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I have a strange image (actually several) that I need to figure out the type of. It opens correctly in the standard Windows photo viewer, but doesn't make any indication of the type. I can rename the file to .jpg, .png, etc. and it will still open the same.

The first 3 bytes of the file are 'BMB' (not BMP, that isn't a typo) and then it's raw binary data that doesn't translate into readable characters. Usually a tag like this is the file/image format/type. Does anyone know what type of image this is?

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up vote 2 down vote accepted

The magic for Windows bitmap files is actually two bytes – BM, not BMP. The next four bytes are the size of the file itself, and the B is just a coincidence.

Most Unixes, have a file command that can recognize many file formats using a database. For Windows, Cygwin and GnuWin32 come with this command.

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Extra kudos for the link to the file command so I could verify it myself. I feel a little silly for being confounded by a bitmap... – BlargleMonster Aug 26 '13 at 14:54

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