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Object Graphics slow??

In recent discussion about object graphics vs direct graphics it has been
generally accepted that the object graphics system is slower. In an idle
moment (ha!) I was inspired to run a couple of quick tests to see just how
much slower. Here are the results:

* Plot a line graph with 1000000 (that's 1 million) points:

Object graphics (create and draw an IDLgrplot object): 1.45 s
Direct graphics (call 'plot'): 2.90 s

* Draw 100 byte arrays, each [256, 256], in succession as gray-scale images:

Object graphics (create, draw and destroy 100 IDLgrImage objects): 2.9 s
Direct graphics (call 'tv' 100 times): 6.2 s

These examples (and I accept that they're limited) don't bear out the
general opinion.

Tests done on Windows NT, IDL 5.3, Compaq machine with Pentium II 400 MHz
CPU, 256 MB RAM.

Mark Hadfield
m.hadfield@niwa.cri.nz  http://katipo.niwa.cri.nz/~hadfield/
National Institute for Water and Atmospheric Research
PO Box 14-901, Wellington, New Zealand