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Path: utzoo!mnetor!seismo!rutgers!cbmvax!carolyn
From: carolyn@cbmvax.cbm.UUCP (Carolyn Scheppner)
Newsgroups: comp.sys.amiga
Subject: Re: IFF/ILBM HAM encoded images.
Message-ID: <1272@cbmvax.cbmvax.cbm.UUCP>
Date: Wed, 21-Jan-87 19:32:41 EST
Article-I.D.: cbmvax.1272
Posted: Wed Jan 21 19:32:41 1987
Date-Received: Thu, 22-Jan-87 02:14:30 EST
References: <7640@decwrl.DEC.COM> <1333@cadovax.UUCP>
Reply-To: carolyn@cbmvax.UUCP (Carolyn Scheppner)
Organization: Commodore Technology, West Chester, PA
Lines: 42

In article <1333@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes:

  (RE: grabbing HAM images)
>Unfortunately, I renamed the program to 'saveiff' from whatever the original
>name was.  I'm not sure where the program came from, though I have the
>source.  You type 'saveiff filename' and then it will output a message
>something like 'save highest screen in 5 seconds? (y/n)'...

   That sounds like my my first screen-saver program.  I forget
what I called it.  It was written using the original IFF code
before the ILBM "CAMG" chunk existed.  So it does NOT save a
CAMG chunk!  And ALL HAM ILBM's should have a CAMG chunk ! 
Note that "CAMG" is an Amiga ViewModes chunk which contains the
flags for HIRES,LACE,HAM, etc.  

   In other words, DO NOT use my old screen-saver to save HAM images.

   We used "Grabbit" (Discovery Software) to save Display'd Wecker pics.
This is a hotkey screen save/dump program which DOES save a CAMG chunk.


 (RE: using planecount of 6 as flag that file is HAM)
>                ...If anyone knows what a more CORRECT way
>of testing the incoming IFF file for HAM mode, let me know.
> 

   Read the IFF ILBM docs description of the CAMG (Amiga ViewModes)
chunk.  If this chunk is found in a file, its contents (a ULONG)
should be used for your screen or viewport/view ViewModes.
If NO CAMG chunk is found, then you must use the BitMapHeader
page width and height to decide if your ViewModes need HIRES
or LACE flag, and I guess you would have to assume HAM for 6 planes.
But every proper HAM ILBM should have a CAMG chunk.  Yours didn't
because you used my old pre-CAMG screen-saver to create the file.

carolyn
-- 
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Carolyn Scheppner -- CBM   >>Amiga Technical Support<<
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