Unhappy [Q] Extracting certain files from .obb

Hello. Noobie here.

I really wanted to get the artworks from the game Deemo. It seems that they're not in the .apk file, so I tried the .obb file. I changed the extension to .zip, but when I opened it up, there wasn't any image files. All I see is the "file" extension name. I was just wondering if there are any ways to extract image files from an .obb file? Thanks in advance.