diff options
Diffstat (limited to 'vendor/github.com/disintegration/imaging/effects.go')
| -rw-r--r-- | vendor/github.com/disintegration/imaging/effects.go | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/vendor/github.com/disintegration/imaging/effects.go b/vendor/github.com/disintegration/imaging/effects.go new file mode 100644 index 000000000..fe92e10a2 --- /dev/null +++ b/vendor/github.com/disintegration/imaging/effects.go @@ -0,0 +1,187 @@ +package imaging + +import ( + "image" + "math" +) + +func gaussianBlurKernel(x, sigma float64) float64 { + return math.Exp(-(x*x)/(2*sigma*sigma)) / (sigma * math.Sqrt(2*math.Pi)) +} + +// Blur produces a blurred version of the image using a Gaussian function. +// Sigma parameter must be positive and indicates how much the image will be blurred. +// +// Usage example: +// +// dstImage := imaging.Blur(srcImage, 3.5) +// +func Blur(img image.Image, sigma float64) *image.NRGBA { + if sigma <= 0 { + // sigma parameter must be positive! + return Clone(img) + } + + src := toNRGBA(img) + radius := int(math.Ceil(sigma * 3.0)) + kernel := make([]float64, radius+1) + + for i := 0; i <= radius; i++ { + kernel[i] = gaussianBlurKernel(float64(i), sigma) + } + + var dst *image.NRGBA + dst = blurHorizontal(src, kernel) + dst = blurVertical(dst, kernel) + + return dst +} + +func blurHorizontal(src *image.NRGBA, kernel []float64) *image.NRGBA { + radius := len(kernel) - 1 + width := src.Bounds().Max.X + height := src.Bounds().Max.Y + + dst := image.NewNRGBA(image.Rect(0, 0, width, height)) + + parallel(width, func(partStart, partEnd int) { + for x := partStart; x < partEnd; x++ { + start := x - radius + if start < 0 { + start = 0 + } + + end := x + radius + if end > width-1 { + end = width - 1 + } + + weightSum := 0.0 + for ix := start; ix <= end; ix++ { + weightSum += kernel[absint(x-ix)] + } + + for y := 0; y < height; y++ { + + r, g, b, a := 0.0, 0.0, 0.0, 0.0 + for ix := start; ix <= end; ix++ { + weight := kernel[absint(x-ix)] + i := y*src.Stride + ix*4 + r += float64(src.Pix[i+0]) * weight + g += float64(src.Pix[i+1]) * weight + b += float64(src.Pix[i+2]) * weight + a += float64(src.Pix[i+3]) * weight + } + + r = math.Min(math.Max(r/weightSum, 0.0), 255.0) + g = math.Min(math.Max(g/weightSum, 0.0), 255.0) + b = math.Min(math.Max(b/weightSum, 0.0), 255.0) + a = math.Min(math.Max(a/weightSum, 0.0), 255.0) + + j := y*dst.Stride + x*4 + dst.Pix[j+0] = uint8(r + 0.5) + dst.Pix[j+1] = uint8(g + 0.5) + dst.Pix[j+2] = uint8(b + 0.5) + dst.Pix[j+3] = uint8(a + 0.5) + + } + } + }) + + return dst +} + +func blurVertical(src *image.NRGBA, kernel []float64) *image.NRGBA { + radius := len(kernel) - 1 + width := src.Bounds().Max.X + height := src.Bounds().Max.Y + + dst := image.NewNRGBA(image.Rect(0, 0, width, height)) + + parallel(height, func(partStart, partEnd int) { + for y := partStart; y < partEnd; y++ { + start := y - radius + if start < 0 { + start = 0 + } + + end := y + radius + if end > height-1 { + end = height - 1 + } + + weightSum := 0.0 + for iy := start; iy <= end; iy++ { + weightSum += kernel[absint(y-iy)] + } + + for x := 0; x < width; x++ { + + r, g, b, a := 0.0, 0.0, 0.0, 0.0 + for iy := start; iy <= end; iy++ { + weight := kernel[absint(y-iy)] + i := iy*src.Stride + x*4 + r += float64(src.Pix[i+0]) * weight + g += float64(src.Pix[i+1]) * weight + b += float64(src.Pix[i+2]) * weight + a += float64(src.Pix[i+3]) * weight + } + + r = math.Min(math.Max(r/weightSum, 0.0), 255.0) + g = math.Min(math.Max(g/weightSum, 0.0), 255.0) + b = math.Min(math.Max(b/weightSum, 0.0), 255.0) + a = math.Min(math.Max(a/weightSum, 0.0), 255.0) + + j := y*dst.Stride + x*4 + dst.Pix[j+0] = uint8(r + 0.5) + dst.Pix[j+1] = uint8(g + 0.5) + dst.Pix[j+2] = uint8(b + 0.5) + dst.Pix[j+3] = uint8(a + 0.5) + + } + } + }) + + return dst +} + +// Sharpen produces a sharpened version of the image. +// Sigma parameter must be positive and indicates how much the image will be sharpened. +// +// Usage example: +// +// dstImage := imaging.Sharpen(srcImage, 3.5) +// +func Sharpen(img image.Image, sigma float64) *image.NRGBA { + if sigma <= 0 { + // sigma parameter must be positive! + return Clone(img) + } + + src := toNRGBA(img) + blurred := Blur(img, sigma) + + width := src.Bounds().Max.X + height := src.Bounds().Max.Y + dst := image.NewNRGBA(image.Rect(0, 0, width, height)) + + parallel(height, func(partStart, partEnd int) { + for y := partStart; y < partEnd; y++ { + for x := 0; x < width; x++ { + i := y*src.Stride + x*4 + for j := 0; j < 4; j++ { + k := i + j + val := int(src.Pix[k]) + (int(src.Pix[k]) - int(blurred.Pix[k])) + if val < 0 { + val = 0 + } else if val > 255 { + val = 255 + } + dst.Pix[k] = uint8(val) + } + } + } + }) + + return dst +} |