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Bad Footage Under Florescent Lights

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Ryan ZernecBad Footage Under Florescent Lights
by on Jun 21, 2010 at 5:42:43 pm

Hey guys,

I'm sorry, I don't know if there's a technical term for this, but I was given some footage that was shot under florescent lights with incorrect shutter speed, and as you can probably guess it's got scrolling bars moving through it all. Is there any way to correct, or even minimize this?

Thanks!


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Michael SzalapskiRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 6:13:01 pm

I've never had florescent lights cause bars of color to move through the footage. I've had the lighting color change over time, but that was across the image. There could be some sort of interference. For example, I work at a place with a lot of radio, radar, laser and related military equipment and sometimes our cameras will have brown bars running up the image until we walk out of the building with the camera and it goes back to normal.

As far as fixing it goes, you'll want to include a screenshot so we can see how it looks. My initial thought is to do color correction on an adjustment layer and use masks to reveal it where the bars are. Do the bars move uniformly and at the same pace? You may only have to keyframe one or two, then loop the keyframes with expressions.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Ryan ZernecRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 6:47:31 pm

Here are a few screenshots:






They are like scrolling bars of discoloration. I'm not sure it's interference, we shot in the apartment 20 feet away and everything came out fine, the only difference was the lights, but you could be right. They DO seem to scroll uniformly, so your suggestion might be the way to go.


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Michael SzalapskiRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 7:03:43 pm

The problem just started for us recently. We need to do some more testing with ours, but all I had to do was walk a few feet away from our building and the problem seemed to stop.

We really haven't had time to test it though.

What kind of camera are you using?

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Ryan ZernecRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 7:19:19 pm

I believe it's a Sony HDVRA1U. I've been told by others that it's a problem with the 24p mode vs. the florescent lights, but at this point I just need to try and fix it, I don't think reshooting is an option (and we can't turn off the florescents even if it was).

I'll try your idea to fix it though, thanks for suggesting it. Do you know offhand what the expression would be to loop my "bars?" I'm terrible with expressions...


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Michael SzalapskiRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 9:26:03 pm

The expression would be a loopOut expression.

Our cameras were just out on a shoot, I hope to have them back tomorrow so I can try some more testing on them. We didn't use to have that problem until very recently.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Brian MossRe: Bad Footage Under Florescent Lights
by on Jun 21, 2010 at 11:11:06 pm

No suggestion here on how to fix your problem but i have seen this before and it was due to the florescent bulbs in the ceiling. If you have your shutter on the camera set high you will see the frequency cycle in the bulb. Florescent light that are bought at a hardware store are notorious to have color change in the spike during the frequency cycle.




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Ryan ZernecRe: Bad Footage Under Florescent Lights
by on Jun 22, 2010 at 1:06:17 am

Ah yep that's exactly what I've been told it is. Now I just need to fix it. The scene in question wasn't very well written to begin with, so maybe this was God's say of telling me to cut it. :)



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