I’d love to but I didn’t composite in Blender. It kept crashing on me. But I can show you what I did in Photoshop!
First I took the rough passes from Blender
Then I took the AO pass, removed the black from the windows and placed it on top and did an Overlay
If you look at the OG renders, you can see the HDRI in the back and it looks pixelated. So I took a cue from Blender Guru and the Classroom example from the Blender Website, I just blew it out to white. How you want to get there is up to you but I liked the lighting so I just took the window openings and filled them to white.
I thought the volume light was a little light so I took the Noisey Pass and put a screen filter onto of the current render and adjusted the light shaft brightness a little. As a happy bonus, it cleared up some of the darker spots from the OG render
So just to add a little sauce to the render, an old trick I’ve done is a spec bloom. So what that is, you find the brightest spot in your render, color range select, expand it, feather it
From there, you make a new layer and then use a fill, you should be filling whatever the bright color you selected. Then you take your spec bloom layer and find a filter that looks good to you.
So I don’t care what anyone tells you, when you move a render from Program to Program, Your render from your DCC app will lose some detail opening it anything not the original DCC app. When I look at my render from Blender and look at the same PNG is Photoshop, there’s small details that were lost. (or maybe there isnt, i want to think I’m right, Ha!) So an old trick I use is use and Unsharpen Filter. I put the amount to max, a straight 500 and when its done, its a very gritty picture. BUT at that point, you pick a filter, i use darker color and just turn the opacity to something around 20% or less and from that I get a lot of small details that were lost.
So one of the things that always bugs me about some renders are they are too perfect. Nothing is perfect so I force a “human error” So in Photoshop I use a lens correction and go into the advanced settings and force the red and green ranges to push in the positive and negative. This image is obviously way too much but its easier to see what I’m talking about. You find a nice range and then use the vignette and push that into the negative to push the ranges just a little bit more and it also pushes focus
After all that, I did a simple color balance and put my signature on it.
Hope that helps!