How to apply zdepth for distance fog

[Crayox13]

Hi guys,
so I just applied a bit of zdepth but I get terrible edges on my trees on the background image. I use PS for composting, and applied zdepth in "screen" mode.

You can see it in the upper part of the image trees over blue sky.

Without the zdepth overlay the transition is normal.

[Svetlozar Draganov]

I believe it should be in a "normal" mode not in screen mode.
How exactly did you apply the zdepth element, with Lens Blur Filter with Zdepth element as Alpha Mask?

[Crayox13]

No actually I wanted a bit of distance fog, so I used "screen". With screen (similar to Linear dodge or add) Dark areas basically don't affect the overall image and bright areas (in the distance) give it a bit of fog. If I use normal, dark (near) areas will darken my image.

[Morne]

Try an unfiltered version of the zdepth (default is filtered) You'll have to rerender to get it

On a side note, for that image, the blue sky is way too blue. Make it much lighter

[Morbid Angel]

I typically create a colored layer (for the ozone color) and use zdepth as alpha (mask) to dial it in as intensity over the entire image. You shouldn't screen or add the fog on since its technically not correct. If anything the fog terminates / scatters the reflected light so the brights / mids become less visible.

[Crayox13]

Oh cool, will try both, turn off filtering and this better method of applying the fog.
Thanks!

[Crayox13]

Yep, filtering got rid of those weird edges! Thanks!