GraphicsMagick Perl API

GraphicsMagick Perl API -- PerlMagick

- Introduction

- Installation

- Overview

- Example Script

- Read or Write an Image

- Manipulate an Image

- Set an Image Attribute

- Get an Image Attribute

- Create an Image Montage

- Working with Blobs

- Miscellaneous Methods

- Handling Errors

- Copyright

Introduction

  PerlMagick is an objected-oriented Perl interface to GraphicsMagick. Use the module to read, manipulate, or write an image or image sequence from within a Perl script. This makes it very suitable for Web CGI scripts. You must have GraphicsMagick 1.0.0 or above and Perl version 5.005_02 or greater installed on your system for either of these utilities to work.
  There are a number of useful scripts available to show you the value of PerlMagick. The PerlMagick demo directory provides a number of sample demos. You can try PerlMagick from your Web browser at the ImageMagick Studio. Or, you can see examples of select PerlMagick functions.

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Installation

  UNIX

> PerlMagick is installed by default by installing GraphicsMagick. Installing PerlMagick as a subordinate package of GraphicsMagick is the best way to avoid problems.

> For Unix, you typically need to be `root` to install the software. There are ways around this. Consult the Perl manual pages for more information.

> Windows XP / Windows 2000

> Please note that a nice GUI installer is available for GraphicsMagick. PerlMagick is included in this installer. If you are using the installer, then there is no need to compile PerlMagick.

> After GraphicsMagick has been compiled from the GraphicsMagick Windows source distribution using Microsoft Visual C++, PerlMagick may be manually built and installed by opening a CLI window and performing the following steps:

     cd PerlMagick
     copy Makefile.nt Makefile.PL
     perl Makefile.PL
     nmake
     nmake install

> See the PerlMagick Windows HowTo page for further installation instructions.

> Running the Regression Tests

> To verify a correct installation, type

     make test

> Use `nmake test` under Windows. There are a few demonstration scripts available to exercise many of the functions PerlMagick can perform. Type

     cd demo
     make

> You are now ready to utilize the PerlMagick methods from within your Perl scripts.

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Overview

  Any script that wants to use PerlMagick methods must first define the methods within its namespace and instantiate an image object. Do this with:

     use Graphics::Magick;
     $image=Graphics::Magick->new;

> Note that this differs from the ImageMagick version of PerlMagick which uses the namespace Image::Magick. Any PerlMagick code written for the ImageMagick version of PerlMagick requires a global substition of `Image::Magick` to `Graphics::Magick` in order to work with the GraphicsMagick version.

> The new() method takes the same parameters as SetAttribute . For example,

     $image=Graphics::Magick->new(size=>'384x256');

> Next you will want to read an image or image sequence, manipulate it, and then display or write it. The input and output methods for PerlMagick are defined in Read or Write an Image. See Set an Image Attribute for methods that affect the way an image is read or written. Refer to Manipulate an Image for a list of methods to transform an image. Get an Image Attribute describes how to retrieve an attribute for an image. Refer to Create an Image Montage for details about tiling your images as thumbnails on a background. Finally, some methods do not neatly fit into any of the categories just mentioned. Review Miscellaneous Methods for a list of these methods.

> Once you are finished with a PerlMagick object you should consider destroying it. Each image in an image sequence is stored in either virtual memory or as a file in the system's temporary file directory. This can potentially add up to megabytes of memory or disk. Upon destroying a PerlMagick object, the memory is returned for use by other Perl methods. The recommended way to destroy an object is with `undef`:

     undef $image;

> To delete all the images but retain the `Graphics::Magick` object use

     @$image = ();

> and finally, to delete a single image from a multi-image sequence, use

     undef $image->[x];

> The next section illustrates how to use various PerlMagick methods to manipulate an image sequence.

> Some of the PerlMagick methods require external programs such as Ghostscript. This may require an explicit path in your PATH environment variable to work properly. For example,

     $ENV{PATH}='/bin:/usr/bin:/usr/local/bin';

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Example Script

  Here is an example script to get you started:

     #!/usr/local/bin/perl
     use Graphics::Magick;
     my($image, $x);
     $image = Graphics::Magick->new;
     $x = $image->Read('girl.png', 'logo.png', 'rose.png');
     warn "$x" if "$x";
     $x = $image->Crop(geometry=>'100x100"+1"00"+1"00');
     warn "$x" if "$x";
     $x = $image->Write('x.png');
     warn "$x" if "$x";

