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Line Mode / Photo Finish mode

  • udicom

    Hi !

    I've got a 333 Elphel Cam and am especially interested in the line mode aka photo finish mode. There are some impressive pictures reachable by the wiki, but I have problems doing this with my cam. I can reduce the picture height to 32 lines, everything below seems to not be allowed for the jpeg compressor. I can lower it to 4 and read the image myself from the cmos. But setting it to anything lower than 4 doesn't work. :(
    With a setting of 4 I get a "framerate" of 812 fps, that's 812*4 lines per seconds, but using both pairs of of lines in line mode is problematic. This is way beyond the theoretical value 20000 lines per seconds according to the doc from the chip manufacturer. Any hints/ideas/suggestions?

    Best regards

    • Hi Bernhard,

      you need to program camera into "photofinish mode" by specifying the height of each "frame" (i.e. pfh=2 will make 2 lines - total of 6 including minimal of 4 blanking). You may set wh=1536 - then 768 line pairs will be assembled into 2048x1536 frame (no problems with multiple of 16 lines fro JPEG). There should be no gap between composite frames.

      http://wiki.elphel.com/index.php?title=Ccam.cgi :

      "* pfh - photofinish mode strip height (0 - normal mode, not photofinish). In this mode each frame will consist of multiple
              pfh-high horizontal (camera should be oriented 90 deg. to make vertical) strips, and no extra lines will be added to the frames
              for demosaic"