Tags: patch

Hi,

While trying to speed up "emacs as an image viewer", I found that emacs
is using libjpeg with color quantization and it seems that removing this
quantization could speed up JPEG loading a bit.

My simple limited benchmark:

          - M-: (clear-image-cache)
          - Open an image in folder with some large enough pictures in
            it (4000x3000 here)
          - M-: (benchmark-run 10 (image-next-file 1))

Here are the results I get:

without this path: (5.415405491 1 0.09232176400000025)
with: (3.079911418 1 0.0751190459999993)

I don't think that this patch could be applied as is (it is rather
ugly).  And I also think that I probably have missed some (many?) use
case (where color quantization is mandatory).  But I'm submitting this
patch anyway as a conversation starter on the subject.

Thanks,

In GNU Emacs 31.0.50 (build 9, x86_64-unknown-openbsd7.6, X toolkit) of
 2024-11-22 built on computer
Repository revision: c66c0942ea9ac10e6d6324e472150de403a03b69
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101014
System Description: OpenBSD computer 7.6 GENERIC.MP#437 amd64

Configured using:
 'configure CC=egcc CPPFLAGS=-I/usr/local/include
 LDFLAGS=-L/usr/local/lib MAKEINFO=gmakeinfo --prefix=/home/manuel/emacs
 --bindir=/home/manuel/bin --with-x-toolkit=lucid
 --with-toolkit-scroll-bars=no --without-cairo
 --without-compress-install'