> The script reads three images, crops them, and writes a single image as a GIF animation sequence. In many cases you may want to access individual images of a sequence. The next example illustrates how this is done:

     #!/usr/local/bin/perl
     use Graphics::Magick;
     my($image, $p, $q);
     $image = new Graphics::Magick;
     $image->Read('x1.png');
     $image->Read('j*.jpg');
     $image->Read('k.miff[1, 5, 3]');
     $image->Contrast();
     for ($x = 0; $image->[x]; $x++)
     {
     $image->[x]->Frame('100x200') if $image->[x]->Get('magick') eq 'GIF';
     undef $image->[x] if $image->[x]->Get('columns') < 100;
     }
     $p = $image->[1];
     $p->Draw(stroke=>'red', primitive=>'rectangle', points=>20,20 100,100');
     $q = $p->Montage();
     undef $image;
     $q->Write('x.miff');

> Suppose you want to start out with a 100 by 100 pixel white canvas with a red pixel in the center. Try

     $image = Graphics::Magick->new;
     $image->Set(size=>'100x100');
     $image->ReadImage('xc:white');
     $image->Set('pixel[49,49]'=>'red');

> Or suppose you want to convert your color image to grayscale:

     $image->Quantize(colorspace=>'gray');

> Here we annotate an image with a Taipai TrueType font:

     $text = 'Works like magick!';
     $image->Annotate(font=>'kai.ttf', pointsize=>40, fill=>'green', text=>$text);

> Other clever things you can do with a PerlMagick objects include

     $i = $#$p"+1"; # return the number of images associated with object p
     push(@$q, @$p); # push the images from object p onto object q
     @$p = (); # delete the images but not the object p
     $p->Convolve([1, 2, 1, 2, 4, 2, 1, 2, 1]); # 3x3 Gaussian kernel

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Read or Write an Image

  Use the methods listed below to either read, write, or display an image or image sequence.

Read or Write Methods

  Method | Parameters | Return Value | Description
  --- | --- | --- | ---
  Read | one or more filenames | the number of images read | read an image or image sequence
  Write | filename | the number of images written | write an image or image sequence
  Display | server name | the number of images displayed | display the image or image sequence to an X server
  Animate | server name | the number of images animated | animate image sequence to an X server

> For convenience, methods Write(), Display(), and Animate() can take any parameter that SetAttribute knows about. For example,

     $image->Write(filename=>'image.png', compression=>'None');

> Use `-` as the filename to method Read() to read from standard in or to method Write() to write to standard out:

     binmode STDOUT;
     $image->Write('png:-');

> To read an image in the GIF format from a PERL filehandle, use:

     $image = Graphics::Magick->new;
     open(IMAGE, 'image.gif');
     $image->Read(file=>\*IMAGE);
     close(IMAGE);

> To write an image in the PNG format to a PERL filehandle, use:

     $filename = "image.png";
     open(IMAGE, ">$filename");
     $image->Write(file=>\*IMAGE, filename=>$filename);
     close(IMAGE);

> If `%0Nd, %0No, or %0Nx` appears in the filename, it is interpreted as a printf format specification and the specification is replaced with the specified decimal, octal, or hexadecimal encoding of the scene number. For example,

        image%03d.miff

> converts files image000.miff, image001.miff, etc.

> You can optionally add Image to any method name. For example, ReadImage() is an alias for method Read().

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Manipulate an Image

  Once you create an image with, for example, method ReadImage() you may want to operate on it. Below is a list of all the image manipulations methods available to you with PerlMagick. There are examples of select PerlMagick methods. Here is an example call to an image manipulation method:

     $image->Crop(geometry=>'100x100"+1"0+20');
     $image->[x]->Frame("100x200");

> Image method parameters are often redundant. For example, a 'geometry' string parameter (e.g. 800x600+10+20) is equivalent to the explicit use of width, height, x, and y, parameters.

