add Dockerfile

14 files changed, 2707 insertions, 0 deletions

diff --git a/vendor/github.com/disintegration/imaging/.travis.yml b/vendor/github.com/disintegration/imaging/.travis.yml
new file mode 100644
index 0000000..89370ed
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/.travis.yml
@@ -0,0 +1,13 @@
+language: go
+go:
+  - "1.7.x"
+  - "1.8.x"
+  - "1.9.x"
+  - "1.10.x"
+
+before_install:
+  - go get github.com/mattn/goveralls
+
+script:
+  - go test -v -race -cover
+  - $GOPATH/bin/goveralls -service=travis-ci
diff --git a/vendor/github.com/disintegration/imaging/LICENSE b/vendor/github.com/disintegration/imaging/LICENSE
new file mode 100644
index 0000000..c68f7ab
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2012-2018 Grigory Dryapak
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file
diff --git a/vendor/github.com/disintegration/imaging/README.md b/vendor/github.com/disintegration/imaging/README.md
new file mode 100644
index 0000000..c7ee30f
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/README.md
@@ -0,0 +1,188 @@
+# Imaging

+

+[![GoDoc](https://godoc.org/github.com/disintegration/imaging?status.svg)](https://godoc.org/github.com/disintegration/imaging)

+[![Build Status](https://travis-ci.org/disintegration/imaging.svg?branch=master)](https://travis-ci.org/disintegration/imaging)

+[![Coverage Status](https://coveralls.io/repos/github/disintegration/imaging/badge.svg?branch=master&service=github)](https://coveralls.io/github/disintegration/imaging?branch=master)

+[![Go Report Card](https://goreportcard.com/badge/github.com/disintegration/imaging)](https://goreportcard.com/report/github.com/disintegration/imaging)

+

+Package imaging provides basic image processing functions (resize, rotate, crop, brightness/contrast adjustments, etc.).

+

+All the image processing functions provided by the package accept any image type that implements `image.Image` interface

+as an input, and return a new image of `*image.NRGBA` type (32bit RGBA colors, not premultiplied by alpha).

+

+## Installation

+

+    go get -u github.com/disintegration/imaging

+    

+## Documentation

+

+http://godoc.org/github.com/disintegration/imaging

+

+## Usage examples

+

+A few usage examples can be found below. See the documentation for the full list of supported functions. 

+

+### Image resizing

+

+```go

+// Resize srcImage to size = 128x128px using the Lanczos filter.

+dstImage128 := imaging.Resize(srcImage, 128, 128, imaging.Lanczos)

+

+// Resize srcImage to width = 800px preserving the aspect ratio.

+dstImage800 := imaging.Resize(srcImage, 800, 0, imaging.Lanczos)

+

+// Scale down srcImage to fit the 800x600px bounding box.

+dstImageFit := imaging.Fit(srcImage, 800, 600, imaging.Lanczos)

+

+// Resize and crop the srcImage to fill the 100x100px area.

+dstImageFill := imaging.Fill(srcImage, 100, 100, imaging.Center, imaging.Lanczos)

+```

+

+Imaging supports image resizing using various resampling filters. The most notable ones:

+- `NearestNeighbor` - Fastest resampling filter, no antialiasing.

+- `Box` - Simple and fast averaging filter appropriate for downscaling. When upscaling it's similar to NearestNeighbor.

+- `Linear` - Bilinear filter, smooth and reasonably fast.

+- `MitchellNetravali` - А smooth bicubic filter.

+- `CatmullRom` - A sharp bicubic filter.

+- `Gaussian` - Blurring filter that uses gaussian function, useful for noise removal.

+- `Lanczos` - High-quality resampling filter for photographic images yielding sharp results, slower than cubic filters.

+

+The full list of supported filters:  NearestNeighbor, Box, Linear, Hermite, MitchellNetravali, CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine. Custom filters can be created using ResampleFilter struct.

