The image ID number can be seen when you hover your mouse over the image, its title, the word “edit” or
“delete permanently” in the Media Library. When you hover the mouse over one of the above, look at the
status bar of your browser window (if you don’t have it enabled, you will have to do so) and you will
see something like
It’s the number (highlighted above) following “attachment_id=” which needs to be mentioned in any include or exclude.