Graphic Format

There are many graphic formats available; the most commonly used are Joint Photographic
Experts Group (JPEG), Graphics Interchange Format (GIF), and Portable Network Graphics
(PNG).

The difference between each graphic format depends on the following characteristics:

Color Depth – It is defied by the number of distinct colors that are represented by a hardware or software. Color depth is defied by the number of bits per pixel (bpp) and it is also called as bit depth. Higher the color depth indicates higher range of colors used.

Compression/file size – Graphic files are large, so images are compressed using various techniques. Compression stores the original images in a reduced number of bytes using an algorithm. This image can be expanded back to the original size using a decompression algorithm. In some compression formats, images with less complexity results in smaller compressed fie sizes.

The two types of image fie compression algorithms used are as follows:

Lossless compression – In this algorithm, fie size is reduced but preserves a copy of the original uncompressed image. Lossless compression avoids accumulating stages of re-compression when editing images.

Lossy compression – In this algorithm, a representation of the original uncompressed image is preserved. The image appears to be a copy of the original image but in actuality it is not a copy. Lossy compression achieves smaller fie sizes when compared with lossless compression. Generally, lossy compression algorithms allow variable compression that comprises on image quality for file size.

Animation – Some graphic format consists of a series of frames that are played one after the other giving an impression of animation. Animated graphics are typically used on a Web page to attract visitor’sattention.

shows an animated graphic.

Transparency – It is very common on the Web to display an image on a Web page that appears directly against the background color of the page. The background color of the Web page shows through the transparent portion of the image. In a transparent image, one and only one color can be hidden. If the color chosen to make transparent is same as the background of the inserted image, then an irregularly shaped image appears to flat on the page. Figure shows a transparent image