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

xma2's icon

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?

Joshua Kit Clayton's icon
Max Patch
Copy patch and select New From Clipboard in Max.

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.

maybites's icon

Hi

I recently pointed out a difference between jit.qt.grab and jit.dx.grab: https://cycling74.com/forums/jit-qt-grab-is-capturing-with-lower-resolution-than-jit-dx-grab

nobody has confirmed this phenomenon (but I am pretty sure), but maybe it is related?

Joshua Kit Clayton's icon

Totally unrelated issue. As mentioned on that thread, you should just avoid jit.qt.movie on windows, unless your application requires it.