Add information on image formats;

note required tools in the makefile

diff --git a/doc/infosrc/attrs b/doc/infosrc/attrs
index 8616a56eeec3082f8b3a962bd04d6ab2baef96af..b7a13aebb64a94e57312736c1330b455f8fd40c6 100644 (file)
--- a/doc/infosrc/attrs
+++ b/doc/infosrc/attrs
@@ -381,7 +381,8 @@ If no id attribute is provided, then a unique internal id is used, however this
 An externally provided id is not used internally.
 :image:N:string:"";
 Gives the name of a file containing an image to be displayed inside
-a node. The image file must be in one of the recognized formats,
+a node. The image file must be in one of the recognized 
+<A HREF=output.html#d:image_fmts>formats</A>,
 typically JPEG, PNG, GIF or Postscript, and be able to be converted
 into the desired output format.
 <P>
@@ -946,6 +947,7 @@ The image in the shapefile must be
 rectangular. The image formats supported as well as the precise semantics of
 how the file is used depends on the
 <A HREF="http://www.graphviz.org/doc/info/output.html">output format</A>.  For further details, see
+<A HREF=output.html#d:image_fmts>Image Formats</A> and
 <A HREF=http://www.graphviz.org/Documentation/html/shapehowto.html#ext_image>External PostScript files</A>.
 <P>
 There is one exception to this usage.