Switch to dep

14 files changed, 2482 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..b16781f
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/effects.go
@@ -0,0 +1,165 @@
+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)
+		for y := range ys {
+			src.scan(0, y, src.w, y+1, scanLine)
+			for x := 0; x < src.w; x++ {
+				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 := float64(scanLine[i+3]) * weight
+					r += float64(scanLine[i+0]) * wa
+					g += float64(scanLine[i+1]) * wa
+					b += float64(scanLine[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
+}
+
+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)
+		for x := range xs {
+			src.scan(x, 0, x+1, src.h, scanLine)
+			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 := float64(scanLine[i+3]) * weight
+					r += float64(scanLine[i+0]) * wa
+					g += float64(scanLine[i+1]) * wa
+					b += float64(scanLine[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/helpers.go b/vendor/github.com/disintegration/imaging/helpers.go
new file mode 100644
index 0000000..7193e47
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/helpers.go
@@ -0,0 +1,280 @@
+package imaging
+
+import (
+	"errors"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"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 (
+	// 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{}
+
+// Decode reads an image from r.
+func Decode(r io.Reader) (image.Image, error) {
+	img, _, err := image.Decode(r)
+	return img, err
+}
+
+// Open loads an image from file
+func Open(filename string) (image.Image, error) {
+	file, err := fs.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	return Decode(file)
+}
+
+type encodeConfig struct {
+	jpegQuality         int
+	gifNumColors        int
+	gifQuantizer        draw.Quantizer
+	gifDrawer           draw.Drawer
+	pngCompressionLevel png.CompressionLevel
+}
+
+var defaultEncodeConfig = encodeConfig{
+	jpegQuality:         95,
+	gifNumColors:        256,
+	gifQuantizer:        nil,
+	gifDrawer:           nil,
+	pngCompressionLevel: png.DefaultCompression,
+}
+
+// EncodeOption sets an optional parameter for the Encode and Save functions.
+type EncodeOption func(*encodeConfig)
+
+// JPEGQuality returns an EncodeOption that sets the output JPEG quality.
+// Quality ranges from 1 to 100 inclusive, higher is better. Default is 95.
+func JPEGQuality(quality int) EncodeOption {
+	return func(c *encodeConfig) {
+		c.jpegQuality = quality
+	}
+}
+
+// GIFNumColors returns an EncodeOption that sets the maximum number of colors
+// used in the GIF-encoded image. It ranges from 1 to 256.  Default is 256.
+func GIFNumColors(numColors int) EncodeOption {
+	return func(c *encodeConfig) {
+		c.gifNumColors = numColors
+	}
+}
+
+// GIFQuantizer returns an EncodeOption that sets the quantizer that is used to produce
+// a palette of the GIF-encoded image.
+func GIFQuantizer(quantizer draw.Quantizer) EncodeOption {
+	return func(c *encodeConfig) {
+		c.gifQuantizer = quantizer
+	}
+}
+
+// GIFDrawer returns an EncodeOption that sets the drawer that is used to convert
+// the source image to the desired palette of the GIF-encoded image.
+func GIFDrawer(drawer draw.Drawer) EncodeOption {
+	return func(c *encodeConfig) {
+		c.gifDrawer = drawer
+	}
+}
+
+// PNGCompressionLevel returns an EncodeOption that sets the compression level
+// of the PNG-encoded image. Default is png.DefaultCompression.
+func PNGCompressionLevel(level png.CompressionLevel) EncodeOption {
+	return func(c *encodeConfig) {
+		c.pngCompressionLevel = level
+	}
+}
+
+// Encode writes the image img to w in the specified format (JPEG, PNG, GIF, TIFF or BMP).
+func Encode(w io.Writer, img image.Image, format Format, opts ...EncodeOption) error {
+	cfg := defaultEncodeConfig
+	for _, option := range opts {
+		option(&cfg)
+	}
+
+	var err error
+	switch format {
+	case JPEG:
+		var rgba *image.RGBA
+		if nrgba, ok := img.(*image.NRGBA); ok {
+			if nrgba.Opaque() {
+				rgba = &image.RGBA{
+					Pix:    nrgba.Pix,
+					Stride: nrgba.Stride,
+					Rect:   nrgba.Rect,
+				}
+			}
+		}
+		if rgba != nil {
+			err = jpeg.Encode(w, rgba, &jpeg.Options{Quality: cfg.jpegQuality})
+		} else {
+			err = jpeg.Encode(w, img, &jpeg.Options{Quality: cfg.jpegQuality})
+		}
+
+	case PNG:
+		enc := png.Encoder{CompressionLevel: cfg.pngCompressionLevel}
+		err = enc.Encode(w, img)
+
+	case GIF:
+		err = gif.Encode(w, img, &gif.Options{
+			NumColors: cfg.gifNumColors,
+			Quantizer: cfg.gifQuantizer,
+			Drawer:    cfg.gifDrawer,
+		})
+
+	case TIFF:
+		err = tiff.Encode(w, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
+
+	case BMP:
+		err = bmp.Encode(w, img)
+
+	default:
+		err = ErrUnsupportedFormat
+	}
+	return err
+}
+
+// Save saves the image to file with the specified filename.
+// The format is determined from the filename extension: "jpg" (or "jpeg"), "png", "gif", "tif" (or "tiff") and "bmp" are supported.
+//
+// Examples:
+//
+//	// Save the image as PNG.
+//	err := imaging.Save(img, "out.png")
+//
+//	// Save the image as JPEG with optional quality parameter set to 80.
+//	err := imaging.Save(img, "out.jpg", imaging.JPEGQuality(80))
+//
+func Save(img image.Image, filename string, opts ...EncodeOption) (err error) {
+	formats := map[string]Format{
+		".jpg":  JPEG,
+		".jpeg": JPEG,
+		".png":  PNG,
+		".tif":  TIFF,
+		".tiff": TIFF,
+		".bmp":  BMP,
+		".gif":  GIF,
+	}
+
+	ext := strings.ToLower(filepath.Ext(filename))
+	f, ok := formats[ext]
+	if !ok {
+		return ErrUnsupportedFormat
+	}
+
+	file, err := fs.Create(filename)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		cerr := file.Close()
+		if err == nil {
+			err = cerr
+		}
+	}()
+
+	return Encode(file, img, f, opts...)