+

+**Resampling filters comparison**

+

+Original image:

+

+![srcImage](testdata/branches.png)

+

+The same image resized from 600x400px to 150x100px using different resampling filters.

+From faster (lower quality) to slower (higher quality):

+

+Filter                    | Resize result

+--------------------------|---------------------------------------------

+`imaging.NearestNeighbor` | ![dstImage](testdata/out_resize_nearest.png) 

+`imaging.Linear`          | ![dstImage](testdata/out_resize_linear.png)

+`imaging.CatmullRom`      | ![dstImage](testdata/out_resize_catrom.png)

+`imaging.Lanczos`         | ![dstImage](testdata/out_resize_lanczos.png)

+

+

+### Gaussian Blur

+

+```go

+dstImage := imaging.Blur(srcImage, 0.5)

+```

+

+Sigma parameter allows to control the strength of the blurring effect.

+

+Original image                     | Sigma = 0.5                            | Sigma = 1.5

+-----------------------------------|----------------------------------------|---------------------------------------

+![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_blur_0.5.png) | ![dstImage](testdata/out_blur_1.5.png)

+

+### Sharpening

+

+```go

+dstImage := imaging.Sharpen(srcImage, 0.5)

+```

+

+`Sharpen` uses gaussian function internally. Sigma parameter allows to control the strength of the sharpening effect.

+

+Original image                     | Sigma = 0.5                               | Sigma = 1.5

+-----------------------------------|-------------------------------------------|------------------------------------------

+![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_sharpen_0.5.png) | ![dstImage](testdata/out_sharpen_1.5.png)

+

+### Gamma correction

+

+```go

+dstImage := imaging.AdjustGamma(srcImage, 0.75)

+```

+

+Original image                     | Gamma = 0.75                             | Gamma = 1.25

+-----------------------------------|------------------------------------------|-----------------------------------------

+![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_gamma_0.75.png) | ![dstImage](testdata/out_gamma_1.25.png)

+

+### Contrast adjustment

+

+```go

+dstImage := imaging.AdjustContrast(srcImage, 20)

+```

+

+Original image                     | Contrast = 15                              | Contrast = -15

+-----------------------------------|--------------------------------------------|-------------------------------------------

+![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_contrast_p15.png) | ![dstImage](testdata/out_contrast_m15.png)

+

+### Brightness adjustment

+

+```go

+dstImage := imaging.AdjustBrightness(srcImage, 20)

+```

+

+Original image                     | Brightness = 10                              | Brightness = -10

+-----------------------------------|----------------------------------------------|---------------------------------------------

+![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_brightness_p10.png) | ![dstImage](testdata/out_brightness_m10.png)

+

+## Example code

+

+```go

+package main

+

+import (

+	"image"

+	"image/color"

+	"log"

+

+	"github.com/disintegration/imaging"

+)

+

+func main() {

+	// Open a test image.

+	src, err := imaging.Open("testdata/flowers.png")

+	if err != nil {

+		log.Fatalf("failed to open image: %v", err)

+	}

+

+	// Crop the original image to 300x300px size using the center anchor.

+	src = imaging.CropAnchor(src, 300, 300, imaging.Center)

+

+	// Resize the cropped image to width = 200px preserving the aspect ratio.

+	src = imaging.Resize(src, 200, 0, imaging.Lanczos)

+

+	// Create a blurred version of the image.

+	img1 := imaging.Blur(src, 5)

+

+	// Create a grayscale version of the image with higher contrast and sharpness.

+	img2 := imaging.Grayscale(src)

+	img2 = imaging.AdjustContrast(img2, 20)

+	img2 = imaging.Sharpen(img2, 2)

+

+	// Create an inverted version of the image.

+	img3 := imaging.Invert(src)

+

+	// Create an embossed version of the image using a convolution filter.

+	img4 := imaging.Convolve3x3(

+		src,

+		[9]float64{

+			-1, -1, 0,

+			-1, 1, 1,

+			0, 1, 1,

+		},

+		nil,

+	)

+

+	// Create a new image and paste the four produced images into it.

