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TOPIC: Any hints on removing banding from LED lights?

Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223007

  • JimDaddyO
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I upgraded my shop lighting to LED lights. I shoot in 30 (29.98) fps and edit the same with the free version of Lightworks. I have noticed that there are dark bands that travel from the bottom to the top of my footage due to the 60 Hz frequency of the electricity through the lights. Any tips on how to eliminate or reduce this?

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223008

  • hugly
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Hello,

Difficult task. I cannot help you on this, but I can imagine when the anti-banding wizards pass by they'll appreciate one or more shared video samples to test their magic.

Edit: Writing the above I silently assumed that you mean reducing in post. If you mean reducing when shooting, see if this helps:

It's better to travel well than to arrive...
Last Edit: 2 months, 3 weeks ago by hugly.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223011

  • briandrys
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Usually this type of issue is solved by shooting with what called in film a 180 degree shutter at a frame rate that's half or the same as the mains frequency. Here's a video that explains the principals.



NOTE using 1/30th of a second may give you ghosting on action, the standard shutter is 1/60 at 30 fps* (that's the 180 degree shutter's speed). I would use the latter shutter speed unless you're really stuck with a LED flicker issues.

In Europe ideally a 1/50th at 25 fps, that matches the mains frequency.

Don't dim LED lights, that can produce flickering.

BTW this can also be an issue with fluorescent lights and discharge lights.

There are plug ins to remove LED flicker on some NLEs, however, I don't think there's currently one for Lightworks.

It's something that's best avoided at the shooting stage,

*In practice 30fps is often 29,97fps
Last Edit: 2 months, 3 weeks ago by briandrys.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223039

  • JimDaddyO
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I guess I should have put that information in there....sorry.

I shoot at 30 fps in manual mode with my shutter at 1/60. That is why it is confounding me. I have increased the gain, brightness and gamma a bit in post and it reduces but doesn't eliminate it. Yes, I am wondering about fixing it in post. I am open to the idea of adjusting the shutter speed in the future though.

Note: My camera lists as 30 fps, but the file imported to lightworks lists the actual fps as 29.97.

I need some better lighting in my shop also as I find that I get segments of very bright light washing everything out. I believe it's because I wear dark clothing and when I get closer to the lens the auto white balance trys to compensate. At least that is my theory on that one.

Thanks for the videos, I am about to watch them now.
Last Edit: 2 months, 3 weeks ago by JimDaddyO.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223052

  • hugly
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Automatic white balance is the worst thing you can do, but washed out black on close up usually isn't caused by automatic white balance, but automatic exposure. Do you shoot with automatic exposure too?
It's better to travel well than to arrive...

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223053

  • briandrys
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Be aware that dimming your LED lights can cause flicker. I would test using a 1/30 shutter speed if 1/60 is causing issues.

30fps is commonly used as short hand for 29.97fps.
Last Edit: 2 months, 3 weeks ago by briandrys.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223058

  • JimDaddyO
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As I said, I shoot in full manual mode. Except I had the white balance on auto. It's not the black that gets washed out, it is like a segment gets overexposed when I get part of the frame covered with my black clothing. Oddly enough, I used to use a programmed custom setting on my camera that I put in myself with the white balance set to 6500K. I went to manual because I changed the lights in my shop (studio) with a different K value (5500K). Now in full manual I left the WB on auto...so I will have to pay attention to that. I usually adjust the exposure by changing the aperture or sometimes the ISO. Depending on my concern on depth of field.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223059

  • JimDaddyO
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I will try that. I am thinking that is the banding problem. I always try to ask those with more experience than me when I have an issue. Thanks!

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223063

  • schrauber
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JimDaddyO wrote:
[..] Yes, I am wondering about fixing it in post.


If they are such horizontal lines as in the video from post #223008, then you probably need a Dynamic Mask for gain color correction. The mask would have to simulate the lines and their movement, which requires keyframing.

I don't have a finished effect, but documented function code for creating line patterns.

The code called "multilines_total_H" creates horizontal lines with constant spacing, which can be rolled vertically.

The code "multilines_total_H02" also has an angle parameter and edge softness parameter.

But I don't have time today to make a correction-test effect out of it.
Mainly automatically translated
--------------------------------------------
Software: Lightworks 2020.1.1; || Windows 10 Home 1909, 64 Bit
Hardware: Intel i5-4440 (3,1 GHz); || RAM: 8 GB; || Intel HD Graphics 4600 (can use max. 2 GB of shared RAM)
Last Edit: 2 months, 3 weeks ago by schrauber. Reason: Additional code link added.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223065

  • asilnevs
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I'm not shure of banding and flicker is the same but if there is not so much moving in the clip then you can try this fix:
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Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223071

  • JimDaddyO
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schrauber wrote:
JimDaddyO wrote:
[..] Yes, I am wondering about fixing it in post.


