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  28  <H2><A NAME="3_4">3.4 Image formats and external image libraries</A></H2>
  29  <P> Per default the standard GD image library supports PNG graphic
  30   formats. You will need to have that installed together with your PHP
  31   module for this library to work at all. Please refer to PHP
  32   documentation on specifics. Note that the newer versions of GD does not
  33   support the GIF format due to copyright problems. Hence by default only
  34   PNG is supported.</P>
  35  <P> If you want JPEG support you will also need an additional library
  36   for PHP, again please see PHP documentation for specifics. For most
  37   practical purposes PNG is a better format since it normally achieves
  38   better compression then GIF (typically by a factor of 2 for the types
  39   of images generated by JpGraph). In comparison with JPEG format PNG is
  40   also better for the type of images generated by this library. So, the
  41   bottom line is, you should have a very good reason to choose any other
  42   format then PNG.</P>
  43  <P> By default the image format is set to &quot;auto&quot;. This means that
  44   JpGraph automatically chooses the best available graphic using the
  45   preferred order &quot;PNG&quot;, &quot;GIF&quot;, &quot;JPG&quot;.</P>
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