+	dst := imaging.New(400, 400, color.NRGBA{0, 0, 0, 0})

+	dst = imaging.Paste(dst, img1, image.Pt(0, 0))

+	dst = imaging.Paste(dst, img2, image.Pt(0, 200))

+	dst = imaging.Paste(dst, img3, image.Pt(200, 0))

+	dst = imaging.Paste(dst, img4, image.Pt(200, 200))

+

+	// Save the resulting image as JPEG.

+	err = imaging.Save(dst, "testdata/out_example.jpg")

+	if err != nil {

+		log.Fatalf("failed to save image: %v", err)

+	}

+}

+```

+

+Output:

+

+![dstImage](testdata/out_example.jpg)
\ No newline at end of file
diff --git a/vendor/github.com/disintegration/imaging/adjust.go b/vendor/github.com/disintegration/imaging/adjust.go
new file mode 100644
index 0000000..fb3a9ce
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/adjust.go
@@ -0,0 +1,222 @@
+package imaging
+
+import (
+	"image"
+	"image/color"
+	"math"
+)
+
+// Grayscale produces a grayscale version of the image.
+func Grayscale(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	parallel(0, src.h, func(ys <-chan int) {
+		for y := range ys {
+			i := y * dst.Stride
+			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
+			for x := 0; x < src.w; x++ {
+				r := dst.Pix[i+0]
+				g := dst.Pix[i+1]
+				b := dst.Pix[i+2]
+				f := 0.299*float64(r) + 0.587*float64(g) + 0.114*float64(b)
+				y := uint8(f + 0.5)
+				dst.Pix[i+0] = y
+				dst.Pix[i+1] = y
+				dst.Pix[i+2] = y
+				i += 4
+			}
+		}
+	})
+	return dst
+}
+
+// Invert produces an inverted (negated) version of the image.
+func Invert(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	parallel(0, src.h, func(ys <-chan int) {
+		for y := range ys {
+			i := y * dst.Stride
+			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
+			for x := 0; x < src.w; x++ {
+				dst.Pix[i+0] = 255 - dst.Pix[i+0]
+				dst.Pix[i+1] = 255 - dst.Pix[i+1]
+				dst.Pix[i+2] = 255 - dst.Pix[i+2]
+				i += 4
+			}
+		}
+	})
+	return dst
+}
+
+// AdjustContrast changes the contrast of the image using the percentage parameter and returns the adjusted image.
+// The percentage must be in range (-100, 100). The percentage = 0 gives the original image.
+// The percentage = -100 gives solid gray image.
+//
+// Examples:
+//
+//	dstImage = imaging.AdjustContrast(srcImage, -10) // decrease image contrast by 10%
+//	dstImage = imaging.AdjustContrast(srcImage, 20) // increase image contrast by 20%
+//
+func AdjustContrast(img image.Image, percentage float64) *image.NRGBA {
+	percentage = math.Min(math.Max(percentage, -100.0), 100.0)
+	lut := make([]uint8, 256)
+
+	v := (100.0 + percentage) / 100.0
+	for i := 0; i < 256; i++ {
+		if 0 <= v && v <= 1 {
+			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*v) * 255.0)
+		} else if 1 < v && v < 2 {
+			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*(1/(2.0-v))) * 255.0)
+		} else {
+			lut[i] = uint8(float64(i)/255.0+0.5) * 255
+		}
+	}
+
+	return adjustLUT(img, lut)
+}
+
+// AdjustBrightness changes the brightness of the image using the percentage parameter and returns the adjusted image.
+// The percentage must be in range (-100, 100). The percentage = 0 gives the original image.
+// The percentage = -100 gives solid black image. The percentage = 100 gives solid white image.
