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https://github.com/aheckmann/gm

GraphicsMagick for node
https://github.com/aheckmann/gm

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GraphicsMagick for node

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# gm [![Build Status](https://travis-ci.org/aheckmann/gm.png?branch=master)](https://travis-ci.org/aheckmann/gm)  [![NPM Version](https://img.shields.io/npm/v/gm.svg?style=flat)](https://www.npmjs.org/package/gm)



GraphicsMagick and ImageMagick for node



## Bug Reports



When reporting bugs please include the version of graphicsmagick/imagemagick you're using (gm -version/convert -version) as well as the version of this module and copies of any images you're having problems with.



## Getting started

First download and install [GraphicsMagick](http://www.graphicsmagick.org/) or [ImageMagick](http://www.imagemagick.org/). In Mac OS X, you can simply use [Homebrew](http://mxcl.github.io/homebrew/) and do:



    brew install imagemagick

    brew install graphicsmagick



then either use npm:



    npm install gm



or clone the repo:



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



## Use ImageMagick instead of gm



Subclass `gm` to enable [ImageMagick 7+](https://imagemagick.org/script/porting.php)



```js

const fs = require('fs')

const gm = require('gm').subClass({ imageMagick: '7+' });

```



Or, to enable ImageMagick legacy mode (for ImageMagick version < 7)



```js

const fs = require('fs')

const gm = require('gm').subClass({ imageMagick: true });

```



## Specify the executable path



Optionally specify the path to the executable.



```js

const fs = require('fs')

const gm = require('gm').subClass({

  appPath: String.raw`C:\Program Files\ImageMagick-7.1.0-Q16-HDRI\magick.exe`

});

```



## Basic Usage



```js

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');

});



// some files would not be resized appropriately

// http://stackoverflow.com/questions/5870466/imagemagick-incorrect-dimensions

// you have two options:

// use the '!' flag to ignore aspect ratio

gm('/path/to/my/img.jpg')

.resize(240, 240, '!')

.write('/path/to/resize.png', function (err) {

  if (!err) console.log('done');

});



// use the .resizeExact with only width and/or height arguments

gm('/path/to/my/img.jpg')

.resizeExact(240, 240)

.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 (err, size) {

  if (!err)

    console.log(size.width > size.height ? 'wider' : 'taller than you');

});



// output all available image properties

gm('/path/to/img.png')

.identify(function (err, data) {

  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) {

  // ...

});

```



## Streams



```js

// 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');

});



// passing a downloadable image by url



var request = require('request');

var url = "www.abc.com/pic.jpg"



gm(request(url))

.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 (err, stdout, stderr) {

  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 (err, stdout, stderr) {

  var writeStream = fs.createWriteStream('/path/to/my/reformatted.png');

  stdout.pipe(writeStream);

});



// or without the callback

var writeStream = fs.createWriteStream('/path/to/my/reformatted.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)

.resize('200', '200')

.stream(function (err, stdout, stderr) {

  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)

.size({bufferStream: true}, function(err, size) {

  this.resize(size.width / 2, size.height / 2)

  this.write('/path/to/resized.jpg', function (err) {

    if (!err) console.log('done');

  });

});



```



## Buffers



```js

// 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 (err, buffer) {

  if (err) return handle(err);

  console.log('done!');

})

```



## Custom Arguments



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:



```bash

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

```



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



```js

gm()

.label('Offline')

.stream();

```



would yield:



```bash

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

```



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



```js

gm()

.out('label:Offline')

.stream();

```



which correctly yields:



```bash

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

```



### Custom Identify Format String



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](http://www.imagemagick.org/script/escape.php) when using `gm().identify(format, callback)`.

For example,



```js

gm('img.png').format(function (err, format) {



})



// is equivalent to



gm('img.png').identify('%m', function (err, format) {



})

```



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



## Platform differences



Please document and refer to any [platform or ImageMagick/GraphicsMagick issues/differences here](https://github.com/aheckmann/gm/wiki/GraphicsMagick-and-ImageMagick-versions).



## Examples:



  Check out the [examples](http://github.com/aheckmann/gm/tree/master/examples/) directory to play around.

  Also take a look at the [extending gm](http://wiki.github.com/aheckmann/gm/extending-gm)

  page to see how to customize gm to your own needs.



## Constructor:



  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.

  - 2) `gm(stream || buffer, [filename])` You may also pass a ReadableStream or Buffer as the first argument, with an optional file name for format inference.

