File Formats

File Formats

JPEG, TIF, and PNG are the most common file formats and are most commonly used on the Internet.

JPEG, or Joint Photographic Experts Group, image files are one of the choices offered when saving images on digital cameras (the DOS extension for JPEG is JPG). While creating relatively small files, this format supports 8-bit per color RGB (red, green, and blue) for a 24-bit total. Usually, the compression doesn't distract from the image quality.

However, JPEG files have a problem with generational degradation, and degrade more as they are repeatedly saved. Images should always be stored in a lossless non-JPEG format.

TIFF, or Tagged Image File Format, normally saves 16-bit per color (RGB) red, green and blue for a total of 48 bits, and it is a flexible image format. It can also save 8-bit color for a total of 24 bits; the file extension is TIFF or TIF.

The flexibility of this format can be either a feature or a curse; there is no single reader that is able to handle all the different types of TIFF files. TIFF can fall either in the lossy or lossless compression; some types offer good lossless compression for bi-level black and white, no gray images. The option is available on some of the high-end digital cameras to save images in this format, with LZW compression algorithm for lossless storage.

Web browsers do not widely support the TIFF image format, and it shouldn't be used on the World Wide Web.  It is still accepted as the standard for photography in the printing industry. This format is able to handle device-specific color spaces used in particular printing press inks.

Some digital cameras offer the RAW image format; using lossless compression the format creates much smaller files than the TIFF format. However, the RAW format is not used by all manufacturers, and some image editors and graphic programs do not accept this format.

PNG, or Portable Network Graphics, supports truecolor (16 million colors); GIF, which PNG replaced, only allows 256 colors. When an image has large areas of uniform color, PNG is the best format. Many of the older browsers don't support PNG, but all of the modern browsers do.