README.md

JPEG Encoder for Golang

MozJPEG Encoder for Golang based on unofficial mozjpeg distribution

Install

go get -u github.com/nickalie/go-mozjpegbin

Example of usage

package main

import (
	"image"
	"image/color"
	"log"
	"os"
	"github.com/nickalie/go-mozjpegbin"
)

func main() {
	const width, height = 256, 256

	// Create a colored image of the given width and height.
	img := image.NewNRGBA(image.Rect(0, 0, width, height))

	for y := 0; y < height; y++ {
		for x := 0; x < width; x++ {
			img.Set(x, y, color.NRGBA{
				R: uint8((x + y) & 255),
				G: uint8((x + y) << 1 & 255),
				B: uint8((x + y) << 2 & 255),
				A: 255,
			})
		}
	}

	f, err := os.Create("image.jpg")
	if err != nil {
		log.Fatal(err)
	}

	if err := mozjpegbin.Encode(f, img, nil); err != nil {
		f.Close()
		log.Fatal(err)
	}

	if err := f.Close(); err != nil {
		log.Fatal(err)
	}
}

CJpeg

CJpeg is a wrapper for cjpeg command line tool.

Example to convert image.pgm to image.jpg:

err := mozjpegbin.NewCJpeg().
		Quality(70).
		InputFile("image.pgm").
		OutputFile("image_min.jpg").
		Run()

JpegTran

JpegTran is a wrapper for jpegtran command line tool.

Example to optimize and crop image.jpg to image_opt.jpg:

err := mozjpegbin.NewJpegTran().
		InputFile("image.jpg").
		Crop(10, 5, 100, 100)
		OutputFile("image_opt.jpg").
		Run()

mozjpeg distribution

Under the hood library uses cjpeg and jpegtrans command line tools from mozjpeg. To avoid compatibility issues, it's better to build mozjpeg for your target platform and call mozjpegbin.SkipDownload() to avoid using of prebuilt binaries

Snippet to build mozjpeg on alpine:

apk add --no-cache --update g++ make autoconf automake libtool nasm wget

wget https://github.com/mozilla/mozjpeg/releases/download/v3.2-pre/mozjpeg-3.2-release-source.tar.gz && \
tar -xvzf mozjpeg-3.2-release-source.tar.gz && \
rm mozjpeg-3.2-release-source.tar.gz && \
cd mozjpeg && \
./configure && \
make install && \
cd / && rm -rf mozjpeg && \
ln -s /opt/mozjpeg/bin/jpegtran /usr/local/bin/jpegtran && \
ln -s /opt/mozjpeg/bin/cjpeg /usr/local/bin/cjpeg