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Bob at IndigoHealth
Bob at IndigoHealth
Inspiring
September 21, 2020
Answered

Clamp brightness?

  • September 21, 2020
  • 3 replies
  • 1085 views

I have a video clip where the camera is mounted on a tripod. The subject of the clip is a person in the foreground; the background is unchanging. The camera reacts to something in the scene (presumably the changing brightness on the person's face) by increasing or decreasing the overall brightness, causing the background to radically change its brightness. Is there a way for me to choose a point or an area in the scene background and have Premiere Pro adjust the brightness to maintain that point or area at a constant brightness (luma only)?

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Correct answer R Neil Haugen

No, Premiere doesn't have that capability. You can keyframe Lumetri controls as some do.

 

You can also put an adjustment layer with Lumetri set to what's needed to darken the lighter segments, Lumetri on the clip itself set for correct image in the darker times ... and keyframe the opacity of the AL. The less opacity, the more that Lumetri will affect the image.

 

For some longer projects, where sun/clouds outside affected a long program shot inside a building with the main light through the windows, I've had to go to Resolve. There are two options in Resolve, one that keeps the overall screen the same sorta general brightness, and for the other option you select an area of the image to have that stay the same. Whether it's a wall or a face or whatever.

 

I don't in general like working in Resolve, so that's a last-stop for me if keyframing in Premiere is going to take too much work.

 

Neil

3 replies

chrisw44157881
chrisw44157881
Inspiring
September 22, 2020

some additional thoughts. 1. premiere has a match color feature, 2. you can use a special fill paint exclusion preset to make everything turn into 18% gamma IRE for instant global 'average' adjustment. 3. after effects can auto color exposure, white balance. Resolve probably is the best option, I just wanted to give a few more.

    R Neil Haugen
    R Neil Haugen
    Legend
    September 22, 2020

    I've found when the brightness changes, I may want to do some other changes to contrast or whatever.

     

    Also ... when you use several controls to nail the image match from darker to brighter sections, you would need to keyframe all of them. That's why for most of the things I've worked that just shift because say of clouds over sun back to sun ... I use opacity. It wasn't just brightness, the color shifts a bit also. Correcting several controls is a TON more work than simply changing the opacity ... one control.

     

    I did have a job where I had to keyframe something like 15 different controls of Lumetri as it was shot on a GoPro ... and the color balance, brightness, and contrast were all shifting independently of one another. That was a mess, and thankfully having the Tangent Elements panel made it a ton "easier" than it would have been by mouse, as I was changing controls and setting keyframes from my panel not the mouse.

     

    And I've shot a couple say hour long programs that would shift up/down every so often, where I just went over to Resolve and used the option to select a bit of the image and auto-manipulate the image so that section stayed the same.

     

    Neil

    Everyone's mileage always varies ...
    R Neil Haugen
    R Neil HaugenCorrect answer
    Legend
    September 21, 2020

    No, Premiere doesn't have that capability. You can keyframe Lumetri controls as some do.

     

    You can also put an adjustment layer with Lumetri set to what's needed to darken the lighter segments, Lumetri on the clip itself set for correct image in the darker times ... and keyframe the opacity of the AL. The less opacity, the more that Lumetri will affect the image.

     

    For some longer projects, where sun/clouds outside affected a long program shot inside a building with the main light through the windows, I've had to go to Resolve. There are two options in Resolve, one that keeps the overall screen the same sorta general brightness, and for the other option you select an area of the image to have that stay the same. Whether it's a wall or a face or whatever.

     

    I don't in general like working in Resolve, so that's a last-stop for me if keyframing in Premiere is going to take too much work.

     

    Neil

    Everyone's mileage always varies ...
    Bob at IndigoHealth
    Bob at IndigoHealthAuthor
    Inspiring
    September 22, 2020

    Thanks for the quick reply. This question is actually related to a different issue that I'm having. I'll post a separate question to explore solutions to that issue.

     

    Currently, I keyframe a Lumetri property and scrub the timeline in the Color workspace, watching the scope (and the image itself) to see when the brightness changes, manually adjusting the property to compensate. That's a really time-consuming exercise that results in a gross approximation of my desired behavior.

     

    Curious minds want to know: What is the advantage of using an adjustment layer rather than keyframing a Lumetri property directly?

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