Within the controls of the digital camera, the photographer is given a choice of file types ranging from the low quality Standard Quality (SQ), to the very large TIFF, to the color negative of the digital world, raw. Your choice will forever impact your ability to edit, print, and manage the image.
■ Standard or High Quality If you are shooting images for web use, and the images will always remain small or for web only, you should consider using this file type. Limited by its small (640 × 480 or a bit larger) file size, a 4 × 6 inch photo is about as large as you can print this file. In addition, any work on the
image done in photo editing software will further deteriorate the quality of the file. Generally, these image files will be less than 1MB in size, which is a good size for sending as e-mail attachments or for web gallery display.
■ Best Quality with least compression JPEG A great, all-around file type to shoot, JPEG has been available since 1986. Compressible in varying degrees, this file will take up less space on your hard drive than a raw image and will print quite well. However, remember that you should always do your editing/ tweaking to a TIFF or PSD (Photoshop) file that you have converted from the original JPEG, not the original JPEG. For the A Day in the Life of Africa book project, we all shot JPEGs. These images
were reproduced in a large coffee table book, and they looked beautiful. On a 5 megapixel camera, these files are each about 3MB in size.
■ Raw Think of this file type as closest to a color negative. This is pure data, meaning that no in-camera processing (sharpness, white balance, saturation, or contrast) will be imposed on the file. In raw, the image, as it is seen, is recorded. Many pros shoot only this file type, because it gives them the greatest control over their images. However, you must convert the raw files in either the proprietary software that comes with the camera or with Photoshop CS43 or CS4. This can slow down the editing process, as each image has to be opened and then saved as either a JPEG or TIFF. A side benefit to this, however, is that if anyone claims a photo has been altered or manipulated, you can show the raw file, which is unalterable. National Geographic has decided to handle the controversial manipulation issue by requiring that all digital shoots for the magazine be done
in raw.
The raw algorithms written by each manufacturer are a closely guarded secret. Conversion in anything but the proprietary converter does not take full advantage of the raw file, and doing this
type of conversion can cause noise in the image and imperfections in shadow detail. Proprietary conversion is being challenged by Adobe Camera Raw, as it is suggesting that proprietary development of raw is
unnecessary and that Adobe can do as well or better. The Adobe DNG (Digital Negative) format was developed to address the lack of an open standard for raw files created for each digital camera. DNG allows photographers to archive their raw camera files to a single format (DNG) for easy access and cataloging of those files.
Upon opening raw files in a raw converter, the photographer has the choice of an 8-bit or 16-bit file. This is very important, as a 16-bit file provides a much larger well of color on which to draw. This allows you to perform critical
adjustments such as levels and curves with far less deterioration of the image file.
If you want to function well within the digital darkroom, you should use the raw format for its absolute controllability.
■ TIFF Fewer manufacturers are incorporating TIFF files into the working file types. Raw provides more control of the image at a smaller size. TIFF files will be the largest files to reside in your media card or hard drive. About five times bigger than a JPEG, a TIFF file offers a great advantage, in that it will not lose data when it is opened, tweaked, and saved, regardless of how many times this is done. Because a “lossless” compression can be used, the image file can take up less space. TIFF is a good file format for shooting large prints, as the artifacts (tiny, jagged edges that appear as the file is enlarged) that inhabit JPEGs will not be evident in a TIFF.
All digital cameras record images at a 43
bit depth of 12 or 14 bits. When you shoot TIFFs and JPEGs, the camera uses its internal settings to create an 8-bit image, throwing away perfectly usable image information. A raw file will allow a file with more bit depth to be created, giving the photographer far more color information to draw from when working on the file.