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keylight and poor picture quality
I’m attempting to do a fairly simple key, and having many problems. I filmed using a Sony Z1U (DV) at our school’s green screen studio. I brought the footage into AE CS2 and using Keylight, I removed the green. No problems. I played with the Clip White, Clip Black and Shrink. The key looks great! I load in my background picture – a very nice high resolution image. Everything looks good. I play it in AE and it is very nice.
Then the problem: Export. I export the file as an AVI, trying both the cinepax and uncompressed formats. Either way there is the same result: I watch the output and there is a lot of distortion. The top layer (video) is very rough around the edges, and seems to have horizontal lines going through it. I’m going crazy. I don’t know why it looks great in AE at 100%, but looks horrible when exporting!
Frustratedly yours,
Drew -
5 Replies
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This sounds like an interlacing issue rather than a keylight issue. Search for interlacing and deinterlacing.
Simon Bonner
youtube.com/simonsaysFX -
I may add…it seems like it could be an interlace issue on both ends (import of original clip, and rendered improperly and seen on a computer monitor)…Also, cinepak is not a good codec to use….
Finally, DV is brutal for green screen work….you may be seeing artifacting around the edges. DV compresses majorly the chroma, which is the very information you need to pull a good key…avoid it like the plague for keying.
Regards
Mark
Mark Harvey
Senior Editor
Le Réseau des sports -
Okay, I’ve done some reading on interlacing and deinterlacing and consequently made some changes… for the better.
I kept my original key that looked good, but instead of doing Export – AVI, I did Make Movie, and then chose to render the lower fields first and at NTSC DV 48khz. That made a definite improvement. However, I’m still left with a lot of “flashing dots”… I’m not sure if this has to do with aliasing or interlacing, or something else altogether. I tried the reduce interlace flicker effect, but that simply blurs the foreground image (the keyed video).
Any thoughts?
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If the dots are in the subject (not the edges), there is a replace method in the key effect….choose original source as replacement method (I believe by default it is set to solid colour)…
Mark
Mark Harvey
Senior Editor
Le Réseau des sports -
Wow, a very big thank you to everyone for your help. My product was just finished and it looks just as I hoped. I couldn’t have done it without your help and the assistance of some of the AE podcast tutorials.
Simply Thrilled,
Drew
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