[comp.sys.mac.programmer] PICT2 - bitmap compression

cc4b+@andrew.cmu.edu (Christopher Brian Cox) (04/20/88)

I need some help:

        I would like to find out exactly what compression scheme Apple is using
in the PICT2 bitmap format.  I assumed that it would be the same PackBits as
the older monochrome PICT.  When I tried using PackBits to compress the bitmap
the machine crashed while reading the bitmap.  Inside Mac V is definately wrong
in it's description of the compression, in addition to other facts about the
PICT2 format.
        Does anyone know what compression scheme they are using?  Could you
please send me some information about it?

        The reason I'm asking is:  I am trying to convert images off of a
larger computer system to PICT2 format.  I want to (almost have to) do all of
the conversion work on the larger system, so I can't use QuickDraw.


Thank you very much,

Chris Cox
cc4b@andrew.cmu.edu

oster@dewey.soe.berkeley.edu (David Phillip Oster) (04/22/88)

Inside Mac V.5 says that color pixmaps, for now, have a packType code of
0, i.e., are un-compressed. Does this not work in PICT2s?

cc4b+@andrew.cmu.edu (Christopher Brian Cox) (04/23/88)

>Inside Mac V.5 says that color pixmaps, for now, have a packType code of
>0, i.e., are un-compressed. Does this not work in PICT2s?

That's what I thought when I first read it.
When I tried using uncompressed data the machine crashed.
The working PICT2 files I looked at were shorter (much) than they should be if
uncompressed.

Chris Cox