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Could wiggle fix the light flickering
I am having a problem that could kill my shot. i am shooting infront of a greenscreen, the light i am using had a flicker that wasn’t visible to the naked eye, but its easily visible on the footage. it flickers around 20 times per second. i could fix it on each frame if i key frame the brightness to the exact values of 0 and 8. but there is no way i could key frame each frame of the footage, so i was wondering if there is any way i could link the change of the color to the wiggle expression so that when its darker its a 0 Brightness and then when its lighter, the brightness goes up to 8?
Thanks in advance 🙂
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5 Replies
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wiggle won’t help you because it is random.
If you think you can fix it with repeating keyframes, then set a few keyframes and use the loopOut(“cycle”,0); expression to repeat those keyframes indefinetely.
IN theory the “Color Stabilizer” effect could help by doing the brighness adjustment work for you. But I’ve never had truly useable results from this.
And if all else fails, you may have to use the echo-effect to blend two frames together using the ‘Maximum’ operator.
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The Loop cycle fixed it 😀 but i got lucky cuz the stupid light had a pattern of 2:1 flickering, if it was random i would be dead now 🙂 thanks alot Filip 🙂 you saved my butt.. i guess i will be using this forum way more than i thought 🙂
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I just came up with this expression that might work for you:
- Add a Brightness & Contrast Effect to your footage
- Add a Point Control to your footage
- Add a Slider Control to your footage
Drag the point of the point control to a good consistent part of the green screen where there are no shadows or moving areas.
Move your mouse over the green screen for that point and look in the info panel to see the green color of it. I’m guessing it will be somewhere around 116 (depending on how you lit your screen)?
Now adjust the slider control to equal that number. (You may want to tweak this a little later)
Then apply this expression to the brightness control:
NormalGreen = effect("Slider Control")("Slider");
samplePoint = effect("Point Control")("Point");
sampleRadius = [5,5];
sampledColor_8bpc = 255 * sampleImage(samplePoint, sampleRadius);
(sampledColor_8bpc[1]-NormalGreen)*-1;Jon Geddes
http://www.precomposed.com -
Hey Jon.. thanks alot for the reply =), i tried what you suggested but it didn’t work, the whole footage (greenscreen, and actor) became brighter, and the brightness value was stuck on 100 through out the footage. the light that was causing the problem was on the actor only, but the green screen lighting was nice and consistent.. it was about 112, so i guess it was very close to what u suggested. i would be happy if you have more suggestions, i was compromising by making the background flicker like the actor just for the sake of the composition, but i would rather cancel both of the flickering.
Thanks alot in advance =)
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The script I wrote doesn’t necessarily have to be used on the green screen. It can be used on any part that is pretty consistent throughout the shot, but does have the flickering. You could even use the motion tracker to track the point of the color sampler to an object that is moving. You might also need to adjust the sample radius as well. I tested it out and it worked perfectly for me (brightness was not stuck at 100).
It should be ok if the background flickers after you remove the flicker from the actor, since the background will be keyed out anyways. You will have to adjust the key so it also keys out the brighter frames.
Jon Geddes
http://www.precomposed.com
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