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

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 12

[ These procedures have not been exercised for some time ]

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 substitution 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().

To set encoder parameters when saving a file use AddDefinition($magick, $key, $value); this returns 0 on success or 1 on failure. A comma-delimited list of parameters can also be set using AddDefinition($values); this returns 0 on success or 1 on failure. To remove parameters use RemoveDefinitions($keys) (comma-delimited; the special key * can be used to remove all definitions); this returns 1 if the specified keys were present and removed, 0 otherwise. To get the current value of a parameter use AccessDefinition($magick, $key); note that if no value was explicitly set then undef is returned. These are equivalent to using the commandline gm utility's -define option. For example, to save a lossless WebP image one can use:

$image->AddDefinition('webp', 'lossless', 'TRUE'); $image->Write(filename=>'webp:output.webp');

$image->AddDefinitions('webp:lossless=TRUE'); $image->Write(filename=>'webp:output.webp');

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);