Complete Communications Engineering

VOCAL’s implementation of  JPEG2000 image transmission using JPIP enables convenient viewing of detailed maps, medical, and other large image files as individual tiles, layers, or resolutions over IP networks.

JPEG2000 is a wavelet based image compression protocol. One of the most important features of JPEG2000 is that the compressed image data (i.e. codestream) is created in such a way as to allow access to portions of the codestream individually. The nature of the JPEG2000 encoding then allows the user to decode only the portions of the codestream needed to create a version of the original image which is either reduced in size, quality, or both. In the standard ITU-T Rec. T.808, this is taken further with the JPEG2000 Interactivity protocol (JPIP).

JPIP defines a server client interface that allows direct access to these portions of an image directly through a network. An individual tile, layer or resolution is selected at the client side, and only that component is transmitted by the server. This allows the server to only transmit what the client needs for the application, reducing unnecessary waste of bandwidth and resources.

Beyond the bandwidth savings, JPIP has found a lot of use and support in medical applications and in ultra high resolution (> 1 gigapixel) applications. In medical imaging, high resolution lossless images are often required. Traditionally, these images were stored either uncompressed or with low compression so that important medical data was not lost. However, this causes major problems for viewing that image at a remote location (such as in a patients room or home). As medical imaging technology increases, file sizes increase and this problem becomes worse. At the same time, medical care is trending towards home care which makes the need for remote viewing even more important.

JPIP effectively solves this problem. A high resolution medical image (such as an MRI) can be compressed and stored on a remote server using JPEG2000 in lossless mode. Medical personnel can then download only a low resolution wide view of the image. The user can then zoom in on specific portions of the image, and data from those portions will be downloaded to increase the resolution in real time. This is even more useful in a home care situation where data is generally stored on a remote server connected through the relatively slow cellular network.

The current popularity of smartphones presents another obvious application for this protocol. Along with the cellular network connection, these devices generally have a very small screen. JPIP would allow the phone to only download resolution which it is able to display based on the zoom level. This allows a server to hold one high resolution version of an image (a map for instance) and users can access only that portion of the image which they are interested in.