Design Rule For Camera File System - Directory and File Structure

Directory and File Structure

The filesystem in a digital camera contains a DCIM (Digital Camera IMages) directory which contains possibly multiple subdirectories with names such as "123ABCDE", which consist of a unique directory number (in the range 100…999) and five alphanumeric characters, which may be freely chosen and often refer to a camera maker. These directories contain files with names such as "ABCD1234.JPG", which consist of four alphanumeric characters (often "DSC_" or "IMG_"), followed by a number. The file extension is "JPG" for Exif files and "THM" for Exif files that represent thumbnails of other files than "JPG". Other file formats use different extensions. Multiple files sharing a number (even if the file extension or the four alphanumeric characters are different) are considered related and form a DCF object.

For example, the files on a Nikon D40 are arranged according to the above specification. Thus, a card formatted by the camera will have a partition named "NIKOND40", with a subdirectory named "DCIM". This directory contains a subdirectory named by default "100NCD40", in which images are stored. Images are named "DSC_xxxx", where xxxx represents the file's sequential number.

As this is an industry standard, similar directory structures and naming procedures can be found in most digital cameras.

An example of DCF directory and file structure:

  • Root
    • DCIM (directory)
      • 100ABCDE (a DCF directory)
        • ABCD0001.JPG (a DCF basic file or DCF optional file)
        • ABCD0002.JPG
        • ABCD0003.TIF (a DCF extended image file)
        • ABCD0003.THM (a DCF thumbnail file for extended image file; it is not allowed for ".JPG" files)
        • ABCD0004.WAV (a DCF object need not include an image file)
        • ABCD0005.JPG
        • ABCD0005.WAV (a DCF object formed by naming non-image file with the same file number as an image file)
        • ...
        • ABCD9999.JPG
        • README.TXT (other file names and extensions may be assigned freely)
        • ETC (directories other than DCF directories are also allowed; they shall not have the same name as DCF file)
      • ...
      • 999ABCDE (a DCF directory)
        • ABCD0001.JPG (a DCF basic file or DCF optional file)
        • ... etc.

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