I'm trying to write some code to extract Exif information from a JPG.
Exif is stored in the APP1 segment of a JPG file. According to the Exif spec, the format of the APP1 segment is supposed to start like this:
FF E1 // APP1 segment marker nn nn // Length of segment 45 // 'E' 78 // 'x' 69 // 'i' 66 // 'f'
And it goes until there is an
FF followed by something other than
Looking at a JPG in a hex editor, I can see
FF E1 and the
Exif string, but I'm having trouble decoding the length bytes. An example: In one jpg, my hex editor tells me the APP1 segment is 686 bytes long, but the length bytes are
How should I use those bytes to come up with 686 decimal?
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