+//
+// Examples:
+//
+//	dstImage = imaging.AdjustBrightness(srcImage, -15) // decrease image brightness by 15%
+//	dstImage = imaging.AdjustBrightness(srcImage, 10) // increase image brightness by 10%
+//
+func AdjustBrightness(img image.Image, percentage float64) *image.NRGBA {
+	percentage = math.Min(math.Max(percentage, -100.0), 100.0)
+	lut := make([]uint8, 256)
+
+	shift := 255.0 * percentage / 100.0
+	for i := 0; i < 256; i++ {
+		lut[i] = clamp(float64(i) + shift)
+	}
+
+	return adjustLUT(img, lut)
+}
+
+// AdjustGamma performs a gamma correction on the image and returns the adjusted image.
+// Gamma parameter must be positive. Gamma = 1.0 gives the original image.
+// Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it.
+//
+// Example:
+//
+//	dstImage = imaging.AdjustGamma(srcImage, 0.7)
+//
+func AdjustGamma(img image.Image, gamma float64) *image.NRGBA {
+	e := 1.0 / math.Max(gamma, 0.0001)
+	lut := make([]uint8, 256)
+
+	for i := 0; i < 256; i++ {
+		lut[i] = clamp(math.Pow(float64(i)/255.0, e) * 255.0)
+	}
+
+	return adjustLUT(img, lut)
+}
+
+// AdjustSigmoid changes the contrast of the image using a sigmoidal function and returns the adjusted image.
+// It's a non-linear contrast change useful for photo adjustments as it preserves highlight and shadow detail.
+// The midpoint parameter is the midpoint of contrast that must be between 0 and 1, typically 0.5.
+// The factor parameter indicates how much to increase or decrease the contrast, typically in range (-10, 10).
+// If the factor parameter is positive the image contrast is increased otherwise the contrast is decreased.
+//
+// Examples:
+//
+//	dstImage = imaging.AdjustSigmoid(srcImage, 0.5, 3.0) // increase the contrast
+//	dstImage = imaging.AdjustSigmoid(srcImage, 0.5, -3.0) // decrease the contrast
+//
+func AdjustSigmoid(img image.Image, midpoint, factor float64) *image.NRGBA {
+	if factor == 0 {
+		return Clone(img)
+	}
+
+	lut := make([]uint8, 256)
+	a := math.Min(math.Max(midpoint, 0.0), 1.0)
+	b := math.Abs(factor)
+	sig0 := sigmoid(a, b, 0)
+	sig1 := sigmoid(a, b, 1)
+	e := 1.0e-6
+
+	if factor > 0 {
+		for i := 0; i < 256; i++ {
+			x := float64(i) / 255.0
+			sigX := sigmoid(a, b, x)
+			f := (sigX - sig0) / (sig1 - sig0)
+			lut[i] = clamp(f * 255.0)
+		}
+	} else {
+		for i := 0; i < 256; i++ {
+			x := float64(i) / 255.0
+			arg := math.Min(math.Max((sig1-sig0)*x+sig0, e), 1.0-e)
+			f := a - math.Log(1.0/arg-1.0)/b
+			lut[i] = clamp(f * 255.0)
+		}
+	}
+
+	return adjustLUT(img, lut)
+}
+
+func sigmoid(a, b, x float64) float64 {
+	return 1 / (1 + math.Exp(b*(a-x)))
+}
+
+// adjustLUT applies the given lookup table to the colors of the image.
+func adjustLUT(img image.Image, lut []uint8) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	parallel(0, src.h, func(ys <-chan int) {
+		for y := range ys {
+			i := y * dst.Stride
+			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
+			for x := 0; x < src.w; x++ {
+				dst.Pix[i+0] = lut[dst.Pix[i+0]]
+				dst.Pix[i+1] = lut[dst.Pix[i+1]]
+				dst.Pix[i+2] = lut[dst.Pix[i+2]]
+				i += 4
+			}
+		}
+	})
+	return dst
+}
+
+// AdjustFunc applies the fn function to each pixel of the img image and returns the adjusted image.
