Re: [Openexr-devel] JPEG-HDR/JPEG 2000/JPEG-XR on OpenEXR images ready

[Florian Kainz]

Hi Thomas,

Do you have data on the relative speed of the algorithms?
A couple of years ago we experimented JPEG2000 to compress
HALF channels in OpenEXR.  Image quality at acceptable compression
rates was excellent, but encoding and decoding were so slow that
we abandoned the effort.  (If I remember correctly, compression
was about ten times slower than PIZ, which isn't particularly
fast in the first place.)

Florian


Thomas Richter wrote:
> Hi folks,
>
> in case you're interested, I completed the study of floating-point compression 
> algorithms on the OpenEXR image set, comparing the
> compression performance of JPEG-HDR with that of the floating-point JPEG-XR 
> compression and a JPEG 2000 based floating point
> compression format. Anyone interested in a pre-print might simply sent me a 
> note.
>
> Short results for the impatient: In almost all cases, JPEG 2000 performs best 
> here. There is one interesting corner case, namely
> the OpenEXR "StillLife" image where JPEG-HDR outperforms all other compression 
> schemes, which is due to the extreme nature of the
> image - here JPEG-HDR profits from its adaptive tone-mapper. JPEG 2000/JPEG-XR 
> use a fixed mapping from floating point to integer,
> offering the advantage of making lossless compression of floats possible.
>
> So long,
>         Thomas
>
>
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