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Gamma Levels
Here is the problem: I digitize D5 videotape footage into FCP, then export it as .tiff or .tga files. Then those files are imported to our Flame system and the files look darker than the ones we digitize directly into the Flame. We would like to use our FCP system to digitize, lay off to tape, and exchange files with our Flame but we can’t do that because of this shift.
I have FCP 6.0.2, and am using a Kona 2 card set to digitize at 8 bit uncompressed.Any help would be greatly appreciated!
-Gregory
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5 Replies
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Tried 10 bit?
Are the Scopes in the two machines showing you that this is really happening, or is this an ‘eye ball’ thing… i.e. I know that the gamma differences between platforms might be at work here. i.e. Mac vs the Flame’s CPU… It’s a PC right? All Mac files will look darker on a PC I know. BUt they really aren’t any different on the scopes.
Jerry
Apple Certified Trainer
Author: “Jerry Hofmann on Final Cut Pro 4” Click here
Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D
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Jerry – your reply has intrigued me….Its not a problem i have as all my work is done in the mac and never touchs a pc, but how can mac files that appear darker on a pc show no change on the scopes?
Can you explain it in a bit more detail, please?adam
Editor/Mixer
Character Options Ltd
Oldham, UK -
It’s the gamma differences between what a PC’s display system uses and the one that a Mac uses… Mac images on a PC will look darker than they did on a Mac, however the scopes should show if there REALLY is a difference… This is the real reason one should be paying attention to scopes, and external video monitors for color judgements rather than a computer display. They just don’t sing the same tunes from Mac to PC or vice versa…
This is why H.264 is such a great way to compress for the web… it senses whether a PC is accessing it or a Mac, and makes the gamma changes necessary automatically for the platform accessing the file.
Jerry
Apple Certified Trainer
Author: “Jerry Hofmann on Final Cut Pro 4” Click here
Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D
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Hi Gregory
This sounds like a colourspace issue. FCP works with RGB levels in the range 0-255, whereas some systems use 16-235. Try applying a levels adjustment in Flame to bring the incoming file into the 16-235 range and see if it matches the digitised footage.
You may also need a gamma adjustment to go from 1.8 to 2.2 gamma. Try an adjustment of 1.2 (or 0.8 if 1.2 makes it darker!)
HTH
K
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Adam, the gamma curve used on the computer displays on Macs is different from the one used on PCs. I think it’s 2.2 on the Mac & 1.8 on the PC, but don’t quote me.
Gregory, does the Flame work in RGB or YUV color space? If it’s RGB, that could be at the root of the shift that you see.
Arnie
Now in post: Peristroika, a film by Slava Tsukerman
https://www.arniepix.com/blog
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