feat: Add optimal seam finding

imageutils/image_analyzer.go

@@ -16,25 +16,25 @@ func getEnergy(
 	secondPixel color.Color,
 ) float64 {
 	firstRed, firstGreen, firstBlue, _ := firstPixel.RGBA()
-	firstRed, firstGreen, firstBlue = firstRed >> 8, firstGreen >> 8, firstBlue >> 8
+	firstRed, firstGreen, firstBlue = firstRed>>8, firstGreen>>8, firstBlue>>8
 	secondRed, secondGreen, secondBlue, _ := secondPixel.RGBA()
-	secondRed, secondGreen, secondBlue = secondRed >> 8, secondGreen >> 8, secondBlue >> 8
+	secondRed, secondGreen, secondBlue = secondRed>>8, secondGreen>>8, secondBlue>>8
 
 	return float64(
-		math.Abs(float64(firstRed - secondRed)) +
-		math.Abs(float64(firstGreen - secondGreen)) +
-		math.Abs(float64(firstBlue - secondBlue)),
+		math.Abs(float64(firstRed-secondRed)) +
+			math.Abs(float64(firstGreen-secondGreen)) +
+			math.Abs(float64(firstBlue-secondBlue)),
 	)
 }
 
 // Calculate a 0-255 grayscale value from a color using the NTSC formula
 func colorToGray(color color.Color) float64 {
 	red, green, blue, _ := color.RGBA()
-	red, green, blue = red >> 8, green >> 8, blue >> 8
+	red, green, blue = red>>8, green>>8, blue>>8
 
-	return 0.299 * float64(red) +
-		0.587 * float64(green) +
-		0.114 * float64(blue)
+	return 0.299*float64(red) +
+		0.587*float64(green) +
+		0.114*float64(blue)
 }
 
 func sumSlice(slice []float64) float64 {
@@ -48,35 +48,35 @@ func sumSlice(slice []float64) float64 {
 func (image *ImageAnalyzer) CalculateEnergyAt(x int, y int) float64 {
 	northPixel := image.At(
 		x,
-		max(0, y - 1),
+		max(0, y-1),
 	)
 	northEastPixel := image.At(
-		min(image.Bounds().Max.X, x + 1),
-		max(0, y - 1),
+		min(image.Bounds().Max.X, x+1),
+		max(0, y-1),
 	)
 	eastPixel := image.At(
-		min(image.Bounds().Max.X, x + 1),
+		min(image.Bounds().Max.X, x+1),
 		y,
 	)
 	southEastPixel := image.At(
-		min(image.Bounds().Max.X, x + 1),
-		min(image.Bounds().Max.Y, y + 1),
+		min(image.Bounds().Max.X, x+1),
+		min(image.Bounds().Max.Y, y+1),
 	)
 	southPixel := image.At(
 		x,
-		min(image.Bounds().Max.Y, y + 1),
+		min(image.Bounds().Max.Y, y+1),
 	)
 	southWestPixel := image.At(
-		max(0, x - 1),
-		min(image.Bounds().Max.Y, y + 1),
+		max(0, x-1),
+		min(image.Bounds().Max.Y, y+1),
 	)
 	westPixel := image.At(
-		max(0, x - 1),
+		max(0, x-1),
 		y,
 	)
 	northWestPixel := image.At(
-		max(0, x - 1),
-		max(0, y - 1),
+		max(0, x-1),
+		max(0, y-1),
 	)
 
