Andreas, The JP4* formats are illustrated on http://community.elphel.com/jp4/jp4demo.php . All of them are targeted to efficiently compress raw Bayer mosaic data, jp4-hdr does it somewhat better than jus jp46. But for the de-mosaic algorithm development there is no difference, this is why I suggested to start with jp46+ImageJ that is possible to decode with unmodified JPEG library. That plugin reads (and un-applies) the analog gain settings together with non-linear gamma conversion with the data provided in the image metadata. So you just need to adjust the 2 green gains to different values - the easiest would be to disable automatic white balance and specify all 4 different gains manually.
Andrey On Fri, May 28, 2010 at 10:49 PM, Andreas Bean <[email protected]> wrote: > Hello Andrey, > > I'm interested in the example shown at > http://wiki.elphel.com/index.php?title=JP4_HDR > The author is Kimstik. > > I really want to work on the de-mosaic algorithm processing two > different greens. > Are you saying that the two greens are stored in jp4 too and not only in > jp4-hdr? > > Anyway, can you give me your debug version? Because currently I can't > open the > jp4 files and thats a problem for me because I can't even start > developing a > de-mosaic algorithm. > > Andreas > > > > Andrey Filippov schrieb: >> 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 >> > > _______________________________________________ Support-list mailing list [email protected] http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