+}
+
+// New creates a new image with the specified width and height, and fills it with the specified color.
+func New(width, height int, fillColor color.Color) *image.NRGBA {
+	if width <= 0 || height <= 0 {
+		return &image.NRGBA{}
+	}
+
+	dst := image.NewNRGBA(image.Rect(0, 0, width, height))
+	c := color.NRGBAModel.Convert(fillColor).(color.NRGBA)
+
+	if c.R == 0 && c.G == 0 && c.B == 0 && c.A == 0 {
+		return dst
+	}
+
+	// Fill the first row.
+	i := 0
+	for x := 0; x < width; x++ {
+		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
+	}
+
+	// Copy the first row to other rows.
+	size := width * 4
+	parallel(1, height, func(ys <-chan int) {
+		for y := range ys {
+			i = y * dst.Stride
+			copy(dst.Pix[i:i+size], dst.Pix[0:size])
+		}
+	})
+
+	return dst
+}
+
+// Clone returns a copy of the given image.
+func Clone(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+	size := src.w * 4
+	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+size])
+		}
+	})
+	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/resize.go b/vendor/github.com/disintegration/imaging/resize.go
new file mode 100644
index 0000000..97f498a
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/resize.go
@@ -0,0 +1,572 @@
+package imaging
+
+import (
+	"image"
+	"math"
+)
+
+type indexWeight struct {
+	index  int
+	weight float64
+}
+
+func precomputeWeights(dstSize, srcSize int, filter ResampleFilter) [][]indexWeight {
+	du := float64(srcSize) / float64(dstSize)
+	scale := du
+	if scale < 1.0 {
+		scale = 1.0
+	}
+	ru := math.Ceil(scale * filter.Support)
+
+	out := make([][]indexWeight, dstSize)
+	tmp := make([]indexWeight, 0, dstSize*int(ru+2)*2)
+
+	for v := 0; v < dstSize; v++ {
+		fu := (float64(v)+0.5)*du - 0.5
+
+		begin := int(math.Ceil(fu - ru))
+		if begin < 0 {
+			begin = 0
+		}
+		end := int(math.Floor(fu + ru))
+		if end > srcSize-1 {
+			end = srcSize - 1
+		}
+
+		var sum float64
+		for u := begin; u <= end; u++ {
+			w := filter.Kernel((float64(u) - fu) / scale)
+			if w != 0 {
+				sum += w
+				tmp = append(tmp, indexWeight{index: u, weight: w})
+			}
+		}
+		if sum != 0 {
+			for i := range tmp {
+				tmp[i].weight /= sum
+			}
+		}
+
+		out[v] = tmp
+		tmp = tmp[len(tmp):]
+	}
+
+	return out
+}
+
+// Resize resizes the image to the specified width and height using the specified resampling
+// filter and returns the transformed image. If one of width or height is 0, the image aspect
+// ratio is preserved.
+//
+// Supported resample filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali,
+// CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine.
+//
+// Usage example:
+//
+//	dstImage := imaging.Resize(srcImage, 800, 600, imaging.Lanczos)
+//
+func Resize(img image.Image, width, height int, filter ResampleFilter) *image.NRGBA {
+	dstW, dstH := width, height
+	if dstW < 0 || dstH < 0 {
+		return &image.NRGBA{}
+	}
+	if dstW == 0 && dstH == 0 {
+		return &image.NRGBA{}
+	}
+
+	srcW := img.Bounds().Dx()
+	srcH := img.Bounds().Dy()
+	if srcW <= 0 || srcH <= 0 {
+		return &image.NRGBA{}
+	}
+
+	// If new width or height is 0 then preserve aspect ratio, minimum 1px.
+	if dstW == 0 {
+		tmpW := float64(dstH) * float64(srcW) / float64(srcH)
+		dstW = int(math.Max(1.0, math.Floor(tmpW+0.5)))
+	}
+	if dstH == 0 {
+		tmpH := float64(dstW) * float64(srcH) / float64(srcW)
+		dstH = int(math.Max(1.0, math.Floor(tmpH+0.5)))
+	}
+
+	if filter.Support <= 0 {
+		// Nearest-neighbor special case.
+		return resizeNearest(img, dstW, dstH)
+	}
+
+	if srcW != dstW && srcH != dstH {
+		return resizeVertical(resizeHorizontal(img, dstW, filter), dstH, filter)
+	}
+	if srcW != dstW {
+		return resizeHorizontal(img, dstW, filter)
+	}
+	if srcH != dstH {
+		return resizeVertical(img, dstH, filter)
+	}
+	return Clone(img)
+}
+
+func resizeHorizontal(img image.Image, width int, filter ResampleFilter) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, width, src.h))
+	weights := precomputeWeights(width, src.w, filter)
+	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)
+			j0 := y * dst.Stride
+			for x := 0; x < width; x++ {
+				var r, g, b, a float64
+				for _, w := range weights[x] {
+					i := w.index * 4
+					aw := float64(scanLine[i+3]) * w.weight
+					r += float64(scanLine[i+0]) * aw
+					g += float64(scanLine[i+1]) * aw
+					b += float64(scanLine[i+2]) * aw
+					a += aw
+				}
+				if a != 0 {
+					aInv := 1 / a
+					j := j0 + x*4
+					dst.Pix[j+0] = clamp(r * aInv)
+					dst.Pix[j+1] = clamp(g * aInv)
+					dst.Pix[j+2] = clamp(b * aInv)
+					dst.Pix[j+3] = clamp(a)
+				}
+			}
+		}
+	})
+	return dst
+}
+
+func resizeVertical(img image.Image, height int, filter ResampleFilter) *image.NRGBA {
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, src.w, height))
+	weights := precomputeWeights(height, src.h, filter)
+	parallel(0, src.w, func(xs <-chan int) {
+		scanLine := make([]uint8, src.h*4)
+		for x := range xs {
+			src.scan(x, 0, x+1, src.h, scanLine)
+			for y := 0; y < height; y++ {
+				var r, g, b, a float64
+				for _, w := range weights[y] {
+					i := w.index * 4
+					aw := float64(scanLine[i+3]) * w.weight
+					r += float64(scanLine[i+0]) * aw
+					g += float64(scanLine[i+1]) * aw
+					b += float64(scanLine[i+2]) * aw
+					a += aw
+				}
+				if a != 0 {
+					aInv := 1 / a
+					j := y*dst.Stride + x*4
+					dst.Pix[j+0] = clamp(r * aInv)
+					dst.Pix[j+1] = clamp(g * aInv)
+					dst.Pix[j+2] = clamp(b * aInv)
+					dst.Pix[j+3] = clamp(a)
+				}
+			}
+		}
+	})
+	return dst
+}
+
+// resizeNearest is a fast nearest-neighbor resize, no filtering.
