fix: resolving carving issue on image enlargment (#65)

carver.go

@@ -122,7 +122,7 @@ func (c *Carver) ComputeSeams(img *image.NRGBA, p *Processor) error {
 	}
 
 	if p.BlurRadius > 0 {
-		srcImg = StackBlur(sobel, uint32(p.BlurRadius))
+		srcImg = c.StackBlur(sobel, uint32(p.BlurRadius))
 	} else {
 		srcImg = sobel
 	}

cmd/caire/main.go

@@ -62,7 +62,6 @@ var (
 	percentage     = flag.Bool("perc", false, "Reduce image by percentage")
 	square         = flag.Bool("square", false, "Reduce image to square dimensions")
 	debug          = flag.Bool("debug", false, "Use debugger")
-	scale          = flag.Bool("scale", false, "Proportional scaling")
 	faceDetect     = flag.Bool("face", false, "Use face detection")
 	faceAngle      = flag.Float64("angle", 0.0, "Plane rotated faces angle")
 	workers        = flag.Int("conc", runtime.NumCPU(), "Number of files to process concurrently")
@@ -89,7 +88,6 @@ func main() {
 		Percentage:     *percentage,
 		Square:         *square,
 		Debug:          *debug,
-		Scale:          *scale,
 		FaceDetect:     *faceDetect,
 		FaceAngle:      *faceAngle,
 	}

process.go

@@ -21,8 +21,6 @@ import (
 	"golang.org/x/image/bmp"
 )
 
-const maxResizeWithoutScaling = 2000
-
 //go:embed data/facefinder
 var classifier embed.FS
 
@@ -48,7 +46,6 @@ type Processor struct {
 	Percentage       bool
 	Square           bool
 	Debug            bool
-	Scale            bool
 	FaceDetect       bool
 	FaceAngle        float64
 	PigoFaceDetector *pigo.Pigo
@@ -92,6 +89,7 @@ func (p *Processor) Resize(img *image.NRGBA) (image.Image, error) {
 	if p.NewHeight == 0 {
 		newHeight = p.NewHeight
 	}
+
 	reduce := func() error {
 		width, height := img.Bounds().Max.X, img.Bounds().Max.Y
 		c = NewCarver(width, height)
@@ -175,28 +173,26 @@ func (p *Processor) Resize(img *image.NRGBA) (image.Image, error) {
 		}
 		img = c.RotateImage270(img)
 	} else if newWidth > 0 || newHeight > 0 {
-		// Use this option to rescale the image proportionally prior resizing.
+		// We are trying to rescale the image proportionally prior resizing.
-		// First the image is scaled down preserving the image aspect ratio,
+		// First the image is scaled down or up by preserving the image aspect ratio,
 		// then the seam carving algorithm is applied only to the remaining pixels.
 
-		// Prevent memory overflow issue in case of huge images by switching to scaling first option
-		if img.Bounds().Dx() > maxResizeWithoutScaling ||
-			img.Bounds().Dy() > maxResizeWithoutScaling {
-			p.Scale = true
-		}
-
-		if p.Scale {
-			// Find the scale factor for width and height.
 		// Scale the width and height by the smaller factor (i.e Min(wScaleFactor, hScaleFactor))
-			// This will scale one side directly to the target length,
-			// and the other proportionally larger than the target length.
 		// Example: input: 5000x2500, scale: 2160x1080, final target: 1920x1080
 		wScaleFactor := float64(c.Width) / float64(p.NewWidth)
 		hScaleFactor := float64(c.Height) / float64(p.NewHeight)
-			scaleWidth := math.Round(float64(c.Width) / math.Min(wScaleFactor, hScaleFactor))   //post scale width
+		scaleWidth := math.Round(float64(c.Width) / math.Min(wScaleFactor, hScaleFactor))
-			scaleHeight := math.Round(float64(c.Height) / math.Min(wScaleFactor, hScaleFactor)) // post scale height
+		scaleHeight := math.Round(float64(c.Height) / math.Min(wScaleFactor, hScaleFactor))
 
 		newImg = imaging.Resize(img, int(scaleWidth), int(scaleHeight), imaging.Lanczos)
+
+		dx0, dy0 := img.Bounds().Max.X, newImg.Bounds().Max.Y
+		dx1, dy1 := newImg.Bounds().Max.X, newImg.Bounds().Max.Y
+
+		// Rescale the image only when it's resized both horizontally and vertically
+		// and the new image width or height are preserved, otherwise it might happen, that
+		// the generated image size does not match with the requested image size.
+		if !((p.NewWidth == 0 && dx0 == dx1) || (p.NewHeight == 0 && dy0 == dy1)) {
 			// The amount needed to remove by carving. One or both of these will be 0.
 			newWidth = int(scaleWidth) - p.NewWidth
 			newHeight = int(scaleHeight) - p.NewHeight
@@ -206,13 +202,12 @@ func (p *Processor) Resize(img *image.NRGBA) (image.Image, error) {
 			img = dst
 		}
 
