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Using footage luma value to drive opacity of effect
I’m not really sure if i’m using right terminology here, but this is what i’m trying to achieve:
i have a shot of a flickering candle which i’m adding lens bokeh to on a separate level. It would make sense that effect’s opacity/intensity changes with amount of light candle is giving off.
Right now i have effect’s opacity animated manually, i keyframed opacity value for each frame, but there has to be a smarter approach to that…i’m just not sure how to get an overall luminosity value of the whole frame.thank you,
-Katya -
4 Replies
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try something like this:
target = thisComp.layer("Candle"); // this would be your footage layer
maxO = 100; // set the max opacity value
minO = 0; // set the min opacity value
lum = rgbToHsl(target.sampleImage(anchorPoint, radius = [target.width/2, target.height/2], postEffect = true, t = time))[2];
linear(lum, minO, maxO)you’ll need to change the first line so that your candle footage layer name is in the quotes and then use the maxO and minO values to adjust the range of opacity that you want per luminance of the frame.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW -
This expression is crashing my CS6. Everytime I apply it.
Is anyone else having this problem? Is there a difference in language for CS6? or alternative expression I could use?
target = thisComp.layer("Candle"); // this would be your footage layer
maxO = 100; // set the max opacity value
minO = 0; // set the min opacity value
lum = rgbToHsl(target.sampleImage(anchorPoint, radius = [target.width/2, target.height/2], postEffect = true, t = time))[2];
linear(lum, minO, maxO) -
I can’t get it to crash with that expression. Are you running Version 11.0.1.12?
Dan
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I am running 11.1.. I’m getting a few errors at the moment perhaps these are symptoms of a larger issue.
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