+//
+// Example:
+//
+//	dstImage = imaging.AdjustFunc(
+//		srcImage,
+//		func(c color.NRGBA) color.NRGBA {
+//			// shift the red channel by 16
+//			r := int(c.R) + 16
+//			if r > 255 {
+//				r = 255
+//			}
+//			return color.NRGBA{uint8(r), c.G, c.B, c.A}
+//		}
+//	)
+//
+func AdjustFunc(img image.Image, fn func(c color.NRGBA) color.NRGBA) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	parallel(0, src.h, func(ys <-chan int) {
+		for y := range ys {
+			i := y * dst.Stride
+			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
+			for x := 0; x < src.w; x++ {
+				r := dst.Pix[i+0]
+				g := dst.Pix[i+1]
+				b := dst.Pix[i+2]
+				a := dst.Pix[i+3]
+				c := fn(color.NRGBA{r, g, b, a})
+				dst.Pix[i+0] = c.R
+				dst.Pix[i+1] = c.G
+				dst.Pix[i+2] = c.B
+				dst.Pix[i+3] = c.A
+				i += 4
+			}
+		}
+	})
+	return dst
+}
diff --git a/vendor/github.com/disintegration/imaging/convolution.go b/vendor/github.com/disintegration/imaging/convolution.go
new file mode 100644
index 0000000..9e6404d
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/convolution.go
@@ -0,0 +1,146 @@
+package imaging
+
+import (
+	"image"
+)
+
+// ConvolveOptions are convolution parameters.
+type ConvolveOptions struct {
+	// If Normalize is true the kernel is normalized before convolution.
+	Normalize bool
+
+	// If Abs is true the absolute value of each color channel is taken after convolution.
+	Abs bool
+
+	// Bias is added to each color channel value after convolution.
+	Bias int
+}
+
+// Convolve3x3 convolves the image with the specified 3x3 convolution kernel.
+// Default parameters are used if a nil *ConvolveOptions is passed.
+func Convolve3x3(img image.Image, kernel [9]float64, options *ConvolveOptions) *image.NRGBA {
+	return convolve(img, kernel[:], options)
+}
+
+// Convolve5x5 convolves the image with the specified 5x5 convolution kernel.
+// Default parameters are used if a nil *ConvolveOptions is passed.
+func Convolve5x5(img image.Image, kernel [25]float64, options *ConvolveOptions) *image.NRGBA {
+	return convolve(img, kernel[:], options)
+}
+
+func convolve(img image.Image, kernel []float64, options *ConvolveOptions) *image.NRGBA {
+	src := toNRGBA(img)
+	w := src.Bounds().Max.X
+	h := src.Bounds().Max.Y
+	dst := image.NewNRGBA(image.Rect(0, 0, w, h))
+
+	if w < 1 || h < 1 {
+		return dst
+	}
+
+	if options == nil {
+		options = &ConvolveOptions{}
+	}
+
+	if options.Normalize {
+		normalizeKernel(kernel)
+	}
+
+	type coef struct {
+		x, y int
+		k    float64
+	}
+	var coefs []coef
+	var m int
+
+	switch len(kernel) {
+	case 9:
+		m = 1
+	case 25:
+		m = 2
+	}
+
+	i := 0
+	for y := -m; y <= m; y++ {
+		for x := -m; x <= m; x++ {
+			if kernel[i] != 0 {
+				coefs = append(coefs, coef{x: x, y: y, k: kernel[i]})
+			}
+			i++
+		}
+	}
+
+	parallel(0, h, func(ys <-chan int) {
+		for y := range ys {
+			for x := 0; x < w; x++ {
+				var r, g, b float64
+				for _, c := range coefs {
+					ix := x + c.x
+					if ix < 0 {
+						ix = 0
+					} else if ix >= w {
+						ix = w - 1
+					}
+
+					iy := y + c.y
+					if iy < 0 {
+						iy = 0
+					} else if iy >= h {
+						iy = h - 1
