An image server is web server software which specializes in delivering (and often modifying) images. However, not all image servers support HTTP or can be used on web sites. While traditional web servers generally supply clients with static copies of image files, image servers usually perform additional image processing before serving the file. These functions may include frame/format selection, resizing, cropping, alpha blending, compositing source images, rotating, , and filtering. A major use of image servers is to support browser-based pan-and-zoom viewers. port/1188