  - 3) `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](http://github.com/aheckmann/gm/blob/master/examples/new.js) for an example.



The links below refer to an older version of gm but everything should still work, if anyone feels like updating them please make a PR



## Methods



  - getters

    - [size](http://aheckmann.github.io/gm/docs.html#getters) - returns the size (WxH) of the image

    - [orientation](http://aheckmann.github.io/gm/docs.html#getters) - returns the EXIF orientation of the image

    - [format](http://aheckmann.github.io/gm/docs.html#getters) - returns the image format (gif, jpeg, png, etc)

    - [depth](http://aheckmann.github.io/gm/docs.html#getters) - returns the image color depth

    - [color](http://aheckmann.github.io/gm/docs.html#getters) - returns the number of colors

    - [res](http://aheckmann.github.io/gm/docs.html#getters)   - returns the image resolution

    - [filesize](http://aheckmann.github.io/gm/docs.html#getters) - returns image filesize

    - [identify](http://aheckmann.github.io/gm/docs.html#getters) - returns all image data available. Takes an optional format string.



  - manipulation

    - [adjoin](http://aheckmann.github.io/gm/docs.html#adjoin)

    - [affine](http://aheckmann.github.io/gm/docs.html#affine)

    - [antialias](http://aheckmann.github.io/gm/docs.html#antialias)

    - [append](http://aheckmann.github.io/gm/docs.html#append)

    - [authenticate](http://aheckmann.github.io/gm/docs.html#authenticate)

    - [autoOrient](http://aheckmann.github.io/gm/docs.html#autoOrient)

    - [average](http://aheckmann.github.io/gm/docs.html#average)

    - [backdrop](http://aheckmann.github.io/gm/docs.html#backdrop)

    - [bitdepth](http://aheckmann.github.io/gm/docs.html#bitdepth)

    - [blackThreshold](http://aheckmann.github.io/gm/docs.html#blackThreshold)

    - [bluePrimary](http://aheckmann.github.io/gm/docs.html#bluePrimary)

    - [blur](http://aheckmann.github.io/gm/docs.html#blur)

    - [border](http://aheckmann.github.io/gm/docs.html#border)

    - [borderColor](http://aheckmann.github.io/gm/docs.html#borderColor)

    - [box](http://aheckmann.github.io/gm/docs.html#box)

    - [channel](http://aheckmann.github.io/gm/docs.html#channel)

    - [charcoal](http://aheckmann.github.io/gm/docs.html#charcoal)

    - [chop](http://aheckmann.github.io/gm/docs.html#chop)

    - [clip](http://aheckmann.github.io/gm/docs.html#clip)

    - [coalesce](http://aheckmann.github.io/gm/docs.html#coalesce)

    - [colors](http://aheckmann.github.io/gm/docs.html#colors)

    - [colorize](http://aheckmann.github.io/gm/docs.html#colorize)

    - [colorMap](http://aheckmann.github.io/gm/docs.html#colorMap)

    - [colorspace](http://aheckmann.github.io/gm/docs.html#colorspace)

    - [comment](http://aheckmann.github.io/gm/docs.html#comment)

    - [compose](http://aheckmann.github.io/gm/docs.html#compose)

    - [compress](http://aheckmann.github.io/gm/docs.html#compress)

    - [contrast](http://aheckmann.github.io/gm/docs.html#contrast)

    - [convolve](http://aheckmann.github.io/gm/docs.html#convolve)

    - [createDirectories](http://aheckmann.github.io/gm/docs.html#createDirectories)

    - [crop](http://aheckmann.github.io/gm/docs.html#crop)

    - [cycle](http://aheckmann.github.io/gm/docs.html#cycle)

    - [deconstruct](http://aheckmann.github.io/gm/docs.html#deconstruct)

    - [delay](http://aheckmann.github.io/gm/docs.html#delay)

    - [define](http://aheckmann.github.io/gm/docs.html#define)

    - [density](http://aheckmann.github.io/gm/docs.html#density)

    - [despeckle](http://aheckmann.github.io/gm/docs.html#despeckle)

    - [dither](http://aheckmann.github.io/gm/docs.html#dither)

    - [displace](http://aheckmann.github.io/gm/docs.html#dither)

    - [display](http://aheckmann.github.io/gm/docs.html#display)

    - [dispose](http://aheckmann.github.io/gm/docs.html#dispose)

    - [dissolve](http://aheckmann.github.io/gm/docs.html#dissolve)

