Photoshop isn't the only useful thing you can use via a subprocess call. GIMP (https://www.gimp.org/) has an easy usable Python-Interface for years. ImageMagick is a tool made fo be called via subprocess (original download: https://github.com/ImageMagick/ImageMagick). OpenCV is maybe the most advanced tool if it comes to image processing. And the list goes on and on, Most of them Open Source and free to use.

With P12 it is even possible to use mutch of this tools "embedded" in Poser instead of using subprocess calls. Because PIP is supported in P12.

Do you know "Krita"? (https://krita.org)

from krita import *

d = Krita.instance().createDocument(512, 512, "Python test document", "RGBA", "U8", "", 120.0)
Krita.instance().activeWindow().addView(d)

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