/ic/ - Artwork/Critique

>>3977407
samefag here
Turns out the second method was most likely used.

I've extracted as proof of concept both indirect and direct lighting layer approximations and combined them. Looks close enough.
Layers are blended the following way (from top to bottom):

>1. direct light, blending mode: Linear Light
>2. ambient lighting, blending mode: Hard Light
>3. base values, blending mode: Default

The trick is that "Hard Light" and "Linear Light" take into account value of the pixel from the top layer.
If value is lighter then 0.5 gray then pixel is used to lighten and if it's darker then it's used to darken.
If value is spot on 0.5 gray nothing happens.
Difference between Hard and Linear is based on blend modes used for lighting and darkening.
It's Screen/Multiply and Linear Dodge/Linear Burn respectively
(My choice of Hard vs Linear Lighting was arbitrary).

Overlay is similar to Hard Light but it checks lightness of bottom layer instead, go figure.