Understanding post-processing in Unreal Engine

In the context of Unreal Engine, post-process refers to a screen pass shader or effect that’s typically applied after the main rendering pass when the entire scene is already rendered: at the end of the rendering pipeline to the entire frame. It acts as a pixel shader that processes each pixel of the final image, independent of individual objects.

So, why do we perform post-processing? Apart from regulating technical algorithms for lighting and reflections, the primary purpose is to adjust the image’s appearance through color grading and tone mapping, which is the process of mapping high dynamic range (HDR) images to a lower dynamic range (LDR) image – in simpler terms, it is the process of remapping all the light information into values that result in a realistic image in terms of light, shadows, and contrast.

This allows us to achieve the desired look, whether it’s filmic, photorealistic, or cartoonish...