+					}
+
+					off := iy*src.Stride + ix*4
+					r += float64(src.Pix[off+0]) * c.k
+					g += float64(src.Pix[off+1]) * c.k
+					b += float64(src.Pix[off+2]) * c.k
+				}
+
+				if options.Abs {
+					if r < 0 {
+						r = -r
+					}
+					if g < 0 {
+						g = -g
+					}
+					if b < 0 {
+						b = -b
+					}
+				}
+
+				if options.Bias != 0 {
+					r += float64(options.Bias)
+					g += float64(options.Bias)
+					b += float64(options.Bias)
+				}
+
+				srcOff := y*src.Stride + x*4
+				dstOff := y*dst.Stride + x*4
+				dst.Pix[dstOff+0] = clamp(r)
+				dst.Pix[dstOff+1] = clamp(g)
+				dst.Pix[dstOff+2] = clamp(b)
+				dst.Pix[dstOff+3] = src.Pix[srcOff+3]
+			}
+		}
+	})
+
+	return dst
+}
+
+func normalizeKernel(kernel []float64) {
+	var sum, sumpos float64
+	for i := range kernel {
+		sum += kernel[i]
+		if kernel[i] > 0 {
+			sumpos += kernel[i]
+		}
+	}
+	if sum != 0 {
+		for i := range kernel {
+			kernel[i] /= sum
+		}
+	} else if sumpos != 0 {
+		for i := range kernel {
+			kernel[i] /= sumpos
+		}
+	}
+}
diff --git a/vendor/github.com/disintegration/imaging/doc.go b/vendor/github.com/disintegration/imaging/doc.go
new file mode 100644
index 0000000..5d59b46
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/doc.go
@@ -0,0 +1,7 @@
+/*
+Package imaging provides basic image processing functions (resize, rotate, crop, brightness/contrast adjustments, etc.).
+
+All the image processing functions provided by the package accept any image type that implements image.Image interface
+as an input, and return a new image of *image.NRGBA type (32bit RGBA colors, not premultiplied by alpha).
+*/
+package imaging
diff --git a/vendor/github.com/disintegration/imaging/effects.go b/vendor/github.com/disintegration/imaging/effects.go
new file mode 100644
index 0000000..149cfeb
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/effects.go
@@ -0,0 +1,173 @@
+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 {
+		return Clone(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)
+	}
+
+	return blurVertical(blurHorizontal(img, kernel), kernel)
+}
+
+func blurHorizontal(img image.Image, kernel []float64) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	radius := len(kernel) - 1
+
+	parallel(0, src.h, func(ys <-chan int) {
+		scanLine := make([]uint8, src.w*4)
+		scanLineF := make([]float64, len(scanLine))
+		for y := range ys {
+			src.scan(0, y, src.w, y+1, scanLine)
+			for i, v := range scanLine {
+				scanLineF[i] = float64(v)
+			}
+			for x, idx := 0, 0; x < src.w; x, idx = x+1, idx+4 {
+				min := x - radius
+				if min < 0 {
+					min = 0
+				}
+				max := x + radius
+				if max > src.w-1 {
+					max = src.w - 1
+				}
+
+				var r, g, b, a, wsum float64
+				for ix := min; ix <= max; ix++ {
+					i := ix * 4
+					weight := kernel[absint(x-ix)]
+					wsum += weight
+					wa := scanLineF[i+3] * weight
+					r += scanLineF[i+0] * wa
+					g += scanLineF[i+1] * wa
+					b += scanLineF[i+2] * wa
+					a += wa
+				}
+				if a != 0 {
+					r /= a
+					g /= a
+					b /= a
+				}
+
+				scanLine[idx+0] = clamp(r)
+				scanLine[idx+1] = clamp(g)
+				scanLine[idx+2] = clamp(b)
+				scanLine[idx+3] = clamp(a / wsum)
+			}
