bimg

Small Go package for fast high-level image processing using libvips via C bindings. Provides 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 and TIFF formats and output to JPEG, PNG and WEBP, including conversion between 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.

To get started you could take a look to the examples and API documentation.

If you're looking for a HTTP based image processing solution, see imaginary. bimg was heavily inspired in sharp, its homologous package built for node.js.

Prerequisites

libvips v7.40.0+ (7.42.0+ recommended)
C compatible compiler such as gcc 4.6+ or clang 3.0+
Go 1.3+

Installation

go get -u gopkg.in/h2non/bimg.v0

libvips

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

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

The install script requires curl and pkg-config

For platform specific installations, see Mac OS tips or Windows tips

Supported image operations

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

Performance

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

Benchmarks

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

API

Examples

import (
  "fmt"
  "os"
  "gopkg.in/h2non/bimg.v0"
)

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

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

Programmatic API

const HasMagickSupport = int(C.VIPS_MAGICK_SUPPORT) == 1

const Version = "0.1.20"

const WATERMARK_FONT = "sans 10"

func ColourspaceIsSupported

func ColourspaceIsSupported(buf []byte) (bool, error)

Check in the image colourspace is supported by libvips

func DetermineImageTypeName

func DetermineImageTypeName(buf []byte) string

Determines the image type format by name (jpeg, png, webp or tiff)

func Initialize

func Initialize()

Explicit thread-safe start of libvips. Only call this function if you've previously shutdown libvips

func IsTypeNameSupported

func IsTypeNameSupported(t string) bool

Check if a given image type name is supported

func IsTypeSupported

func IsTypeSupported(t ImageType) bool

Check if a given image type is supported

func Read

func Read(path string) ([]byte, error)

func Resize

func Resize(buf []byte, o Options) ([]byte, error)

func Shutdown

func Shutdown()

Thread-safe function to shutdown libvips. You can call this to drop caches as well. If libvips was already initialized, the function is no-op

func VipsDebugInfo

func VipsDebugInfo()

Output to stdout vips collected data. Useful for debugging

func Write

func Write(path string, buf []byte) error

type Angle

type Angle int

const (
  D0   Angle = 0
  D90  Angle = 90
  D180 Angle = 180
  D270 Angle = 270
)

type Color

type Color struct {
  R, G, B uint8
}

Color represents a traditional RGB color scheme

type Direction

type Direction int

const (
  HORIZONTAL Direction = C.VIPS_DIRECTION_HORIZONTAL
  VERTICAL   Direction = C.VIPS_DIRECTION_VERTICAL
)

type GaussianBlur

type GaussianBlur struct {
  Sigma   float64
  MinAmpl float64
}

type Gravity

type Gravity int

const (
  CENTRE Gravity = iota
  NORTH
  EAST
  SOUTH
  WEST
)

type Image

type Image struct {
}

func NewImage

func NewImage(buf []byte) *Image

Creates a new image

func (*Image) Colourspace

func (i *Image) Colourspace(c Interpretation) ([]byte, error)

Colour space conversion

func (*Image) ColourspaceIsSupported

func (i *Image) ColourspaceIsSupported() (bool, error)

Check if the current image has a valid colourspace

func (*Image) Convert

func (i *Image) Convert(t ImageType) ([]byte, error)

Convert image to another format

func (*Image) Crop

func (i *Image) Crop(width, height int, gravity Gravity) ([]byte, error)

Crop the image to the exact size specified

func (*Image) CropByHeight

func (i *Image) CropByHeight(height int) ([]byte, error)

Crop an image by height (auto width)

func (*Image) CropByWidth

func (i *Image) CropByWidth(width int) ([]byte, error)

Crop an image by width (auto height)

func (*Image) Enlarge

func (i *Image) Enlarge(width, height int) ([]byte, error)

Enlarge the image by width and height. Aspect ratio is maintained

func (*Image) EnlargeAndCrop

func (i *Image) EnlargeAndCrop(width, height int) ([]byte, error)

Enlarge the image by width and height with additional crop transformation

func (*Image) Extract

func (i *Image) Extract(top, left, width, height int) ([]byte, error)

Extract area from the by X/Y axis

func (*Image) Flip

func (i *Image) Flip() ([]byte, error)

