I’ve used Photoshop for texturing for years. Anyone who has used software for such a long time gets comfortable with its functionality, quirks, UI, etc. My favorite function, by far, in Photoshop was Blend-If. It was almost a “make awesome” slider. Blend-If will “knock out” pixels of a current layer based on the shadows/midtones/highlights of itself, or the layer beneath. This function was essential in creating believable masks or combining photo-sourced textures.
I made a Substance node that emulates Blend-If.
Here, two images are plugged into the Blend-If Color node.
Blending by Base Map will make the Top Map visible based on the shadows/midtones/highlights of the Base map. Turn it off and it will just use the Top Map’s values. You can change blend mode, the range of clamps, and the inward and outward falloffs.
I wanted to take the crud pattern of one image and believably apply it to another. Blend-If is the only way to do it right. Here is the result from Substance Designer:
Greyscale maps can also be used to get really unique masks that don’t look like ones prebuilt from SD:
Download here: https://share.allegorithmic.com/libraries/1152