Image server
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An image server is a type of web server software that is specialized in delivering images. They are used as a complement to existing web servers such as Apache to speed up image retrieval.
While traditional web servers generally supply clients with static copies of image files, image servers often perform additional useful processing tasks. These image processing functions may include alpha blending, compositing source images, rotating, color adjustment etc.
Applications of image servers
Since images are typically the most bandwidth-intensive part of serving a web page, image servers are typically used to reduce the load on primary web servers.
Image servers are also used for more advanced applications, such as the navigation of very large image sets, the management of various images sizes and regions from a single source, and for streaming media.
In e-commerce, image servers are qualified by their abilities to scale to hundreds of thousands of images, to multiple CPUs or load-balanced server machines, and to the quantity and quality of their image processing functionalities, such as resizing, compositing, zoom and 3-d viewers, and the addition of dynamic data to the images in the form of overlaid text or graphics. Open APIs and standardized client applications add to the value of an Image Server.
A well-known imaging protocol implemented on top of HTTP is known as the Internet Imaging Protocol (IIP). This protocol is promulgated by the International Imaging Industry Association. Implementors of some or all of this imaging standard include Equilibrium's patented MediaRich Server, YaWah, Scene 7 (formerly Truespectra), iseemedia, IIPimage and Sun's Java Advanced Imaging Group.
Additional possible applications of image servers
One problem that plagues web masters is that for their site to be compatible with as many web browsers as possible, they have to use very general images to fit all. An image with a width of 400 pixels will take up half of the screen in an 800x600 resolution, but in a 1280x1024 resolution it will only cover a third. Therefore, if the page is designed for 800x600 resolution it will look considerably worse in 1280x1024. An image server can solve that by dynamically adjusting the size of the image according to the users browser settings. Similarly, old versions of Internet Explorer have trouble displaying PNG and MNG images, but an image server could detect the users browser version and send the image in a supported format such as GIF instead.
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