gm GraphicsMagick for node.js

Manipulation
Getters
Drawing
Using Imagemagick

manipulation
- antialias
  By default all imgs are anti-aliased by GrahpicsMagick. To disable it pass false.
```
gm("img.png").antialias(false)
```
- autoOrient
  Auto-orients the image according to its EXIF data.
  
  GraphicsMagick doesn't actually have the -auto-orient option but we emulate this by first reading the EXIF data and rotate/flip from there.
```
gm("img.jpg").autoOrient()
```
- bitdepth
  Specifies the number of bits of color to preserve in the image. See the docs for more detail.
```
gm("img.png").bitdepth(bits)
```
- blur
  Accepts a radius and optional sigma (standard deviation).
```
gm("img.png").blur(radius [, sigma])
```
- charcoal
  Simulates a charcoal drawing. Accepts a factor.
```
gm("img.png").charcoal(factor)
```
- chop
  Removes pixels from the interior of an image.
```
gm("img.png").chop(width, height, x, y)
```
- colors
  Sets the preferred number of colors for the image (color reduction).
```
gm("img.png").colors(int)
```
- colorize
  Colorize the image with optionally separate red, green, and blue values.
```
gm("img.png").colorize(red [, green [, blue]])
```
- colorspace
  Specifies the type of colorspace. See the GraphicsMagick docs for val details.
```
gm("img.png").colorspace(val)
```
- comment
  Annotates an image. See the docs for more info.
```
gm("img.png").comment(text|format)
```
- contrast
  Increases or reduces the image contrast. Accepts a multiplier.
```
gm("img.png").contrast([+-]multiplier)
```
- crop
  Crops the image to the given width and height at the given x and y position.
```
gm("img.png").crop(width, height, x, y)
```
- cycle
  Displace the image colormap by amount. amount is the number of positions each colormap entry is shifted.
```
gm("img.png").cycle(amount)
```
- density
  This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering (reading) vector formats into an image.
```
gm("img.png").density(width, height)
```
- despeckle
  Reduces the speckles within the image.
```
gm("img.png").despeckle()
```
- dither
  Applies Floyd/Steinberg error diffusion to the image. Pass false to disable dithering.
  Note: either .colors() or .monochrome() must be used for this to take effect.
```
gm("img.png").dither([bool])
```
- edge
  Emphasizes edges in an image. Takes an optional radius of the emphasis to apply.
```
gm("img.png").edge([radius])
```
- emboss
  Embosses the image. Takes an optional radius.
```
gm("img.png").emboss([radius])
```
- enhance
  Enhances the image.
```
gm("img.png").enhance()
```
- equalize
  Performs histogram equalization to the image.
```
gm("img.png").equalize()
```
- extent
  composite image on background color canvas image.
```
gm("img.png").extent([width, height, options])
```
- filter
  Specifies the filter to use when resizing. see link for available types.
```
gm("img.png").filter(type)
```
- flip
  Creates a mirror image (vertically).
```
gm("img.png").flip()
```
- flop
  Creates a mirror image (horizontally).
```
gm("img.png").flop()
```
- gamma
  Adjusts the level of gamma correction.
```
gm("img.png").gamma(r, g, b)
```
- gravity
  The direction the primitive gravitates to when annotating the image. Defaults to NorthWest.
  
  direction
  
  NorthWest|North|NorthEast|West|Center|East|SouthWest|South|SouthEast
```
gm("img.png").gravity(direction)
```
- implode
  Implodes the image pixels around the center. Takes an optional factor.
```
gm("img.png").implode([factor])
```
- interlace
  Specifies the type of interlacing scheme. Defaults to None.
  
  type
  
  None|Line|Plane|Partition
```
gm("img.png").interlace(type)
```
- label
  Assigns a label to an image.
```
gm("img.png").label(name)
```
- limit
  Sets resource limits.
  
  type
  
  disk|file|map|memory|pixels|threads
  
  val
  
  follows the same rules as specified in the GraphicsMagick docs
```
gm("img.png").limit(type, val)
```
- lower
  Creates a pseudo 3D lowering effect of the images edges.
```
gm("img.png").lower(width, height)
```
- magnify
  Magnifies the image factor times.
```
gm("img.png").magnify(factor)
```
- median
  Applies a median filter to the image. The optional param radius adjusts the weight of the effect.
```
gm("img.png").median([radius])
```
- minify
  Minifies the image factor times.
```
gm("img.png").minify(factor)
```
- modulate
  Varies the brightness, saturation, and hue of the image.
```
gm("img.png").modulate(b [, s [, h]])
```
- monochrome
  Transforms the image to black and white.
```
gm("img.png").monochrome()
```
- morph
  Morphs two images together.
  
