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Crawly artifacts in footage fixes?

Mar 27, 2013 3:08 PM

I have some older footage shot on tape in SD on a green screen. I'm not sure of the process of how the vendor got it from tape to digital, but they told me it was the highest quality footage they had. When I pull it into Ae, it's got alot of crawly artifacts on his suit and hair, as seen here: crawly-darks-2.png

Actually the compression that adobe put on the image you can hardly see them in this image, but believe me they are there. What can you do with that? I've tried curves, to crush the blacks a little, and that helps, but is there a better solution?

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    Mar 28, 2013 7:12 AM   in reply to bradmagnus

    I can't see the artifacts, so I can only guess.


    A little bit of Bilateral Blur can be good for smoothing out artifacts while keeping detail.

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    Mar 27, 2013 3:27 PM   in reply to bradmagnus

    I hope Todd's suggestion works for you.


    But I have to tell you: that green background is extremely washed-out.  Not very good for a color key, for shich you need COLOR.  However, you might have success with AE's Rotobrush tool instead of a chorma key.  If you haven't used it before, you need to look at the Rotobrush tutorials, which you'll find by going to AE's online Hep and entering the search term rotobrush.

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    Mar 28, 2013 12:04 AM   in reply to bradmagnus

    If you mean scanlines/ interlacing, then there's a million ways to remove them, most easily done with RevisionFX FieldsKit. But as Dave already said, this won't be keyable easily, if at all. You'll spend a lot of time rotoscoping manually. Good luck!



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    Mar 28, 2013 9:38 AM   in reply to Mylenium

    What I see is typical interlacing artifacts from tape captured by a video card. I also see what could be DV color compression artifacts. They can be fixed in a number of ways. The first thing to check is interlacing.


    First, make sure that the video is interlaced and that the fields are properly separated. The easiest way to do this is to drop the footage in the new composition icon at the bottom of the project panel or select the footage in the project panel and select Create New Comp from selection.


    Open up the interpret footage panel and set separate fields. if the footage is NTSC and 480 pixels high it's likely lower field first. If it's PAL it's likely upper field first. AE may have already made an educated guess.


    With the composition open open up the composition settings and double the frame rate by selecting it, moving the cursor to the right and typing in *2.


    Now step through the comp one frame at a time and check movement of the edges. There should be two distinct frames all moving in the right direction. You can use the page up or page down keys or Cmnd/Ctrl + Right or Left arrow keys.


    If there are two distinct frames and the footage is moving in the right direction then the fields are properly separated. If the action goes back and forth, one frame to the right and the next to the left then the fields are separated in the wrong order. If you have 2 duplicates and then 3 or 2 duplicates and 1 in any kind of pattern then the footage has had 3:2 pulldown introduced. You'll have to remove that. Let me know if you think there's 3:2 pulldown. If there is, then I'll help you fix that.


    Here's the worst case scenario, duplicate pairs of frames. This means that someone took interlaced footage, didn't properly separate fields, then rendered the footage as progressive. If that is the case then you'll have to figure out how to minimize the effects in other ways.


    Now let's deal with the color artifacts from DV 4:2:0 color compression. What happens is that the luminance data in a DV signal is sampled a pixel for a pixel, but the color sampling gives you 4 pixels for every color value. There are some plug-ins that can help remove these artifacts. You can do it yourself by duplicating the footage adding some blur, changing the blend mode of the top copy to blur or overlay, adjusting the levels of the blured copy, pulling your key from a pre-comp if the two layers, and then using that key with some matte choking as a track matte for the original footage.


    Here's a thread on DV artifacts. I talk about some of the solutions.


    Try looking at your footage at 800%. I think you'll see the artifacts are in 4 pixel blocks.

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    Mar 28, 2013 9:51 AM   in reply to Rick Gerard

    Ah, I couldn't see the artifacts. If it's because of bad field treatment, definitely follow Rick's advice.

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