#Convert image format change file extension windows#
I'm personally more familiar with the Windows filesystem. Using Paint on Windows to save a PNG to JPG format indeed changed the header from PNG to JFIF, and subsequently its contents. Neither in Ubuntu nor Windows I've been able to spot a difference. I also encourage you to display the header on your terminal through less to not overflow it, or even better, head -c 100 to only view the first 100 bytes to get a grasp of what cmp and your OS is actually reading. You can even check if there really is any difference between the two files comparing them using the GNU cmp utility together with the -verbose -bytes=100 options to limit and view the differing bytes. In Linux this is a given since you always specify the program you want to open your file with. Is there some similarity between these formats which allows this to be done?Īlthough some similarities exist between the two file formats, the main point is that the extension in the filename does not always represent the filetype its describing. You must be doing something different than I do. To be really sure about filetypes, there is a command called file that shows you detailed file information.įrom my personal experience, I can tell that, at least on my system, EOG cannot be tricked into recognizing a renamed image file. jpg, while in reality they are being tricked into running a malicious exe! Viruses sometimes exploit this "feature" by making the user believe they are opening a. This way, a file named "document.pdf" will show as "document", and renaming it to "document.dvi" will actually be processed as "". Explorer practices a behavior by default that cuts off the file extension from the filename. This all may apply to Ubuntu, Windows is a completely different story. It's just that Linux applications tend to rely on different detection methods than file extensions, though many modern desktops actually look for the file extension to determine what application to open, since this method is probably quicker. Note that the behavior of EOG may very well be exceptional, and also beware that no actual conversion is done. I suspect this application does not determine the file type based on the extension, rather it seeks for the magic number. png: these are all handled by EOG (GNOME's Eye Of Gnome). The application designated to open files with the file types you mention, is the same across all of those.gif.
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