> The following image manipulation methods are available:

Image Manipulation Methods

  Method | Parameters | Description
  --- | --- | ---
  AdaptiveThreshold | geometry=>geometry, width=>integer, height=> integer, offset=>integer | Local adaptive thresholding. Width and height specify the size of the local region while offset specifies the amount to subtract from the average of the region.
  AddNoise | noise=>{Uniform, Gaussian, Multiplicative, Impulse, Laplacian, Poisson} | Add noise to an image across the red, green, and blue, channels. Set the image colorspace to GRAY to obtain intensity noise.
  AffineTransform | affine=>array of float values, translate=>float, float, scale=> float, float, rotate=>float, skewX=>float, skewY=>float | Affine transform image
  Annotate | text=>string, font=>string, family=>string, style=>{Normal, Italic, Oblique, Any}, stretch=>{Normal, UltraCondensed, ExtraCondensed, Condensed, SemiCondensed, SemiExpanded, Expanded, ExtraExpanded, UltraExpanded}, weight=>integer, pointsize=>integer, density=>geometry, stroke=> color name, strokewidth=>integer, fill=>color name, undercolor=>color name, geometry=>geometry, gravity=>{NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast}, antialias=>{true, false}, x=>integer, y=>integer, affine=>array of float values, translate=>float, float, scale=>float, float, rotate=>float. skewX=>float, skewY=> float, align=>{Left, Center, Right}, encoding=>{UTF-8} | annotate an image with text. See QueryFontMetrics to get font metrics without rendering any text.
  Blur | geometry=>geometry, radius=>double, sigma=> double | blur the image with a Gaussian operator of the given radius and standard deviation (sigma).
  Border | geometry=>geometry, width=>integer, height=> integer, fill=>color name | surround the image with a border of color
  Channel | channel=>{Red, Cyan, Green, Magenta, Blue, Yellow, Opacity, Black} | extract a channel from the image
  Charcoal | order=>integer | simulate a charcoal drawing
  Chop | geometry=>geometry, width=>integer, height=> integer, x=>integer, y=>integer | chop an image
  Coalesce |  | merge a sequence of images
  Clip |  | apply any clipping path information as an image clip mask.
  ColorFloodfill | geometry=>geometry, x=>integer, y=>integer , fill=>color name, bordercolor=> color name | changes the color value of any pixel that matches the color of the target pixel and is a neighbor. If you specify a border color, the color value is changed for any neighbor pixel that is not that color.
  Colorize | fill=>color name, opacity=>string | colorize the image with the fill color
  Comment | string | add a comment to your image
  Compare | image=>image-handle | compare image to a reference image
  Composite | image=>image-handle, compose=>{Over, In, Out, Atop, Xor, Plus, Minus, Add, Subtract, Difference, Multiply, Bumpmap, Copy, CopyRed, CopyGreen, CopyBlue, CopyMatte, Dissolve, Clear, Displace, Modulate, Threshold}, mask=>image-handle, geometry=>geometry, x=>integer, y=>integer, gravity=>{NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast}, opacity=>integer, tile=>{True, False}, rotate=>double, color=>color name | composite one image onto another
  Contrast | sharpen=>{True, False} | enhance or reduce the image contrast
  Convolve | coefficients=>array of float values | apply a convolution kernel to the image. Given a kernel order , you would supply order*order float values (e.g. 3x3 implies 9 values).
  Crop | geometry=>geometry, width=>integer, height=> integer, x=>integer, y=>integer | crop an image
  CycleColormap | amount=>integer | displace image colormap by amount
  Deconstruct |  | break down an image sequence into constituent parts
  Despeckle |  | reduce the speckles within an image
  Draw | primitive=>{point, line, rectangle, arc, ellipse, circle, path, polyline, polygon, bezier, color, matte, text, @filename}, points=>string , method=>{Point, Replace, Floodfill, FillToBorder, Reset}, stroke=> color name, fill=>color name, tile=>image-handle, strokewidth=>float, antialias=>{true, false}, bordercolor=>color name, x=> float, y=>float, affine=>array of float values, translate=>float, float, scale=> float, float, rotate=>float. skewX=>float, skewY=> float | annotate an image with one or more graphic primitives
  Edge | radius=>double | enhance edges within the image with a convolution filter of the given radius.
  Emboss | geometry=>geometry, radius=>double, sigma=> double | emboss the image with a convolution filter of the given radius and standard deviation (sigma).
  Enhance |  | apply a digital filter to enhance a noisy image
  Equalize |  | perform histogram equalization to the image
  Flatten |  | flatten a sequence of images
  Flip |  | create a mirror image by reflecting the image scanlines in the vertical direction
  Flop |  | create a mirror image by reflecting the image scanlines in the horizontal direction
