[Elphel-support] JP4-HDR

[Andrey Filippov]

Andreas,

When I was developing the FPGA encoder for different JP4 flavors I
used modified libjpeg - it had a lot of debug output that I needed to
troubleshoot encoder. The state of my modification was not really
usable for anything but encoder development, I believe Paulo has now
more usable code.

On the other hand, Jp4-hdr advantage over jp4/ (and even jp46) is just
better compression (smaller file size for the same quality), the most
challenge of decoding it is not the decoding of the format (you may
start with JP46 and ImageJ plugin), but de-mosaic algorithm combined
with processing of 2 different greens. And it has to be done in a
single step - you need a modified de-mosaic algorithm that is aware of
those gains. When that part will work - you can get back to the format
and get some extra compression ratio.

Andrey