+func resizeNearest(img image.Image, width, height int) *image.NRGBA {
+	dst := image.NewNRGBA(image.Rect(0, 0, width, height))
+	dx := float64(img.Bounds().Dx()) / float64(width)
+	dy := float64(img.Bounds().Dy()) / float64(height)
+
+	if dx > 1 && dy > 1 {
+		src := newScanner(img)
+		parallel(0, height, func(ys <-chan int) {
+			for y := range ys {
+				srcY := int((float64(y) + 0.5) * dy)
+				dstOff := y * dst.Stride
+				for x := 0; x < width; x++ {
+					srcX := int((float64(x) + 0.5) * dx)
+					src.scan(srcX, srcY, srcX+1, srcY+1, dst.Pix[dstOff:dstOff+4])
+					dstOff += 4
+				}
+			}
+		})
+	} else {
+		src := toNRGBA(img)
+		parallel(0, height, func(ys <-chan int) {
+			for y := range ys {
+				srcY := int((float64(y) + 0.5) * dy)
+				srcOff0 := srcY * src.Stride
+				dstOff := y * dst.Stride
+				for x := 0; x < width; x++ {
+					srcX := int((float64(x) + 0.5) * dx)
+					srcOff := srcOff0 + srcX*4
+					copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
+					dstOff += 4
+				}
+			}
+		})
+	}
+
+	return dst
+}
+
+// Fit scales down the image using the specified resample filter to fit the specified
+// maximum width and height and returns the transformed image.
+//
+// Supported resample filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali,
+// CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine.
+//
+// Usage example:
+//
+//	dstImage := imaging.Fit(srcImage, 800, 600, imaging.Lanczos)
+//
+func Fit(img image.Image, width, height int, filter ResampleFilter) *image.NRGBA {
+	maxW, maxH := width, height
+
+	if maxW <= 0 || maxH <= 0 {
+		return &image.NRGBA{}
+	}
+
+	srcBounds := img.Bounds()
+	srcW := srcBounds.Dx()
+	srcH := srcBounds.Dy()
+
+	if srcW <= 0 || srcH <= 0 {
+		return &image.NRGBA{}
+	}
+
+	if srcW <= maxW && srcH <= maxH {
+		return Clone(img)
+	}
+
+	srcAspectRatio := float64(srcW) / float64(srcH)
+	maxAspectRatio := float64(maxW) / float64(maxH)
+
+	var newW, newH int
+	if srcAspectRatio > maxAspectRatio {
+		newW = maxW
+		newH = int(float64(newW) / srcAspectRatio)
+	} else {
+		newH = maxH
+		newW = int(float64(newH) * srcAspectRatio)
+	}
+
+	return Resize(img, newW, newH, filter)
+}
+
+// Fill scales the image to the smallest possible size that will cover the specified dimensions,
+// crops the resized image to the specified dimensions using the given anchor point and returns
+// the transformed image.
+//
+// Supported resample filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali,
+// CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine.
+//
+// Usage example:
+//
+//	dstImage := imaging.Fill(srcImage, 800, 600, imaging.Center, imaging.Lanczos)
+//
+func Fill(img image.Image, width, height int, anchor Anchor, filter ResampleFilter) *image.NRGBA {
+	minW, minH := width, height
+
+	if minW <= 0 || minH <= 0 {
+		return &image.NRGBA{}
+	}
+
+	srcBounds := img.Bounds()
+	srcW := srcBounds.Dx()
+	srcH := srcBounds.Dy()
+
+	if srcW <= 0 || srcH <= 0 {
+		return &image.NRGBA{}
+	}
+
+	if srcW == minW && srcH == minH {
+		return Clone(img)
+	}
+
+	srcAspectRatio := float64(srcW) / float64(srcH)
+	minAspectRatio := float64(minW) / float64(minH)
+
+	var tmp *image.NRGBA
+	if srcAspectRatio < minAspectRatio {
+		tmp = Resize(img, minW, 0, filter)
+	} else {
+		tmp = Resize(img, 0, minH, filter)
+	}
+
+	return CropAnchor(tmp, minW, minH, anchor)
+}
+
+// Thumbnail scales the image up or down using the specified resample filter, crops it
+// to the specified width and hight and returns the transformed image.
+//
+// Supported resample filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali,
+// CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine.
+//
+// Usage example:
+//
+//	dstImage := imaging.Thumbnail(srcImage, 100, 100, imaging.Lanczos)
+//
+func Thumbnail(img image.Image, width, height int, filter ResampleFilter) *image.NRGBA {
+	return Fill(img, width, height, Center, filter)
+}
+
+// ResampleFilter is a resampling filter struct. It can be used to define custom filters.
+//
+// Supported resample filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali,
+// CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine.
+//
+//	General filter recommendations:
+//
+//	- Lanczos
+//		High-quality resampling filter for photographic images yielding sharp results.
+//		It's slower than cubic filters (see below).
+//
+//	- CatmullRom
+//		A sharp cubic filter. It's a good filter for both upscaling and downscaling if sharp results are needed.
+//
+//	- MitchellNetravali
+//		A high quality cubic filter that produces smoother results with less ringing artifacts than CatmullRom.
+//
+//	- BSpline
+//		A good filter if a very smooth output is needed.
+//
+//	- Linear
+//		Bilinear interpolation filter, produces reasonably good, smooth output.
+//		It's faster than cubic filters.
+//
+//	- Box
+//		Simple and fast averaging filter appropriate for downscaling.
+//		When upscaling it's similar to NearestNeighbor.
+//
+//	- NearestNeighbor
+//		Fastest resampling filter, no antialiasing.
+//
+type ResampleFilter struct {
+	Support float64
+	Kernel  func(float64) float64
+}
+
+// NearestNeighbor is a nearest-neighbor filter (no anti-aliasing).
