Moiré is an interference pattern that occurs when a digital camera tries to capture a pattern with lots of small, repetitive details. It can look like rainbow waves of circles or stripes that buzz when they move. It can really distract from your image.
If you’ve ever taken a photo of your computer screen, you may have seen some moiré. Architectural elements can also cause moiré. But by far the most common culprit is clothing. Any fabric with thin stripes, tiny polka-dots or other small patterning can cause nasty moiré.
What’s really happening is that the pattern being captured matches the pattern of the imaging chip. When the two patterns meet, a new pattern is created – the moiré pattern.
You can avoid moiré by camera-testing your costumes before the shoot and telling actors not to wear certain patterns. Alterations to your camera’s position and focus point will sometimes lessen the effect, as well.
Sometimes, though, you can’t control what your subjects will be wearing, like in a documentary, or you didn’t have access for a full camera test of your costumes, props or locations.
We recently had a film in our facility with this problem. Their main actor wore a gray shirt with a very subtle pattern of dots on it, and nobody had flagged it as a possible problem on set. When they cut the film, they realized there was moiré in every shot. We offered to help them resolve it.
Many people think that if you have moiré in your footage, it’s impossible to get rid of in post. However, mitigating moiré in post is now achievable with a number of tools. You may not be able eliminate 100% of it, but maybe 95%. And if you can significantly lessen it to the point where it no longer distracts from your story, then that’s worth doing.
I used DaVinci Resolve to attack the moiré shot by shot. By making a selection of just the color of the character’s shirt, changing the contrast and adding a tiny amount of blur, sometimes to just one channel of color, I was able to see pretty remarkable results. I then created shapes to limit the change to just the area we wanted, making sure to leave enough detail so that creases of his shirt wouldn’t be affected. I then tracked the corrections so that they follow the character as he moves. It took me a little over an hour to work through the 13-minute film.
You can see the results in this gallery. Be sure to look at them full-screen to see the results clearly. And at the end is a video showing before and after.
Hopefully, this article has given you a little light at the end of the tunnel if you’re battling with a bad case of moiré. All is not lost!
Have you ever had to deal with moiré patterns on your projects? How did you handle it? Let us know in the comments!