  Frame | geometry=>geometry, width=>integer, height=> integer, inner=>integer, outer=>integer, fill=> color name | surround the image with an ornamental border
  Gamma | gamma=>string, red=>double, green=>double , blue=>double | gamma correct the image
  Implode | amount=>double | implode image pixels about the center
  Label | string | assign a label to an image
  Level | level=>string, 'black-point'=>double, 'mid-point'=>double, 'white-point'=>double | adjust the level of image contrast
  Magnify |  | double the size of an image
  Map | image=>image-handle, dither=>{True, False} | choose a particular set of colors from this image
  MatteFloodfill | geometry=>geometry, x=>integer, y=>integer , matte=>integer, bordercolor=>color name | changes the matte value of any pixel that matches the color of the target pixel and is a neighbor. If you specify a border color, the matte value is changed for any neighbor pixel that is not that color.
  MedianFilter | radius=>double | replace each pixel with the median intensity pixel of a neighborhood.
  Minify |  | half the size of an image
  Modulate | brightness=>double, saturation=>double, hue=> double | vary the brightness, saturation, and hue of an image by the specified percentage
  MotionBlur | geometry=>geometry, radius=>double, sigma=> double, angle=>double | blur the image with a Gaussian operator of the given radius and standard deviation (sigma) at the given angle to simulate the effect of motion
  Negate | gray=>{True, False} | replace every pixel with its complementary color (white becomes black, yellow becomes blue, etc.)
  Normalize |  | transform image to span the full range of color values
  OilPaint | radius=>integer | simulate an oil painting
  Opaque | color=>color name, fill=> color name | change this color to the fill color within the image
  Quantize | colors=>integer, colorspace=>{RGB, Gray, Transparent, OHTA, XYZ, YCbCr, YIQ, YPbPr, YUV, CMYK}, treedepth=> integer, dither=>{True, False}, measure_error=>{True, False}, global_colormap=>{True, False} | preferred number of colors in the image
  Profile | name=>{ICM, IPTC}, profile=>blob | add or remove ICC or IPTC image profile
  Raise | geometry=>geometry, width=>integer, height=> integer, x=>integer, y=>integer, raise=>{True, False} | lighten or darken image edges to create a 3-D effect
  ReduceNoise | radius=>double | reduce noise in the image with a noise peak elimination filter
  Resize | geometry=>geometry, width=>integer, height=> integer, filter=>{Point, Box, Triangle, Hermite, Hanning, Hamming, Blackman, Gaussian, Quadratic, Cubic, Catrom, Mitchell, Lanczos, Bessel, Sinc}, blur=>double | scale image to desired size. Specify `blur` > 1 for blurry or < 1 for sharp
  Roll | geometry=>geometry, x=>integer, y=>integer | roll an image vertically or horizontally
  Rotate | degrees=>double, color=>color name | rotate an image
  Sample | geometry=>geometry, width=>integer, height=> integer | scale image with pixel sampling
  Scale | geometry=>geometry, width=>integer, height=> integer | scale image to desired size
  Segment | colorspace=>{RGB, Gray, Transparent, OHTA, XYZ, YCbCr, YCC, YIQ, YPbPr, YUV, CMYK}, verbose={True, False}, cluster=>double, smooth= double | segment an image by analyzing the histograms of the color components and identifying units that are homogeneous
  Shade | geometry=>geometry, azimuth=>double, elevation=> double, gray=>{true, false} | shade the image using a distant light source
  Sharpen | geometry=>geometry, radius=>double, sigma=> double | sharpen the image with a Gaussian operator of the given radius and standard deviation (sigma).
  Shave | geometry=>geometry, width=>integer, height=> integer | shave pixels from the image edges
  Shear | geometry=>geometry, x=>double, y=>double color=>color name | shear the image along the X or Y axis by a positive or negative shear angle
  Signature |  | generate an SHA-256 message digest for the image pixel stream
  Solarize | threshold=>integer | negate all pixels above the threshold level
  Spread | amount=>integer | displace image pixels by a random amount
  Stereo | image=>image-handle | composites two images and produces a single image that is the composite of a left and right image of a stereo pair
  Stegano | image=>image-handle, offset=>integer | hide a digital watermark within the image
  Swirl | degrees=>double | swirl image pixels about the center
  Texture | texture=>image-handle | name of texture to tile onto the image background
  Threshold | threshold=>string | threshold the image
  Transparent | color=>color name | make this color transparent within the image
  Trim |  | remove edges that are the background color from the image
  UnsharpMask | geometry=>geometry, radius=>double, sigma=> double, amount=>double, threshold=>double | sharpen the image with the unsharp mask algorithm.
  Wave | geometry=>geometry, amplitude=>double, wavelength=> double | alter an image along a sine wave

