gm

GraphicsMagick and ImageMagick for node.js

gm v1.17.0

GraphicsMagick and ImageMagick for node

First download and install GraphicsMagick or ImageMagick. In Mac OS X, you can simply use Homebrew and do:

brew install imagemagick
brew install graphicsmagick

If you want WebP support with ImageMagick, you must add the WebP option:

brew install imagemagick --with-webp

then either use npm:

npm install gm

or clone the repo:

git clone git://github.com/aheckmann/gm.git

Just pass the option {imageMagick: true} to enable ImageMagick

var fs = require('fs')
  , gm = require('./gm');
 
// resize and remove EXIF profile data 
gm('/path/to/my/img.jpg')
.options({imageMagick: true})
.resize(240, 240)
...
var fs = require('fs')
  , gm = require('./gm');
 
// resize and remove EXIF profile data 
gm('/path/to/my/img.jpg')
.resize(240, 240)
.noProfile()
.write('/path/to/resize.png', function (err) {
  if (!err) console.log('done');
});
 
// obtain the size of an image 
gm('/path/to/my/img.jpg')
.size(function (errsize) {
  if (!err)
    console.log(size.width > size.height ? 'wider' : 'taller than you');
});
 
// output all available image properties 
gm('/path/to/img.png')
.identify(function (errdata) {
  if (!err) console.log(data)
});
 
// pull out the first frame of an animated gif and save as png 
gm('/path/to/animated.gif[0]')
.write('/path/to/firstframe.png', function (err) {
  if (err) console.log('aaw, shucks');
});
 
// auto-orient an image 
gm('/path/to/img.jpg')
.autoOrient()
.write('/path/to/oriented.jpg', function (err) {
  if (err) ...
})
 
// crazytown 
gm('/path/to/my/img.jpg')
.flip()
.magnify()
.rotate('green', 45)
.blur(7, 3)
.crop(300, 300, 150, 130)
.edge(3)
.write('/path/to/crazy.jpg', function (err) {
  if (!err) console.log('crazytown has arrived');
})
 
// annotate an image 
gm('/path/to/my/img.jpg')
.stroke("#ffffff")
.drawCircle(10, 10, 20, 10)
.font("Helvetica.ttf", 12)
.drawText(30, 20, "GMagick!")
.write("/path/to/drawing.png", function (err) {
  if (!err) console.log('done');
});
 
// creating an image 
gm(200, 400, "#ddff99f3")
.drawText(10, 50, "from scratch")
.write("/path/to/brandNewImg.jpg", function (err) {
  // ... 
});
// passing a stream 
var readStream = fs.createReadStream('/path/to/my/img.jpg');
gm(readStream, 'img.jpg')
.write('/path/to/reformat.png', function (err) {
  if (!err) console.log('done');
});
 
// can also stream output to a ReadableStream 
// (can be piped to a local file or remote server) 
gm('/path/to/my/img.jpg')
.resize('200', '200')
.stream(function (errstdoutstderr) {
  var writeStream = fs.createWriteStream('/path/to/my/resized.jpg');
  stdout.pipe(writeStream);
});
 
// without a callback, .stream() returns a stream 
// this is just a convenience wrapper for above. 
var writeStream = fs.createWriteStream('/path/to/my/resized.jpg');
gm('/path/to/my/img.jpg')
.resize('200', '200')
.stream()
.pipe(writeStream);
 
// pass a format or filename to stream() and 
// gm will provide image data in that format 
gm('/path/to/my/img.jpg')
.stream('png', function (errstdoutstderr) {
  var writeStream = fs.createWriteStream('/path/to/my/reformated.png');
  stdout.pipe(writeStream);
});
 
// or without the callback 
var writeStream = fs.createWriteStream('/path/to/my/reformated.png');
gm('/path/to/my/img.jpg')
.stream('png')
.pipe(writeStream);
 
// combine the two for true streaming image processing 
var readStream = fs.createReadStream('/path/to/my/img.jpg');
gm(readStream, 'img.jpg')
.resize('200', '200')
.stream(function (errstdoutstderr) {
  var writeStream = fs.createWriteStream('/path/to/my/resized.jpg');
  stdout.pipe(writeStream);
});
 
// GOTCHA: 
// when working with input streams and any 'identify' 
// operation (size, format, etc), you must pass "{bufferStream: true}" if 
// you also need to convert (write() or stream()) the image afterwards 
// NOTE: this buffers the readStream in memory! 
var readStream = fs.createReadStream('/path/to/my/img.jpg');
gm(readStream, 'img.jpg')
.size({bufferStream: true}, function(errsize) {
  this.resize(size.width / 2, size.height / 2)
  this.write('/path/to/resized.jpg', function (err) {
    if (!err) console.log('done');
  });
});
 
