removeBordersWithTolerance...!

crop-tolerance.go

func removeBordersWithTolerance(inputPath, outputPath string, tolerance, minBorderWidth int) error {
	// Open the input file
	file, err := os.Open(inputPath)
	if err != nil {
		return err
	}
	defer file.Close()

	// Decode the image
	img, format, err := image.Decode(file)
	if err != nil {
		return err
	}

	// Get image bounds
	bounds := img.Bounds()
	width, height := bounds.Max.X, bounds.Max.Y

	// Function to check if a pixel is different from the background
	isDifferent := func(x, y int) bool {
		r, g, b, _ := img.At(x, y).RGBA()
		bgR, bgG, bgB, _ := img.At(0, 0).RGBA()
		diff := math.Abs(float64(r)-float64(bgR)) +
			math.Abs(float64(g)-float64(bgG)) +
			math.Abs(float64(b)-float64(bgB))
		return diff > float64(tolerance*3*256)
	}

	// Find content edges
	var top, bottom, left, right int
	for y := 0; y < height; y++ {
		for x := 0; x < width; x++ {
			if isDifferent(x, y) {
				top = y
				goto foundTop
			}
		}
	}
foundTop:
	for y := height - 1; y >= 0; y-- {
		for x := 0; x < width; x++ {
			if isDifferent(x, y) {
				bottom = y
				goto foundBottom
			}
		}
	}
foundBottom:
	for x := 0; x < width; x++ {
		for y := 0; y < height; y++ {
			if isDifferent(x, y) {
				left = x
				goto foundLeft
			}
		}
	}
foundLeft:
	for x := width - 1; x >= 0; x-- {
		for y := 0; y < height; y++ {
			if isDifferent(x, y) {
				right = x
				goto foundRight
			}
		}
	}
foundRight:

	// Apply minimum border width
	top = max(minBorderWidth, top-minBorderWidth)
	bottom = min(height-minBorderWidth, bottom+minBorderWidth)
	left = max(minBorderWidth, left-minBorderWidth)
	right = min(width-minBorderWidth, right+minBorderWidth)

	// Create the cropped image
	croppedImg := image.NewRGBA(image.Rect(0, 0, right-left, bottom-top))
	for y := top; y < bottom; y++ {
		for x := left; x < right; x++ {
			croppedImg.Set(x-left, y-top, img.At(x, y))
		}
	}

	// Save the cropped image
	outFile, err := os.Create(outputPath)
	if err != nil {
		return err
	}
	defer outFile.Close()

	switch format {
	case "jpeg":
		return jpeg.Encode(outFile, croppedImg, nil)
	case "png":
		return png.Encode(outFile, croppedImg)
	default:
		return png.Encode(outFile, croppedImg)
	}
}