The photos you take are stored as files on your camera's storage device following rules spelled out in a variety of standards adopted by camera companies. These standards assure that files and storage devices can be moved among cameras and other digital imaging hardware and software. Since file storage and organization are so important you should understand how drives, folders, and files relate to one another. When someone takes up digital photography without having mastered these few simple concepts, they may not be able to locate the photos they want to use, or know how to organize their images so working with them is fast and easy.
DCF (Design Rule for Camera File System) defines the entire file system of digital cameras including the naming and organization of folders, file naming methods, characters allowed in file names, and file formats.
A new hard disk drive (1), like an empty file drawer, has no files nor organization. Dividing a hard disk into folders (2) is like dividing a file drawer with hanging folders. Nesting subfolders inside folders (3) is like putting manila file folders into the hanging folders. Files, including images, can be stored in any of the folders or subfolders (4)—or even in the drawer outside of the folders, called the drive's root directory.
You may encounter the interchangeable terms directory and folder. When computers were used primarily by professionals,
the term directory was introduced. As computers became more widespread, the more user-friendly folder was substituted. In photo sharing you'll also find the names albums and galleries used for the same things.
Almost all computers have more than one drive. To tell them apart, they are assigned letters or names such as Macintosh HD, and icons are used to identify their type. For example, the now defunct floppy disk drive was assigned both drive A and B and those drive letters now go unused. The hard drive that the computer looks to for the operating system when you turn it on is drive C. Additional drives vary from computer to computer but often include other hard drives, CD or DVD drives. When you attach your camera, a card reader, or even a digital picture frame to the computer, these too become drives. Many devices are recognized automatically when you plug them in, but a few require you to install small programs called drivers so the computer knows they are there.
Folders are used to organize files on a drive. Imagine working in a photo stock agency where you're told to find a photo of "Yosemite" only to discover that all of the photos the agency ever acquired are stored in unorganized boxes. You have to pick through everything to gather together what you
want. Contrast this with an agency that uses a well-organized file cabinet with labeled hanging folders grouping related images together. For example, there might be a hanging folder labeled California National Parks. If a further breakdown is needed, labeled manila folders are inserted into any of the hanging folders—basically, folders within folders. There might be one labelled Yosemite containing images of the park. With everything labelled and organized, it's easy to locate the images you need. The same is true of your memory cards and drives on your computer system. Both are equivalent to the empty file cabinet—plenty of storage space but no organization. The organization you need to find things on the camera's memory device (which we discuss here) is created by the camera, but on your computer, you have to create it yourself (as you will see later).
If you use operating system tools or applications to look at a storage device in the camera or card reader, you will find it is listed like the other drives on your system. If it contains more than one folder, the one photographers care about is named DCIM (for Digital Camera IMages). If you delete this folder, the camera will recreate it (but not any images it contained). The purpose of this folder, called the image root directory, is to keep together all of the images you capture with the camera. If you use the same card with other devices, there may also be other folders on the same card holding MP3 music or other files.
As you take pictures, your camera automatically creates and names subfolders within the DCIM folder to hold them (like placing manila folders in a hanging folder). The first three characters in a folder's name, called the directory number, are numbers between 100 and 999. The next five characters are known as free characters and can be any uppercase alphanumeric characters chosen by the camera manufacturer. When a new folder is created, as one is when the current folder is full, it is given a number one digit higher than the previous folder. Some cameras allow you to create and name your own folders, or select among folders the camera creates. This lets you route new images into a specific folder and also play back images from just one folder rather than the entire card.
When an image is saved, the camera assigns it a filename and stores it in the current folder. Filenames have two parts, an 8-character filename and a 3-character extension. Think of them as first and last names. The name is unique to each file, and the extension, separated from the name by a period, identifies the file's format. For example, a JPG extension means it's a JPEG image file, TIF means it's a TIFF image file.
Extensions play another important role. An extension can be associated with a program on your system so if you double-click a file, the associated program opens and then it in turn opens the file you clicked. Also, when you use an application program's File > Open command it often lists only those files with extensions that it can open. (You can list other file types but it usually requires an additional step or two). If you change the extension, your system may no longer know what to do with the file.
The first four characters in an image file's name, called free characters, can only be uppercase letters A—Z. The last four characters form a number between 0001 and 9999 and are called the file number. Canon uses the first four free characters IMG_ followed by the file number, Nikon uses DSC_,
and Sony uses DSC0. Once transferred to your computer, or sometimes while transferring them, you can rename images with more descriptive names.
One way to illustrate the organization of folders on a drive is to display them as a tree. In this view, all folders branch off from the drive—something like an organization chart. If any of these folders contain subfolders, those subfolders are shown as a second branch from the first. When using a tree, you can expand and collapse the entire tree or any branch. This allows you to alternate
between a summary of the computer's contents, and details of each drive or folder.
With files stored in folders on a disk, you specify a path to get to them. For example, if a file named IMG_4692.JPG
is in a subfolder named 146CANON
that's in a folder named DCIM
on drive H, the path to that file is H:\DCIM\146CANON\IMG_4692.JPG
. The key elements of a path—the drive, folder, subfolder, and filename—are separated by backslashes (\). You might be more familiar with paths from your Web browser that uses a similar approach using slashes. For example, the URL...
... is a path to a specific page on the Web. Normally you don't type in paths, you click drives or folders to open them. However, many programs display paths on the screen as a navigational aide and so it's easy to confirm the actual location of the file on your system.
Here is the path to the file IMG_4692.JPG in subfolder 146CANON that's in the DCIM folder on drive H. The drive, folder, subfolder, and filename are separated by backslashes.
Here is the path to an image as displayed in Lightroom.