Thread: Highlights in range but...

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  1. #1 Highlights in range but... 
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    Could someone give me some insight into why these "hot spots" are well within range (around 80-90 on the scale) but they seem to have no detail and be clipped?





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  2. #2  
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    STH, with Mysterium-X sensor?



    Metadata says no interchangeable OLPFs.



    And this looks pretty overexposed to me:






    There's your scorched highlights...
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    Senior Member Bob Gundu's Avatar
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    First off, the image is really over exposed. Second. change your pipeline to IPP2 and you will see a huge improvement to the image. The ND you are using will also greatly skew the color but thats a different discussion.

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  4. #4  
    Senior Member rand thompson's Avatar
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    as Sabovic said it was overexposed and the hightlights were clipped. Even when you try to bring it back, there is still no highlight info to recover. If you look at the highlight area the tops are flat and have been harshly cutoff.




    Last edited by rand thompson; 04-08-2019 at 06:53 PM.
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    Senior Member Aaron Lochert's Avatar
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    The reason is you've clipped them at the sensor-level, but you have some metadata curves set which are bringing that white-point down to like 90%, giving you the false idea that they should be within range. You're also processing your footage in RedGamma3 which brings that white point down even further than the more current RedGamma4. Clear the curves and set the camera to RedGamma4, and you'll see those highlights get pushed to 100% where you guess they'd be.

    Ultimately I suggest going IPP2 over RedGamma4, though. Processing in IPP2 will run this clip through a highlight extension algorithm, which will rebuild the peaks and allow for a smoother transition to full clipping.
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    Senior Member Tom Gleeson's Avatar
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    Quote Originally Posted by Tyler Besh View Post
    Could someone give me some insight into why these "hot spots" are well within range (around 80-90 on the scale) but they seem to have no detail and be clipped?
    Tyler,

    It only looks like it is in range because you are looking at the Redcine scope where the exposure values being represented are the result of the image processing and in your case it looks like the legacy Redgamma 3. So if you have over exposed pixels this image processing never maps these pixels past 98-99IRE even when clipped. The scope in Redcine is not responding like an older video camera where you might even see overexposure push past 100IRE. Unsure if there are any tools in Redcine that will indicate clip but there are many tools on the camera that will show you when you have saturated your pixels starting with the goal posts. Assuming a 800asa base than this image is a little over a stop overexposed but using Redcine especially with the more sophisticated tools in IPP2 image pipeline most of the detail is still there.
    Tom Gleeson
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  7. #7  
    Quote Originally Posted by Tyler Besh View Post
    Could someone give me some insight into why these "hot spots" are well within range (around 80-90 on the scale) but they seem to have no detail and be clipped?
    Signal range on scopes in post is relative to gamma.

    It is a normal highlight peak/clip.
    You have sunlight directly hitting a white surface. Nothing unusual here.






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    Quote Originally Posted by Šabović Adis View Post
    STH, with Mysterium-X sensor?



    Metadata says no interchangeable OLPFs.



    And this looks pretty overexposed to me:






    There's your scorched highlights...
    I did a post about how I changed the OLPFs in the Epic. I now have the skin tone permanently in there because it offers better results.
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  9. #9  
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    Quote Originally Posted by Aaron Lochert View Post
    The reason is you've clipped them at the sensor-level, but you have some metadata curves set which are bringing that white-point down to like 90%, giving you the false idea that they should be within range. You're also processing your footage in RedGamma3 which brings that white point down even further than the more current RedGamma4. Clear the curves and set the camera to RedGamma4, and you'll see those highlights get pushed to 100% where you guess they'd be.

    Ultimately I suggest going IPP2 over RedGamma4, though. Processing in IPP2 will run this clip through a highlight extension algorithm, which will rebuild the peaks and allow for a smoother transition to full clipping.
    This helps a lot thank you!
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  10. #10  
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    Appreciate the insight guys! This was the first time I've recorded outside without a meter or any kind of charts, just used the goal posts. Need to work on my understanding of dynamic range and exposure tools.
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