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Web site Designing - ADOBE PHOTOSHOP

Graphics and graphic design play an important part in building a web site. Graphics provide with a way to establish a visual hierarchy in information. A user viewing a web page will initially see it as a mass of shapes and colors. This is where well-designed graphics supported by good page layout can grab viewer attention.

Graphics are defined in terms of “pixels” or picture elements. Each pixel has a small amount of memory allocated to it for its color information. An image in which only one bit is allocated to a pixel can have only two color’s, since the bit can be either 0 or 1.

When 8 bits of memory are allocated to each pixel, the pixel can have one of upto 256 colours.

This forms the basis for a lot of Web graphics. The GIF, used extensively on the web, is an eight bit graphic format, where the image can have a maximum of 256 unique colours. Eight bits per pixel, which means a Photograph measuring 640x480 pixels a standard monitor resolution, would be 640x480 bytes in size which makes 307,200 bytes, or over 300k. Of course, GIF files use internal compression techniques to reduce the size in bytes, but the fact is - more colours=bigger file size.

Creating small graphics files is key to distributing images on the World Wide Web, with smaller files, Web savers can store and transmit images more efficiently, and viewers can download images more quickly. To decrease file size by saving artwork in one of several compressed file formats. Formats used on Web - Graphics Interchange Format{GIF} and Joint Photographic Experts Group{JPEG}


Higher quality images use less compression {and thus take longer to download} than lower quality images. The JPEG format uses lossy compression method, in which data is discarded during compression.

Data is discarded from a JPEG image each time we save the file. We should always save JPEG files from the original artwork, not from a previously saved JPEG file.

The GIF format uses a losses compression method, in which no data is discarded during compression. GIF file can save multiple times without discarding data. Most images viewed on the Web are created using 24-bit colour displays, but many Web browsers are on computers using only 8-bit colour displays.

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