In rec.photo.digital wrote:
Are some graphics programs better than others for compressing JPEG?

GIMP is probably the best because it gives you all the control you need
with a relatively simple user interface.

A friend swears that Image Ready is the best for getting the
smallest file with same quality.

I doubt anything from Adobe would be good at JPEG.
Supporting NIH public standards is not their forte.
Photoshop is particularly poor at JPEG rewriting,
because it lacks flexibility.

But I see a few companies have made utilities purely for
compressing pictures, and claim they obtain better
compression than the top tier graphics programs.

Using 4:2:2 chroma subsampling saves a lot of space
without reducing quality.

I presume there are different numerical routines used by
different companies in their software, but I would guess
maybe 5% variation in file size at best.

Much of the variation comes from preview, header comments, EXIF, etc.

I know there was a comparison done several years ago,
but the website with the pictures seems to be kaput.
(www.imagecompress.com ?)

There is a good article about JPEG on the photo.net site:
http://photo.net/learn/jpeg/

Is there a recent comparison of different programs to see
who offers the best compression? That is, best quality
for same size, or smallest size for same quality.

Nowadays the discussion is about old JPEG versus JPEG 2000.