> Note, that the `geometry` parameter is a short cut for the `width` and `height` parameters (e.g. `geometry=>'106x80'` is equivalent to `width=>106, height=>80` ).

> You can specify `@filename` in both Annotate() and Draw(). This reads the text or graphic primitive instructions from a file on disk. For example,

     $image->Draw(fill=>'red', primitive=>'rectangle',
     points=>'20,20 100,100 40,40 200,200 60,60 300,300');

> Is equivalent to

     $image->Draw(fill=>'red', primitive=>'@draw.txt');

> Where `draw.txt` is a file on disk that contains this:

     rectangle 20, 20 100, 100
     rectangle 40, 40 200, 200
     rectangle 60, 60 300, 300

> The text parameter for methods, Annotate(), Comment(), Draw(), and Label() can include the image filename, type, width, height, or other image attribute by embedding these special format characters:

     %b file size
     %d comment
     %d directory
     %e filename extension
     %f filename
     %h height
     %m magick
     %p page number
     %s scene number
     %t top of filename
     %w width
     %x x resolution
     %y y resolution
     \n newline
     \r carriage return

> For example,

     text=>"%m:%f %wx%h"

> produces an annotation of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.

> You can optionally add Image to any method name. For example, TrimImage() is an alias for method Trim().

> Most of the attributes listed above have an analog in convert. See the documentation for a more detailed description of these attributes.

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Set an Image Attribute

  Use method Set() to set an image attribute. For example,

     $image->Set(dither=>'True');
     $image->[$x]->Set(delay=>3);

> And here is a list of all the image attributes you can set:

Image Attributes

  Attribute | Values | Description
  --- | --- | ---
  adjoin | {True, False} | join images into a single multi-image file
  antialias | {True, False} | remove pixel aliasing
  authenticate | string | decrypt image with this password.
  background | color name | image background color
  blue-primary | x-value, y-value | chromaticity blue primary point (e.g. 0.15, 0.06)
  bordercolor | color name | set the image border color
  clip-mask | image | Associate a clip mask with the image.
  colormap[i] | color name | color name (e.g. red) or hex value (e.g. #ccc) at position i
  colorspace | {RGB, CMYK} | type of colorspace
  comment | string | Append to the image comment.
  compression | {None, BZip, Fax, Group4, JPEG, LosslessJPEG, LZW, RLE, Zip} | type of image compression
  debug | {No, Configure, Annotate, Render, Locale, Coder, X11, Cache, Blob, All} | display copious debugging information
  delay | integer | this many 1/100ths of a second\fP must expire before displaying the next image in a sequence
  density | geometry | vertical and horizontal resolution in pixels of the image
  disk-limit | integer | set disk resource limit in megabytes
  dispose | {Undefined, None, Background, Previous} | GIF disposal method
  dither | {True, False} | apply error diffusion to the image
  display | string | specifies the X server to contact
  file | filehandle | set the image filehandle
  filename | string | set the image filename
  fill | color | The fill color paints any areas inside the outline of drawn shape.
  font | string | use this font when annotating the image with text
  fuzz | integer | colors within this distance are considered equal
  gamma | double | gamma level of the image
  Gravity | {Forget, NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast} | type of image gravity
  green-primary | x-value, y-value | chromaticity green primary point (e.g. 0.3, 0.6)
  index[x, y] | string | colormap index at position (x, y)
  interlace | {None, Line, Plane, Partition} | the type of interlacing scheme
  iterations | integer | add Netscape loop extension to your GIF animation
  label | string | Append to the image label.
  loop | integer | add Netscape loop extension to your GIF animation
  magick | string | set the image format
  matte | {True, False} | True if the image has transparency
  mattecolor | color name | set the image matte color
  map-limit | integer | set map resource limit in megabytes
  memory-limit | integer | set memory resource limit in megabytes
  monochrome | {True, False} | transform the image to black and white
  page | { Letter, Tabloid, Ledger, Legal, Statement, Executive, A3, A4, A5, B4, B5, Folio, Quarto, 10x14} or geometry | preferred size and location of an image canvas
  pixel[x, y] | string | hex value (e.g. #ccc) at position (x, y)
  pointsize | integer | pointsize of the Postscript or TrueType font
  preview | { Rotate, Shear, Roll, Hue, Saturation, Brightness, Gamma, Spiff, Dull, Grayscale, Quantize, Despeckle, ReduceNoise, AddNoise, Sharpen, Blur, Threshold, EdgeDetect, Spread, Solarize, Shade, Raise, Segment, Swirl, Implode, Wave, OilPaint, CharcoalDrawing, JPEG} | type of preview for the Preview image format
  quality | integer | JPEG/MIFF/PNG compression level
  red-primary | x-value, y-value | chromaticity red primary point (e.g. 0.64, 0.33)
  rendering-intent | {Undefined, Saturation, Perceptual, Absolute, Relative} | the type of rendering intent
  sampling-factor | geometry | horizontal and vertical sampling factor
  scene | integer | image scene number
  subimage | integer | subimage of an image sequence
  subrange | integer | number of images relative to the base image
  server | string | specifies the X server to contact
  size | string | width and height of a raw image
  stroke | color | The stroke color paints along the outline of a shape.
  tile | string | tile name
  texture | string | name of texture to tile onto the image background
  type | {Bilevel, Grayscale, GrayscaleMatte, Palette, PaletteMatte, TrueColor, TrueColorMatte, ColorSeparation, ColorSeparationMatte, Optimize } | image type
  units | { Undefined, PixelsPerInch, PixelsPerCentimeters} | units of image resolution
  verbose | {True, False} | print detailed information about the image
  virtual-pixel | {Constant, Edge, Mirror, Tile} | the virtual pixel method
  white-point | x-value, y-value | chromaticity white point (e.g. 0.3127, 0.329)