    - [edge](http://aheckmann.github.io/gm/docs.html#edge)

    - [emboss](http://aheckmann.github.io/gm/docs.html#emboss)

    - [encoding](http://aheckmann.github.io/gm/docs.html#encoding)

    - [enhance](http://aheckmann.github.io/gm/docs.html#enhance)

    - [endian](http://aheckmann.github.io/gm/docs.html#endian)

    - [equalize](http://aheckmann.github.io/gm/docs.html#equalize)

    - [extent](http://aheckmann.github.io/gm/docs.html#extent)

    - [file](http://aheckmann.github.io/gm/docs.html#file)

    - [filter](http://aheckmann.github.io/gm/docs.html#filter)

    - [flatten](http://aheckmann.github.io/gm/docs.html#flatten)

    - [flip](http://aheckmann.github.io/gm/docs.html#flip)

    - [flop](http://aheckmann.github.io/gm/docs.html#flop)

    - [foreground](http://aheckmann.github.io/gm/docs.html#foreground)

    - [frame](http://aheckmann.github.io/gm/docs.html#frame)

    - [fuzz](http://aheckmann.github.io/gm/docs.html#fuzz)

    - [gamma](http://aheckmann.github.io/gm/docs.html#gamma)

    - [gaussian](http://aheckmann.github.io/gm/docs.html#gaussian)

    - [geometry](http://aheckmann.github.io/gm/docs.html#geometry)

    - [gravity](http://aheckmann.github.io/gm/docs.html#gravity)

    - [greenPrimary](http://aheckmann.github.io/gm/docs.html#greenPrimary)

    - [highlightColor](http://aheckmann.github.io/gm/docs.html#highlightColor)

    - [highlightStyle](http://aheckmann.github.io/gm/docs.html#highlightStyle)

    - [iconGeometry](http://aheckmann.github.io/gm/docs.html#iconGeometry)

    - [implode](http://aheckmann.github.io/gm/docs.html#implode)

    - [intent](http://aheckmann.github.io/gm/docs.html#intent)

    - [interlace](http://aheckmann.github.io/gm/docs.html#interlace)

    - [label](http://aheckmann.github.io/gm/docs.html#label)

    - [lat](http://aheckmann.github.io/gm/docs.html#lat)

    - [level](http://aheckmann.github.io/gm/docs.html#level)

    - [list](http://aheckmann.github.io/gm/docs.html#list)

    - [limit](http://aheckmann.github.io/gm/docs.html#limit)

    - [log](http://aheckmann.github.io/gm/docs.html#log)

    - [loop](http://aheckmann.github.io/gm/docs.html#loop)

    - [lower](http://aheckmann.github.io/gm/docs.html#lower)

    - [magnify](http://aheckmann.github.io/gm/docs.html#magnify)

    - [map](http://aheckmann.github.io/gm/docs.html#map)

    - [matte](http://aheckmann.github.io/gm/docs.html#matte)

    - [matteColor](http://aheckmann.github.io/gm/docs.html#matteColor)

    - [mask](http://aheckmann.github.io/gm/docs.html#mask)

    - [maximumError](http://aheckmann.github.io/gm/docs.html#maximumError)

    - [median](http://aheckmann.github.io/gm/docs.html#median)

    - [minify](http://aheckmann.github.io/gm/docs.html#minify)

    - [mode](http://aheckmann.github.io/gm/docs.html#mode)

    - [modulate](http://aheckmann.github.io/gm/docs.html#modulate)

    - [monitor](http://aheckmann.github.io/gm/docs.html#monitor)

    - [monochrome](http://aheckmann.github.io/gm/docs.html#monochrome)

    - [morph](http://aheckmann.github.io/gm/docs.html#morph)

    - [mosaic](http://aheckmann.github.io/gm/docs.html#mosaic)

    - [motionBlur](http://aheckmann.github.io/gm/docs.html#motionBlur)

    - [name](http://aheckmann.github.io/gm/docs.html#name)

    - [negative](http://aheckmann.github.io/gm/docs.html#negative)

    - [noise](http://aheckmann.github.io/gm/docs.html#noise)

    - [noop](http://aheckmann.github.io/gm/docs.html#noop)

    - [normalize](http://aheckmann.github.io/gm/docs.html#normalize)

    - [noProfile](http://aheckmann.github.io/gm/docs.html#profile)

    - [opaque](http://aheckmann.github.io/gm/docs.html#opaque)

    - [operator](http://aheckmann.github.io/gm/docs.html#operator)

