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White sky replacement

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Michiel Xyz
White sky replacement
on Jul 6, 2014 at 11:43:02 am


I'm bizzy on a vacation movie in Africa and I want to color grade a white sky to a blue sky. I have tried many tings: sony vegas color correction, BCC color correction, BCC color key and replace the sky, masking in after effects, color keying in after effects. Nothing works.... Can anyone help me, if there's another way to do this (or just know how to do it better)?

I've included the files:
---Yeah this isn't a blue solid it is actually a perfect blue sky.---
---This is the video file.---



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Oki Pienandoro
Re: White sky replacement
on Jul 6, 2014 at 2:03:06 pm
Last Edited By Oki Pienandoro on Jul 7, 2014 at 5:21:39 pm

If you intend to make sky replacement on the whole footage. I don't think it would work with color correction. The first part of the video is completely washed out (255 on all channel).

The best approach is probably separate them into two/three parts. Since the sky on the later part of the footage is not washed out.
You can key out the white using extract key/luma, put solid underneath

Here's my take, obviously this can be improved if you're willing to mask-out trouble area. :

Sorry for the english, not native speaker.

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Dave LaRonde
Re: White sky replacement
on Jul 6, 2014 at 8:51:05 pm

Here's the deal on this kind of sky replacement: the leaves kill you.

There is a phenomenon known as Light Wrap, where a bright background -- like a white sky makes the edges of darker foreground objects brighter... like leaves.

I'll bet that on your best attempt, the leaves still looked funny. I'll also bet that the camera moves in these shots... not to mention the leaves.

You would have to devise a way to tell After Effects to 1) find the leaves 2) make the edges of the leaves a lot darker and 3) affect nothing else. Then you could do a pretty darn cool sky repplacement.

.....assuming, of course, that the trees and everything else in these shots had SOME kind of sunlight falling on them. But if they dont, think about this: the sky eould be blue, bright & shiny... but the foreground objects wouldn't have any shadows falling on them!

Anyone looking at such a shot would instantly smell a rat-- "Fake! Fake! Fake!"

See the issue?

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

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John Cuevas
Re: White sky replacement
on Jul 7, 2014 at 1:48:09 pm
Last Edited By John Cuevas on Jul 7, 2014 at 1:57:02 pm

It's an extremely long shot, so you might want to do some editing---particularly when you pan from the land to ocean.

I adjusted the color of your sky background to be a bit more natural. For your foreground---I precomp and did added an auto contrast. Then in the master comp, I just used a luma key effect---set it to key out brighter, increased the edge feather, then added a simple choker to pull back the areas where "light wrap" would come into play. The simple choke cut off some of the top and bottom, so I scaled up a little.

Take a look at my project, it should give you a starting point on how to proceed. Mine was pretty quick & rough, so in the end you will need to do some masking, and I would probably color correct the entire final result also.

Johnny Cuevas, Editor

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.

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