I've been noticing artifacts in high detailed ares such as sand on a beach in time lapses that start as Jpeg sequences. Using CS6 and I'm on Win 7. You can only see the issues when the video is played back and not in the individual frames.
Rendering to DNxHD avid codecs. I have noticed the artifacts when doing ram preview so I don't think it is the avid codec. Any help would be appreciated. TL shots are for Survivor. We have only seen this issue the last 2 season, before that there wasn't an issue.
It's probably a moire pattern. I would batch process your image sequence in Lightroom and reduce the detail or clarity a bit and resize them so they're close to the final comp size.
If that doesn't help I think there's a moire reducing plug-in from digital anarchy.