    - [orderedDither](http://aheckmann.github.io/gm/docs.html#orderedDither)

    - [outputDirectory](http://aheckmann.github.io/gm/docs.html#outputDirectory)

    - [paint](http://aheckmann.github.io/gm/docs.html#paint)

    - [page](http://aheckmann.github.io/gm/docs.html#page)

    - [pause](http://aheckmann.github.io/gm/docs.html#pause)

    - [pen](http://aheckmann.github.io/gm/docs.html#pen)

    - [ping](http://aheckmann.github.io/gm/docs.html#ping)

    - [pointSize](http://aheckmann.github.io/gm/docs.html#pointSize)

    - [preview](http://aheckmann.github.io/gm/docs.html#preview)

    - [process](http://aheckmann.github.io/gm/docs.html#process)

    - [profile](http://aheckmann.github.io/gm/docs.html#profile)

    - [progress](http://aheckmann.github.io/gm/docs.html#progress)

    - [quality](http://aheckmann.github.io/gm/docs.html#quality)

    - [raise](http://aheckmann.github.io/gm/docs.html#raise)

    - [rawSize](http://aheckmann.github.io/gm/docs.html#rawSize)

    - [randomThreshold](http://aheckmann.github.io/gm/docs.html#randomThreshold)

    - [recolor](http://aheckmann.github.io/gm/docs.html#recolor)

    - [redPrimary](http://aheckmann.github.io/gm/docs.html#redPrimary)

    - [region](http://aheckmann.github.io/gm/docs.html#region)

    - [remote](http://aheckmann.github.io/gm/docs.html#remote)

    - [render](http://aheckmann.github.io/gm/docs.html#render)

    - [repage](http://aheckmann.github.io/gm/docs.html#repage)

    - [resample](http://aheckmann.github.io/gm/docs.html#resample)

    - [resize](http://aheckmann.github.io/gm/docs.html#resize)

    - [roll](http://aheckmann.github.io/gm/docs.html#roll)

    - [rotate](http://aheckmann.github.io/gm/docs.html#rotate)

    - [sample](http://aheckmann.github.io/gm/docs.html#sample)

    - [samplingFactor](http://aheckmann.github.io/gm/docs.html#samplingFactor)

    - [scale](http://aheckmann.github.io/gm/docs.html#scale)

    - [scene](http://aheckmann.github.io/gm/docs.html#scene)

    - [scenes](http://aheckmann.github.io/gm/docs.html#scenes)

    - [screen](http://aheckmann.github.io/gm/docs.html#screen)

    - [segment](http://aheckmann.github.io/gm/docs.html#segment)

    - [sepia](http://aheckmann.github.io/gm/docs.html#sepia)

    - [set](http://aheckmann.github.io/gm/docs.html#set)

    - [setFormat](http://aheckmann.github.io/gm/docs.html#setformat)

    - [shade](http://aheckmann.github.io/gm/docs.html#shade)

    - [shadow](http://aheckmann.github.io/gm/docs.html#shadow)

    - [sharedMemory](http://aheckmann.github.io/gm/docs.html#sharedMemory)

    - [sharpen](http://aheckmann.github.io/gm/docs.html#sharpen)

    - [shave](http://aheckmann.github.io/gm/docs.html#shave)

    - [shear](http://aheckmann.github.io/gm/docs.html#shear)

    - [silent](http://aheckmann.github.io/gm/docs.html#silent)

    - [solarize](http://aheckmann.github.io/gm/docs.html#solarize)

    - [snaps](http://aheckmann.github.io/gm/docs.html#snaps)

    - [stegano](http://aheckmann.github.io/gm/docs.html#stegano)

    - [stereo](http://aheckmann.github.io/gm/docs.html#stereo)

    - [strip](http://aheckmann.github.io/gm/docs.html#strip) _imagemagick only_

    - [spread](http://aheckmann.github.io/gm/docs.html#spread)

    - [swirl](http://aheckmann.github.io/gm/docs.html#swirl)

    - [textFont](http://aheckmann.github.io/gm/docs.html#textFont)

    - [texture](http://aheckmann.github.io/gm/docs.html#texture)

    - [threshold](http://aheckmann.github.io/gm/docs.html#threshold)

    - [thumb](http://aheckmann.github.io/gm/docs.html#thumb)

    - [tile](http://aheckmann.github.io/gm/docs.html#tile)

    - [transform](http://aheckmann.github.io/gm/docs.html#transform)

