http://www.math.tu-berlin.de/~thor/img/

this time including ITU-T Rec. T.851.

In case you don't want to go thru all the graphs, here a short
conclusion:

The Q15 in ITU-T T.851 behaives almost like the QM coder in JPEG-1
and the improvement over baseline JPEG-1 in PSNR is mostly around 5% to
10%.

However, I've found some images where ITU-T T.851 actually performs
worse than JPEG-1, especially in the high-rate regime. (E.g., see the
statistics of the bike3 image). Whether that's a bug in the current
implementation or the consequence of the bitstuffing or the lack of
the MSB/LSB interchange in Q15 is currently unknown.

In none of the images, ITU-T T.851 outperformed JPEG2000, and it almost
never came close to it. It is closer to JPEG-1 than to JPEG2000. Some of
the problems detected in JPEG-1 also hold for T.851, unfortunately,
which is of course not a suprise.

The PSNR gap between ITU-T T.851 and JPEG2000 opens for larger rates,
which came as a surprise for me. Especially, T.851 as JPEG-1 do not
always follow the hi-bitrate approximation for higher rates, thus
there`s definitely a problem somewhere, likely in the quantizer
settings. Likely the lack of any suitable R/D optimization within the
code, and can likely be fixed by computing the quantizer settings
smarter than the current simple scaling.

So long,
        Thomas