-		// Check if the new width does not match with the rescaled image width.
 		// Run the carver function if the desired image width is not identical with the rescaled image width.
 		if newWidth > 0 && newWidth != img.Bounds().Max.X {
-			// Because scaling horizontally and vertically at the same time using the scale option
+			// Because of scaling horizontally and vertically at the same time it might happen
-			// it might happen that the scaled image exceeds the desired image size, we need to make sure
+			// that the scaled image exceeds the desired image size, we need to make sure
 			// that the new width and|or height is reduced and not enlarged.
-			if p.NewWidth > c.Width && newWidth < p.NewWidth && img.Bounds().Max.X < p.NewWidth {
+			if p.NewWidth > c.Width && img.Bounds().Max.X < p.NewWidth {
 				for x := 0; x < newWidth; x++ {
 					if err = enlarge(); err != nil {
 						return nil, err
@@ -227,12 +222,11 @@ func (p *Processor) Resize(img *image.NRGBA) (image.Image, error) {
 				}
 			}
 		}
-		// Check if the new height does not match with the rescaled image height.
 		// Run the carver function if the desired image height is not identical with the rescaled image height.
 		if newHeight > 0 && newHeight != img.Bounds().Max.Y {
 			img = c.RotateImage90(img)
 			// Check new height against the width of the image because the image is rotated 90deg.
-			if p.NewHeight > c.Height && (newHeight < p.NewHeight && img.Bounds().Max.X < p.NewHeight) {
+			if p.NewHeight > c.Height && img.Bounds().Max.X < p.NewHeight {
 				for y := 0; y < newHeight; y++ {
 					if err = enlarge(); err != nil {
 						return nil, err

process_test.go

@@ -22,7 +22,6 @@ func reduceImageH(t *testing.T) {
 		Percentage:     false,
 		Square:         false,
 		Debug:          false,
-		Scale:          false,
 	}
 	// Reduce image size horizontally
 	for x := 0; x < newWidth; x++ {
@@ -51,7 +50,6 @@ func reduceImageV(t *testing.T) {
 		Percentage:     false,
 		Square:         false,
 		Debug:          false,
-		Scale:          false,
 	}
 	// Reduce image size horizontally
 	img = c.RotateImage90(img)

stackblur.go

@@ -7,10 +7,10 @@ import (
 	"image"
 )
 
-// blurStack is a linked list containing the color value and a pointer to the next struct.
+// blurstack is a linked list containing the color value and a pointer to the next struct.
-type blurStack struct {
+type blurstack struct {
 	r, g, b, a uint32
-	next       *blurStack
+	next       *blurstack
 }
 
 var mulTable = []uint32{
@@ -51,15 +51,10 @@ var shgTable = []uint32{
 	24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
 }
 
-// NewBlurStack is a constructor function returning a new struct of type blurStack.
-func (bs *blurStack) NewBlurStack() *blurStack {
-	return &blurStack{bs.r, bs.g, bs.b, bs.a, bs.next}
-}
-
 // StackBlur applies a blur filter to the provided image.
 // The radius defines the bluring average.
-func StackBlur(img *image.NRGBA, radius uint32) *image.NRGBA {
+func (c *Carver) StackBlur(img *image.NRGBA, radius uint32) *image.NRGBA {
-	var stackEnd, stackIn, stackOut *blurStack
+	var stackEnd, stackIn, stackOut *blurstack
 	var width, height = uint32(img.Bounds().Dx()), uint32(img.Bounds().Dy())
 	var (
 		div, widthMinus1, heightMinus1, radiusPlus1, sumFactor uint32
@@ -76,12 +71,11 @@ func StackBlur(img *image.NRGBA, radius uint32) *image.NRGBA {
 	radiusPlus1 = radius + 1
 	sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2
 
-	bs := blurStack{}
+	stackStart := new(blurstack)
-	stackStart := bs.NewBlurStack()
 	stack := stackStart
 
 	for i = 1; i < div; i++ {
-		stack.next = bs.NewBlurStack()
+		stack.next = new(blurstack)
 		stack = stack.next
 		if i == radiusPlus1 {
 			stackEnd = stack

vendor/github.com/esimov/pigo/core/pigo.go

@@ -136,6 +136,7 @@ func (pg *Pigo) classifyRegion(r, c, s int, pixels []uint8, dim int) float32 {
 	r = r * 256
 	c = c * 256
 
+	if pg.treeNum > 0 {
 		for i := 0; i < int(pg.treeNum); i++ {
 			idx := 1
 
@@ -160,6 +161,8 @@ func (pg *Pigo) classifyRegion(r, c, s int, pixels []uint8, dim int) float32 {
 		}
 		return out - pg.treeThreshold[pg.treeNum-1]
 	}
+	return 0.0
+}
 
 // classifyRotatedRegion applies the face classification function over a rotated image based on the parsed binary data.
 func (pg *Pigo) classifyRotatedRegion(r, c, s int, a float64, nrows, ncols int, pixels []uint8, dim int) float32 {
@@ -175,6 +178,7 @@ func (pg *Pigo) classifyRotatedRegion(r, c, s int, a float64, nrows, ncols int,
 	qsin := s * qSinTable[int(32.0*a)] //s*(256.0*math.Sin(2*math.Pi*a))
 	qcos := s * qCosTable[int(32.0*a)] //s*(256.0*math.Cos(2*math.Pi*a))
 
+	if pg.treeNum > 0 {
 		for i := 0; i < int(pg.treeNum); i++ {
 			var idx = 1
 
@@ -202,6 +206,8 @@ func (pg *Pigo) classifyRotatedRegion(r, c, s int, a float64, nrows, ncols int,
 		}
 		return out - pg.treeThreshold[pg.treeNum-1]
 	}
+	return 0.0
+}
 
 // Detection struct contains the detection results composed of
 // the row, column, scale factor and the detection score.