I'd like to open/load a PSD or AI with Processing and load for instance the 4 or 5 layers from them into different PImage in order to move them on the screen
AI format is more or less PostScript, I think. Not easy to parse, as it is a programming language of its own. But Illustrator can export them to SVG, that Processing can read, with more or less accuracy.
PSD is a proprietary, binary format, probably not publicly documented, so I don't know if there is a Java library to parse it. AFAIK, Gimp can load (some) PSD files.
Answers
You are better of with svg. It will make your life a lot easier. There is only a export library for AI.
I also believe adobe didn't update there reference on AI files since ILL 8.0.
https://processing.org/reference/PShape.html
If you name the layers in AI you can access them by name: https://processing.org/reference/PShape_getChild_.html
AI format is more or less PostScript, I think. Not easy to parse, as it is a programming language of its own. But Illustrator can export them to SVG, that Processing can read, with more or less accuracy.
PSD is a proprietary, binary format, probably not publicly documented, so I don't know if there is a Java library to parse it. AFAIK, Gimp can load (some) PSD files.