+var NearestNeighbor ResampleFilter
+
+// Box filter (averaging pixels).
+var Box ResampleFilter
+
+// Linear filter.
+var Linear ResampleFilter
+
+// Hermite cubic spline filter (BC-spline; B=0; C=0).
+var Hermite ResampleFilter
+
+// MitchellNetravali is Mitchell-Netravali cubic filter (BC-spline; B=1/3; C=1/3).
+var MitchellNetravali ResampleFilter
+
+// CatmullRom is a Catmull-Rom - sharp cubic filter (BC-spline; B=0; C=0.5).
+var CatmullRom ResampleFilter
+
+// BSpline is a smooth cubic filter (BC-spline; B=1; C=0).
+var BSpline ResampleFilter
+
+// Gaussian is a Gaussian blurring Filter.
+var Gaussian ResampleFilter
+
+// Bartlett is a Bartlett-windowed sinc filter (3 lobes).
+var Bartlett ResampleFilter
+
+// Lanczos filter (3 lobes).
+var Lanczos ResampleFilter
+
+// Hann is a Hann-windowed sinc filter (3 lobes).
+var Hann ResampleFilter
+
+// Hamming is a Hamming-windowed sinc filter (3 lobes).
+var Hamming ResampleFilter
+
+// Blackman is a Blackman-windowed sinc filter (3 lobes).
+var Blackman ResampleFilter
+
+// Welch is a Welch-windowed sinc filter (parabolic window, 3 lobes).
+var Welch ResampleFilter
+
+// Cosine is a Cosine-windowed sinc filter (3 lobes).
+var Cosine ResampleFilter
+
+func bcspline(x, b, c float64) float64 {
+	var y float64
+	x = math.Abs(x)
+	if x < 1.0 {
+		y = ((12-9*b-6*c)*x*x*x + (-18+12*b+6*c)*x*x + (6 - 2*b)) / 6
+	} else if x < 2.0 {
+		y = ((-b-6*c)*x*x*x + (6*b+30*c)*x*x + (-12*b-48*c)*x + (8*b + 24*c)) / 6
+	}
+	return y
+}
+
+func sinc(x float64) float64 {
+	if x == 0 {
+		return 1
+	}
+	return math.Sin(math.Pi*x) / (math.Pi * x)
+}
+
+func init() {
+	NearestNeighbor = ResampleFilter{
+		Support: 0.0, // special case - not applying the filter
+	}
+
+	Box = ResampleFilter{
+		Support: 0.5,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x <= 0.5 {
+				return 1.0
+			}
+			return 0
+		},
+	}
+
+	Linear = ResampleFilter{
+		Support: 1.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 1.0 {
+				return 1.0 - x
+			}
+			return 0
+		},
+	}
+
+	Hermite = ResampleFilter{
+		Support: 1.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 1.0 {
+				return bcspline(x, 0.0, 0.0)
+			}
+			return 0
+		},
+	}
+
+	MitchellNetravali = ResampleFilter{
+		Support: 2.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 2.0 {
+				return bcspline(x, 1.0/3.0, 1.0/3.0)
+			}
+			return 0
+		},
+	}
+
+	CatmullRom = ResampleFilter{
+		Support: 2.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 2.0 {
+				return bcspline(x, 0.0, 0.5)
+			}
+			return 0
+		},
+	}
+
+	BSpline = ResampleFilter{
+		Support: 2.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 2.0 {
+				return bcspline(x, 1.0, 0.0)
+			}
+			return 0
+		},
+	}
+
+	Gaussian = ResampleFilter{
+		Support: 2.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 2.0 {
+				return math.Exp(-2 * x * x)
+			}
+			return 0
+		},
+	}
+
+	Bartlett = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * (3.0 - x) / 3.0
+			}
+			return 0
+		},
+	}
+
+	Lanczos = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * sinc(x/3.0)
+			}
+			return 0
+		},
+	}
+
+	Hann = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * (0.5 + 0.5*math.Cos(math.Pi*x/3.0))
+			}
+			return 0
+		},
+	}
+
+	Hamming = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * (0.54 + 0.46*math.Cos(math.Pi*x/3.0))
+			}
+			return 0
+		},
+	}
+
+	Blackman = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * (0.42 - 0.5*math.Cos(math.Pi*x/3.0+math.Pi) + 0.08*math.Cos(2.0*math.Pi*x/3.0))
+			}
+			return 0
+		},
+	}
+
+	Welch = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * (1.0 - (x * x / 9.0))
+			}
+			return 0
+		},
+	}
+
+	Cosine = ResampleFilter{
+		Support: 3.0,
+		Kernel: func(x float64) float64 {
+			x = math.Abs(x)
+			if x < 3.0 {
+				return sinc(x) * math.Cos((math.Pi/2.0)*(x/3.0))
+			}
+			return 0
+		},
+	}
+}
diff --git a/vendor/github.com/disintegration/imaging/scanner.go b/vendor/github.com/disintegration/imaging/scanner.go
new file mode 100644
index 0000000..c4dbfe1
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/scanner.go
@@ -0,0 +1,250 @@
+package imaging
+
+import (
+	"image"
+	"image/color"
+)
+
+type scanner struct {
+	image   image.Image
+	w, h    int
+	palette []color.NRGBA
+}
+
+func newScanner(img image.Image) *scanner {
+	s := &scanner{
+		image: img,
+		w:     img.Bounds().Dx(),
+		h:     img.Bounds().Dy(),
+	}
+	if img, ok := img.(*image.Paletted); ok {
+		s.palette = make([]color.NRGBA, len(img.Palette))
+		for i := 0; i < len(img.Palette); i++ {
+			s.palette[i] = color.NRGBAModel.Convert(img.Palette[i]).(color.NRGBA)
+		}
+	}
+	return s
+}
+
+// scan scans the given rectangular region of the image into dst.
