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From: jmunkki@kampi.hut.fi (Juri Munkki)
Newsgroups: comp.sys.next,comp.graphics
Subject: Re: NeXT's Tiff format
Message-ID: <18693@santra.UUCP>
Date: 7 Jan 89 11:44:13 GMT
References: <18758@agate.BERKELEY.EDU>
Sender: news@santra.UUCP
Reply-To: jmunkki@kampi.UUCP (Juri Munkki)
Organization: Helsinki University of Technology, Finland
Lines: 53

In article <18758@agate.BERKELEY.EDU> edmoy@violet.berkeley.edu writes:
>Here is some more info on the NeXT TIFF question.  To recap, the TIFF files
>used in the Webster's dictionary could not be read into MacVision or Canvas
>on the Macintosh (both these programs support TIFF, MacVision even creates
>TIFF files, that Canvas can read).
...
>If TIFF is a standard, why isn't it standard :-)

The TIFF standard is quite large. TIFF comes from the words Tag Image File
Format. These tags are some kind of opcodes that a program should read and
write. Some common problems when opening TIFF files:

  a)  Byte ordering.
	The first two bytes of a TIFF file specify the byte ordering.
	II is intel style, MM is for Motorola. Apple and NeXT use
	Motorola processors: the files should begin with "MM".

  b)  Bitmap depth.
	A TIFF file is usually 8-bit or single-bit on the Macintosh.
	Some programs also support 4-bit files, but simple paint/draw
	programs usually support only single-bit images. The version
	of canvas that we have seems to support only 1-bit images.
	ImageStudio reads at least 1-bit and 8-bit, but writes only
	8-bit TIFF. Since NeXT machines have a 2-bit deep display,
	they might use 2-bit deep TIFF, although I doubt it, since
	they are using the grayscales for the user interface.

  c)  Packing
	The TIFF standard recognizes several different packing methods.
	Most scanner programs create unpacked files and most programs
	seem to be able to read these. Macintosh programmers are most
	familiar with PackBits...unfortunately it is only one of many
	possible formats.

The best way to verify that a file is really TIFF, seems to be to
include it into a Pagemaker document. Since Aldus and Microsoft are
the strongest supporters of the standard, their implementations for
reading these files should be pretty complete.

The problem with NeXT TIFF is probably packing. They might be using
a very advanced packing algorithm to save disp space.

Disclaimer: I read the TIFF standard documentation about a year ago.
	    I might not have all my facts straight, since I didn't
	    bother to dig up the document.

TIFF standard specifications have been posted to comp.graphics and
some mac group less than six months ago.

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|     Juri Munkki jmunkki@hut.fi  jmunkki@fingate.bitnet        I Want   Ne   |
|     Helsinki University of Technology Computing Centre        My Own   XT   |
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