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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="generator" content=
"HTML Tidy for Linux/x86 (vers 1st July 2003), see www.w3.org" />
<title>RMagick: class Image::Info - Optional method
arguments</title>
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"text/html; charset=us-ascii" />
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<meta name="Copyright" content=
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<body>
<h6 id="header">RMagick User's Guide and Reference</h6>
<div class="nav">
« <a href="struct.html">Prev</a> | <a href=
"index.html">Contents</a> | <a href=
"constants.html">Next</a> »
</div>
<h1>class Image::Info - Optional method arguments</h1>
<div id="toc">
<h2>Table of Contents</h2>
<h3>instance methods</h3>
<ul>
<li><a href="#define">define</a></li>
</ul>
<h3>attribute methods</h3>
<div class="toccol">
<ul>
<li><a href="#antialias">antialias</a></li>
<li><a href="#background_color">background_color</a></li>
<li><a href="#border_color">border_color</a></li>
<li><a href="#colorspace">colorspace</a></li>
<li><a href="#compression">compression</a></li>
<li><a href="#density">density</a></li>
<li><a href="#depth">depth</a></li>
<li><a href="#dither">dither</a></li>
<li><a href="#extract">extract</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#filename">filename</a></li>
<li><a href="#font">font</a></li>
<li><a href="#format">format</a></li>
<li><a href="#fuzz">fuzz</a></li>
<li><a href="#image_type">image_type</a></li>
<li><a href="#interlace">interlace</a></li>
<li><a href="#matte_color">matte_color</a></li>
<li><a href="#monochrome">monochrome</a></li>
<li><a href="#number_scenes">number_scenes</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#page">page</a></li>
<li><a href="#quality">quality</a></li>
<li><a href="#scene">scene</a></li>
<li><a href="#server_name">server_name</a></li>
<li><a href="#size">size</a></li>
<li><a href="#subimage">subimage</a></li>
<li><a href="#subrange">subrange</a></li>
<li><a href="#tile">tile</a></li>
<li><a href="#units">units</a></li>
<li><a href="#view">view</a></li>
</ul>
</div>
</div>
<div id="intro">
<h2>The Image::Info class</h2>
<p>Some <code>Image</code> and <code>ImageList</code> methods,
such as <code>read</code> and <code>write</code>, accept an
"optional arguments" block in which you can set attributes that
modify the method's output. These attributes belong to the
<code>Image::Info</code> class. The <code>Image::Info</code>
class exists only to accept optional arguments for those Image
and ImageList methods.</p>
<p>This page explains the methods defined in the
<code>Image::Info</code> class. Generally, each
<code>Image</code> or <code>ImageList</code> method that uses
the <code>Image::Info</code> class to get optional arguments
will only accept some of the attributes listed on this page,
that is, only those attributes that are meaningful for the
particular method. Any other attributes that you set are
ignored. Also, some attributes are only used by a subset of the
image formats. See the ImageMagick documentation for more
information.</p>
<p>Remember, you do not ever need to create an
I<code>mage::Info</code> object. The object is created for you
before the optional arguments block is entered and destroyed
after the block is exited.</p>
<p>All the attributes in the Image::Info class are read/write.
For simplicity, and because usually you only set these
attributes, just the setter version of each attribute method is
described.</p>
</div>
<h2 class="methods">instance methods</h2>
<div class="sig">
<h3 id="define">define</h3>
<p><span class="arg">self</span>.define(<span class=
"arg">format</span>, <span class="arg">key</span>[,
<span class="arg">value</span>])</p>
</div>
<div class="desc">
<h4>Description</h4>Define a format-specific option. The
<code>define</code> method is a new, general-purpose way of
specifying options that apply to specific image formats. This
method is available in ImageMagick 6.0.0 and GraphicsMagick
1.1.
