I can’t believe how miserably GUI tools fail at file formats. So, I received a transparent JPEG recently. After the WTF moment, I ran /usr/bin/file and it told me it’s a PNG file (renamed to .jpg).

Here’s how GUI apps handle it:

OS X’s Finder actually ran the format detection to display it correctly in Quick Look, but didn’t say “PNG renamed to JPEG” as the file format. It just said “JPEG image!”

Photoshop showed an error and refused to open it.