  otherImg
  
  the path to another img
  
  outName
  
  the path where the image will be saved
  
  callback
  
  A function to be executed when morphing is complete. callback will be passed the standard args that .write() receives.
```
gm("img.png").morph(otherImg, outName, callback)
```
- negative
  Replaces every pixel with its complementary color.
```
gm("img.png").negative()
```
- noise
  Add or reduce noise in the image.
  radius|type
  To add noise pass one of the following:
  - uniform
  - gaussian
  - multiplicative
  - impulse
  - laplacian
  - poisson
  Otherwise the argument will be interpreted as a radius which adjusts the weight of the effect.
```
gm("img.png").noise(radius|type)
```
- noProfile
  Removes EXIF, ICM, etc profile data.
```
gm("img.png").noProfile()
```
- paint
  Simulates an oil painting.
```
gm("img.png").paint(radius)
```
- quality
  Adjusts the jpeg|miff|png|tiff compression level. val ranges from 0 to 100 (best).
```
gm("img.png").quality(val)
```
- raise
  Creates a pseudo 3D raising effect of the images edges.
```
gm("img.png").raise(width, height)
```
- region
  Specifies that all following methods only apply to the area specified by width, height, x, y.
```
gm("img.png").region(width, height, x, y).sepia()
```
  In this case, the sepia effect would only be applied within the area specified by width, height, x, y.
- resample
  Resamples the image to specified horizontal and vertical resolution.
```
gm("img.png").resample(horizontal, vertical)
```
- resize
  Resize the image.
```
gm("img.png").resize(width, height)
```
- roll
  Rolls an image vertically or horizontally.
```
gm("img.png").roll(horizontalInt, verticalInt)
```
- rotate
  Rotates the image by degrees and fills the background with color.
```
gm("img.png").rotate(color, degrees)
```
- scale
  Scales the image.
```
gm("img.png").scale(width, height)
```
- sepia
  A convenience method to apply a sepia effect to the image.
```
gm("img.png").sepia()
```
- setFormat
  Overriddes the output image format.
  
  Helpful if we are outputting an image with no extention but need to change formats.
```
gm("img.png").setFormat(format)
```
- sharpen
  Sharpens the image.
```
gm("img.png").sharpen(radius [, sigma])
```
- solarize
  Negates all pixels above threshold percent.
```
gm("img.png").solarize(threshold)
```
- spread
  Desplaces pixels by a random amount.
```
gm("img.png").spread(amount)
```
- strip
  Strips the image of any profiles or comments.
  
  Similar to noProfile() but removes both profile and comment data. only works with imageMagick.
```
gm("img.png").strip()
```
- swirl
  Swirls pixels arount the center of the image. degrees specifies the tightness of the swirl.
```
gm("img.png").swirl(degrees)
```
- thumb
  Creates a thumbnail based on minimum sizes.
  
  width
  
  the minimum width of the thumbnail
  
  height
  
  the minimum height of the thumbnail
  
  outName
  
  the path where the image will be saved
  
  quality
  
  Adjusts the image compression level. Ranges from 0 to 100 (best).
  
  callback
  
  called after the thumbnail is written. receives the same args that .write(err, stdout, stderr, command) receives.
```
gm("img.png").thumb(width, height, outName, quality, callback)
```
- trim
  Trim an image by removing any edges that are exactly the same color as the corner pixels.
```
gm("img.png").trim()
```
- type
  Specifies the image type.
  type
  Can be one of the following:
  - Bilevel
  - Grayscale
  - Palette
  - PaletteMatte
  - TrueColor
  - TrueColorMatte
  - ColorSeparation
  - ColorSeparationMatte
  - Optimize
```
gm("img.png").type(type)
```
getters

All getters have the same signature:
```
gm("image.png").size(function(err, value){
  // note : value may be undefined
})
```
- size - returns the size (WxH) of the image
- format - returns the image format (gif, jpeg, png, etc)
- depth - returns the image color depth
- color - returns the number of colors
- res - returns the image resolution
- filesize - returns image filesize
- identify - returns all image data available
- orientation - returns the EXIF orientation of the image
Drawing Primitives

Take a look at drawing.js for examples.
- draw
  Annotate an image with one or more graphic primitives (shapes, text, transformations, pixel operations). Used internally for all drawing methods.
```
gm("img.png").draw(args)
```
- drawArc
  Inscribe an elliptical arc within a rectangle. Requires a start and end point as well as the degrees of rotation.
```
gm("img.png").drawArc(x0, y0, x1, y1, r0, r1)
```
- drawBezier
  Draw a Bezier curve.
```
gm("img.png").drawBezier([x0, y0], ... [xn, yn])
```
- drawCircle
  Draws a Circle.
```
gm("img.png").drawCircle(x0, y0, x1, y1)
```
- drawEllipse
  Draws an Ellipse.
```
gm("img.png").drawEllipse(x0, y0, r0, ry, r0, r1)
```
- drawLine
  Draws a Line.
```
gm("img.png").drawLine(x0, y0, x1, y1)
```
- drawPoint
  Draws a Point.
```
gm("img.png").drawPoint(x, y)
```
- drawPolygon
  Draws a Polygon.
```
gm("img.png").drawPolygon([x0, y0] ... [xn, yn])
```
- drawPolyline
  Draws a Polyline.
```
gm("img.png").drawPolyline([x0, y0] ... [xn, yn])
```
- drawRectangle
  Draws a Rectangle. wc and hc are optional and add roundness to the corners.
```
gm("img.png").drawRectangle(x0, y0, x1, y1 [, wc, hc])
```
- drawText
  Draws text on an image at x/y coordinates.
```
gm("img.png").drawText(x, y, text [, gravity])
```
- fill
  Specifies the color to use when filling a drawn shape.
```
gm("img.png").fill(color)
```
- font
  Specifies the font to use when you drawText.
```
gm("img.png").font(name)
```
- fontSize
  Specifies the font size to use when you drawText.
```
gm("img.png").fontSize(size)
```
- stroke
  Specifies the color to use when stroking a drawn shape.
```
gm("img.png").stroke(color [, width])
```
- strokeWidth
  Specifies the stroke width to use when stroking a drawn shape.
```
gm("img.png").strokeWidth(width)
```
- setDraw
  Sets drawing properties. property can be either "color" or "matte".
```
gm("img.png").setDraw(property, x, y, method)
```
Using ImageMagick

We have compatibility with ImageMagick too. Just subclass the gm constructor passing the imageMagick option.
```
var imageMagick = gm.subClass({ imageMagick: true });
```
Then use imageMagick the same way you'd normally use gm.
```
imageMagick("img.png").autoOrient().write('/path', callback);
```

gm GraphicsMagick for node.js

manipulation

getters

Drawing Primitives

Using ImageMagick