<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!--Copyright (c) 2000, 2007, Oracle and/or its affiliates. All rights reserved.DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. This code is free software; you can redistribute it and/or modify itunder the terms of the GNU General Public License version 2 only, aspublished by the Free Software Foundation.  Oracle designates thisparticular file as subject to the "Classpath" exception as providedby Oracle in the LICENSE file that accompanied this code. This code is distributed in the hope that it will be useful, but WITHOUTANY WARRANTY; without even the implied warranty of MERCHANTABILITY orFITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public Licenseversion 2 for more details (a copy is included in the LICENSE file thataccompanied this code). 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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USAor visit www.oracle.com if you need additional information or have anyquestions.--> </head> <body bgcolor="white"> The main package of the Java Image I/O API. <p> Many common image I/O operations may be performed using the staticmethods of the <code>ImageIO</code> class. <p> This package contains the basic classes and interfaces for describingthe contents of image files, including metadata and thumbnails(<code>IIOImage</code>); for controlling the image reading process(<code>ImageReader</code>, <code>ImageReadParam</code>, and<code>ImageTypeSpecifier</code>) and image writing process(<code>ImageWriter</code> and <code>ImageWriteParam</code>); forperforming transcoding between formats (<code>ImageTranscoder</code>),and for reporting errors (<code>IIOException</code>). <p>All implementations of javax.imageio provide the following standardimage format plug-ins:</p><div><table border=1 align='center' cellpadding=5><tr>    <th>&nbsp;</th> <th>Reading</th> <th>Writing</th>    <th>Notes</th> <th>Metadata</th></tr><!-- JPEG plugin --><tr>    <td> <a href="http://www.jpeg.org">JPEG</a></td>    <td align='center'>yes</td>    <td align='center'>yes</td>    <td align='center'>none</td>    <td align='center'><a href='metadata/doc-files/jpeg_metadata.html'>    JPEG metadata format</a></td></tr><!-- PNG plugin --><tr>    <td><a href="http://www.libpng.org/pub/png/spec/">PNG</a></td>    <td align='center'>yes</td>    <td align='center'>yes</td>    <td align='center'>none</td>    <td align='center'><a href='metadata/doc-files/png_metadata.html'>    PNG metadata format</a></td></tr><!-- BMP plugin --><tr>    <td>BMP</td>    <td align='center'>yes</td>    <td align='center'>yes</td>    <td align='center'>none</td>    <td align='center'><a href='metadata/doc-files/bmp_metadata.html'>    BMP metadata format</a></td></tr><!-- WBMP plugin --><tr>    <td><a href="http://www.wapforum.org/what/technical/SPEC-WAESpec-19990524.pdf">WBMP</a></td>    <td align='center'>yes</td>    <td align='center'>yes</td>    <td align='center'>none</td>    <td align='center'><a href='metadata/doc-files/wbmp_metadata.html'>    WBMP metadata format</a></td></tr><!-- GIF plugin --><tr>    <td><a href="http://www.w3.org/Graphics/GIF/spec-gif89a.txt">GIF</a></td>    <td align='center'>yes</td>    <td align='center'>yes</td>    <td align='center'><a href="#gif_plugin_notes">    GIF plug-in notes</a></td>    <td align='center'><a href='metadata/doc-files/gif_metadata.html'>    GIF metadata format</a></td></tr></table></div><BR><BR><BR> <h2> Standard Plug-in Notes</h2><h3><a name="gif_plugin_notes">Standard plug-in for GIF image format</a></h3>  <p>ImageIO provides <code>ImageReader</code> and <code>ImageWriter</code>plug-ins for the <a href="http://www.w3.org/Graphics/GIF/spec-gif89a.txt">Graphics Interchange Format (GIF)</a> image format. These are the "standard" GIF plug-ins, meaning those that are included in theJRE, as distinct from those included in standard extensions, or 3rd partyplug-ins. The following notes and metadata specification apply to thestandard plug-ins. <h3>Writing GIF images</h3> The GIF image writer plug-in guarantees lossless writing for images which meet the following requirements:<ul><li>the number of bands is 1;<li>the number of bits per sample is not greater than 8;<li>the size of a color component is not greater than 8;</ul> </p> <p> By default the GIF writer plug-in creates version "89a" images. This can be changed to "87a" by explicitly setting the version in the stream metadata (see <a href="metadata/doc-files/gif_metadata.html#gif_stream_metadata_format"> GIF Stream Metadata Format Specification</a>).</p>   <!-- animated images --><p> The GIF writer plug-in supports the creation of animated GIF images through the standard sequence writing methods defined in the <code>ImageWriter</code> class.  <!-- TODO: add example here --> </p> <!--  color tables --><p> A global color table is written to the output stream if one of the following conditions is met: <ul> <li> stream metadata containing a GlobalColorTable element is  supplied; </li> <li> a sequence is being written and image metadata containing a  LocalColorTable element is supplied for the first image in the  sequence;</li> <li>image metadata is not supplied or does not contain a LocalColorTable  element. </li> </ul>  <p> In the first case the global color table in the stream metadata is  used, in the second the local color table in the image metadata is  used, and in the third a global color table is created from the  ColorModel or SampleModel of the (first) image. </p>  <p> A local color table is written to the output stream only if image  metadata containing a LocalColorTable element is supplied to the  writer, or no image metadata is supplied to the writer and the local  color table which would be generated from the image itself is not  equal to the global color table. </p>  <p> A Graphic Control Extension block is written to the output stream only  if image metadata containing a GraphicControlExtension element is  supplied to the writer, or no image metadata is supplied and the  local color table generated from the image requires a transparent  index. Application, Plain Text, and Comment Extension blocks are  written only if they are supplied to the writer via image metadata.   </p>  <!-- writing interlaced images --> <p>   The writing of interlaced images can be controlled by the progressive  mode of the provided <code>ImageWriteParam</code> instance.  If progressive mode is  <code>MODE_DISABLED</code> then a non-interlaced image will be written. If  progressive mode is <code>MODE_DEFAULT</code> then an interlaced image will  be written. If progressive mode is <code>MODE_COPY_FROM_METADATA</code>, then  the metadata setting is used (if it is provided, otherwise an interlaced  image will be written). </p>  <p> The GIF image writer plug-in supports setting output stream metadata from metadata supplied to the writer in either the native GIF stream metadata format <a href="metadata/doc-files/gif_metadata.html#gif_stream_metadata_format"> javax_imageio_gif_stream_1.0 </a> or the standard metadata format <a href="metadata/doc-files/standard_metadata.html"> javax_imageio_1.0</a>, and setting output image metadata from metadata supplied to the writer in either the native GIF image metadata format <a href="metadata/doc-files/gif_metadata.html#gif_image_metadata_format"> javax_imageio_gif_image_1.0 </a> or the standard metadata format <a href="metadata/doc-files/standard_metadata.html">javax_imageio_1.0</a>.   The mapping of standard metadata format to the GIF native stream and image metadata formats is given in the tables <a href="metadata/doc-files/gif_metadata.html#mapping"> here </a>. </p>  <!-- <HR> Java<SUP><FONT SIZE="-2">TM</FONT></SUP> Image I/O API Specification<BR><BR>Public Draft 2 (specification version 0.5)<BR>Release: October 1, 2000<BR><BR> <HR> --> @since 1.4</body></html>