> Note, that the `geometry` parameter is a short cut for the `width` and `height` parameters (e.g. `geometry=>'106x80'` is equivalent to `width=>106, height=>80`).

> SetAttribute() is an alias for method Set().

> Most of the attributes listed above have an analog in gm convert. See the gm documentation for a more detailed description of these attributes.

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Get an Image Attribute

  Use method Get() to get an image attribute. For example,

     ($a, $b, $c) = $image->Get('colorspace', 'magick', 'adjoin');
     $width = $image->[3]->Get('columns');

> In addition to all the attributes listed in Set an Image Attribute , you can get these additional attributes:

Image Attributes

  Attribute | Values | Description
  --- | --- | ---
  base-columns | integer | base image width (before transformations)
  base-filename | string | base image filename (before transformations)
  base-rows | integer | base image height (before transformations)
  class | {Direct, Pseudo} | image class
  colors | integer | number of unique colors in the image
  comment | string | image comment
  columns | integer | image width
  depth | integer | image depth
  directory | string | tile names from within an image montage
  error | double | the mean error per pixel computed with methods Compare() or Quantize()
  filesize | integer | number of bytes of the image on disk
  format | string | get the descriptive image format
  geometry | string | image geometry
  height | integer | the number of rows or height of an image
  id | integer | GraphicsMagick registry id
  label | string | image label
  maximum-error | double | the normalized max error per pixel computed with methods Compare() or Quantize()
  mean-error | double | the normalized mean error per pixel computed with methods Compare() or Quantize()
  montage | geometry | tile size and offset within an image montage
  rows | integer | the number of rows or height of an image
  signature | string | SHA-256 message digest associated with the image pixel stream
  taint | {True, False} | True if the image has been modified
  width | integer | the number of columns or width of an image
  x-resolution | integer | x resolution of the image
  y-resolution | integer | y resolution of the image

> GetAttribute() is an alias for method Get().

> Most of the attributes listed above have an analog in convert. See the documentation for a more detailed description of these attributes.

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Create an Image Montage

  Use method Montage() to create a composite image by combining several separate images. The images are tiled on the composite image with the name of the image optionally appearing just below the individual tile. For example,

     $image->Montage(geometry=>'160x160', tile=>'2x2', texture=>'granite:');

> And here is a list of Montage() parameters you can set:

Montage Parameters

  Parameter | Values | Description
  --- | --- | ---
  background | color name | background color name
  borderwidth | integer | image border width
  compose | {Over, In, Out, Atop, Xor, Plus, Minus, Add, Subtract, Difference, Bumpmap, Copy, Mask, Dissolve, Clear, Displace} | composite operator
  filename | string | name of montage image
  fill | color name | fill color for annotations
  font | string | X11 font name
  frame | geometry | surround the image with an ornamental border
  geometry | geometry | preferred tile and border size of each tile of the composite image
  gravity | {NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast} | direction image gravitates to within a tile
  ICM | blob | color information profile
  IPTC | blob | newswire information profile
  label | string | assign a label to an image
  mode | {Frame, Unframe, Concatenate} | thumbnail framing options
  pointsize | integer | pointsize of the Postscript or TrueType font
  shadow | {True, False} | add a shadow beneath a tile to simulate depth
  stroke | color name | stroke color for annotations
  texture | string | name of texture to tile onto the image background
  tile | geometry | number of tiles per row and column
  title | string | assign a title to the image montage
  transparent | string | make this color transparent within the image

> Note, that the `geometry` parameter is a short cut for the `width` and `height` parameters (e.g. `geometry=>'106x80'` is equivalent to `width=>106, height=>80`).

