GraphicsMagick

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# GraphicsMagick Perl API -- PerlMagick

- Introduction
- Installation
  - UNIX
  - Windows XP - Windows 8
  - Running the Regression Tests
- 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

# 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.

# 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 8

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.

# 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';

# Example Script

Here is an example script to get you started:

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

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

# 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 from a disk file, use::
  $image = Graphics::Magick->new; $filename = 'test.gif'; $status = $image->Read ($filename);

and to write the image back to the disk file, use:

    $status = $image->Write($filename);

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

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

If %0Nd appears in the filename, it is interpreted as a printf format specification and the specification is replaced with the specified decimal 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().

# 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, Random} | 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, Matte, All, Gray} | 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, CopyOpacity, Clear, Dissolve, Displace, Modulate, Threshold, No, Darken, Lighten, Hue, Saturate, Colorize, Luminize, Screen, Overlay, CopyCyan, CopyMagenta, CopyYellow, CopyBlack, Divide, HardLight}, 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, roundRectangle, arc, ellipse, circle, polyline, polygon, ,bezier, path, color, matte, text, image, @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.

# 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, LZMA JPEG2000, JBIG1, JBIG2} | type of image compression
debug | {No, Configure, Annotate, Render, Transform, Locale, Coder, X11, Cache, Blob, Deprecate, User, Resource, TemporaryFile, Exception,All} | log copious debugging information for one or more event types
delay | integer | this many 1/100ths of a second 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
endian | {Undefined, LSB, MSB, Native} | specifies the ordering of bytes in a multi-byte word. MSB is big-endian, LSB is little-endian, and Native is whatever the current host uses by default.
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, Charcoal, 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.

# 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.

# 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.

# 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);

# 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
    'text' parameter must be specified since there can be no default for
    the text to render. 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().

# 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()):

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

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

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

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

>       $status = $image->Montage(...);
>       warn "$status" if !ref($status); # print the error message
>       $status =~ /(\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:

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

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