Further investigations, creating TIFF files with several different
programs, reveals the following pattern of POV compatibility:-

Compression     1-bit       4-bit          8-bit     24-bit
   
FAX CCITT 3     Inverted    -              -         -
FAX CCITT 4[1]  Inverted    -              -         -
Huffman         Inverted    -              -         -
LZW             Bad         Bad            Bad       Bad
LZW+Hz Predict  Bad         Bad            Bad       Bad
PackBits        Inverted    Bad colour     Good      Inverted
ZIP[1]          Inverted    Bad colour     Good      Inverted
JPEG[2]         -           -              -         *Crash*
None            Inverted    Bad colour[2]  Good      Inverted

Notes:

[1] Irfanview is the only program I have that outputs CCITT4, ZIP or
JPEG compression.

[2] The 4-bit uncompressed image from MGI Photosuite caused POV to
crash. Those from other programs just caused incorrect colours.

Overall:-

LZW compression doesn't work at all.

JPEG compression causes a crash.

4-bit images have their palettes decoded incorrectly.

1-bit and 24-bit images are upside down.

Images are not checked for compatibility, POV just goes ahead and tries
to decode them anyway.

The image data does not appear to be being checked to see if what POV
considers to be a pointer (but may not be when POV is trying to decode
stuff it doesn't understand) points off the end of the image data.

The only TIFF images that are fully supported (have 8-bit colour) and
(are compressed with Packbits or ZIP or are uncompressed).

-- 
Mike Williams
Gentleman of Leisure

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