Bug 691475

Summary: jpeg 8b related changes
Product: Ghostscript Reporter: Hin-Tak Leung <htl10>
Component: ImagesAssignee: Chris Liddell (chrisl) <chris.liddell>
Status: RESOLVED FIXED    
Severity: enhancement CC: christinedelight.top85
Priority: P4    
Version: master   
Hardware: Other   
OS: All   
Customer: Word Size: ---
Attachments: jpeg 8b related base/jpeg.mak change

Description Hin-Tak Leung 2010-07-18 23:37:10 UTC
Created attachment 6504 [details]
jpeg 8b related base/jpeg.mak change 

Just trying to see what changes between jpeg 6b and jpeg 8b.

The attached patch updated the base/jpeg.mak - in jpeg 8b jdphuff.c no longer exists, but its function seems to be served by jdarith.c (and jcarith.c encoder part is added).

As for the jpeg/ directory - jdmarker.c contains some bug fixes from Raph Levien which were never sent upstream; and need to revert r11471 which updated config.guess/config.sub to an intermediate version, before the jpeg6b->jpeg8b is applied.

Apparently there are some incompatibility (enhancement...) between 8b and 6b, and jpegs written by 8b involving the new SmoothScale functionality may not be readable by 6b, so this change probably should be regarded as something for the long term.

e.g. when Linux distros start to ship jpeg 8b (some are shipping jpeg 7), one might want to follow. Also the jdmarker.c change from Raph probably needs to go upstream.
Comment 1 Hin-Tak Leung 2010-08-12 14:54:24 UTC
FYI, the upcoming fedora 14 is switching to libjpeg-turbo:
http://fedoraproject.org/wiki/Features/libjpeg-turbo
there might be some significant performance reason to go in that direction (instead of just a "routine" upgrade to a larger official version number).
Comment 2 Hin-Tak Leung 2011-07-29 09:15:05 UTC
closing in light of the follow commit.

commit f3b1a56bb0c5d716868b7914bee6c3740f3f035a
Author: Chris Liddell <chris.liddell@artifex.com>
Date:   Sun Jun 26 11:20:33 2011 +0100

    Update to libjpeg 8c.

BTW, both redhat and ubuntu (and google chrom) has started shipping libjpeg-turbo, which is a mildly incompatible fork on 6b.