// A buffer can be passed instead of a filepath as well 
var buf = require('fs').readFileSync('/path/to/image.jpg');
 
gm(buf, 'image.jpg')
.noise('laplacian')
.write('/path/to/out.jpg', function (err) {
  if (err) return handle(err);
  console.log('Created an image from a Buffer!');
});
 
/*
A buffer can also be returned instead of a stream
The first argument to toBuffer is optional, it specifies the image format
*/
gm('img.jpg')
.resize(100, 100)
.toBuffer('PNG',function (errbuffer) {
  if (err) return handle(err);
  console.log('done!');
})

If gm does not supply you with a method you need or does not work as you'd like, you can simply use gm().in() or gm().out() to set your own arguments.

  • gm().command() - Custom command such as identify or convert
  • gm().in() - Custom input arguments
  • gm().out() - Custom output arguments

The command will be formatted in the following order:

  1. command - ie convert
  2. in - the input arguments
  3. source - stdin or an image file
  4. out - the output arguments
  5. output - stdout or the image file to write to

For example, suppose you want the following command:

gm "convert" "label:Offline" "PNG:-"

However, using gm().label() may not work as intended for you:

gm()
.label('Offline')
.stream();

would yield:

gm "convert" "-label" "\"Offline\"" "PNG:-"

Instead, you can use gm().out():

gm()
.out('label:Offline')
.stream();

which correctly yields:

gm "convert" "label:Offline" "PNG:-"

When identifying an image, you may want to use a custom formatting string instead of using -verbose, which is quite slow. You can use your own formatting string when using gm().identify(format, callback). For example,

gm('img.png').format(function (errformat) {
 
})
 
// is equivalent to 
 
gm('img.png').identify('%m', function (errformat) {
 
})

since %m is the format option for getting the image file format.

Please document and refer to any platform or ImageMagick/GraphicsMagick issues/differences here.

Check out the examples directory to play around. Also take a look at the extending gm page to see how to customize gm to your own needs.

There are a few ways you can use the gm image constructor.

    1. gm(path) When you pass a string as the first argument it is interpreted as the path to an image you intend to manipulate.
    1. gm(stream || buffer, [filename]) You may also pass a ReadableStream or Buffer as the first argument, with an optional file name for format inference.
    1. gm(width, height, [color]) When you pass two integer arguments, gm will create a new image on the fly with the provided dimensions and an optional background color. And you can still chain just like you do with pre-existing images too. See here for an example.

##compare

Graphicsmagicks compare command is exposed through gm.compare(). This allows us to determine if two images can be considered "equal".

Currently gm.compare only accepts file paths.

gm.compare(path1, path2 [, options], callback)
gm.compare('/path/to/image1.jpg', '/path/to/another.png', function (errisEqualequalityrawpath1path2) {
  if (err) return handle(err);
 
  // if the images were considered equal, `isEqual` will be true, otherwise, false. 
  console.log('The images were equal: %s', isEqual);
 
  // to see the total equality returned by graphicsmagick we can inspect the `equality` argument. 
  console.log('Actual equality: %d', equality);
 
  // inspect the raw output 
  console.log(raw);
 
  // print file paths 
  console.log(path1, path2);
})

You may wish to pass a custom tolerance threshold to increase or decrease the default level of 0.4.

gm.compare('/path/to/image1.jpg', '/path/to/another.png', 1.2, function (errisEqual) {
  ...
})

To output a diff image, pass a configuration object to define the diff options and tolerance.

var options = {
  file: '/path/to/diff.png',
  highlightColor: 'yellow',
  tolerance: 0.02
}
gm.compare('/path/to/image1.jpg', '/path/to/another.png', options, function (errisEqualequalityraw) {
  ...
})

##composite

GraphicsMagick supports compositing one image on top of another. This is exposed through gm.composite(). Its first argument is an image path with the changes to the base image, and an optional mask image.

Currently, gm.composite() only accepts file paths.

gm.composite(other [, mask])
gm('/path/to/image.jpg')
.composite('/path/to/second_image.jpg')
.geometry('+100+150')
.write('/path/to/composite.png', function(err) {
    if(!err) console.log("Written composite image.");
});

https://github.com/aheckmann/gm/contributors

http://github.com/quiiver/magickal-node

https://github.com/aheckmann/gm/wiki

(The MIT License)

Copyright (c) 2010 Aaron Heckmann

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.