Problem creating mask for blown-out sky

[OldRadioGuy]

Is there a way to use a 2-color black and white layer as a mask to replace a blown-out sky rather than the Layers/Channels panel Mask -> Convert for Previous procedure, which in my project produces jaggies/ghosts between the remaining foreground and the new sky? There is no adjustment in the Tool Settings to deal with this.

My layer stack is:

1. black and white image (2 color, selected layer)
2. copy of original image
3. clouds to replace the blown-out sky
4. original image/background (off)

Thanks in advance.

Bob

[Hoogo]

A real 2-color-mask, only made of true black and true white, is mostly useless for real-world pictures. No matter how sharp a lens could be, the pixels at edges always are a mixture of fore- and background. If the foreground is black and the background is white, there will always be a whole bunch of different grays where they had to share a pixel. When you try to separate the foreground from the background, the color of the foreground is poisoned. The foreground isn't gray, it's black with some amount of coverage (=transparency).

First step to solve that is to use a gray scale mask instead of a monochrome mask. Create a mask where the real 100% foreground is white and the real 100% sky is black, and all the pixels in-between have a kind of gray. For blown out skies I would try "tool > color > select color, chose "smooth selection" and "new image" as destination, enable color warning (the button with the red blob on it at the bottom of the preview), select white and increase tolerance until the real foreground gets selected, too. Then you are too far, decrease the tolerance again a bit.

Or try paths or any other method of creating a mask.

Turning that layer into a layer mask is the first step to solve the problem. If the new sky is quite similar to the old one, this might already be enough. But if the new sky is clearly darker, then you will find that there are bright halos around the foreground where some parts of the old sky are still mixed into the picture. The poisoned colors have to be cleaned up.

Can you follow so far?

[franky68]

This cirtainly is not what you've been looking for so please forgive me if my approach does not help but did you try blending the replacement sky into the original image by using the blend-mode "darken"?

If the sky is blown out it usually is plain white and brighter then the sky you using for replacement. If you have other white parts in your image its pretty easy to mask them out with a brush.

Thats what I am doing. Maybe it helps?

Kind regards
Frank