<h4>Arguments</h4>
<dl>
<dt>format</dt>
<dd>An image format name such as "ps" or "tiff".</dd>
<dt>key</dt>
<dd>A string that identifies the option.</dd>
<dt>value</dt>
<dd>The value of the option. If omitted, the key is simply
defined to an null value.</dd>
</dl>
<h4>Returns</h4>
<p>self</p>
<h4>Example</h4>
<p>See the ×Magick documentation for the -define utility
command option for a list of valid formats, keys, and
values.</p>
<pre>
self.define("tiff", "bits-per-sample", 2)
</pre>
<h4>Magick API</h4>
<p>SetImageOption (ImageMagick 6.0.0), AddDefinitions
(GraphicsMagick 1.1)</p>
</div>
<h2 class="methods">attribute methods</h2>
<div class="sig">
<h3 id="antialias">antialias</h3>
<p><span class="arg">self.</span>antialias= <span class=
"arg"><code>true</code></span> or <span class=
"arg"><code>false</code></span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p><span class="imquote">Control antialiasing of rendered
Postscript and Postscript or TrueType fonts.</span> The default
is <code>true</code>.</p>
</div>
<div class="sig">
<h3 id="background_color">background_color</h3>
<p><span class="arg">self.</span>background_color= <span class=
"arg">aPixel</span> or <em>aPixel</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the image background color. The default is "white".</p>
<h4>Arguments</h4>
<p>A <a href="imusage.html#color_names">color name</a> or a
<a href="struct.html#Pixel">aPixel</a>.</p>
</div>
<div class="sig">
<h3 id="border_color">border_color</h3>
<p><span class="arg">self.</span>border_color= <span class=
"arg">aString</span> or <span class="arg">aPixel</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the image border color. The default is "#dfdfdf".</p>
<h4>Arguments</h4>
<p>A <a href="imusage.html#color_names">color name</a> or a
<a href="struct.html#Pixel">aPixel</a>.</p>
</div>
<div class="sig">
<h3 id="colorspace">colorspace</h3>
<p><span class="arg">self.</span>colorspace= <span class=
"arg">aColorspaceType</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the image pixel interpretation.</p>
<h4>Arguments</h4>A <a href=
"constants.html#ColorspaceType">ColorspaceType</a> constant.
</div>
<div class="sig">
<h3 id="compression">compression</h3>
<p><span class="arg">self.</span>compression= <span class=
"arg">aCompressionType</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the image compression type. Not all compression
types are supported for all image formats. If you specify an
unsupported compression type, the default compression type is
used instead.</p>
<h4>Arguments</h4>A <a href=
"constants.html#CompressionType">CompressionType</a> constant.
</div>
<div class="sig">
<h3 id="density">density</h3>
<p><span class="arg">self.</span>density= <span class=
"arg">aString</span> or <span class="arg">aGeometry</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the vertical and horizontal resolution in pixels.
The default density is "72.0x72.0".</p>
<h4>Arguments</h4>
<p>The argument can be either a string in the form "XxY" where
"X" is the horizontal resolution and "Y" is the vertical
resolution, or a <a href="struct.html#Geometry">Geometry</a>
object where <code>width</code> is the horizontal resolution
and <code>height</code> is the vertical resolution.</p>
</div>
<div class="sig">
<h3 id="depth">depth</h3>
<p><span class="arg">self.</span>depth= <span class=
"arg">aNumber</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the image depth.</p>
<h4>Arguments</h4>
<p>Either 8, 16, or 32. You can specify 16 and 32 only when
×Magick was compiled with a QuantumDepth that allows
these depth values.</p>
</div>
<div class="sig">
<h3 id="dither">dither</h3>
<p><span class="arg">self.</span>dither= <span class=
"arg"><code>true</code></span> or <span class=
"arg"><code>false</code></span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Apply Floyd/Steinberg error diffusion to the
image. The basic strategy of dithering is to trade intensity
resolution for spatial resolution by averaging the intensities
of several neighboring pixels. Images which suffer from severe
contouring when reducing colors can be improved with this
option.</p>
</div>
<div class="sig">
<h3 id="extract">extract</h3>
<p><span class="arg"><em>self.</em></span>extract= <span class=
"arg">aString</span> or <span class="arg">aGeometry</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify a portion of an image to be extracted when the image
is constituted. This attribute can be used to identify a subset
of an image that is otherwise too large to keep in memory.</p>
<h4>Arguments</h4>
<p>Either a geometry string or a <a href=
"struct.html#Geometry">Geometry</a> object. For example:
<code>self.extract = "200x200+100+100"</code>.</p>
<h4>Notes</h4>
<p>This attribute replaces the <a href="#Info.tile_eq">tile</a>
attribute, which is deprecated in ImageMagick 5.5.6 and
later.</p>
</div>
<div class="sig">
<h3 id="filename">filename</h3>
<p><span class="arg">self.</span>filename= <span class=
"arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>See <a href="image1.html#capture">capture</a>.</p>
</div>
<div class="sig">
<h3 id="font">font</h3>
<p><span class="arg">self.</span>font= <span class=
"arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the text rendering font.</p>
</div>
<div class="sig">
<h3 id="format">format</h3>
<p><span class="arg">self.</span>format= <span class=
"arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the image format, "GIF" or "JPG" for example.</p>
<h4>Arguments</h4>
<p>See <a href=
"http://www.imagemagick.org/www/formats.html">File
Formats</a>.</p>
</div>
<div class="sig">
<h3 id="fuzz">fuzz</h3>
<p><span class="arg">self.</span>fuzz= <span class=
"arg">aNumeric</span> or <span class="arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the level of "fuzziness" for comparing pixels. By
default the pixels must be identical to be considered equal.
