Keying a bad image is challenging... After applying keylight in After effects and the footage is keyed I got the bad compression effects, you know, when you play the footage different blocks and noise appear and disappear frequently.
The image didn't look like that before keying though.
Do you know what causes that effect?
Also does it have a solution?
The blockiness is in your original footage. You just can't see it. Here's why: it's compressed to keep the file sizes tiny, but the compression is designed to be invisible to the human eye. Problem is, it's not invisible to the computer. If something is compressed, the more processing done to it, the more obvious the compression becomes. Check out this post by Dave LaRonde explains it well. This post covers getting a better keylight key. Here's a tutorial that should help too.
Also look for a tutorial on super-tight junk mattes.
- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')
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