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REHov520
11-18-2009, 03:02 PM
Hey,

when i bring footage shot on the 7D into after effects and look at the histogram there a big gaps in it. I remember reading about this in the dv rebels guide, and that it's a problem with 16 bit vs. 8 bit processing however if i change the AE project to 16 bit, the gaps are still there.

can someone explain to me why those gaps are there and how i can get rid of them? thanks!

PDR
11-18-2009, 03:30 PM
can someone explain to me why those gaps are there and how i can get rid of them? thanks!


Windows?

The gaps are there because of 8-bit video. The number of "shades" of each R,B,G channel are expressed by 2^8 = 256 values. Even minor changes will cause quantization or banding. You can see this by playing with the levels filter, and applying a 2nd levels instance and watching the results. By using a 16bpc project, the number of intermediate "shades" are now 2^16=65536. Note these are interpolated values from an 8-bit source - worse than if your original source was 10-bits - but it still will be better than staying in 8bpc mode, especially for intermediate calculations and color correction.

AE (at least on windows) "doesn't like" the .mov container. If you re-wrap your video asset into an .mp4 container, you will see it will function normally (smooth out the quantization "bumps") in 16bpc mode by doing the 2 levels filter exercise I described above. You could use mp4box (yamb is a gui for it) to rewrap, for example. I don't know if this behaviour occurs on MAC

Niebs
11-20-2009, 02:03 AM
Why did you quit the game, RE?