If i understand this correctly you want to change all textures but not with some internal settings (nowadays maybe with nodes). So maybe with some node based images processing tools.. like for example mentioned here: https://www.pixcores.com/2022/01/4-free-open-source-node-based-image-editor ?? So you can use the same…
G'mic is "something similar" and there is even an addon for blender to use it with nodes so one does not have to do the scripting (IDK about iterating over all images) . You might have look at the G’MIC Node Editor thread from BlenderArtists.
thanks okidoki but node based something is still too much troubles . I look for some pre-build script that would scan resource folder for texture files with a list of specific suffixes and then process their green channel with certain value remapping or curve editing. Probably a task for chat GPT and Photoshop javascript.…