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Old November 26th 07, 07:11 PM posted to rec.photo.digital
John Navas[_2_]
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Posts: 3,956
Default NEWS: HD Photo to become JPEG XR

Why JPEG XR is badly needed:

The problem is 8-bit (per channel) JPEG. Although non-linearity gives it
roughly 11 stop dynamic range, 8-bit luminosity resolution is more
limited than many camera sensors (often 10-12 bits). While 8-bit JPEG is
fine for scenes with lower luminosity range, more bits are needed for
best results with higher luminosity range. This is a major, if not the
major, reason to shoot RAW.

* An alternative would be 12-bit JPEG, but there's too little support
for that to be practical.

* Another alternative is JPEG 2000, which also has a useful lossless
mode, but it's still not widely supported, has EXIF issues, has
potential patent issues, and puts a higher computational burden on the
camera processor than JPEG.

* Yet another alternative would be Adobe DNG as an alternative to
proprietary camera RAW, but major camera manufacturers seem resultant to
adopt it.

* Lastly there's Microsoft's JPEG XR (HD Photo), which is more like JPEG
than JPEG 2000 in terms of computational burden with compression
efficiency comparable to JPEG 2000, but is not yet standardized.

Until this is sorted out, RAW remains an important tool for scenes with
higher luminosity range, despite its drawbacks. I personally don't use
RAW often, but I do sometimes use it.

--
Best regards,
John Navas
Panasonic DMC-FZ8 (and several others)