> MontageImage() is an alias for method Montage().

> Most of the attributes listed above have an analog in montage. See the documentation for a more detailed description of these attributes.

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Working with Blobs

  A blob contains data that directly represent a particular image format in memory instead of on disk. PerlMagick supports blobs in any of these image formats and provides methods to convert a blob to or from a particular image format.

Blob Methods

  Method | Parameters | Return Value | Description
  --- | --- | --- | ---
  ImageToBlob | any image attribute | an array of image data in the respective image format | convert an image or image sequence to an array of blobs
  BlobToImage | one or more blobs | the number of blobs converted to an image | convert one or more blobs to an image

> ImageToBlob() returns the image data in their respective formats. You can then print it, save it to an ODBC database, write it to a file, or pipe it to a display program:

     @blobs = $image->ImageToBlob();
     open(DISPLAY,"| display -") || die;
     binmode DISPLAY;
     print DISPLAY $blobs[0];
     close DISPLAY;

> Method BlobToImage() returns an image or image sequence converted from the supplied blob:

     @blob=$db->GetImage();
     $image=Graphics::Magick->new(magick=>'jpg');
     $image->BlobToImage(@blob);

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Miscellaneous Methods

  The Append() method append a set of images. For example,

     $p = $image->Append(stack=>{true,false});

> appends all the images associated with object `$image`. By default, images are stacked left-to-right. Set `stack` to True to stack them top-to-bottom.

> The Average() method averages a set of images. For example,

     $p = $image->Average();

> averages all the images associated with object `$image`.

> The Clone() method copies a set of images. For example,

     $p = $image->Clone();

> copies all the images from object `$q` to `$p`. You can use this method for single or multi-image sequences.

> The Morph() method morphs a set of images. Both the image pixels and size are linearly interpolated to give the appearance of a meta-morphosis from one image to the next:

     $p = $image->Morph(frames=>integer);

> where frames is the number of in-between images to generate. The default is 1.

> Mosaic() creates an mosaic from an image sequence.

> Method Mogrify() is a single entry point for the image manipulation methods (Manipulate an Image). The parameters are the name of a method followed by any parameters the method may require. For example, these calls are equivalent:

     $image->Crop('340x256+0+0');
     $image->Mogrify('crop', '340x256+0+0');

> Method MogrifyRegion() applies a transform to a region of the image. It is similar to Mogrify() but begins with the region geometry. For example, suppose you want to brighten a 100x100 region of your image at location (40, 50):

     $image->MogrifyRegion('100x100+40+50', 'modulate', brightness=>50);

> Ping() is a convenience method that returns information about an image without having to read the image into memory. It returns the width, height, file size in bytes, and the file format of the image. You can specify more than one filename but only one filehandle:

      ($width, $height, $size, $format) = $image->Ping('logo.png');
      ($width, $height, $size, $format) = $image->Ping(file=>\*IMAGE);
      ($width, $height, $size, $format) = $image->Ping(blob=>$blob);

> This is a more efficient and less memory intensive way to query if an image exists and what its characteristics are.

> To have full control over text positioning you need font metric information. Use

     ($x_ppem, $y_ppem, $ascender, $descender, $width, $height, $max_advance) =
     $image->QueryFontMetrics(parameters);

> Where parameters is any parameter of the Annotate method. The return values are

- > character width

- > character height

- > ascender

- > descender

- > text width

- > text height

- > maximum horizontal advance

> Call QueryColor() with no parameters to return a list of known colors names or specify one or more color names to get these attributes: red, green, blue, and opacity value.

     @colors = $image->QueryColor();
     ($red, $green, $blue, $opacity) = $image->QueryColor('cyan');
     ($red, $green, $blue, $opacity) = $image->QueryColor('#716bae');

> QueryColorname() accepts a color value and returns its respective name or hex value;

     $name = $image->QueryColorname('rgba(80,60,0,0)');

> Call QueryFont() with no parameters to return a list of known fonts or specify one or more font names to get these attributes: font name, description, family, style, stretch, weight, encoding, foundry, format, metrics, and glyphs values.

