IIPImage is an Open Source light-weight client-server system for the remote viewing of very high-resolution images. The project is designed to be bandwidth and memory efficient and usable even over a slow internet connection. The system is fast because the client only needs to download the portion of the whole image that is visible on the screen of the user at their current viewing resolution.

The client requests a view of an image and the server only needs to send back the image tiles necessary for that particular view. This makes it possible to view, navigate and zoom around very large images that would be impossible to download and manipulate on the local machine. It also makes the system very scalable as the image tile downloads will take the same regardless of the size of the source image. In addition, to reduce the bandwidth necessary even further, the tiles sent back are dynamically JPEG compressed with a level of compression that can be optimized for the available bandwidth by the client. In this way it is possible to view extremely large gigapixel images in real-time over the internet.

In order for the system to be as efficient as possible, the images are stored in the multi-resolution TIFF tiled pyramidal format. This allows the server to extract regions of the full image at different resolutions very quickly with little processing overhead. Image of several gigapixels in size can be stored on a central server and viewed by many different users without the need to download large amounts of data.
The system was originally devised by the National Gallery in London and the University of Southampton for the Viseum (1996) and Acohir (1999) EU projects.

The aim of these projects was to create a system for viewing very high resolution colorimetric museum images over the internet. In the case of Acohir, to extend the system to handle 3D object sequences. A published paper describing this work is available online. The current versions of the software, though, have been completely rewritten since then. This kind of system, though, is also applicable to other areas such as geographical informations systems or medical imaging.

Here are some key features of "IIPImage":

· Fast lightweight Fast CGI server module that can be embedded in most web servers (Apache, Lighttpd, MyServer etc)
· Several clients available - java applet, javascript etc
· Instant dynamic generation of JPEG overviews or details at any resolution
· Allows easy viewing of extremely large images (gigapixel size) with no significant memory requirements
· Standard TIFF-based image format that can be read by many image processing tools (Photoshop, GIMP, VIPS etc)
· 16 bits per channel image handling
· Greyscale, sRGB and CIE L*a*b* colour spaces
· Panoramic 3D object image sequences
· Secure image distribution: only JPEG-compressed views of the image are sent to the client. The full-resolution image does not need to be accessible
· Example uses: high resolution museum images, geographical information systems, medical imaging etc.

Whats New in This Release:

· The major new feature is a hillshading function for image relief maps.
· In addition, major stability and performance enhancements have been made to the tile cache.
· There has also been a major code cleanup and refactoring to make the core fully modular.