dendrite/vendor/src/gopkg.in/h2non/bimg.v1

bimg

Small Go package for fast high-level image processing using libvips via C bindings, providing a simple, elegant and fluent programmatic API.

bimg was designed to be a small and efficient library supporting a common set of image operations such as crop, resize, rotate, zoom or watermark. It can read JPEG, PNG, WEBP natively, and optionally TIFF, PDF, GIF and SVG formats if libvips@8.3+ is compiled with proper library bindings.

bimg is able to output images as JPEG, PNG and WEBP formats, including transparent conversion across them.

bimg uses internally libvips, a powerful library written in C for image processing which requires a low memory footprint and it's typically 4x faster than using the quickest ImageMagick and GraphicsMagick settings or Go native image package, and in some cases it's even 8x faster processing JPEG images.

If you're looking for an HTTP based image processing solution, see imaginary.

bimg was heavily inspired in sharp, its homologous package built for node.js. bimg is used in production environments processing thousands of images per day.

v1 notice: bimg introduces some minor breaking changes in v1 release. If you're using gopkg.in, you can still rely in the v0 without worrying about API breaking changes.

bimg is currently maintained by Kirill Danshin.

Contents

• Supported image operations
• Prerequisites
• Installation
• Performance
• Benchmark
• Examples
• Debugging
• API
• Authors
• Credits

Supported image operations

• Resize
• Enlarge
• Crop (including smart crop support)
• Rotate (with auto-rotate based on EXIF orientation)
• Flip (with auto-flip based on EXIF metadata)
• Flop
• Zoom
• Thumbnail
• Extract area
• Watermark (text only)
• Gaussian blur effect
• Custom output color space (RGB, grayscale...)
• Format conversion (with additional quality/compression settings)
• EXIF metadata (size, alpha channel, profile, orientation...)

Prerequisites

• libvips 7.42+ or 8+ (8.4+ recommended)
• C compatible compiler such as gcc 4.6+ or clang 3.0+
• Go 1.3+

Note: libvips v8.3+ is required for GIF, PDF and SVG support.

Installation

go get -u gopkg.in/h2non/bimg.v1

libvips

Run the following script as sudo (supports OSX, Debian/Ubuntu, Redhat, Fedora, Amazon Linux):

curl -s https://raw.githubusercontent.com/h2non/bimg/master/preinstall.sh | sudo bash -

If you wanna take the advantage of OpenSlide, simply add --with-openslide to enable it:

curl -s https://raw.githubusercontent.com/h2non/bimg/master/preinstall.sh | sudo bash -s --with-openslide

The install script requires curl and pkg-config.

Performance

libvips is probably the faster open source solution for image processing. Here you can see some performance test comparisons for multiple scenarios:

• libvips speed and memory usage

Benchmark

Tested using Go 1.5.1 and libvips-7.42.3 in OSX i7 2.7Ghz

BenchmarkRotateJpeg-8     	      20	  64686945 ns/op
BenchmarkResizeLargeJpeg-8	      20	  63390416 ns/op
BenchmarkResizePng-8      	     100	  18147294 ns/op
BenchmarkResizeWebP-8     	     100	  20836741 ns/op
BenchmarkConvertToJpeg-8  	     100	  12831812 ns/op
BenchmarkConvertToPng-8   	      10	 128901422 ns/op
BenchmarkConvertToWebp-8  	      10	 204027990 ns/op
BenchmarkCropJpeg-8       	      30	  59068572 ns/op
BenchmarkCropPng-8        	      10	 117303259 ns/op
BenchmarkCropWebP-8       	      10	 107060659 ns/op
BenchmarkExtractJpeg-8    	      50	  30708919 ns/op
BenchmarkExtractPng-8     	    3000	    595546 ns/op
BenchmarkExtractWebp-8    	    3000	    386379 ns/op
BenchmarkZoomJpeg-8       	      10	 160005424 ns/op
BenchmarkZoomPng-8        	      30	  44561047 ns/op
BenchmarkZoomWebp-8       	      10	 126732678 ns/op
BenchmarkWatermarkJpeg-8  	      20	  79006133 ns/op
BenchmarkWatermarPng-8    	     200	   8197291 ns/op
BenchmarkWatermarWebp-8   	      30	  49360369 ns/op

Examples

import (
  "fmt"
  "os"
  "gopkg.in/h2non/bimg.v1"
)

Resize

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).Resize(800, 600)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

size, err := bimg.NewImage(newImage).Size()
if size.Width == 400 && size.Height == 300 {
  fmt.Println("The image size is valid")
}

bimg.Write("new.jpg", newImage)

Rotate

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).Rotate(90)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

bimg.Write("new.jpg", newImage)

Convert

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).Convert(bimg.PNG)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

if bimg.NewImage(newImage).Type() == "png" {
  fmt.Fprintln(os.Stderr, "The image was converted into png")
}

Force resize

Force resize operation without perserving the aspect ratio:

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).ForceResize(1000, 500)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

size := bimg.Size(newImage)
if size.Width != 1000 || size.Height != 500 {
  fmt.Fprintln(os.Stderr, "Incorrect image size")
}

Custom colour space (black & white)

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).Colourspace(bimg.INTERPRETATION_B_W)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

colourSpace, _ := bimg.ImageInterpretation(newImage)
if colourSpace != bimg.INTERPRETATION_B_W {
  fmt.Fprintln(os.Stderr, "Invalid colour space")
}

Custom options

See Options struct to discover all the available fields

options := bimg.Options{
  Width:        800,
  Height:       600,
  Crop:         true,
  Quality:      95,
  Rotate:       180,
  Interlace:    true,
}

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

newImage, err := bimg.NewImage(buffer).Process(options)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

bimg.Write("new.jpg", newImage)

Watermark

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

watermark := bimg.Watermark{
  Text:       "Chuck Norris (c) 2315",
  Opacity:    0.25,
  Width:      200,
  DPI:        100,
  Margin:     150,
  Font:       "sans bold 12",
  Background: bimg.Color{255, 255, 255},
}

newImage, err := bimg.NewImage(buffer).Watermark(watermark)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

bimg.Write("new.jpg", newImage)

Fluent interface

buffer, err := bimg.Read("image.jpg")
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

image := bimg.NewImage(buffer)

// first crop image
_, err := image.CropByWidth(300)
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

// then flip it
newImage, err := image.Flip()
if err != nil {
  fmt.Fprintln(os.Stderr, err)
}

// save the cropped and flipped image
bimg.Write("new.jpg", newImage)

Debugging

Run the process passing the DEBUG environment variable

DEBUG=bimg ./app

Enable libvips traces (note that a lot of data will be written in stdout):

VIPS_TRACE=1 ./app

You can also dump a core on failure, as John Cuppit said:

g_log_set_always_fatal(
                G_LOG_FLAG_RECURSION |
                G_LOG_FLAG_FATAL |
                G_LOG_LEVEL_ERROR |
                G_LOG_LEVEL_CRITICAL |
                G_LOG_LEVEL_WARNING );

Or set the G_DEBUG environment variable:

export G_DEBUG=fatal-warnings,fatal-criticals

API

See godoc reference for detailed API documentation.

Authors

• Tomás Aparicio - Original author and architect.
• Kirill Danshin - Maintainer since April 2017.

Credits

People who recurrently contributed to improve bimg in some way.

• John Cupitt
• Yoan Blanc
• Christophe Eblé
• Brant Fitzsimmons
• Thomas Meson

Thank you!

License

MIT - Tomas Aparicio