Original filepath when importing a file

Hey guys,
I am trying to create a texture programmatically when importing a custom file.
When I drag the file in one of the folder of my project in unity, I already have an assetpostprocesso running but...the path I read is the new one, and instead I would like to read the original coming from the directory I dragged the file FROM.
I need that because in that directory (and subdirectories) there are other resources I need to import as well.

Is there any way to do it ?

Thank you!