GIF Definition

  File Formats

GIF Definition

Stands for “Graphics Interchange Format.” GIF is an image file format commonly used for images on the web and sprites in software programs. Unlike the JPEG image format, GIFs uses lossless compression that does not degrade the quality of the image. However, GIFs store image data using indexed color, meaning a standard GIF image can include a maximum of 256 colors.

The original GIF format, also known as “GIF 87a,” was published by CompuServe in 1987. In 1989, CompuServe released an updated version of the format called “GIF 89a.” The 89a format is similar to the 87a specification, but includes support for transparent backgrounds and image metadata. Both formats support animations by allowing a stream of images to be stored in a single file. However, the 89a format also includes support for animation delays.

Even though the GIF format was published more than a quarter century ago, it is still widely used on the web. Nearly all GIFs use the 89a format. You can check the version of a specific GIF image by opening it in a text editor and looking at the first six characters listed in the document (GIF87a or GIF89a).

Since GIFs may only contain 256 colors, they are not ideal for storing digital photos, such as those captured with a digital camera. Even when using a custom color palette and applying dithering to smooth out the image, photos saved in the GIF format often look grainy and unrealistic. Therefore, the JPEG format, which supports millions of colors, is more commonly used for storing digital photos.

GIFs are better suited for buttons and banners on websites, since these types of images typically do not require a lot of colors. However, most web developers prefer to use the newer PNG format, since PNGs support a broader range of colors and include an alpha channel. (The alpha channel makes it possible for a single image with transparency to blend smoothly with any webpage background color.) Still, neither JPEGs nor PNGs support animations, so animated GIFs remain popular on the web.

NOTE: A GIF image can actually store more than 256 colors. This is accomplished by separating the image into multiple blocks, which each continue unique 256 color palettes. The blocks can be combined into a single rectangular image, which can theoretically produce a “true color” or 24-bit image. However, this method is rarely used because the resulting file size is much larger than a comparable .JPEG file.

How to pronounce “GIF”

According to Steve Wilhite, the creator of the original GIF format, it is pronounced “jiff” (like the peanut butter brand). However, most people still pronounce it “gif” (with a hard G). Therefore, either pronunciation is acceptable.

File extension: .GIF

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