The larger the <code>fuzz</code> value the more difference is
tolerated.See <a href="imageattrs.html#fuzz">fuzz</a>.</p>
<h4>Arguments</h4>
<p>The argument may be a numeric value or a string in the form
"NN%". In the second case, the argument is computed as a
percentage of <a href=
"constants.html#Miscellaneous_constants">MaxRGB</a>. For
example, a value of '5%' sets <code>fuzz</code> to
0.05*MaxRGB.</p>
</div>
<div class="sig">
<h3 id="image_type">image_type</h3>
<p><span class="arg">self.</span>image_type= <span class=
"arg">anImageType</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>The image type classification. For example, GrayscaleType.
Don't confuse this attribute with the <a href=
"#format">format</a> such as "GIF" or "JPG".</p>
<h4>Arguments</h4>
<p>An <a href="constants.html#ImageType">ImageType</a>
constant.</p>
</div>
<div class="sig">
<h3 id="interlace">interlace</h3>
<p><span class="arg">self.</span>interlace= <span class=
"arg">anInterlaceType</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p><span class="imquote">[S]pecify the type of interlacing
scheme for raw image formats such as RGB or YUV. NoInterlace
means do not interlace, LineInterlace uses scanline
interlacing, and PlaneInterlace uses plane interlacing.
PartitionInterlace is like PlaneInterlace except the different
planes are saved to individual files (e.g. image.R, image.G,
and image.B). Use LineInterlace or PlaneInterlace to create an
interlaced GIF or progressive JPEG image.</span> The default is
NoInterlace.</p>
<h4>Arguments</h4>An <a href=
"constants.html#InterlaceType">InterlaceType</a> constant.
</div>
<div class="sig">
<h3 id="matte_color">matte_color</h3>
<p><span class="arg">self.</span>matte_color= <span class=
"arg">aString</span> or <span class="arg">aPixel</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the image transparent color. The default is
"#bdbdbd".</p>
<h4>Arguments</h4>
<p>A <a href="imusage.html#color_names">color name</a> or a
<a href="struct.html#Pixel">aPixel</a>.</p>
</div>
<div class="sig">
<h3 id="monochrome">monochrome</h3>
<p><span class="arg">self.</span>monochrome= <span class=
"arg"><code>true</code></span> or <span class=
"arg"><code>false</code></span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Transform the image to black and white on input. Only the
ETP, PDF, and PS formats respect this attribute.</p>
</div>
<div class="sig">
<h3 id="number_scenes">number_scenes</h3>
<p><span class="arg">self.</span>number_scenes= <span class=
"arg">anInteger</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Used in conjunction with <a href="#scene">scene</a> to
specify the range of frames to be extracted when constituting a
multi-frame image.</p>
<h4>Note</h4>
<p>This attribute replaces the <a href="#subrange">subrange</a>
attribute, which is deprecated in ImageMagick 5.5.6 and later.
