JPEG Compression?
John M McIntosh
johnmci at smalltalkconsulting.com
Mon Sep 10 05:42:52 UTC 2001
> >
> >That sounds strange ... if I'm not mistaken then LIBTIFF uses LIBJPEG
>>directly and thus all you'd need to do is to expose the interface of LIBJPEG
>>to Squeak.
>>
>
>Which means wrapping two APIs instead of one. I.e. the LIBTIFF and LIBJPEG
>APIs need to be wrapped separately. If it were possible to easily tweak
>LIBTIFF to read and write .JPG files, that would be cool, but I don't think
>that's an easy hack.
>
> -Bob
I did look at this earlier this evening. All that is occurring is
that LIBJPEG is linked into LIBTIFF so that you can read or write
TIFF files using JPEG compression, this is because LZW compression
isn't offered by default, so other compression methods have moved
into the TIFF arena. Therefore one just needs to expose the JPEG
public entry points via some glue code. Or as I and pointed out in
another note to Juan one could use the Squeak ioLoadFunctionFrom
logic and make calls to a JPEG plugin versus linking that code into
the LIBTIFF plugin.
ps I should point out zlib 1.1.3 a general purpose compression
library is also linked into the TIFF stuff, but not exposed either.
--
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John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com
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