 	thisPixel := image.At(

imageutils/seam.go

@@ -0,0 +1,142 @@
+package imageutils
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+)
+
+type SeamNode struct {
+	// if null = root node
+	PreviosNode      *SeamNode
+	X                int
+	Y                int
+	ThisCost         uint
+	AccumulatedCosts uint
+}
+
+func (s SeamNode) String() string {
+	if s.PreviosNode == nil {
+		return fmt.Sprintf("(%d, %d; %d)", s.X, s.Y, s.AccumulatedCosts)
+	} else {
+		return fmt.Sprintf("(%d, %d; %d) -> %v", s.X, s.Y, s.AccumulatedCosts, s.PreviosNode)
+	}
+}
+
+func (s SeamNode) WriteSeamChainToImage(img *image.RGBA) {
+	img.Set(
+		s.X,
+		s.Y,
+		color.RGBA{255, 0, 0, 1},
+	)
+
+	if s.PreviosNode != nil {
+		s.PreviosNode.WriteSeamChainToImage(img)
+	}
+}
+
+type Position struct {
+	X int
+	Y int
+}
+
+type ImageSeams struct {
+	// map of <y row> -> SeamNodes
+	Seams [][]*SeamNode
+}
+
+func NewImageSeams() ImageSeams {
+	return ImageSeams{
+		Seams: make([][]*SeamNode, 0),
+	}
+}
+
+func (i *ImageSeams) CreateSeamsFromRectangle(rect image.Rectangle) {
+	for y := range rect.Max.Y {
+		rowSeams := make([]*SeamNode, 0)
+
+		for x := range rect.Max.X {
+			rowSeams = append(rowSeams, &SeamNode{
+				X: x,
+				Y: y,
+			})
+		}
+
+		i.Seams = append(i.Seams, rowSeams)
+	}
+}
+
+// Get the nodes above a given x, y coordinate.
+// Get the left and right neighbors, if there are any.
+func (i *ImageSeams) GetNodesAbove(x int, y int) []*SeamNode {
+	if y == 0 {
+		return nil
+	}
+
+	rowSeams := i.Seams[y-1]
+
+	seams := make([]*SeamNode, 0, 3)
+
+	// Left node
+	if x != 0 {
+		seams = append(seams, rowSeams[x-1])
+	}
+	// Middle node
+	seams = append(seams, rowSeams[x])
+	// Right node
+	if x < (len(rowSeams) - 1) {
+		seams = append(seams, rowSeams[x+1])
+	}
+
+	return seams
+}
+
+// Find the best node that's above the current one at `(x, y)`
+func (i *ImageSeams) FindBestNodeAbove(x int, y int) *SeamNode {
+	nodes := i.GetNodesAbove(x, y)
+	lowestCostNode := nodes[0]
+
+	for _, node := range nodes {
+		if node.AccumulatedCosts < lowestCostNode.AccumulatedCosts {
+			lowestCostNode = node
+		}
+	}
+
+	return lowestCostNode
+}
+
+func (i *ImageSeams) CreateOptimizedRoutesForRow(y int) {
+	row := i.Seams[y]
+
+	for x, node := range row {
+		bestNode := i.FindBestNodeAbove(x, y)
+
+		node.PreviosNode = bestNode
+		node.AccumulatedCosts = bestNode.AccumulatedCosts + node.ThisCost
+	}
+}
+
+func (i *ImageSeams) CreateOptimizedRoutes() {
+	for y := 1; y < len(i.Seams); y++ {
+		i.CreateOptimizedRoutesForRow(y)
+	}
+}
+
+func (i *ImageSeams) GetLowestSeam() *SeamNode {
+	lastRow := i.Seams[len(i.Seams)-1]
+	lowestNode := lastRow[0]
+
+	for _, node := range lastRow {
+		if node.AccumulatedCosts < lowestNode.AccumulatedCosts {
+			lowestNode = node
+		}
+	}
+
+	return lowestNode
+}
+
+func (i *ImageSeams) SetCostForNode(x int, y int, cost uint) {
+	node := i.Seams[y][x]
+	node.ThisCost = cost
+	node.AccumulatedCosts = cost
+}

main.go

@@ -6,12 +6,13 @@ import (
 	"image/png"
 	_ "image/png"
 	"os"
+
 	"myzel394.app/image-stuff/imageutils"
 )
 
 func main() {
 	// Read image
-	reader, _ := os.Open("./assets/water2.png")
+	reader, _ := os.Open("./assets/surfer.png")
 	rawImage, _, _ := image.Decode(reader)
 	readImage := imageutils.ImageAnalyzer{Image: rawImage}
 
@@ -20,16 +21,26 @@ func main() {
 	height := bounds.Max.Y
 	writeImage := image.NewRGBA(bounds)
 
+	seams := imageutils.NewImageSeams()
+	seams.CreateSeamsFromRectangle(bounds)
+
 	// Main action
 	for x := range width {
 		for y := range height {
-			energy := uint8(readImage.CalculateEnergyAt(x, y))
+			energy := uint(readImage.CalculateEnergyAt(x, y))
+			hexColor := uint8(energy)
 
-			color := color.RGBA{energy, energy, energy, 255}
+			color := color.RGBA{hexColor, hexColor, hexColor, 255}
 			writeImage.Set(x, y, color)
+
+			seams.SetCostForNode(x, y, energy)
 		}
 	}
 
+	seams.CreateOptimizedRoutes()
+	lowestSeam := seams.GetLowestSeam()
+	lowestSeam.WriteSeamChainToImage(writeImage)
+
 	// Out image
 	writer, _ := os.Create("image.png")
 	png.Encode(writer, writeImage)