php-doc-en/reference/image/reference.xml

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<reference id="ref.image">
 <title>Image functions</title>
 <titleabbrev>Image</titleabbrev>

 <partintro>
   <section id="image.intro">
    &reftitle.intro;
    <para>
     PHP is not limited to creating just HTML output.  It can also be
     used to create and manipulate image files in a variety of different
     image formats, including gif, png, jpg, wbmp, and xpm. Even more
     convenient, PHP can output image streams directly to a browser. You
     will need to compile PHP with the GD library of image functions for
     this to work. GD and PHP may also require other libraries, depending
     on which image formats you want to work with.
    </para>
    <para>
     You can use the image functions in PHP to get the size of
     <acronym>JPEG</acronym>, <acronym>GIF</acronym>,
     <acronym>PNG</acronym>, <acronym>SWF</acronym>,
     <acronym>TIFF</acronym> and <acronym>JPEG2000</acronym> images.
    </para>
    <para>
     <note>
      <simpara>
       Read requirements section about how to expand image capabilities
       to read, write and modify images and to read meta data of pictures
       taken by digital cameras.
      </simpara>
     </note>
    </para>
   </section>

   <section id="image.requirements">
    &reftitle.required;
    <para>
     If you have the <acronym>GD</acronym> library (available at <ulink
     url="&url.gd;">&url.gd;</ulink>) you will also be able to create
     and manipulate images.
    </para>
    <para>
     The format of images you are able to manipulate depend on the
     version of <acronym>GD</acronym> you install, and any other libraries
     <acronym>GD</acronym> might need to access those image formats.
     Versions of <acronym>GD</acronym> older than gd-1.6
     support gif format images, and do not support png, where versions
     greater than gd-1.6 support png, not gif.
      <note>
       <simpara>
        Since PHP 4.3 there is a bundled version of the GD lib. This bundled
        version has some additional features like alpha blending and should
        be used in preference to the external library since it's codebase is
        better maintained and more stable.
       </simpara>
      </note>
    </para>
    <para>
     If you have PHP compiled with <option role="configure">--enable-exif</option>
     you are able to work with information stored in headers of
     <acronym>JPEG</acronym> and <acronym>TIFF</acronym> images. This way you can
     read meta data generated by digital cameras as mentioned above. These
     functions does not require the <acronym>GD</acronym> library.
     <note>
      <simpara>
      PHP does not require any additional library for exif the module.
      </simpara>
     </note>
    </para>
   </section>

   <section id="image.installation">
    &reftitle.install;
    <para>
     In order to read and write images in jpeg format, you will need to
     obtain and install jpeg-6b (available at
     <ulink url="&url.jpeg;">&url.jpeg;</ulink>), and then recompile
     <acronym>GD</acronym> to make use of jpeg-6b. You will also have to
     compile PHP with 
     <option role="configure">--with-jpeg-dir=/path/to/jpeg-6b</option>.
    </para>
    <para>
     To add support for Type 1 fonts, you can install t1lib (available
     at <ulink url="&url.t1lib;">&url.t1lib;</ulink>), and then add
     <option role="configure">--with-t1lib[=dir]</option>.
    </para>
   </section>

   &reference.image.ini;

   <section id="image.resources">
    &reftitle.resources;
    &no.resource;
   </section>

   &reference.image.constants;

   <section id="image.examples">
    &reftitle.examples;
    <para>
     <example>
      <title>PNG creation with PHP</title>
      <programlisting role="php">
<![CDATA[
<?php
    header("Content-type: image/png");
    $string = $_GET['text'];
    $im     = imagecreatefrompng("images/button1.png");
    $orange = imagecolorallocate($im, 220, 210, 60);
    $px     = (imagesx($im) - 7.5 * strlen($string)) / 2;
    imagestring($im, 3, $px, 9, $string, $orange);
    imagepng($im);
    imagedestroy($im);
?>
]]>
      </programlisting>
     </example>
     This example would be called from a page with a tag like: &lt;img
     src=&quot;button.php?text&quot;&gt;. The above button.php script
     then takes this &quot;text&quot; string and overlays it on top of a
     base image which in this case is &quot;images/button1.png&quot;
     and outputs the resulting image. This is a very convenient way to
     avoid having to draw new button images every time you want to
     change the text of a button. With this method they are
     dynamically generated.
    </para>
   </section>
 </partintro>

&reference.image.functions;

 </reference>
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