Is this aliasing? And what's with the blacks?

L

Lkorver

Well-known member
CC'd: www.vimeo.com/7158704
Raw: www.vimeo.com/7154996
password: bob

This is my first try with the 7d. Used the out of the box camera settings. The blacks are super crushed. I noticed this even with footage in direct sunlight? Is this a camera setting or exposure issue? Also, haven't read too much on aliasing, is the weird warping pattern on the girls leg in the second shot aliasing or jello or neither?

Lens: 17-55 2.8 IS
ISO: 640
Aperture: 2.8 (for most of it)
Shutter: 1/50th
 
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Looks like screen tearing. Perhaps your flash card isn't fast enough and doesn't have enough buffer.
 
Make sure you have the latest version of quicktime and that the contrast on your neutral setting is all the way down. Then your blacks won't crush. Prores the footage and lift the blacks a bit too.
 
thanks for helping out guys. The camera is in STANDARD setting (3,0,0,0) maybe that was the issue. Still curious on the leg thing though. The warping on the leg does match the pattern of the blinds in the background perfectly. is that a clue?
 
Lkorver said:
horizontal warping on legs matching the blinds pattern in the background.
TC: 00:10 to 00:12
Click to expand...

I wonder if that happens no matter what device you use. The human eye even does that if you have line running in front of a bright background...a phenomenon between sharp and blurred, bright objects.
 
Oh, yeah, that's ... hmm. Well, my first guess is that would be a complication of trying to convert frame rates. Did you try to convert 30p to 24p or anything like that?
 
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Barry_Green said:
Oh, yeah, that's ... hmm. Well, my first guess is that would be a complication of trying to convert frame rates. Did you try to convert 30p to 24p or anything like that?
Click to expand...

It was shot and edited in 24p, there are two 60p shots (water pouring and CU of toothbrushing)

www.lukaskorver.com/client_transfer/bob_scew.zip

I'm uploading the Sequence settings, clip properties, and a full frame still of the issue (link above)

I should also note that the footage was converted to proress using compressor (progressive, normal quality). Many parts of the footage, including the clip in question would not play back in the fcp timeline without "skipping" Even when exported to full rez quicktime H264 the movie would skip during playback in QT. Edited on MacBook Pro 2.4 dual core duo, 4gb Ram. OS 10.4.11
 
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My guess is that it's an artifact of the limited dynamic range of the camera. Consider this:
1) It's happening at the border between a really dark part of the image and a really bright part of the image.
2) That part of the shot is slightly out of focus.

So the highlights are being blown-out and the blacks are being crushed in a slightly out-of-focus area. The camera doesn't know how to resolve a proper gradient (due to the limited dynamic range) and instead renders a smearing effect. It's something that I've seen occasionally in video footage (from other camcorders) in the past. I don't recall ever seeing it in film (i.e. celluloid) footage, though. (But film generally has far more dynamic range than video cameras.)
 
It's also very likely to be the blooming and smearing side effects of using an electronic shutter instead of a mechanical shutter. I'll bet that if you redid the shot with burst stills, the artifact would not be there.
 
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