Image manipulation with gm. Refer to gm's documentation for details.

Install with npm

npm install --save-dev gulp-gm

gulp-gm works best with GraphicsMagick.
However, it also supports ImageMagick, but you'll need to set the option imageMagick: true.

Make sure GraphicsMagick or ImageMagick is installed on your system and properly set up in your PATH.

Ubuntu:

apt-get install imagemagick
apt-get install graphicsmagick

Mac OS X (using Homebrew):

brew install imagemagick
brew install graphicsmagick

Windows & others:

• GraphicsMagick: http://www.graphicsmagick.org/download.html
• ImageMagick: http://www.imagemagick.org/script/binary-releases.php

Confirm that GraphicsMagick or ImageMagick is properly set up by executing gm -version or convert -version in a terminal.

var gulp = require('gulp');
var gm = require('gulp-gm');

gulp.task('default', function () {
  gulp.src('test.png')

    .pipe(gm(function (gmfile) {

      return gmfile.resize(100, 100);

    }))

    .pipe(gulp.dest('dist'));
});

gulp.src('test.png')
  .pipe(gm(function (gmfile) {

    return gmfile.setFormat('jpg');

  }))
  .pipe(gulp.dest('dist'));

gulp.src('test.png')
  .pipe(gm(function (gmfile, done) {

    gmfile.size(function (err, size) {

      done(null, gmfile
        .stroke("blue", 6)
        .fill("transparent")
        .drawRectangle(0, 0, size.width, size.height));

    });

  }))
  .pipe(gulp.dest('dist'));

gulp.src('test.png')

  .pipe(gm(function (gmfile) {

    return gmfile.resize(100, 100);

  }, {
    imageMagick: true
  }))

  .pipe(gulp.dest('dist'));

Type: Function

Supply a callback that manipulates the image. The first argument will the gm object with all original properties. Read more in the gm documentation.

Make sure to return your modified gm object.

gulp.src('test.png')
  .pipe(gm(function (gmfile) {
    return gmfile.blur(10);
  }))
  .pipe(gulp.dest('dist'));

If your call back accepts a second argument (done), it will be treated asynchronously. Your code will then need to call done(err, gmfile) at some point.

gulp.src('test.png')
  .pipe(gm(function (gmfile, done) {
    gmfile.size(function (err, size) {

      done(null, gmfile.resize(
        size.width * 0.5,
        size.height * 0.5
      ));

    });
  }))
  .pipe(gulp.dest('dist'));

Type: Boolean Default value: false

Set to true when using ImageMagick instead of GraphicsMagick.

• gm.thumb(...) is not supported because it writes to the file system directly. Consider using gulp-image-resize instead.

1. You need both ImageMagick and GraphicsMagick installed on your system to run the tests.
2. Install all npm dev dependencies npm install
3. Install gulp globally npm install -g gulp
4. Run gulp test

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