1998.04.03 17:42 "Re: Multilayered TIFFs", by Daniel McCoy
I need to write multilayed TIFFs, with minimal problems opening the TIFFs with other viewers.
The TIFFs consist of a black and white main image, with one or more coloured images overlaid - each colour image is stored as a black and white image with the colour stored elsewhere. The images being dealt with are basically black and white with a bit of marker pen - compressing this way and using G4 on each image gets huge compression.
How would other people suggest I do what I'm trying to do?
If you have seven or less 1-bit overlays, it would easily fit into an 8-bit palette-mapped image and then you would have a relatively easy time loading the image into any existing viewer. Since it's so simple to do, I suggest you at least try it and see how your compression looks with LZW or ZIP compression with horizontal differencing turned on (Predictor=2) before you set off creating a nest of new tags and tag values.
It's a lot smoother and the going's easier over here in the middle of the road.
Dan McCoy Pixar firstname.lastname@example.org