Artist's way of visualizing depth

[Josip_ZG]

There is something I'd like to share with you. Don't know if anyone approached post-processing in this way before and would love to hear some opinions or even make others who can do it better interested in showing what can be done with it. I browsed internet for a very short time to see if it there are Photoshop tips about it already, but my basic keywords didn't return anything bar photographic depth of field.
Long story, short, you know that colder tones are perceived as further away and warmer tones are percieved as closer to the spectator of the image. It can especially be seen in classical paintings. It can be used in landscape or any other type of exterior renderings where you want the focus to be on the foreground. Or even change the game and make the focus on the background by switching the warm-cold locations.

This is how it goes:
Render out an image with depth pass. Paste it on the original image in PS as a separate layer. Go to adjustment layer and choose curves. Change the blending mode to color (so it doesn't affect your lighting, just the color!). Make adjustments to emphasize red or magenta or yellow (or combine all of them for the best effect) and paste the depth pass into this newly created layer mask by:
1) copying the depth pass
2) click+alt on layer mask of curves, it will open the mask only.
3) now paste it
Do the same thing again: create another curves adjustment layer, this time make cold colors emphasized (cyan, green, blue). Again, in the described way paste the depth pass into the curves layer mask.
Now you need to play. To be better at this game, know that where the mask is darker it means the curves will have less effect for each respective layer. On the layer whose toning you want to affect closer objects, you need to invert the depth map (image -> mode -> invert) so that whites are closer and blacks are further away. Make brightness and contrast adjustments by using levels on each mask (don't forget to hold alt while clicking the mask! Otherwise, you'll be changing the nearest active layer).

Here are examples of some of the many paintings that utilize this technique and my own post-processed renderings.
These are my old interior renderings, so it's not the best way to showcase this ability, but you'll get what I mean.
I'm also planning on making a tutorial on this technique with a different render.

(first render - nothing; second render - cold tones are closer; third render - warm tones are closer).

[RRIS]

Interesting, but I imagine this mimics what you see in real life long distance views, where the haze in the air colors the objects in the distance (a very unscientific way of saying it). It's a trick to use when painting or rendering such long distance views, that copies what your brain is used to seeing in real life.
I'm not really convinced this same trick works on any subject, no matter the distance..

[Esben Oxholm]

Hi Josip.
Thanks for sharing the process.

What you describe is usually referred to as arial or atmospheric perspective and is caused by the lightening and blue-tinting effect the atmosphere have on object the further away from the camera they are.

Although there is nothing wrong with using this on an interior shot, I don't think it will give you the effect of depth, as the interiors are too small for this effect to happen (in real life at least). Using the technique on exterior shots will make more sense to me

But again. Thanks for sharing. You never know what results will emerge from using know techniques in unusual ways.

[Josip_ZG]

Thanks for your comments.
Interiors are not big enough, that's true. Neither is there sky in any kind of closed interiors regardless of the size, so it's hard to justify the effect with a realism argument. In my shots it just looks like ordinary colour grading. I rarely render architecture and have never done a landscape render. If I ever achieve something notable with this in large exteriors, I'll post it here.
It was mostly interesting to me because of how you can use an image with 3D information to mask layers and apply effects according to distance.

[RRIS]

Ah yes, using the depth map to apply certain effects can be quite interesting, beyond atmospheric perspective. Like applying artistic filters to the background, or b/w.. etc.

[DMerz III]

  thanks for sharing, I have never thought of playing with tone mapping using the Z-depth pass quite this way, it is a nice lever to have for more artistic shots, regardless of the fallacies it might present in some shorter distance renders.