Add note concerning the blending of cairo and gd for png output.

diff --git a/doc/info/output.html b/doc/info/output.html
index 2f49b8c096f2d311418e659273710a2215927e10..678c2de5ba810c85bec9ee2b4d45c6908067e721 100644 (file)
--- a/doc/info/output.html
+++ b/doc/info/output.html
@@ -543,6 +543,20 @@ information provided.
 
 <DT><A NAME=d:png HREF=#a:png><STRONG>png</STRONG></A>
 <DD>Produces output in the PNG (Portable Network Graphics) format.
+<P>
+(25 November 2014) A standard Graphviz installation will render using both
+the Cairo and GD library. 
+By <A HREF=command.html#d:T>mixing the rendering and formatting</A> of these
+libraries, one can achieve different variations in the output.
+<DL> 
+  <DT><TT>-Tpng:gd</TT> (or <TT>-Tpng:gd:gd</TT>) 
+    <DD>Indexed color, no antialiasing
+  <DT><TT>-Tpng:cairo:gd</TT>
+    <DD>Indexed color, with antialiasing
+  <DT><TT>-Tpng</TT> (or <TT>-Tpng:cairo</TT>) 
+    <DD>True color, with antialiasing
+</DL> 
+These options are listed in increasing order of image quality and output size.
 
 <DT><A NAME=d:pov HREF=#a:pov><STRONG>pov</STRONG></A>
 <DD>Scene-description language for 3D modelling for the 

diff --git a/doc/infosrc/outputs b/doc/infosrc/outputs
index 1917c89d1f8453ffde878d9ff179578839b32f42..1b55db050cc0c6f24d0085ff2593eae8f6e31da5 100644 (file)
--- a/doc/infosrc/outputs
+++ b/doc/infosrc/outputs
@@ -57,6 +57,20 @@ Scene-description language for 3D modelling for the
 <A HREF="http://www.povray.org/">Persistence of Vision Raytracer</A>.
 :png:Portable Network Graphics format
 Produces output in the PNG (Portable Network Graphics) format.
+<P>
+(25 November 2014) A standard Graphviz installation will render using both
+the Cairo and GD library. 
+By <A HREF=command.html#d:T>mixing the rendering and formatting</A> of these
+libraries, one can achieve different variations in the output.
+<DL> 
+  <DT><TT>-Tpng:gd</TT> (or <TT>-Tpng:gd:gd</TT>) 
+    <DD>Indexed color, no antialiasing
+  <DT><TT>-Tpng:cairo:gd</TT>
+    <DD>Indexed color, with antialiasing
+  <DT><TT>-Tpng</TT> (or <TT>-Tpng:cairo</TT>) 
+    <DD>True color, with antialiasing
+</DL> 
+These options are listed in increasing order of image quality and output size.
 :wbmp:Wireless BitMap format
 Produces output in the Wireless BitMap (WBMP) format, optimized for
 mobile computing.