Software

True vs. Web image formats

There are a variety of image formats. Find out when you should true image format and when you should use a Web image format.

By Paul Anderson

Anything stored on a computer or sent over the Internet is in a specific format. Images are no exception, and there are a wide variety of image formats in use today. Your choice of image format is based on a variety of factors, such as whether you plan on editing the image in the future and whether you want the smallest possible image for downloading over the Web, or what image editing tools you have at your disposal.

When you want to save or keep a copy of an image for further editing, you need to pick a format that records the image correctly, without losing any details. These are typically called true image formats. As long as you store your original images in a true image format, you can re-edit them later without losing any quality.

However, true image formats tend to have large file sizes, making them unsuitable for sending over the Internet. For Web images, you want to pick a format that will result in the smallest possible file size. The two most common today are the Graphics Interchange Format (GIF) and the Joint Photographic Experts Group (JPEG). The key is that both of these formats compromise the image for the sake of compression, so you shouldn't use them to store original artwork that you may want to modify later. (The exception is an image with no more than 256 colors, which can safely be stored as a GIF.) Most image editors offer a Save As or Export command to let you safely create separate GIF or JPEG versions for posting on the Web while saving the original in a true image format.

Paul Anderson is associate technical editor for CNET Builder.com. His responsibilities don't include handling graphics, so naturally, he handles them all the time.

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