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How can I fix an iris opening/closing in Resolve

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Mark Longchamps
How can I fix an iris opening/closing in Resolve
on May 30, 2014 at 7:57:25 pm

I grade a lot of reality TV and the camera people are constantly opening and closing the iris on the camera. This makes the shot lighter/darker. Is there a way to have the Resolve fix this luma change automagically?

Currently I do this by hand. I go to the properly exposed part of the shot and set a KF. I then go to the brightest/darkest part of the shot and set a KF. I toggle between the two and look at the scopes to get it close. Sometimes it works, sometimes well, it doesn't work as well. If there was a plug-in or another way to do this it would be greatly appreciated. Thanks!


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Marc Wielage
Re: How can I fix an iris opening/closing in Resolve
on May 31, 2014 at 5:48:19 am

[Mark Longchamps] "Currently I do this by hand. I go to the properly exposed part of the shot and set a KF. I then go to the brightest/darkest part of the shot and set a KF. I toggle between the two and look at the scopes to get it close. "
That's the way I've always done it. Tell the camera operators to stop changing the iris, and that you can fix their exposure problems far better in Resolve.

My joke is, this kind of visual problem often requires three sets of keyframe corrections: one when the exposure problem starts; another to compensate for the severe change caused by the operator; and then a third correction to ease the exposure back into normal at the end. If they just left the exposure alone, it'd be a single keyframe event.


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Joseph Owens
Re: How can I fix an iris opening/closing in Resolve
on May 31, 2014 at 10:01:05 am

Yes, dealing with this all the time. No AUTO. There really are at least three types of exposure trajectory. Manual twist, auto-iris (which usually bounces and settles), and then there are the electronic sensitivities which hop between exposures, jump, jump, jump up and down. Actually easier to track the last type.

Pick your poison, save a still, split it with the live footage and if you want to fix it perfectly (if it hasn't been crushed or clipped into oblivion) and then be prepared to essentially keyframe the whole transition. Generally its not just the gain that's changing, its the whole gamut -- whether its going up or down, the black point will shift, the contrast ratio is wandering off somewhere else…

Jut make sure you are charging by the hour, or get the cinematographer to pay for the session. Yeah, like thats going to happen…


jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Mark Longchamps
Re: How can I fix an iris opening/closing in Resolve
on Jun 2, 2014 at 1:54:55 pm

Thanks guys. I was afraid of the no auto answer. Still a little new to this Resolve software. The reason why I asked is because I have used Flame for 15 years and there was a spark by sapphire called Flicker Remove. This is designed to remove a flickering shutter back in film days but it works GREAT for this kind of thing. You set a KF where the shot is "properly" exposed and then hit analyze. The plugin then looks at the whole shot and fixes the exposure. It is not perfect, but 97 times out of 100, it got close enough with only a few button clicks. And since I do mostly reality TV, good is fine. I would not do this for a feature or commercial work, but I wish I had this in Resolve.



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Joseph Owens
Re: How can I fix an iris opening/closing in Resolve
on Jun 2, 2014 at 3:41:12 pm

[Mark Longchamps] "d there was a spark by sapphire called Flicker Remove. "
There is a de-Flicker node in the ancient VFX application SHAKE, and I still use it from time to time. You grab a reference still, box the reference area and let it render. It anchors to the reference area, but it doesn't fix any other non-linearities in the exposure curve.

What would complicate any other auto-de-flicker module would be that there are so many types of intra-frame density fluctuation that you would have to design VFX to look for specific types of frame differences. Those that are brought about by T-stop changes, and those that originate at the source. Those would affect the mediated values in different ways. The other source of flicker -- beating between the frame rate and the lighting source due to strobing -- ie shooting 2398 or 2997 fps with 50Hz lighting is most common, especially for reality. The difference will cause a kind of "hum bar" to migrate through the frame, but it does not affect the frame uniformly from top to bottom... and it travels harmonically proportioned to the difference between the periodicity. In some countries where the mains frequency is not strictly controlled the dark bar is just chaotic.

How would a VFX module differentiate between "flicker" and naturally occurring level differences, even if it was simply a person turning their face into the light?

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Mark Longchamps
Re: How can I fix an iris opening/closing in Resolve
on Jun 2, 2014 at 4:06:49 pm

Very true and all great points Joseph. I have not idea how the plug in would differentiate between natural levels, but the Sapphire one usually worked out well enough - particularly for reality tv Iris changes.

ie shooting 2398 or 2997 fps with 50Hz lighting is most common, especially for reality

This happened to us once and it was a hell of a job to fix it.

back to doing it by hand I guess.



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Yoram Tal
Re: How can I fix an iris opening/closing in Resolve
on Jun 2, 2014 at 4:45:06 pm

Sapphire can be used inside resolve now...
I leave it alone in my CC pass in Resolve and fix it inside the Symphony, once I bring the footage back.
Boris CC has a great de-flicker as well that takes care of most of my Iris problems.

Rseolve 10 New MaPro loaded


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Mark Longchamps
Re: How can I fix an iris opening/closing in Resolve
on Jun 2, 2014 at 6:49:10 pm

Might be worth a look if Resolve can handle the plugin.



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