How to view .obb files? (specifically images)

[Google]

OBB files are just ZIP in disguise. You can use something like WinRAR or 7-zip to open them.

Yeah I know, but as I said in the thread, when I open it with winrar and extract the content, I can't view some of the files (some examples of files I can't open is png or jpg, and is probably due to encryption). PNG Header + hash = ???

Do you suppose there is a way to check if its encrypted, then a way to decrypt it, or why is it so that I can't view the assets?