor.ArgumentNoCropping, sampleWidth, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// convert prominentcolor.ColourItem to colourful.Color
+	for _, colourItem := range colours {
+		golangColor := color.RGBA{
+			uint8(colourItem.Color.R),
+			uint8(colourItem.Color.G),
+			uint8(colourItem.Color.B),
+			255}
+
+		colourfulColor, _ := colorful.MakeColor(golangColor)
+		prominentcolors = append(prominentcolors, colourfulColor)
+	}
+
+	return prominentcolors, nil
+}
+
+func nearestColour(colour color.Color, possibleColours []colorful.Color) color.Color {
+	var (
+		nearestColour   color.Color
+		closestDistance = math.MaxFloat64
+	)
+
+	sourceColour, _ := colorful.MakeColor(colour)
+
+	for _, possibleColour := range possibleColours {
+		var distance = sourceColour.DistanceCIEDE2000(possibleColour)
+		if distance < closestDistance {
+			closestDistance = distance
+			nearestColour = possibleColour
+		}
+	}
+	return nearestColour
+}
+
+func calculateAverageBlockColour(block image.Image) color.Color {
+	var avgR, avgG, avgB uint32
+
+	bounds := block.Bounds()
+
+	for x := bounds.Min.X; x < bounds.Max.X; x++ {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			r, g, b, _ := block.At(x, y).RGBA()
+			avgR += r
+			avgG += g
+			avgB += b
+		}
+	}
+
+	totalPixels := uint32(bounds.Dy() * bounds.Dx())
+	avgR /= totalPixels
+	avgG /= totalPixels
+	avgB /= totalPixels
+
+	return color.RGBA{uint8(avgR / 0x101), uint8(avgG / 0x101), uint8(avgB / 0x101), 255}
+}