Color differences between jit.qt.grab & jit.dx.grab?


    Mar 16 2010 | 10:41 pm
    Hi everyone, I was testing my handycam last night using jit.qt.grab and jit.dx.grab separately on two computers (qtgrab on a PowerMac and dxgrab on a PC). I was using a RCA splitter cable to transmit the video signal from my camcorder to two DFG boxes, and then feed them to jit.qt.grab and jit.dx.grab.
    The problem is, when I was comparing two videos displayed on pwindow, the color from jit.qt.grab is always looks "warmer" than jit.dx.grab, I double checked the "setting" message in both patches, and make sure the brightness, saturation, sharpness... all parameter are set to 50%, but still couldn't get same color quality...!
    Is this caused by the difference in jit.qt.grab and jit.dx.grab? Is there a way to synchronize their color display?

    • Mar 16 2010 | 11:15 pm
      Probably related to gamma correction, and/or YUV -> RGB conversion differences. Here's an example which crossfades between original and a squared version to get gamma correction style results for cheap. Alternately, you can fill a lookup table with an appropriate exponential curve and use jit.charmap for fast color adjustment.
    • Mar 25 2010 | 12:59 pm
      Hi
      I recently pointed out a difference between jit.qt.grab and jit.dx.grab: http://cycling74.com/forums/topic.php?id=24690
      nobody has confirmed this phenomenon (but I am pretty sure), but maybe it is related?
    • Mar 25 2010 | 3:05 pm
      Totally unrelated issue. As mentioned on that thread, you should just avoid jit.qt.movie on windows, unless your application requires it.