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Removing flicker from high-speed video - footage embedded

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Graham Quince
Removing flicker from high-speed video - footage embedded
on Mar 28, 2009 at 11:23:24 am

Hi everyone,

One of our science teachers recently shot some footage using the Casio EX-F1 camera, which can shoot up to 1200fps. The room was well lit, though we didn't bring in additional lights and as you can see, when shooting high speed the camera soaks up every bit of light.



The problem isn't so much that the footage is dark, it's the strobing effect that's distracting. I've tried a couple of the colour correction options, but with not much success.

Does anyone have any suggestions?

Graham

http://www.YouTube.com/ShiveringCactus - Free FX for amateur films


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Filip Vandueren
Re: Removing flicker from high-speed video - footage embedded
on Mar 28, 2009 at 4:12:18 pm

the room was probably lit with TL lights or something else that cycled at a lower rate.

you could start with "auto levels" or "autocontrast", but they won't work because there's always perfect white and black in the shot allready
The 'color stabilize' filter was designed to do stuff like this with more controls than the auto filters.

But perhaps you could just color correct a few frames using the levels (individual controls), and loop those keyframes, since it will probably be perfectly cyclical (looks like 6 frames per cycle)

But if the quality is as bad as this clip, forget it, there's nothing to recover in those blacks.
reshoot with tungsten light or preferably daylight



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Graham Quince
Re: Removing flicker from high-speed video - footage embedded
on Mar 28, 2009 at 6:19:18 pm

Thanks Filip. I never considered that it would a lighting issue. The lights were typical classroom strip lights. I do have a couple of studio lamps, but your daylight suggestion seems the easiest option.

Graham

http://www.YouTube.com/ShiveringCactus - Free FX for amateur films


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Jon Geddes
Re: Removing flicker from high-speed video - footage embedded
on Mar 28, 2009 at 10:22:10 pm

Fluorescent lights typically operate at 120 Hz when powered through an alternating current. This means that the light is actually turning on and off 120 times in a second. Your eyes usually aren't able to detect anything above 50 cycles per second (the flicker fusion threshold). However, your spiffy 1200 fps camera can definitely see the light turning on and off. With better lighting, you will not see the flickering. As suggested by someone else, use tungsten or daylight.

Jon Geddes
Motion Graphics Designer
http://www.precomposed.com


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Scott Roberts
Re: Removing flicker from high-speed video - footage embedded
on Mar 29, 2009 at 8:44:02 am

Have you tried removing the frames that go dark?

Color Grading presets for After Effects, Premiere, etc., plus free presets and more.

LITTLE BLACK BIRD - PROFESSIONAL VISUAL EFFECTS

http://www.littleblackbird.com

http://www.myr3d.com


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Filip Vandueren
Re: Removing flicker from high-speed video - footage embedded
on Mar 29, 2009 at 5:08:09 pm

That would effectively speed the footage up 600%, still a bit slow motion, but it would defy the purpose...

Here are some other solution that seem to help, though they have a few downsides:

Echo Effect:
Echo Time: 0.0345 (=1/29.97)
Number of Echoes: 6
Start: 1
Decay: 1
Echo Operator: Maximum:

this will only show the brightest value in any 6 frame bracket, the flames will in effect be 6 times longer, and when the hand moves quickly away that'll have some ghosting effects too, but it evens out the fluo flickering.

Another option maybe CC Wide time 4 frames Back, 4 frames forward.
This will have more of a motion blurry look and be abit darker, but you can correct for that with some levels.

I think the CC wide time gives the best result, experiment with more and fewer steps.
If it's too blurry, then add the original footage on top with 'lighten' transfer mode,
lower the gamma of the top layer a bit, and raise the gamma of the bottom layer a bit, so the top layer won't re-introduce flicker, but only detail in the flames



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Graham Quince
Re: Removing flicker from high-speed video - footage embedded
on Mar 30, 2009 at 12:37:35 pm

Thanks so much for all the adivce guys. I'll try each out and see which works best. In the meantime though, we're fiming other experiments later today, and are going with natural light.

Graham

http://www.YouTube.com/ShiveringCactus - Free FX for amateur films


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Daniel Larsson
Re: Removing flicker from high-speed video - footage embedded
on Aug 13, 2009 at 7:34:48 pm

A big shout out and thanks for this solution.

I shot footage with RED at 50fps and got flickering from the fluorescent lights above, and Ive solved it before using a few tweaks with auto levels. This time it did not solve the problem for me, but this solution did.

Awesome

Thanks again.

Daniel Larsson


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Eric Addison
Re: Removing flicker from high-speed video - footage embedded
on Aug 1, 2012 at 9:49:07 pm

[Filip Vandueren] "Echo Effect:
Echo Time: 0.0345 (=1/29.97)
Number of Echoes: 6
Start: 1
Decay: 1
Echo Operator: Maximum:
"


This just helped me save a shot!! Thanks so much!!

---Eric
Owner | 100 ACRE FILMS
http://www.100acrefilms.com


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Paul Nordin
Re: Removing flicker from high-speed video - footage embedded
on Feb 25, 2014 at 5:46:44 pm

Filip,
Normally, I don't like to resurrect old threads. But, I was on a shoot in the woods at night last week, shooting overcranked and our kinoflo, which was used for fill had a flickering tube for several shots before it was discovered and fixed. We didn't have time to reshoot those setups. I just had to trust that we could fix the flicker in post.

Your suggestions are right on the money. Thanks again for posting specific solution suggestions. You Rock!

_______________________
EMB Studios
http://www.EMBstudios.com
Emeryville, CA
_______________________


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Filip Vandueren
Re: Removing flicker from high-speed video - footage embedded
on Feb 25, 2014 at 5:51:54 pm

Funny how some solutions keep current 8-)

I hope everyone realises that unless their slomo is as super-pronouced as in the original example, you can get away with much less than 6frames of Echo.
In the original example, the flickers lasted 6 frames, so that's why.

greetingsā€¦



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