Re: JPEG compression in TIFF files. NSTIFFCompressionJPEG
Re: JPEG compression in TIFF files. NSTIFFCompressionJPEG
- Subject: Re: JPEG compression in TIFF files. NSTIFFCompressionJPEG
- From: Heinrich Giesen <email@hidden>
- Date: Thu, 13 Nov 2008 17:36:43 +0100
On 13.11.2008, at 00:34, Alexander Shmelev wrote:
Our customer asks us to save images in TIFF files with JPEG
compression. But in NSImage documentation is written that JPEG
compression is no longer supported. Why Apple decided to stop support
JPEG compression in NSImage class?
The difficulties with JPEG-compression in TIFF-files reach back to
1995. In that year a
draft <http://www.remotesensing.org/libtiff/TIFFTechNote2.html> from
the TIFF-people (formerly Aldus, now Adobe)
was published and give a deep look into these difficulties. One of
the first sentences is:
... TIFF writers are strongly discouraged from using the 6.0 JPEG
design
In another document <http://netghost.narod.ru/gff/graphics/summary/
tiff.htm>
search for a statement by Tom Lane (the jpeg guru) where he explains :
TIFF 6.0 added JPEG to the list of TIFF compression schemes.
Unfortunately, the approach taken in the 6.0 specification is a
very poor design. A new design has been developed by the TIFF
Advisory Committee. If you are considering implementing JPEG in
TIFF, I strongly urge you to follow the revised design described in
TIFF Tech Note #2 rather than that of the 6.0 spec.
Meanwhile some fixes have been made. But we still have TIFF 6.0 and
maybe the long expected
TIFF 7.0 will never come. The Adobe - TIFF story has never been a
love story.
To directly use the current TIFF library tiff-3.8.2 may help if
really needed.
Heinrich
--
Heinrich Giesen
email@hidden
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