If <code>number_scenes</code> is used with a version of
ImageMagick prior to 5.5.6, it is a synonym for the
<code>subrange</code> attribute.</p>
</div>
<div class="sig">
<h3 id="page">page</h3>
<p><span class="arg">self.</span>page= <span class=
"arg">aString</span> or <span class="arg">aGeometry</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the equivalent size of the Postscript page. The default
is "612x792>".</p>
<h4>Arguments</h4>
<p>A <a href="imusage.html#geometry">geometry string</a> or a
<a href="struct.html#Geometry">Geometry</a> object.</p>
</div>
<div class="sig">
<h3 id="quality">quality</h3>
<p><span class="arg">self.</span>quality= <span class=
"arg">anInteger</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the compression level to use when writing JPEG, MIFF,
and PNG images. The default is 75.</p>
</div>
<div class="sig">
<h3 id="scene">scene</h3>
<p><em>self.</em>scene= <em>anInteger</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Used in conjunction with <a href=
"#number_scenes">number_scenes</a> to specify the range of
frames to be extracted when constituting a multi-frame
image.</p>
<h4>Note</h4>
<p>This attribute replaces the <a href="#subimage">subimage</a>
attribute, which is deprecated in ImageMagick 5.5.6 and later.
If <code>scene</code> is used with a version of ImageMagick
prior to 5.5.6, it is a synonym for the <code>subimage</code>
attribute.</p>
</div>
<div class="sig">
<h3 id="server_name">server_name</h3>
<p><span class="arg">self.</span>server_name= <span class=
"arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the X11 display to obtain fonts from.</p>
</div>
<div class="sig">
<h3 id="size">size</h3>
<p><span class="arg"><em>self.</em>size=
<em>aString</em></span> or <span class=
"arg">aGeometry</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Set the width and height of the image when reading a
<a href="imusage.html#builtin_formats">built-in image
format</a> that does not have an inherent size, or when reading
an image from a multi-resolution file format such as Photo CD,
JBIG, or JPEG.</p>
<h4>Arguments</h4>
<p>A g<a href="imusage.html#geometry_string">eometry string</a>
or a <a href="struct.html#Geometry">Geometry</a> object.</p>
</div>
<div class="sig">
<h3 id="subimage">subimage</h3>
<p><span class="arg">self.</span>subimage= <span class=
"arg">anInteger</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify a base image of an image sequence in a multi-frame
image.</p>
<h4>Note</h4>
<p>This attribute is deprecated in ImageMagick 5.5.6 and later.
Use the <a href="#scene">scene</a> attribute instead.</p>
</div>
<div class="sig">
<h3 id="subrange">subrange</h3>
<p><span class="arg">self.</span>subrange= <span class=
"arg">anInteger</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the number of images relative to the base image. See
<a href="#subimage">subimage</a>.</p>
<h4>Note</h4>
<p>This attribute is deprecated in ImageMagick 5.5.6 and later.
Use the <a href="#number_scenes">number_scenes</a> attribute
instead.</p>
</div>
<div class="sig">
<h3 id="tile">tile</h3>
<p><span class="arg">self.</span>tile= <span class=
"arg">aString</span> or <span class="arg">aGeometry</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify a portion of an image to be extracted when the image
is constituted. The argument is a geometry string. For example:
<code>self.tile = "200x200+100+100"</code>. This attribute can
be used to identify a subset of an image that is otherwise too
large to keep in memory.</p>
<h4>Arguments</h4>
<p>A <a href="imusage.html#geometry_string">geometry string</a>
or a <a href="struct.html#Geometry">Geometry</a> object.</p>
<h4>Note</h4>
<p>This attribute is deprecated in ImageMagick 5.5.6 and later.
Use the <a href="#extract">extract</a> attribute instead.</p>
</div>
<div class="sig">
<h3 id="units">units</h3>
<p><span class="arg">self.</span>units= <span class=
"arg">aResolutionType</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify the units of image resolution.</p>
<h4>Arguments</h4>
<p>A <a href="constants.html#ResolutionType">ResolutionType</a>
constant.</p>
</div>
<div class="sig">
<h3 id="view">view</h3>
<p><span class="arg">self.</span>view= <span class=
"arg">aString</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>FlashPix viewing parameters.</p>
</div>
<p class="spacer"> </p>
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