Peter Dalgaard wrote:
d) Use bitmap(). It requires a working Ghostscript install, but is
otherwise much more convenient. Newer versions of Ghostscript have
some quite decent antialiasing built into some of the png devices.
Currently you need a small hack to pass the extra options to
Ghostscript -- we should probably add a gsOptions argument in due
course. This works for me on FC3 (Ghostscript 7.07):
mybitmap(file="foo.png", type="png16m", gsOptions=" -dTextAlphaBits=4
-dGraphicsAlphaBits=4 ")
where mybitmap() is a modified bitmap() that just sticks the options
into the command line. There are definitely better ways...
[The antialiasing is not quite perfect. In particular, the axes stand
out from the box around plots, presumably because an additive model is
used (so that if you draw a line on top of itself, the result becomes
darker). Also, text gets a little muddy at the default 9pt @ 72dpi, so
you probably want to increase the pointsize or the resolution.]
Apart from the significant quality issues which you mention, the other
problem with using bitmap() in a Web server environment is the speed
issue - it takes much longer to produce the output. Whether it takes too
long depends on the users of your Web application, and how many
simultaneous users there are. However, most users are more worried by
the poor quality of the fonts in output produced by bitmap().
Tim C
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