How to remove moiree from DJI cameras for broadcast use.

[toegema]

Hi all. I am a professional video editor for TV 2 in Norway.
My biggest issue with footage from a lot of DJI cameras is moiree. This includes Phantom (all models, not tested P4P) and Osmo.
Professional tv cameras have a low pass filter installed behind the lens and in front of the sensor that eliminates moiree, but most combined stills and video cameras can't have that because that would be useless for the high resolution stills camera part.
Even if the moiree is not always very visible on a computer screen, it might be very visible and annoying when seen on a television screen. I have even seen expensive Hollywood aerials with the dreaded moiree!

The trick to eliminate/reduce moiree can be to lower sharpness in the recording settings in the camera, but it will not always help.
The solution is to make a small blur between the TV lines (vertically).
First I tried using a blur effect built in to the editing programme and make a small vertical blur. This helped, but as I applied more vertical blur, before all the moiree was gone the picture had become too softened.
By coincidence I tried a Boris Continuum effect called Lens Blur, and that seemed too do the trick! This is a third party plugin available for most editing programmes.

I have tried this in Avid Media Composer, Final Cut Pro X, and Quantel and the result were perfect!

The Lens Blur effect is available in Boris Continuum Complete package, or just the Blur and sharpening category if you don't have the whole package.

Here is what you have to do:

This is tested with a 25 frame rate. I guess 24/30 will do good also, but higher frame rates did not give the desired result. I read somewhere this is due to a limitation in the Phantom cameras ability to process the higher rates.)

For Avid Media Composer:
Project setting must be set to 24/25/30P frame rate (according to your footage) while the effect is rendered. When the effect is rendered the project can be switched back to 1080i50 or equivalent.

Apply the Lens Blur effect from Boris Continuum.

Set the following parameters:
Iris: 1,0
Scale X: 10
Scale Y: 50 (this value can be set higher or lower if needed)
Render.

Done! Moiree is gone.

-------

Final Cut Pro X / Quantel:

Do the same as described above for Media Composer, except the Project can be kept in Interlaced mode if that's your original project setting...

I have not tested this for Premiere Pro, so if someone has the possibility to do so, please report back.







Sent from my iPhone using MavicPilots

 

[MacPap]

Great to some other stuff than how battery life is affected on a Mavic pro by the flight of seaguls lol.

Great post thx.

 

[MaxHam]

My biggest issue with footage from a lot of DJI cameras is moiree. This includes Phantom (all models, not tested P4P) and Osmo.

THANKS A LOT FOR THIS POST!
I'm all new to video/editing and this moiree effect drives me crazy.
So far I wasn't able to find an explanation for this...

 

[possenorge]

Let me join in on this, since the first post gave me hope and 2 alternative solutions were found in the process.

Like toegema I'm also shooting for broadcast in Norway, and as an alternative to the larger Inspire models I bought a Mavic to have in my backpack. I also used filters from Polarpro to drag the shutter speed down to around 1/50 for most of the time, to avoid the jitter effect that I thought was the cause of the problem. It seems however like this is an issue because the image has a bit too much details/sharpening, since the sharpness level usually is at +1 to disable internal noise reduction. I was very surprised to see footage from a C300 at 1080 25P 1/50 look so different from a Mavic with the same frame rate and shutter speed.

This is my workflow when I deliver 1080 25p for broadcast use to avoid moiré and aliasing, and get what I feel is the best picture from a Mavic:

D-log
Sharpening/contrast/color
+1/0/0
2,7K 25p
ISO 100
Filters to have the shutter approx. at 1/50

Import into Premiere, apply Neat Noise Reduction with the Mavic noise profile (that only takes away the sensor noise at 100 ISO) or if really necessary, adjust for other noise if you were shooting in really low light or have very hard shadows with noise in them. But in general, it shouldn't be a problem - although I have seen some noise in leaves and such that looked better after a round with the Neat plugin.

I then render as (if this is to be edited on Avid like in our case this time) DNxHR/DNxHD (HQX 10-bit, Render at maximum depth, Use maximum render quality) and make sure you downscale the image from 2,7K (2720x1530) to 1080p. This will re-draw the whole picture, and my onliner says the moiré and aliasing is completely gone. Also, if this is sharing a timeline later with footage from say C300 mkII, it will all be in .mxf containers.

By routine I only deliver the finished render with the best cutouts from the flights, and not the raw recording on microSD's. In some cases I need to level the horizon too, and I want this to be best possible as a starting point for editing and grading. Things look great the moment the file is played with the money shots first, and I don't risk that the edit uses a part that I wasn't all happy with...

Another way to pretty much remove/hide the artifacts is to apply "reduce interlaced flicker" filter in After Effects at 1 to 2 depending on how much you need, wich will soften the image just a bit. I haven't used this method myself, but my onliner says it takes care of most of the artifacts. And it has probably saved some shots in the past.

 

[Pablo]

This is all great advice guys. I'd love to try this. The problem is I'd get about half way through it all then my wife would moan at me incessantly for not getting enough housework done and ignoring her and my daughter

That's the problem with women, they always want moiree.

 

[xeberdee]

I use FFMPEG to convert and add a -vf pp=lb (lb/linblenddeint) de-interlace block filter, removes moire and softens the image even though the souce is progressive. You can also record 50P and convert it to pure 50i with ffmpeg (interlace=lowpass=1), if you are working interlaced and want that.

In the mavick I set the frame shutter ratio to less than 1:2, and work with the sharpening to dull it a little - so for 25P, I might use 1/40 or less - that all helps prevent juddering.