+			copy(dst.Pix[y*dst.Stride:], scanLine)
+		}
+	})
+
+	return dst
+}
+
+func blurVertical(img image.Image, kernel []float64) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	radius := len(kernel) - 1
+
+	parallel(0, src.w, func(xs <-chan int) {
+		scanLine := make([]uint8, src.h*4)
+		scanLineF := make([]float64, len(scanLine))
+		for x := range xs {
+			src.scan(x, 0, x+1, src.h, scanLine)
+			for i, v := range scanLine {
+				scanLineF[i] = float64(v)
+			}
+			for y := 0; y < src.h; y++ {
+				min := y - radius
+				if min < 0 {
+					min = 0
+				}
+				max := y + radius
+				if max > src.h-1 {
+					max = src.h - 1
+				}
+
+				var r, g, b, a, wsum float64
+				for iy := min; iy <= max; iy++ {
+					i := iy * 4
+					weight := kernel[absint(y-iy)]
+					wsum += weight
+					wa := scanLineF[i+3] * weight
+					r += scanLineF[i+0] * wa
+					g += scanLineF[i+1] * wa
+					b += scanLineF[i+2] * wa
+					a += wa
+				}
+				if a != 0 {
+					r /= a
+					g /= a
+					b /= a
+				}
+
+				j := y*dst.Stride + x*4
+				dst.Pix[j+0] = clamp(r)
+				dst.Pix[j+1] = clamp(g)
+				dst.Pix[j+2] = clamp(b)
+				dst.Pix[j+3] = clamp(a / wsum)
+			}
+		}
+	})
+
+	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 {
+		return Clone(img)
+	}
+
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	blurred := Blur(img, sigma)
+
+	parallel(0, src.h, func(ys <-chan int) {
+		scanLine := make([]uint8, src.w*4)
+		for y := range ys {
+			src.scan(0, y, src.w, y+1, scanLine)
+			j := y * dst.Stride
+			for i := 0; i < src.w*4; i++ {
+				val := int(scanLine[i])<<1 - int(blurred.Pix[j])
+				if val < 0 {
+					val = 0
+				} else if val > 0xff {
+					val = 0xff
+				}
+				dst.Pix[j] = uint8(val)
+				j++
+			}
+		}
+	})
+
+	return dst
+}
diff --git a/vendor/github.com/disintegration/imaging/histogram.go b/vendor/github.com/disintegration/imaging/histogram.go
new file mode 100644
index 0000000..5bcb001
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/histogram.go
@@ -0,0 +1,51 @@
+package imaging
+
+import (
+	"image"
+	"sync"
+)
+
+// Histogram returns a normalized histogram of an image.
+//
+// Resulting histogram is represented as an array of 256 floats, where
+// histogram[i] is a probability of a pixel being of a particular luminance i.
+func Histogram(img image.Image) [256]float64 {
+	var mu sync.Mutex
+	var histogram [256]float64
+	var total float64
+
+	src := newScanner(img)
+	if src.w == 0 || src.h == 0 {
+		return histogram
+	}
+
+	parallel(0, src.h, func(ys <-chan int) {
+		var tmpHistogram [256]float64
+		var tmpTotal float64
+		scanLine := make([]uint8, src.w*4)
+		for y := range ys {
+			src.scan(0, y, src.w, y+1, scanLine)
+			i := 0
+			for x := 0; x < src.w; x++ {
+				r := scanLine[i+0]
+				g := scanLine[i+1]
+				b := scanLine[i+2]
+				y := 0.299*float32(r) + 0.587*float32(g) + 0.114*float32(b)
+				tmpHistogram[int(y+0.5)]++
+				tmpTotal++
+				i += 4
+			}
+		}
+		mu.Lock()
+		for i := 0; i < 256; i++ {
+			histogram[i] += tmpHistogram[i]
+		}
+		total += tmpTotal
+		mu.Unlock()
+	})
+
+	for i := 0; i < 256; i++ {
+		histogram[i] = histogram[i] / total
+	}
+	return histogram
+}