If they are such horizontal lines as in the video from post #223008, then you probably need a Dynamic Mask for gain color correction. The mask would have to simulate the lines and their movement, which requires keyframing.

I don't have a finished effect, but documented function code for creating line patterns.

The code called "multilines_total_H" creates horizontal lines with constant spacing, which can be rolled vertically.

The code "multilines_total_H02" also has an angle parameter and edge softness parameter.

But I don't have time today to make a correction-test effect out of it.


Yes, pretty much the same as the clip.

I looked at your effect, and I don't even know where to start to try and understand it...lol. You are obviously at "Genius" level, while I am just a hack making YouTube videos...lol. It has to be dumbed down a lot more for me to come to grips with it. I admit that I am blown away by that level of expertise in the art.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223072

  • JimDaddyO
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Just for gits and shiggles, here is my final of the video as I released it. The banding is still slightly noticable in spots (4:19 mark for example), you can also see the other issue I had with the overexposure happening in places.

Last Edit: 2 months, 3 weeks ago by JimDaddyO.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223135

  • schrauber
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Thanks for the video.
That looks more like a wave than sharp lines.

If you like, you can experiment a little with this effect:

This attachment is hidden for guests. Please log in or register to see it.


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The effect settings still have to be adjusted to your source material, of course.

"Waveform base": You can either choose the standard sine wave, and a sine wave where the negative half-wave is mirrored into the positive one (in the following image link called Full-wave Reflection).
en.wikipedia.org/wiki/Diode_bridge#/media/File:Rectification.svg
The sine wave corresponds to the waveform of the voltage of the power grids.
The mirrored waveform corresponds approximately to the resulting electrical power in a directly connected incandescent lamp (not exact).

"Squareness": Increases the edge steepness of the waveform.

"Roll the Lines" , is controlled by keyframing. If the movement is constant, the last keyframe can be used to set the speed and direction (steepness of the ramp in the Graphs tab).

In the "Line by line Gain correction" category, the brightness (gain) correction can be set.

"Show Mask" shows the correction values coded as black and white mask. Lines that are too bright in the original should be darker in the mask to compensate for them.
If more complex corrections are needed, this mask could be used to control other effects. But we don't want to make it even more complicated.
Mainly automatically translated
--------------------------------------------
Software: Lightworks 2020.1.1; || Windows 10 Home 1909, 64 Bit
Hardware: Intel i5-4440 (3,1 GHz); || RAM: 8 GB; || Intel HD Graphics 4600 (can use max. 2 GB of shared RAM)
Last Edit: 2 months, 3 weeks ago by schrauber. Reason: effect replaced (compatibility optimizations in code)

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223136

  • jwrl
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This is a neat idea. If you would allow one (small) suggestion: usually because this problem is due to an exposure variation a simple gain adjustment isn't enough. You may also need to adjust the gamma somewhat. It should be possible to link the two adjustments to the one setting.

Re: Any hints on removing banding from LED lights? 2 months, 3 weeks ago #223137

  • JimDaddyO
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schrauber wrote:
Thanks for the video.
That looks more like a wave than sharp lines.

If you like, you can experiment a little with this effect:

This attachment is hidden for guests. Please log in or register to see it.


This image is hidden for guests. Please log in or register to see it.


The effect settings still have to be adjusted to your source material, of course.

"Waveform base": You can either choose the standard sine wave, and a sine wave where the negative half-wave is mirrored into the positive one (in the following image link called Full-wave Reflection).
en.wikipedia.org/wiki/Diode_bridge#/media/File:Rectification.svg
The sine wave corresponds to the waveform of the voltage of the power grids.
The mirrored waveform corresponds approximately to the resulting electrical power in a directly connected incandescent lamp (not exact).

"Squareness": Increases the edge steepness of the waveform.

"Roll the Lines" , is controlled by keyframing. If the movement is constant, the last keyframe can be used to set the speed and direction (steepness of the ramp in the Graphs tab).

In the "Line by line Gain correction" category, the brightness (gain) correction can be set.

"Show Mask" shows the correction values coded as black and white mask. Lines that are too bright in the original should be darker in the mask to compensate for them.
If more complex corrections are needed, this mask could be used to control other effects. But we don't want to make it even more complicated.


I downloaded it and extracted it to my effects templates folder in Lightworks. Is that the correct procedure? I will give it a shot next edit. Thank you.
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