Re: TIFFRepresentationUsingCompression not working as it should
Re: TIFFRepresentationUsingCompression not working as it should
- Subject: Re: TIFFRepresentationUsingCompression not working as it should
- From: Marcel Weiher <email@hidden>
- Date: Thu, 4 Jul 2002 19:21:50 +0200
On Thursday, July 4, 2002, at 06:46 Uhr, Ben Mackin wrote:
Well, since no one seems to have any idea on this one, maybe it is a
bug?
Not really. The problem is that the 1 bit-ness is not just a a quality
of the output, but also a requirement for the input. So you have to
convert your bitmap to 1 bit black/white beforehand.
on 7/2/02 10:57 AM, Ben Mackin at email@hidden wrote:
I am working on a objective-c program, and I came across the following
routine:
- (NSData *)TIFFRepresentationUsingCompression:(NSTIFFCompression)comp
factor:(float)aFloat;
Which is just what I needed. So I wrote my code, and used this along
with the
NSTIFFCompression code of NSTIFFCompressionCCITTFAX3, and I outputed
my NSData
to disk. But I got a full color tiff file (definitely not what I
should have).
If you look at the description for NSTIFFCompressionCCITTFAX3 you see:
NSTIFFCompressionCCITTFAX3
CCITT Fax Group 3 compression. It's for one-bit fax images sent over
telephone
lines.
From my understanding of that, and of tiff-f files, I should have
gotten a
1-bit, black and white image. What went wrong? Did I read into this
too much,
or am I not saving it with CCITT Fax Group 3 compression as it should
be?
I need someone that knows something to shed some light. I know this
should
work, as it is documented to work.
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--
Marcel Weiher Metaobject Software Technologies
email@hidden www.metaobject.com
Metaprogramming for the Graphic Arts. HOM, IDEAs, MetaAd etc.
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