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Old 21st June 2018, 03:00   #10  |  Link
WorBry
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Join Date: Jan 2004
Location: Here, there and everywhere
Posts: 1,197
OK, here are my best attempts at correcting the 'Cave' clip in VDub2 using only Channel Mixer for the color balance and applying the 'soft-clip' strategy for dealing as best with the 'skylight'.



Input was the source clip pre-denoised with SMDegrain (same as used in the Resolve grade) - I've yet to get reacquainted with hqdn3d

The applied filters were, in order:

* 'Soft-clip' applied with RGB Gradation Curves
* Channel Mixer
* 6-axis Color Correction - saturation only
* Levels - adjusted only the black point (Input level 44) (I know, why didn't I use '6-axis' - old habits I guess)
* Unsharp Mask
* Color Tools - for scope monitoring, and Resize, Crop when I needed them for isolating the neutral references.

No added contrast was applied - it only hindered the sensitive 'skylight' workaround. Hardly needs contrast anyway.

The first two results (Mix 1A and B) were obtained using the skylight itself as the neutral reference for the channel mix. Mix 1B is a tad warmer. As seen in the Resolve grade, there is more of a residual blue tint on the Sergeant Major fish. The other two results (Mix 3 and 4) attempted to lessen that and reach a better compromise, but at the expense of an arguably less appealing greenish tinge on the margins of the skylight glow.

In all 4 cases I tweaked the 'soft clip' as best to limit spread of the skylight 'glow' whilst avoiding discoloration of the (now obscured) opening. The 'soft clip' curve is not as smooth as I would like - there's a bit of posterization coming through at the outer margins of the skylight glow as it spills over the rocks, but it's difficult to get right by hand. 'Poetic license' might see that as the contours in the rock, which is fine by me. In the original clip there were some flashes of what looked like reddish lens flare on the left side of frame, so attribute it to that

Personally, I think Mix 4 is a bit too green, and it's between the other three. For the fish I'd say Mix 3. For the 'skylight', Mix 1A.

What does Toupe Turtle think ?

http://birdsasart.com/248/Pacifc-Gre...-Galapagos.jpg

Errrrrrrrrrrrrrrrrr......none of them
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Last edited by WorBry; 21st June 2018 at 16:37.
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