Here's how to view image specs on a mac:
Find the image you want to check on your desktop (original file).
Select 'Tools' at the top of the window, then 'Show Inspector'.
Alternatively, hold down 'command' + 'i'.
Here's how to view image specs on a pc:
Find the image you want to check on your desktop.
Right click on the image file.
Select Properties, and then view the Summary tab.