+func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
+	switch img := s.image.(type) {
+	case *image.NRGBA:
+		size := (x2 - x1) * 4
+		j := 0
+		i := y1*img.Stride + x1*4
+		for y := y1; y < y2; y++ {
+			copy(dst[j:j+size], img.Pix[i:i+size])
+			j += size
+			i += img.Stride
+		}
+
+	case *image.NRGBA64:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1*8
+			for x := x1; x < x2; x++ {
+				dst[j+0] = img.Pix[i+0]
+				dst[j+1] = img.Pix[i+2]
+				dst[j+2] = img.Pix[i+4]
+				dst[j+3] = img.Pix[i+6]
+				j += 4
+				i += 8
+			}
+		}
+
+	case *image.RGBA:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1*4
+			for x := x1; x < x2; x++ {
+				a := img.Pix[i+3]
+				switch a {
+				case 0:
+					dst[j+0] = 0
+					dst[j+1] = 0
+					dst[j+2] = 0
+				case 0xff:
+					dst[j+0] = img.Pix[i+0]
+					dst[j+1] = img.Pix[i+1]
+					dst[j+2] = img.Pix[i+2]
+				default:
+					r16 := uint16(img.Pix[i+0])
+					g16 := uint16(img.Pix[i+1])
+					b16 := uint16(img.Pix[i+2])
+					a16 := uint16(a)
+					dst[j+0] = uint8(r16 * 0xff / a16)
+					dst[j+1] = uint8(g16 * 0xff / a16)
+					dst[j+2] = uint8(b16 * 0xff / a16)
+				}
+				dst[j+3] = a
+				j += 4
+				i += 4
+			}
+		}
+
+	case *image.RGBA64:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1*8
+			for x := x1; x < x2; x++ {
+				a := img.Pix[i+6]
+				switch a {
+				case 0:
+					dst[j+0] = 0
+					dst[j+1] = 0
+					dst[j+2] = 0
+				case 0xff:
+					dst[j+0] = img.Pix[i+0]
+					dst[j+1] = img.Pix[i+2]
+					dst[j+2] = img.Pix[i+4]
+				default:
+					r32 := uint32(img.Pix[i+0])<<8 | uint32(img.Pix[i+1])
+					g32 := uint32(img.Pix[i+2])<<8 | uint32(img.Pix[i+3])
+					b32 := uint32(img.Pix[i+4])<<8 | uint32(img.Pix[i+5])
+					a32 := uint32(img.Pix[i+6])<<8 | uint32(img.Pix[i+7])
+					dst[j+0] = uint8((r32 * 0xffff / a32) >> 8)
+					dst[j+1] = uint8((g32 * 0xffff / a32) >> 8)
+					dst[j+2] = uint8((b32 * 0xffff / a32) >> 8)
+				}
+				dst[j+3] = a
+				j += 4
+				i += 8
+			}
+		}
+
+	case *image.Gray:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1
+			for x := x1; x < x2; x++ {
+				c := img.Pix[i]
+				dst[j+0] = c
+				dst[j+1] = c
+				dst[j+2] = c
+				dst[j+3] = 0xff
+				j += 4
+				i++
+			}
+		}
+
+	case *image.Gray16:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1*2
+			for x := x1; x < x2; x++ {
+				c := img.Pix[i]
+				dst[j+0] = c
+				dst[j+1] = c
+				dst[j+2] = c
+				dst[j+3] = 0xff
+				j += 4
+				i += 2
+			}
+		}
+
+	case *image.YCbCr:
+		j := 0
+		x1 += img.Rect.Min.X
+		x2 += img.Rect.Min.X
+		y1 += img.Rect.Min.Y
+		y2 += img.Rect.Min.Y
+		for y := y1; y < y2; y++ {
+			iy := (y-img.Rect.Min.Y)*img.YStride + (x1 - img.Rect.Min.X)
+			for x := x1; x < x2; x++ {
+				var ic int
+				switch img.SubsampleRatio {
+				case image.YCbCrSubsampleRatio444:
+					ic = (y-img.Rect.Min.Y)*img.CStride + (x - img.Rect.Min.X)
+				case image.YCbCrSubsampleRatio422:
+					ic = (y-img.Rect.Min.Y)*img.CStride + (x/2 - img.Rect.Min.X/2)
+				case image.YCbCrSubsampleRatio420:
+					ic = (y/2-img.Rect.Min.Y/2)*img.CStride + (x/2 - img.Rect.Min.X/2)
+				case image.YCbCrSubsampleRatio440:
+					ic = (y/2-img.Rect.Min.Y/2)*img.CStride + (x - img.Rect.Min.X)
+				default:
+					ic = img.COffset(x, y)
+				}
+
+				yy := int(img.Y[iy])
+				cb := int(img.Cb[ic]) - 128
+				cr := int(img.Cr[ic]) - 128
+
+				r := (yy<<16 + 91881*cr + 1<<15) >> 16
+				if r > 0xff {
+					r = 0xff
+				} else if r < 0 {
+					r = 0
+				}
+
+				g := (yy<<16 - 22554*cb - 46802*cr + 1<<15) >> 16
+				if g > 0xff {
+					g = 0xff
+				} else if g < 0 {
+					g = 0
+				}
+
+				b := (yy<<16 + 116130*cb + 1<<15) >> 16
+				if b > 0xff {
+					b = 0xff
+				} else if b < 0 {
+					b = 0
+				}
+
+				dst[j+0] = uint8(r)
+				dst[j+1] = uint8(g)
+				dst[j+2] = uint8(b)
+				dst[j+3] = 0xff
+
+				iy++
+				j += 4
+			}
+		}
+
+	case *image.Paletted:
+		j := 0
+		for y := y1; y < y2; y++ {
+			i := y*img.Stride + x1
+			for x := x1; x < x2; x++ {
+				c := s.palette[img.Pix[i]]
+				dst[j+0] = c.R
+				dst[j+1] = c.G
+				dst[j+2] = c.B
+				dst[j+3] = c.A
+				j += 4
+				i++
+			}
+		}
+
+	default:
+		j := 0
+		b := s.image.Bounds()
+		x1 += b.Min.X
+		x2 += b.Min.X
+		y1 += b.Min.Y
+		y2 += b.Min.Y
+		for y := y1; y < y2; y++ {
+			for x := x1; x < x2; x++ {
+				r16, g16, b16, a16 := s.image.At(x, y).RGBA()
+				switch a16 {
+				case 0xffff:
+					dst[j+0] = uint8(r16 >> 8)
+					dst[j+1] = uint8(g16 >> 8)
+					dst[j+2] = uint8(b16 >> 8)
+					dst[j+3] = 0xff
+				case 0:
+					dst[j+0] = 0
+					dst[j+1] = 0
+					dst[j+2] = 0
+					dst[j+3] = 0
+				default:
+					dst[j+0] = uint8(((r16 * 0xffff) / a16) >> 8)
+					dst[j+1] = uint8(((g16 * 0xffff) / a16) >> 8)
+					dst[j+2] = uint8(((b16 * 0xffff) / a16) >> 8)
+					dst[j+3] = uint8(a16 >> 8)
+				}
+				j += 4
+			}
+		}
+	}
+}
diff --git a/vendor/github.com/disintegration/imaging/tools.go b/vendor/github.com/disintegration/imaging/tools.go
new file mode 100644
index 0000000..fae1fa1
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/tools.go
@@ -0,0 +1,213 @@
+package imaging
+
+import (
+	"image"
+	"math"
+)
+
+// Anchor is the anchor point for image alignment.