    - [transparent](http://aheckmann.github.io/gm/docs.html#transparent)

    - [treeDepth](http://aheckmann.github.io/gm/docs.html#treeDepth)

    - [trim](http://aheckmann.github.io/gm/docs.html#trim)

    - [type](http://aheckmann.github.io/gm/docs.html#type)

    - [update](http://aheckmann.github.io/gm/docs.html#update)

    - [units](http://aheckmann.github.io/gm/docs.html#units)

    - [unsharp](http://aheckmann.github.io/gm/docs.html#unsharp)

    - [usePixmap](http://aheckmann.github.io/gm/docs.html#usePixmap)

    - [view](http://aheckmann.github.io/gm/docs.html#view)

    - [virtualPixel](http://aheckmann.github.io/gm/docs.html#virtualPixel)

    - [visual](http://aheckmann.github.io/gm/docs.html#visual)

    - [watermark](http://aheckmann.github.io/gm/docs.html#watermark)

    - [wave](http://aheckmann.github.io/gm/docs.html#wave)

    - [whitePoint](http://aheckmann.github.io/gm/docs.html#whitePoint)

    - [whiteThreshold](http://aheckmann.github.io/gm/docs.html#whiteThreshold)

    - [window](http://aheckmann.github.io/gm/docs.html#window)

    - [windowGroup](http://aheckmann.github.io/gm/docs.html#windowGroup)



  - drawing primitives

    - [draw](http://aheckmann.github.io/gm/docs.html#draw)

    - [drawArc](http://aheckmann.github.io/gm/docs.html#drawArc)

    - [drawBezier](http://aheckmann.github.io/gm/docs.html#drawBezier)

    - [drawCircle](http://aheckmann.github.io/gm/docs.html#drawCircle)

    - [drawEllipse](http://aheckmann.github.io/gm/docs.html#drawEllipse)

    - [drawLine](http://aheckmann.github.io/gm/docs.html#drawLine)

    - [drawPoint](http://aheckmann.github.io/gm/docs.html#drawPoint)

    - [drawPolygon](http://aheckmann.github.io/gm/docs.html#drawPolygon)

    - [drawPolyline](http://aheckmann.github.io/gm/docs.html#drawPolyline)

    - [drawRectangle](http://aheckmann.github.io/gm/docs.html#drawRectangle)

    - [drawText](http://aheckmann.github.io/gm/docs.html#drawText)

    - [fill](http://aheckmann.github.io/gm/docs.html#fill)

    - [font](http://aheckmann.github.io/gm/docs.html#font)

    - [fontSize](http://aheckmann.github.io/gm/docs.html#fontSize)

    - [stroke](http://aheckmann.github.io/gm/docs.html#stroke)

    - [strokeWidth](http://aheckmann.github.io/gm/docs.html#strokeWidth)

    - [setDraw](http://aheckmann.github.io/gm/docs.html#setDraw)



  - image output

    - **write** - writes the processed image data to the specified filename

    - **stream** - provides a `ReadableStream` with the processed image data

    - **toBuffer** - returns the image as a `Buffer` instead of a stream



## 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)



```js

gm.compare('/path/to/image1.jpg', '/path/to/another.png', function (err, isEqual, equality, raw, path1, path2) {

  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`.



```js

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

  ...

})

```



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



```js

var options = {

  file: '/path/to/diff.png',

  highlightColor: 'yellow',

  tolerance: 0.02

}

gm.compare('/path/to/image1.jpg', '/path/to/another.png', options, function (err, isEqual, equality, raw) {

  ...

})

```



## 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])



```js

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.");

});

```



## montage



GraphicsMagick supports montage for combining images side by side. This is exposed through `gm.montage()`. Its only argument is an image path with the changes to the base image.



Currently, `gm.montage()` only accepts file paths.



    gm.montage(other)



```js

gm('/path/to/image.jpg')

.montage('/path/to/second_image.jpg')

.geometry('+100+150')

.write('/path/to/montage.png', function(err) {

    if(!err) console.log("Written montage image.");

});

```



## Contributors

[https://github.com/aheckmann/gm/contributors](https://github.com/aheckmann/gm/contributors)



## Inspiration

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



## Plugins

[https://github.com/aheckmann/gm/wiki](https://github.com/aheckmann/gm/wiki)



## Tests

`npm test`



To run a single test:



```

npm test -- alpha.js

```



## License



(The MIT License)



Copyright (c) 2010 [Aaron Heckmann]([email protected])



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.