Moire in post production films

[Ian Conrey]

I was watching Hugo as well as The Hunger Games yesterday and noticed a couple of times moire and aliasing showing up. Now I know Hugo was shot on the Arri Alexa, so there should not be any visible moire but it's definitely more possible on any digital camera than film. It was in the dream sequence of the wood grain on the railroad track.

 

Now hunger games I noticed it horribly in the beginning when Gale and Katniss where sitting on a green hill. Gale's shirt had a fabric pattern which had horrible rainbow circular patterns all over it that jittered when he moved; definitely moire. However hunger games was shot on film which shouldn't have any moire.

I did some reseach and found out that in post production moire can show up, but most likely it showed up when it was compressed for tv. I was watching both of these through netflix on a vizeo hdtv. Could that be the case?

Forgive me of my ignorance ive just been discovering all of these new things about filmmaking and now I am noticing things in movies I never have before, such as camera angles, seeing what kind of color correction was done, and even errors.

 

So I guess a question would be, what type of things cause moire in post production? Can it be avoided at all?

[David Mullen ASC]

Moire happens when one fine line pattern interacts with another so it can happen due to the combination of the subject and the sensor, or the combination of the image and the display device. You may have to accept some minor aliasing if the alternative is just softening everything to get rid of it 100% of the time.