+type Anchor int
+
+// Anchor point positions.
+const (
+	Center Anchor = iota
+	TopLeft
+	Top
+	TopRight
+	Left
+	Right
+	BottomLeft
+	Bottom
+	BottomRight
+)
+
+func anchorPt(b image.Rectangle, w, h int, anchor Anchor) image.Point {
+	var x, y int
+	switch anchor {
+	case TopLeft:
+		x = b.Min.X
+		y = b.Min.Y
+	case Top:
+		x = b.Min.X + (b.Dx()-w)/2
+		y = b.Min.Y
+	case TopRight:
+		x = b.Max.X - w
+		y = b.Min.Y
+	case Left:
+		x = b.Min.X
+		y = b.Min.Y + (b.Dy()-h)/2
+	case Right:
+		x = b.Max.X - w
+		y = b.Min.Y + (b.Dy()-h)/2
+	case BottomLeft:
+		x = b.Min.X
+		y = b.Max.Y - h
+	case Bottom:
+		x = b.Min.X + (b.Dx()-w)/2
+		y = b.Max.Y - h
+	case BottomRight:
+		x = b.Max.X - w
+		y = b.Max.Y - h
+	default:
+		x = b.Min.X + (b.Dx()-w)/2
+		y = b.Min.Y + (b.Dy()-h)/2
+	}
+	return image.Pt(x, y)
+}
+
+// Crop cuts out a rectangular region with the specified bounds
+// from the image and returns the cropped image.
+func Crop(img image.Image, rect image.Rectangle) *image.NRGBA {
+	r := rect.Intersect(img.Bounds()).Sub(img.Bounds().Min)
+	if r.Empty() {
+		return &image.NRGBA{}
+	}
+	src := newScanner(img)
+	dst := image.NewNRGBA(image.Rect(0, 0, r.Dx(), r.Dy()))
+	rowSize := r.Dx() * 4
+	parallel(r.Min.Y, r.Max.Y, func(ys <-chan int) {
+		for y := range ys {
+			i := (y - r.Min.Y) * dst.Stride
+			src.scan(r.Min.X, y, r.Max.X, y+1, dst.Pix[i:i+rowSize])
+		}
+	})
+	return dst
+}
+
+// CropAnchor cuts out a rectangular region with the specified size
+// from the image using the specified anchor point and returns the cropped image.
+func CropAnchor(img image.Image, width, height int, anchor Anchor) *image.NRGBA {
+	srcBounds := img.Bounds()
+	pt := anchorPt(srcBounds, width, height, anchor)
+	r := image.Rect(0, 0, width, height).Add(pt)
+	b := srcBounds.Intersect(r)
+	return Crop(img, b)
+}
+
+// CropCenter cuts out a rectangular region with the specified size
+// from the center of the image and returns the cropped image.
+func CropCenter(img image.Image, width, height int) *image.NRGBA {
+	return CropAnchor(img, width, height, Center)
+}
+
+// Paste pastes the img image to the background image at the specified position and returns the combined image.
+func Paste(background, img image.Image, pos image.Point) *image.NRGBA {
+	dst := Clone(background)
+	pos = pos.Sub(background.Bounds().Min)
+	pasteRect := image.Rectangle{Min: pos, Max: pos.Add(img.Bounds().Size())}
+	interRect := pasteRect.Intersect(dst.Bounds())
+	if interRect.Empty() {
+		return dst
+	}
+	src := newScanner(img)
+	parallel(interRect.Min.Y, interRect.Max.Y, func(ys <-chan int) {
+		for y := range ys {
+			x1 := interRect.Min.X - pasteRect.Min.X
+			x2 := interRect.Max.X - pasteRect.Min.X
+			y1 := y - pasteRect.Min.Y
+			y2 := y1 + 1
+			i1 := y*dst.Stride + interRect.Min.X*4
+			i2 := i1 + interRect.Dx()*4
+			src.scan(x1, y1, x2, y2, dst.Pix[i1:i2])
+		}
+	})
+	return dst
+}
+
+// PasteCenter pastes the img image to the center of the background image and returns the combined image.
+func PasteCenter(background, img image.Image) *image.NRGBA {
+	bgBounds := background.Bounds()
+	bgW := bgBounds.Dx()
+	bgH := bgBounds.Dy()
+	bgMinX := bgBounds.Min.X
+	bgMinY := bgBounds.Min.Y
+
+	centerX := bgMinX + bgW/2
+	centerY := bgMinY + bgH/2
+
+	x0 := centerX - img.Bounds().Dx()/2
+	y0 := centerY - img.Bounds().Dy()/2
+
+	return Paste(background, img, image.Pt(x0, y0))
+}
+
+// Overlay draws the img image over the background image at given position
+// and returns the combined image. Opacity parameter is the opacity of the img
+// image layer, used to compose the images, it must be from 0.0 to 1.0.
+//
+// Usage examples:
+//
+//	// Draw spriteImage over backgroundImage at the given position (x=50, y=50).
+//	dstImage := imaging.Overlay(backgroundImage, spriteImage, image.Pt(50, 50), 1.0)
+//
+//	// Blend two opaque images of the same size.
+//	dstImage := imaging.Overlay(imageOne, imageTwo, image.Pt(0, 0), 0.5)
+//
+func Overlay(background, img image.Image, pos image.Point, opacity float64) *image.NRGBA {
+	opacity = math.Min(math.Max(opacity, 0.0), 1.0) // Ensure 0.0 <= opacity <= 1.0.
