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How to emulate exposure with curves


daorus

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Can you please tell me how to emulate increasing and descreasing of Exposure filter with Curves?

 

I already can emulate with cuves brightness and contrast, and now I want to understand how to emulate Exposure in order to apply it to diffrent color channels.

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Hi

 

I can't see why you would want to do this as there is already and Exposure filter which goes from -1.0 to 1.0, 0 being the normal default. The "exposure" can be varied during the playback time of the clip in the normal way by setting keyframes.

 

It would seem that you want to use the RGB effects filter (Curves) to emulate the same effect but using the three channels.

 

Over or under exposure affects all three channels so for a simple over exposure effect you can use the composite RGB channel screen and drag the black dot up to the top of the first vertical line and down about 1/3 of the square and for simple under-exposure, drag the dot down to the bottom of the third vertical line and then up a shade, I presume you could do the same using the all three RGB screens but the effect you get only you can judge as obviously the remaining complmentary colours will come to the fore...i.e. reduce Red will accentuate Green etc.

 

If you want to make some sort of comparison between "Exposure" and the Curve effect you can load a test clip to the sequence line and then apply the Exposure effect to it, e.g. over expose the clip.

Now create an image of the result by clicking the camera icon.

Now remove the effect from the clip so it back to the normal exposure..

Place the copied image onto the overlay track above the clip and crop it so areas of both can be seen in the preview screen.

e.g. the LHS is the normal exposure clip on Video Track1 , and the RHS the overexposed clip image on Video Track2.

 

You will now be able to apply your curves to the normally exposed clip (LHS) to emulate the overexposed image on the RHS.

Unfortunately the Curve effect cannot be animated like the Exposure effect.

 

Nat

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Unfortunately the Curve effect cannot be animated like the Exposure effect.

 

Nat

 

Thank you for your tip that exposure can be animated and curves don't.

 

Now I found how curves can make exposure effect

Here we see almost identical results.

 

Thank you!!

 

2cyr81f.png

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