Differences Of Image File Formats
JPG (Joint Photographic Experts Group)
The JPG file format, short for Joint Photographic Experts Group, is a type of image compression that works best with photographs and complex images. JPGs use a compression method that removes non-human-visible colors from images to decrease file sizes. Be careful, though. If you decrease the quality of a JPG too much, you will begin to lose important color information that cannot be recovered.
The JPG file format also allows you to save progressive JPGs, which will load in stages. You may have experienced this before when visiting a website and watching as an image slowly loses its blurriness and becomes clearer.
Use JPGs for product photos, human portraits, and other images where color variances are important. Do not use JPGs if you need transparency, which is the ability to see through an image and decipher the background behind it. JPGs do not support transparency.
PNG (Portable Network Graphics)
PNGs, or Portable Network Graphics, were created as an alternative to the GIF file format when the GIF technology was copyrighted and required permission to use. PNGs allow for 5 to 25 percent greater compression than GIFs, and with a wider range of colors. Like GIFs, PNG file formats also support transparency, but PNGs support variable transparency, where users can control the degree to which an image is transparent. The downside to advanced transparency in PNGs is that not all older browsers will display the transparency the same.
PNGs also support image interlacing, similar to GIFs, but PNGs use two-dimensional interlacing, which makes them load twice as fast as GIF images. If you are interested in this interlacing technology.
GIF (Graphics Interchange Format)
A GIF, or a Graphics Interchange Format, reduces the number of colors in an image to 256, from potentially thousands of colors coming from a digital camera. GIFs also support transparency.
GIFs have the unique ability to display a sequence of images, similar to videos, called an animated GIF, which is a series of separate GIF images that are linked together to automatically create motion, or animation.
GIFs, like JPGs, also can load in segments on web pages. These images, known as interlaced GIFs, tend to be slightly larger than regular GIFs, but they allow a GIF image to be partially visible as it is loading on a web page.
GIFs can be used effectively for limited-color images, such as logos and graphs, or for images where transparency is important. Do not use GIFs for full-color product photos and staff portraits, for example, where color variances are important, as GIF colors are limited to 256.
Although the GIF format is still in use, it should generally be avoided in favor of the PNG format, which does nearly everything better.
SVG (Scalable Vector Graphics)
Scalable Vector Graphics (SVG) also deserve a mention. SVGs are a web standard based on XML that describes both static images and animations in two dimensions. The standard has been around for more than a decade, but with the recent emergence of HTML5, it is finally coming of age. For now, know that SVG allows you to create very high-quality graphics and animations that do not lose detail as their size increases. This means that with SVG you could create one graphic that looked great on a tiny mobile phone screen or a 60-inch computer monitor.
TIFF (Tagged Image File Format)
The TIFF (Tagged Image File Format) format is a flexible format usually using either the TIFF or TIF filename extension. The tagged structure was designed to be easily extendible, and many vendors have introduced proprietary special-purpose tags with the result that no one reader handles every flavor of the TIFF file. TIFFs can be lossy or lossless, depending on the technique chosen for storing the pixel data. Some offer relatively good lossless compression for bi-level (black&white) images. Some digital cameras can save images in TIFF format, using the LZW compression algorithm for lossless storage. TIFF image format is not widely supported by web browsers. TIFF remains widely accepted as a photograph file standard in the printing business. TIFF can handle device-specific color spaces, such as the CMYK defined by a particular set of printing press inks. OCR (Optical Character Recognition) software packages commonly generate some form of TIFF image (often monochromatic) for scanned text pages.
EXIF (Exchangeable Image File Format)
The Exif (Exchangeable image file format) format is a file standard similar to the JFIF format with TIFF extensions; it is incorporated in the JPEG-writing software used in most cameras. Its purpose is to record and standardize the exchange of images with image metadata between digital cameras and editing and viewing software. The metadata is recorded for individual images and includes such things as camera settings, time and date, shutter speed, exposure, image size, compression, name of the camera, color information. When images are viewed or edited by image editing software, all of this image information can be displayed.
The actual Exif metadata as such may be carried within different host formats, e.g. TIFF, JFIF (JPEG), or PNG. IFF-META is another example.
