Testing guidelines for image filters:

imgtest:  run imgtest on several images (there's a large collection of
images in \\alchemy\gold\graphics).  Test basic functionality including:

decoder:
- decoding into all scalers
- conversion into all in-memory formats (note--you will need to reload the
image after each conversion, or else you will be testing conversion between
in memory formats instead of conversion from your decoder to the in memory
format)
- all the processing filters (as above, make sure this is not done with a
converted image)
- properties (make sure it doesn't crash)
- export:  make sure you can encode into all available formats (testing
communication between your decoder and all the encoder sinks).

encoder:
- encoding from all in memory formats
- encoding directly from all decoders.
- encode into your format, and load the new file using imgtest.exe.  Encode
the new file one more time and reload that file (in case there are some subtle
bugs with your encoding)


thumbtst.exe:  run thumbtst.exe on all the files in \\alchemy\gold of your
format.  Make sure nothing crashes.