Recently we’ve receive a obj file with .mtl and a image pack folder.
When importing to Rhino it appear “Could not find image file” with previous owner’s image path.
You can open the MTL file in a text editor, search for, and replace the relevant parts of the texture paths.
Keep a backup of the original MTL file though, in case this doesn’t work.
If you’re unsure about your current path you can open a terminal and simply drag and drop the MTL file onto its window. This will give you the absolute path to that file.