Why do RGB horizontal bands appear in video under LED lighting?

Asked 2/3/2020

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I’m seeing red/green/blue horizontal stripes in footage from a new Blackmagic Pocket Cinema Camera. It happens with both lenses, and it appears to some degree in most indoor video shots under home LED lighting. I don’t see the issue outdoors in daylight. What causes this, and is it a camera problem or a lighting issue?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

6y ago

2 Answers

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The most probable cause is cheap LED lighting, maybe even using RGB LEDs.

As with most shutterless cams, the image information is read from the sensor in lines. This causes two known effects: The Rolling shutter effect and banding.

What you see here, seems to be banding. To dim LED lights, you have to pulse the light. Your eyes are slow enough not to notice these pulses, but the sensor can see them.

So basically you read some lines from the sensor, then the LED turns less bright, then the next lines are read, then the LED switches on again... and so forth...

What can you do about it? Either use specialized video/photo lights that switch fast enough for the sensor. Or try to even out the pictures in post, which is not an easy task.

A good test if it is related to the light source, is doing a test shot without any artificial lights on and check if the effect still occurs.

Originally by user88965. Source · Licensed CC BY-SA 4.0

user88965

6y ago

0

AI Answer

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This is most likely LED banding/flicker, not a lens problem. Many household LEDs are dimmed or driven by rapid pulsing, and a video camera reads the sensor line-by-line. When the light output changes during that readout, horizontal bands can appear, sometimes with RGB shifts if the LEDs are color-mixed.

The clue is that it happens under home LED lighting but not in daylight. That strongly points to the light source rather than the camera itself.

What you can do:

  • Try different lighting, ideally photo/video lights designed to avoid visible flicker.
  • Adjust shutter settings/frame rate to better match the local power frequency if your camera allows it.
  • As a test, shoot under daylight or a different continuous light source and compare.

If the bands appear in every shot in exactly the same place, regardless of lighting, then it could indicate a camera/sensor issue rather than lighting. But based on your description, cheap or flickering LEDs are the most probable cause.

UniqueBot

AI

6y ago

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