Sky replacement

Today we learned how to replace the sky on some footage with After Effects. The first way of doing it was to use linear colour key. I imported I used linear wipe on the sky I wanted to add, changed the angle to 0, and the transition to 30, then feathered it as much as seemed fitting. Then, I added linear colour key to the top picture and used the drop tool to chose the blue colour of the sky. Then, played with the softness and tolerance to make it look natural.

Blue sky.png

I first tested a blue sky, then decided to make an evening sky to test my skill. For the evening sky, I made a new solid and parented it to the top layer, then chose a colour for it from the sunset, and added the “hue” mode to it, so that it added an orangey glow to the trees and grass


I then learned a new approach to replacing the sky, the colorama effect. Duplicate the image 3 times, then change the trkMat for the second image to Luma inverted Matte. Then pre-compose the top image, and use using the colorama effect to greyscale the picture, and adjust the blacks and whites. Then make a black solid, tick the eye, then use the pen tool to cover any white spots. Then tick the eye and go back.


Put the new sky inbetween the second and last image. Then pre-compose the top two images, and add a matte choker to it, to take away the white lines around the buildings. Then I added the curves effect to play with the colour channels, and I made the ground darker and brought out the blue.

Night colorama replacement.png

I had some problems with the colorama effect. For some reason my screen kept shrinking, and the first time I tried, my whole first picture went entirely red, so I  started over and that didn’t happen again.

Posted in: VFX

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