When you saved the logo from the official site you probably saved the file as doop jpg since that s what the site calls it The jpg extension is a good indication that the image is in the JPEG format If you don t see file extensions on your computer Windows XP hides them by default you can always right click on any image on a Web page and select Properties or something similar there should be a field in the Properties window called Location or Address or the like that will show you the URL of the image which is as before the jpg extension is a good indicator that the image is a JPEG So that original image is already compressed as a JPEG and it will already have compression artifacts But that site doesn t seem to be an official Futurama site it seems to be a fan site unrelated to Fox or any of its affiliates So it s possible that there is an official Fox page that will have a PNG version of the DOOP logo more likely you will find a GIF version which can be losslessly converted to a PNG But you ll have to do some searching