Regardless of whether a person is searching for images to place on her company website or taking pictures for her family scrapbook, the key to a successful digital design experience is to understand the difference between bitmap, JPEG, and GIF files. Each of the file extensions used to label a digital image has its own unique set of advantages and disadvantages.
All images that come from a scanner or digital camera are bitmap files. This file is one that is made up of pixels in a grid. It is a resolution dependent image, so it’s very difficult to increase its size without a noticeable decrease in quality. When a person tries to make a bitmap image larger through an image editing software program, the computer uses a process called interpolation to “guess” what the additional pixels must look like. This may not be noticeable on a computer monitor, but printing the resized graphic almost always results in a blurry and distorted image.
Joint Photographic Experts Group (JPEG) or JPG files are a type of compressed bitmap file. This lossy compression technique reduces the size of an image by discarding details that are typically too insignificant for the human eye to detect. Since the format supports 16 million colors, it does a very good job of analyzing what data is the most important to a particular image. The format is well suited to digital photography, but doesn’t work well for saving line drawings or clip art images that have little available data to compress.
A Graphics Interchange Format (GIF) file is another type of compressed bitmap file. Unlike JPEG images, GIFs are saved using a lossless compression technique. This format works well for line drawings, black and white graphics, or simple text-based images. They also allow transparency and animation, making them quite popular among web designers seeking to create unique effects for their sites. The format is not well suited for photos, however, since it only supports 256 colors.
Choosing what format to use for digital images doesn’t have to be difficult. For printing a photograph, JPEG is the smart choice because it will preserve the vibrancy of the colors with a minimal loss of quality. For simple web graphics and most other types of digital images, however, GIF is the better option.