JPEG-HDR - Was: Re: [HDR-photo] Test...

[Geraldine Joffre]

On Fri, 1 Dec 2006 01:12:50 -0500, listmail wrote
> here is a link to a JPEG-
>  HDR (!) of a 360x180 panorama I shot and stitched for some 3D 
>  lighting and reflections. (Yes, it is a JPEG you can view like any  
> other, but download it and open it in Photosphere to see the full 32-
>  bit HDR range):
> 
> http://www.mab3d.com/temp/skylightentry.jpg

Interesting, let me see whether I understand it correctly. This
"skylightentry.jpg" file is in fact a 32-bit HDR image that has been
compressed with the JPEG-HDR format and saved with the jpg extension. Then
applications that support JPEG but not JPEG-HDR will open it as a normal JPEG
image of the tone mapped version of the original HDR. And applications that do
support JPEG-HDR will be able to decompress it into 32-bit HDR. Is this correct?

I opened this image in Photosphere where I saved it into Radiance (.hdr) image
and ended up with a 3.3 MB file compared to the 316 KB in the compressed form.
So, the compression is really efficient it seems. The drawback is that it is a
lossy compression though. Have you noticed a visible loss in quality due to
the compression?

Geraldine