diff --git a/vendor/github.com/disintegration/imaging/io.go b/vendor/github.com/disintegration/imaging/io.go
new file mode 100644
index 0000000..557bf2f
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/io.go
@@ -0,0 +1,463 @@
+package imaging
+
+import (
+	"encoding/binary"
+	"errors"
+	"image"
+	"image/draw"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/image/bmp"
+	"golang.org/x/image/tiff"
+)
+
+// Format is an image file format.
+type Format int
+
+// Image file formats.
+const (
+	JPEG Format = iota
+	PNG
+	GIF
+	TIFF
+	BMP
+)
+
+func (f Format) String() string {
+	switch f {
+	case JPEG:
+		return "JPEG"
+	case PNG:
+		return "PNG"
+	case GIF:
+		return "GIF"
+	case TIFF:
+		return "TIFF"
+	case BMP:
+		return "BMP"
+	default:
+		return "Unsupported"
+	}
+}
+
+var formatFromExt = map[string]Format{
+	"jpg":  JPEG,
+	"jpeg": JPEG,
+	"png":  PNG,
+	"tif":  TIFF,
+	"tiff": TIFF,
+	"bmp":  BMP,
+	"gif":  GIF,
+}
+
+// FormatFromExtension parses image format from extension:
+// "jpg" (or "jpeg"), "png", "gif", "tif" (or "tiff") and "bmp" are supported.
+func FormatFromExtension(ext string) (Format, error) {
+	if f, ok := formatFromExt[strings.ToLower(strings.TrimPrefix(ext, "."))]; ok {
+		return f, nil
+	}
+	return -1, ErrUnsupportedFormat
+}
+
+// FormatFromFilename parses image format from filename extension:
+// "jpg" (or "jpeg"), "png", "gif", "tif" (or "tiff") and "bmp" are supported.
+func FormatFromFilename(filename string) (Format, error) {
+	ext := filepath.Ext(filename)
+	return FormatFromExtension(ext)
+}
+
+var (
+	// ErrUnsupportedFormat means the given image format (or file extension) is unsupported.
+	ErrUnsupportedFormat = errors.New("imaging: unsupported image format")
+)
+
+type fileSystem interface {
+	Create(string) (io.WriteCloser, error)
+	Open(string) (io.ReadCloser, error)
+}
+
+type localFS struct{}
+
+func (localFS) Create(name string) (io.WriteCloser, error) { return os.Create(name) }
+func (localFS) Open(name string) (io.ReadCloser, error)    { return os.Open(name) }
+
+var fs fileSystem = localFS{}
+
+type decodeConfig struct {
+	autoOrientation bool
+}
+
+var defaultDecodeConfig = decodeConfig{
+	autoOrientation: false,
+}
+
+// DecodeOption sets an optional parameter for the Decode and Open functions.
+type DecodeOption func(*decodeConfig)
+
+// AutoOrientation returns a DecodeOption that sets the auto-orientation mode.
+// If auto-orientation is enabled, the image will be transformed after decoding
+// according to the EXIF orientation tag (if present). By default it's disabled.
+func AutoOrientation(enabled bool) DecodeOption {
+	return func(c *decodeConfig) {
+		c.autoOrientation = enabled
+	}
+}
+
+// Decode reads an image from r.
+func Decode(r io.Reader, opts ...DecodeOption) (image.Image, error) {
+	cfg := defaultDecodeConfig
+	for _, option := range opts {
+		option(&cfg)
+	}
+
+	if !cfg.autoOrientation {
+		img, _, err := image.Decode(r)
+		return img, err
+	}
+
+	var orient orientation
+	pr, pw := io.Pipe()
+	r = io.TeeReader(r, pw)
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		orient = readOrientation(pr)
+		io.Copy(ioutil.Discard, pr)
+	}()
+
+	img, _, err := image.Decode(r)
+	pw.Close()
+	<-done