The best refernce for the image library is at 
<a href=http://www.php.net/manual/en/ref.image.php>http://www.php.net/manual/en/ref.image.php</a>

Here are notes on the three basic image formats<br>

<ul>
<li>GIF -- Designed to work best with line art and such.  Does work with pictures.  Is a lossless format.  There is a copyright on the format, and Compuserve did spend some time trying to enforce the copyright.
<li>JPG -- Designed to work best with photos and art.  Is a LOSSY format.  You can control the tradeoff between image quality and file size.  Not the bext choice for line art.
<li>PNG -- Designed as a patent-free replacement for GIF.  Does everything GIF does.  Works for all browswers.  Always compiled into PHP.
<li>BMP -- A Windows only solution that does not work for other browsers.  Has HUGE HUGE HUGE files.  This is almost always the WRONG choice.
</ul>

Not all versions of PHP have GIF format compiled in.


<pre>
10864 <a href=al_bundy.gif>al_bundy.gif</a>
9644  <a href=al_bundy.png>al_bundy.png</a>

9009   <a href=Rose018-02percent.jpg>Rose018-02percent.jpg</a>
10319  <a href=Rose018-05percent.jpg>Rose018-05percent.jpg</a>
13356  <a href=Rose018-10percent.jpg>Rose018-10percent.jpg</a>
16157  <a href=Rose018-25percent.jpg>Rose018-25percent.jpg</a>
24724  <a href=Rose018-50percent.jpg>Rose018-30percent.jpg</a>
35094  <a href=Rose018-50percent.jpg>Rose018-50percent.jpg</a>
116425 <a href=Rose018.jpg>Rose018.jpg</a> (default)
212368 <a href=Rose018.gif>Rose018.gif</a>
</pre>