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Noise and flickering in clothes

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Mike ThrockNoise and flickering in clothes
by on Apr 19, 2011 at 7:14:29 pm

Can anyone suggest a way to reduce the noise I'm getting in the suit this guy is wearing. The footage was shot on a 7D.

The flickering is only in the suit and it's bad.

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Michael SzalapskiRe: Noise and flickering in clothes
by on Apr 19, 2011 at 8:21:48 pm

That flickering noise you see is called moire and was very common back in the days of SD and tube tv's if the person in charge of wardrobe didn't know what they were doing. It's nice to know it's still around even in the world of HD. :P
Search the forums, there have been many posts about it over the years.
Basically, the reason it's there is, the pattern on the clothes is too small. I would suggest firing the wardrobe guy.
Any chance of a reshoot?

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

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Walter SoykaRe: Noise and flickering in clothes
by on Apr 19, 2011 at 8:47:37 pm

Some -- but not all -- of that moiré can be reduced. The green and purple fringing is color moiré, and this can be reduced.

Use the Channel Combiner [link] effect (set to RGB - YUV), then Channel Blur [link] (G&B channels only), then Channel combiner again (this time, YUV - RGB).

The basic idea here is to blur color independently of luminance. By working in YUV, we can separate color from brightness. YUV is essentially one channel of brightness and two channels of color, while RGB (which AE usually thinks in) is three channels of color values, with brightness distributed throughout.

Unfortunately, it looks from that still like there's a lot of moiré in the luminance as well, and the cure (a blur) is usually just as bad as the disease. Reshooting with different clothing is the only real solution.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
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Tudor "Ted" JelescuRe: Noise and flickering in clothes
by on Apr 19, 2011 at 10:15:21 pm

All the above advice is really good- I will add one more thing: when shooting chroma or any footage that you plan to use in post production/VFX try to use a HD camera and capture to a drive at least 4:2:2. A DSLR may shoot good looking footage but it compresses the color a lot and makes your post work hell.

Tudor "Ted" Jelescu
Senior VFX Artist

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Mike ThrockRe: Noise and flickering in clothes
by on Apr 19, 2011 at 11:04:43 pm

Thank you all for the help, and yes, wardrobe is fired.

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Dave LaRondeRe: Noise and flickering in clothes
by on Apr 20, 2011 at 1:59:21 am

Okay, here's a personal pet peeve: overuse of the term "flickering".

I have seen this term refer to the following: incorrect field order, improper field separation, frame rate mismatches, dropped frames, moire and, of course, actual flickering....

.... which in the dictionary is defined as "shining unsteadily" or "appearing briefly".

It's getting to the point where I just tune out AE woes concerning "flickering, because I don't have the time time to ask the OP, "what do you really MEAN?

Okay, I'm off my soapbox. It still bugs me no end, though.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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