Arithmetic coding in Fedora libjpeg (bug #639531)

[Tom Lane]

Kevin Fenzi <kevin at scrye.com> writes:
> On Sat, 2 Oct 2010 22:53:53 +0530
> Mukund Sivaraman <muks at banu.com> wrote:
>> Arithmetic coding in Fedora libjpeg (bug #639531)

> My thoughts: 

> - We should not be making this change in stable releases even if
>   otherwise like the idea. It could well cause issues and problems with
>   a fragile library used by a lot of things. 

Don't worry, there's exactly 0 chance of that.

> - In f14+ we are not using libjpeg. We are using libjpeg-turbo. See: 
> http://fedoraproject.org/wiki/Features/libjpeg-turbo

Yes.  So actually the OP is pestering the wrong person; he should be
trying to convice the libjpeg-turbo maintainers to expend work on this.

I believe that they'd be best advised to say "no", because at this point
one of JPEG's principal attractions is near-universal compatibility.
Throwing A/C into the mix will throw that away, for what really is a
very marginal gain in compression efficiency.  If you want a new
not-compatible-with-anything image format, you may as well adopt JPEG
2000, or some other format that's less than 20 years old.  The A/C
option to original JPEG is something that missed its chance because of
patents.  Resurrecting it from the dead now is just an exercise in
misplaced priorities.

But having said that, it's not my decision to make; it's the
libjpeg-turbo authors' decision whether to expend effort in that
direction.

			regards, tom lane