There's also the issue of graphic file type, as some up-scale much better than others, pixelate less...

FWIW, using a 'UV UnWrap' program is often exasperating, as may prove very difficult to match existing mapped texture. Some are 'accessible', others are variously 'optimised', different sections docked like 'Tetris' to minimise 'empty' space. Worse, zones may be 'smudge painted', confounding your attempts to identify detail...

This is less a problem for 'native' Poser items than 'ports': eg Identifying an imported but minimally grouped OBJ or FBX vehicle's lights, mirrors, glazing etc so you can mask physical properties may be trivial or require an iterative hunt. A 'binary chop' of such mapped textures will eventually find the needful, too often tucked away obscurely...