+	dst := Clone(background)
+	pos = pos.Sub(background.Bounds().Min)
+	pasteRect := image.Rectangle{Min: pos, Max: pos.Add(img.Bounds().Size())}
+	interRect := pasteRect.Intersect(dst.Bounds())
+	if interRect.Empty() {
+		return dst
+	}
+	src := newScanner(img)
+	parallel(interRect.Min.Y, interRect.Max.Y, func(ys <-chan int) {
+		scanLine := make([]uint8, interRect.Dx()*4)
+		for y := range ys {
+			x1 := interRect.Min.X - pasteRect.Min.X
+			x2 := interRect.Max.X - pasteRect.Min.X
+			y1 := y - pasteRect.Min.Y
+			y2 := y1 + 1
+			src.scan(x1, y1, x2, y2, scanLine)
+			i := y*dst.Stride + interRect.Min.X*4
+			j := 0
+			for x := interRect.Min.X; x < interRect.Max.X; x++ {
+				r1 := float64(dst.Pix[i+0])
+				g1 := float64(dst.Pix[i+1])
+				b1 := float64(dst.Pix[i+2])
+				a1 := float64(dst.Pix[i+3])
+
+				r2 := float64(scanLine[j+0])
+				g2 := float64(scanLine[j+1])
+				b2 := float64(scanLine[j+2])
+				a2 := float64(scanLine[j+3])
+
+				coef2 := opacity * a2 / 255
+				coef1 := (1 - coef2) * a1 / 255
+				coefSum := coef1 + coef2
+				coef1 /= coefSum
+				coef2 /= coefSum
+
+				dst.Pix[i+0] = uint8(r1*coef1 + r2*coef2)
+				dst.Pix[i+1] = uint8(g1*coef1 + g2*coef2)
+				dst.Pix[i+2] = uint8(b1*coef1 + b2*coef2)
+				dst.Pix[i+3] = uint8(math.Min(a1+a2*opacity*(255-a1)/255, 255))
+
+				i += 4
+				j += 4
+			}
+		}
+	})
+	return dst
+}
+
+// OverlayCenter overlays the img image to the center of the background image and
+// returns the combined image. Opacity parameter is the opacity of the img
+// image layer, used to compose the images, it must be from 0.0 to 1.0.
+func OverlayCenter(background, img image.Image, opacity float64) *image.NRGBA {
+	bgBounds := background.Bounds()
+	bgW := bgBounds.Dx()
+	bgH := bgBounds.Dy()
+	bgMinX := bgBounds.Min.X
+	bgMinY := bgBounds.Min.Y
+
+	centerX := bgMinX + bgW/2
+	centerY := bgMinY + bgH/2
+
+	x0 := centerX - img.Bounds().Dx()/2
+	y0 := centerY - img.Bounds().Dy()/2
+
+	return Overlay(background, img, image.Point{x0, y0}, opacity)
+}
diff --git a/vendor/github.com/disintegration/imaging/transform.go b/vendor/github.com/disintegration/imaging/transform.go
new file mode 100644
index 0000000..d788d0d
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/transform.go
@@ -0,0 +1,271 @@
+package imaging
+
+import (
+	"image"
+	"image/color"
+	"math"
+)
+
+// FlipH flips the image horizontally (from left to right) and returns the transformed image.
+func FlipH(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.w
+	dstH := src.h
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcY := dstY
+			src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
+			reverse(dst.Pix[i : i+rowSize])
+		}
+	})
+	return dst
+}
+
+// FlipV flips the image vertically (from top to bottom) and returns the transformed image.
+func FlipV(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.w
+	dstH := src.h
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcY := dstH - dstY - 1
+			src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Transpose flips the image horizontally and rotates 90 degrees counter-clockwise.
+func Transpose(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.h
+	dstH := src.w
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcX := dstY
+			src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Transverse flips the image vertically and rotates 90 degrees counter-clockwise.
+func Transverse(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.h
+	dstH := src.w
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcX := dstH - dstY - 1
+			src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
+			reverse(dst.Pix[i : i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Rotate90 rotates the image 90 degrees counter-clockwise and returns the transformed image.
+func Rotate90(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.h
+	dstH := src.w
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcX := dstH - dstY - 1
+			src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Rotate180 rotates the image 180 degrees counter-clockwise and returns the transformed image.
+func Rotate180(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.w
+	dstH := src.h
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcY := dstH - dstY - 1
+			src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
+			reverse(dst.Pix[i : i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Rotate270 rotates the image 270 degrees counter-clockwise and returns the transformed image.
+func Rotate270(img image.Image) *image.NRGBA {
+	src := newScanner(img)
+	dstW := src.h
+	dstH := src.w
+	rowSize := dstW * 4
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			i := dstY * dst.Stride
+			srcX := dstY
+			src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
+			reverse(dst.Pix[i : i+rowSize])
+		}
+	})
+	return dst
+}
+
+// Rotate rotates an image by the given angle counter-clockwise .
+// The angle parameter is the rotation angle in degrees.
+// The bgColor parameter specifies the color of the uncovered zone after the rotation.