     @fonts = $image->QueryFont();
     $weight = ($image->QueryFont('Helvetica'))[5];

> Call QueryFormat() with no parameters to return a list of known image formats or specify one or more format names to get these attributes: adjoin, blob support, raw, decoder, encoder, description, and module.

     @formats = $image->QueryFormat();
     ($adjoin, $blob_support, $raw, $decoder, $encoder, $description, $module) = $image->QueryFormat('gif');

> Use RemoteCommand() to send a command to an already running display or animate application. The only parameter is the name of the image file to display or animate.

> Finally, the Transform() method accepts a fully-qualified geometry specification for cropping or resizing one or more images. For example,

     $p = $image->Transform(crop=>'100x100');

> You can optionally add Image to any method name above. For example, PingImage() is an alias for method Ping().

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Handling Errors

  All PerlMagick methods return an undefined string context upon success. If any problems occur, the error is returned as a string with an embedded numeric status code. A status code less than 400 is a warning. This means that the operation did not complete but was recoverable to some degree. A numeric code greater or equal to 400 is an error and indicates the operation failed completely. Here is how errors are returned for the different methods:

- Methods which return a number (e.g. Read(), Write()):

       $x = $image->Read(...);
       warn "$x" if "$x"; # print the error message
       $x =~ /(\d+)/;
       print $1; # print the error number
       print 0+$x; # print the number of images read

- Methods which operate on an image (e.g. Resize(), Crop()):

       $x = $image->Crop(...);
       warn "$x" if "$x"; # print the error message
       $x =~ /(\d+)/;
       print $1; # print the error number

- Methods which return images (Average(), Montage(), Clone()) should be checked for errors this way:

       $x = $image->Montage(...);
       warn "$x" if !ref($x); # print the error message
       $x =~ /(\d+)/;
       print $1; # print the error number

> Here is an example error message:

     Error 400: Memory allocation failed

> Below is a list of error and warning codes:

Error and Warning Codes

  Code | Mnemonic | Description
  --- | --- | ---
  0 | Success | method completed without an error or warning
  300 | ResourceLimitWarning | a program resource is exhausted (e.g. not enough memory)
  305 | TypeWarning | A font is unavailable; a substitution may have occurred
  310 | OptionWarning | a command-line option was malformed
  315 | DelegateWarning | an GraphicsMagick delegate returned a warning
  320 | MissingDelegateWarning | the image type can not be read or written because the appropriate Delegate is missing
  325 | CorruptImageWarning | the image file may be corrupt
  330 | FileOpenWarning | the image file could not be opened
  335 | BlobWarning | a binary large object could not be allocated
  340 | StreamWarning | there was a problem reading or writing from a stream
  345 | CacheWarning | pixels could not be saved to the pixel cache
  350 | CoderWarning | there was a problem with an image coder
  355 | ModuleWarning | there was a problem with an image module
  360 | DrawWarning | a drawing operation failed
  365 | ImageWarning | the operation could not complete due to an incompatible image
  380 | XServerWarning | an X resource is unavailable
  385 | MonitorWarning | there was a problem with prgress monitor
  390 | RegistryWarning | there was a problem getting or setting the registry
  395 | ConfigureWarning | there was a problem getting a configuration file
  400 | ResourceLimitError | a program resource is exhausted (e.g. not enough memory)
  405 | TypeError | A font is unavailable; a substitution may have occurred
  410 | OptionError | a command-line option was malformed
  415 | DelegateError | an GraphicsMagick delegate returned a warning
  420 | MissingDelegateError | the image type can not be read or written because the appropriate Delegate is missing
  425 | CorruptImageError | the image file may be corrupt
  430 | FileOpenError | the image file could not be opened
  435 | BlobError | a binary large object could not be allocated
  440 | StreamError | there was a problem reading or writing from a stream
  445 | CacheError | pixels could not be saved to the pixel cache
  450 | CoderError | there was a problem with an image coder
  455 | ModuleError | there was a problem with an image module
  460 | DrawError | a drawing operation failed
  465 | ImageError | the operation could not complete due to an incompatible image
  480 | XServerError | an X resource is unavailable
  480 | MonitorError | there was a progress monitor error
  490 | RegistryError | there was a problem getting or setting the registry
  495 | ConfigureError | there was a problem getting a configuration file

> The following illustrates how you can use a numeric status code:

     $x = $image->Read('rose.png');
     $x =~ /(\d+)/;
     die "unable to continue" if ($1 == ResourceLimitError);

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