Flip the image about the vertical Y axis

func (*Image) Flop

func (i *Image) Flop() ([]byte, error)

Flop the image about the horizontal X axis

func (*Image) ForceResize

func (i *Image) ForceResize(width, height int) ([]byte, error)

Force resize with custom size (aspect ratio won't be maintained)

func (*Image) Image

func (i *Image) Image() []byte

Get image buffer

func (*Image) Interpretation

func (i *Image) Interpretation() (Interpretation, error)

Get the image interpretation type See: http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/VipsImage.html#VipsInterpretation

func (*Image) Metadata

func (i *Image) Metadata() (ImageMetadata, error)

Get image metadata (size, alpha channel, profile, EXIF rotation)

func (*Image) Process

func (i *Image) Process(o Options) ([]byte, error)

Transform the image by custom options

func (*Image) Resize

func (i *Image) Resize(width, height int) ([]byte, error)

Resize the image to fixed width and height

func (*Image) ResizeAndCrop

func (i *Image) ResizeAndCrop(width, height int) ([]byte, error)

Resize the image to fixed width and height with additional crop transformation

func (*Image) Rotate

func (i *Image) Rotate(a Angle) ([]byte, error)

Rotate the image by given angle degrees (0, 90, 180 or 270)

func (*Image) Size

func (i *Image) Size() (ImageSize, error)

Get image size

func (*Image) Thumbnail

func (i *Image) Thumbnail(pixels int) ([]byte, error)

Thumbnail the image by the a given width by aspect ratio 4:4

func (*Image) Type

func (i *Image) Type() string

Get image type format (jpeg, png, webp, tiff)

func (*Image) Watermark

func (i *Image) Watermark(w Watermark) ([]byte, error)

Add text as watermark on the given image

func (*Image) Zoom

func (i *Image) Zoom(factor int) ([]byte, error)

Zoom the image by the given factor. You should probably call Extract() before

type ImageMetadata

type ImageMetadata struct {
  Orientation int
  Channels    int
  Alpha       bool
  Profile     bool
  Type        string
  Space       string
  Colourspace string
  Size        ImageSize
}

func Metadata

func Metadata(buf []byte) (ImageMetadata, error)

Extract the image metadata (size, type, alpha channel, profile, EXIF orientation...)

type ImageSize

type ImageSize struct {
  Width  int
  Height int
}

func Size

func Size(buf []byte) (ImageSize, error)

Get the image size by width and height pixels

type ImageType

type ImageType int

const (
  UNKNOWN ImageType = iota
  JPEG
  WEBP
  PNG
  TIFF
  MAGICK
)

func DetermineImageType

func DetermineImageType(buf []byte) ImageType

Determines the image type format (jpeg, png, webp or tiff)

type Interpolator

type Interpolator int

const (
  BICUBIC Interpolator = iota
  BILINEAR
  NOHALO
)

func (Interpolator) String

func (i Interpolator) String() string

type Interpretation

type Interpretation int

Image interpretation type See: http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/VipsImage.html#VipsInterpretation

const (
  INTERPRETATION_ERROR     Interpretation = C.VIPS_INTERPRETATION_ERROR
  INTERPRETATION_MULTIBAND Interpretation = C.VIPS_INTERPRETATION_MULTIBAND
  INTERPRETATION_B_W       Interpretation = C.VIPS_INTERPRETATION_B_W
  INTERPRETATION_CMYK      Interpretation = C.VIPS_INTERPRETATION_CMYK
  INTERPRETATION_RGB       Interpretation = C.VIPS_INTERPRETATION_RGB
  INTERPRETATION_sRGB      Interpretation = C.VIPS_INTERPRETATION_sRGB
  INTERPRETATION_RGB16     Interpretation = C.VIPS_INTERPRETATION_RGB16
  INTERPRETATION_GREY16    Interpretation = C.VIPS_INTERPRETATION_GREY16
  INTERPRETATION_scRGB     Interpretation = C.VIPS_INTERPRETATION_scRGB
  INTERPRETATION_LAB       Interpretation = C.VIPS_INTERPRETATION_LAB
  INTERPRETATION_XYZ       Interpretation = C.VIPS_INTERPRETATION_XYZ
)

func ImageInterpretation

func ImageInterpretation(buf []byte) (Interpretation, error)