+func Rotate(img image.Image, angle float64, bgColor color.Color) *image.NRGBA {
+	angle = angle - math.Floor(angle/360)*360
+
+	switch angle {
+	case 0:
+		return Clone(img)
+	case 90:
+		return Rotate90(img)
+	case 180:
+		return Rotate180(img)
+	case 270:
+		return Rotate270(img)
+	}
+
+	src := toNRGBA(img)
+	srcW := src.Bounds().Max.X
+	srcH := src.Bounds().Max.Y
+	dstW, dstH := rotatedSize(srcW, srcH, angle)
+	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
+
+	if dstW <= 0 || dstH <= 0 {
+		return dst
+	}
+
+	srcXOff := float64(srcW)/2 - 0.5
+	srcYOff := float64(srcH)/2 - 0.5
+	dstXOff := float64(dstW)/2 - 0.5
+	dstYOff := float64(dstH)/2 - 0.5
+
+	bgColorNRGBA := color.NRGBAModel.Convert(bgColor).(color.NRGBA)
+	sin, cos := math.Sincos(math.Pi * angle / 180)
+
+	parallel(0, dstH, func(ys <-chan int) {
+		for dstY := range ys {
+			for dstX := 0; dstX < dstW; dstX++ {
+				xf, yf := rotatePoint(float64(dstX)-dstXOff, float64(dstY)-dstYOff, sin, cos)
+				xf, yf = xf+srcXOff, yf+srcYOff
+				interpolatePoint(dst, dstX, dstY, src, xf, yf, bgColorNRGBA)
+			}
+		}
+	})
+
+	return dst
+}
+
+func rotatePoint(x, y, sin, cos float64) (float64, float64) {
+	return x*cos - y*sin, x*sin + y*cos
+}
+
+func rotatedSize(w, h int, angle float64) (int, int) {
+	if w <= 0 || h <= 0 {
+		return 0, 0
+	}
+
+	sin, cos := math.Sincos(math.Pi * angle / 180)
+	x1, y1 := rotatePoint(float64(w-1), 0, sin, cos)
+	x2, y2 := rotatePoint(float64(w-1), float64(h-1), sin, cos)
+	x3, y3 := rotatePoint(0, float64(h-1), sin, cos)
+
+	minx := math.Min(x1, math.Min(x2, math.Min(x3, 0)))
+	maxx := math.Max(x1, math.Max(x2, math.Max(x3, 0)))
+	miny := math.Min(y1, math.Min(y2, math.Min(y3, 0)))
+	maxy := math.Max(y1, math.Max(y2, math.Max(y3, 0)))
+
+	neww := maxx - minx + 1
+	if neww-math.Floor(neww) > 0.1 {
+		neww++
+	}
+	newh := maxy - miny + 1
+	if newh-math.Floor(newh) > 0.1 {
+		newh++
+	}
+
+	return int(neww), int(newh)
+}
+
+func interpolatePoint(dst *image.NRGBA, dstX, dstY int, src *image.NRGBA, xf, yf float64, bgColor color.NRGBA) {
+	dstIndex := dstY*dst.Stride + dstX*4
+
+	x0 := int(math.Floor(xf))
+	y0 := int(math.Floor(yf))
+	bounds := src.Bounds()
+	if !image.Pt(x0, y0).In(image.Rect(bounds.Min.X-1, bounds.Min.Y-1, bounds.Max.X, bounds.Max.Y)) {
+		dst.Pix[dstIndex+0] = bgColor.R
+		dst.Pix[dstIndex+1] = bgColor.G
+		dst.Pix[dstIndex+2] = bgColor.B
+		dst.Pix[dstIndex+3] = bgColor.A
+		return
+	}
+
+	xq := xf - float64(x0)
+	yq := yf - float64(y0)
+
+	var pxs [4]color.NRGBA
+	var cfs [4]float64
+
+	for i := 0; i < 2; i++ {
+		for j := 0; j < 2; j++ {
+			k := i*2 + j
+			pt := image.Pt(x0+j, y0+i)
+			if pt.In(bounds) {
+				l := pt.Y*src.Stride + pt.X*4
+				pxs[k].R = src.Pix[l+0]
+				pxs[k].G = src.Pix[l+1]
+				pxs[k].B = src.Pix[l+2]
+				pxs[k].A = src.Pix[l+3]
+			} else {
+				pxs[k] = bgColor
+			}
+		}
+	}
+
+	cfs[0] = (1 - xq) * (1 - yq)
+	cfs[1] = xq * (1 - yq)
+	cfs[2] = (1 - xq) * yq
+	cfs[3] = xq * yq
+
+	var r, g, b, a float64
+	for i := range pxs {
+		wa := float64(pxs[i].A) * cfs[i]
+		r += float64(pxs[i].R) * wa
+		g += float64(pxs[i].G) * wa
+		b += float64(pxs[i].B) * wa
+		a += wa
+	}
+
+	if a != 0 {
+		r /= a
+		g /= a
+		b /= a
+	}
+
+	dst.Pix[dstIndex+0] = clamp(r)
+	dst.Pix[dstIndex+1] = clamp(g)
+	dst.Pix[dstIndex+2] = clamp(b)
+	dst.Pix[dstIndex+3] = clamp(a)
+}
diff --git a/vendor/github.com/disintegration/imaging/utils.go b/vendor/github.com/disintegration/imaging/utils.go
new file mode 100644
index 0000000..3b6ad2e
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/utils.go
@@ -0,0 +1,83 @@
+package imaging
+
+import (
+	"image"
+	"runtime"
+	"sync"
+)
+
+// parallel processes the data in separate goroutines.
+func parallel(start, stop int, fn func(<-chan int)) {
+	count := stop - start
+	if count < 1 {
+		return
+	}
+
+	procs := runtime.GOMAXPROCS(0)
+	if procs > count {
+		procs = count
+	}
+
+	c := make(chan int, count)
+	for i := start; i < stop; i++ {
+		c <- i
+	}
+	close(c)
+
+	var wg sync.WaitGroup
+	for i := 0; i < procs; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			fn(c)
+		}()
+	}
+	wg.Wait()
+}
+
+// absint returns the absolute value of i.
+func absint(i int) int {
+	if i < 0 {
+		return -i
+	}
+	return i
+}
+
+// clamp rounds and clamps float64 value to fit into uint8.
+func clamp(x float64) uint8 {
+	v := int64(x + 0.5)
+	if v > 255 {
+		return 255
+	}
+	if v > 0 {
+		return uint8(v)
+	}
+	return 0
+}
+
+func reverse(pix []uint8) {
+	if len(pix) <= 4 {
+		return
+	}
+	i := 0
+	j := len(pix) - 4
+	for i < j {
+		pix[i+0], pix[j+0] = pix[j+0], pix[i+0]
+		pix[i+1], pix[j+1] = pix[j+1], pix[i+1]
+		pix[i+2], pix[j+2] = pix[j+2], pix[i+2]
+		pix[i+3], pix[j+3] = pix[j+3], pix[i+3]
+		i += 4
+		j -= 4
+	}
+}
+
+func toNRGBA(img image.Image) *image.NRGBA {
+	if img, ok := img.(*image.NRGBA); ok {
+		return &image.NRGBA{
+			Pix:    img.Pix,
+			Stride: img.Stride,
+			Rect:   img.Rect.Sub(img.Rect.Min),
+		}
+	}
+	return Clone(img)
+}