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Date: Fri, 3 Apr 98 09:42 PST
From: mccoy@pixar.com (Daniel McCoy)
To: Brent Foster <B.R.Foster@massey.ac.nz>
Subject: Re:  Multilayered TIFFs
Cc: tiff@sgi.com
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>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   mccoy@pixar.com

