Abstract: In a method and a system for retrieving images in a client-server system, images are stored as a set of independently decodable units (CU's) on the server. A client issues a series of requests for image information. Each request contain a request number, information on what image information the client wants to see next and information on what image information the client had received at the time when the request was issued. The server does not have to store any state information (e.g. previous requests). On receiving a request, the server sends a restart marker, a confirmation of the request number and incremental image information corresponding to the request. The use of the method and the system as described herein will result in that no decoding of the whole bit stream will be required in the server. This will save a lot of time at the sender side (server side), since it not needs to a full decoding of the stream.

Abstract: In a method and a device for partial encryption and progressive transmission of images, a first section of the image file is compressed at reduced quality without decryption, and a second section of the image file is encrypted. Users having access to appropriate decryption keywords can decrypt this second section. The first section together with the decrypted second section can then be viewed as a full quality image. The storage space required for storing the first and section together is essentially the same as the storage space required for storing the unencrypted full quality image. By using the method and device as described herein storage and bandwidth requirements for partially encrypted images is reduced. Furthermore, object based composition and processing of encrypted objects are facilitated, and ROIs can be encrypted. Also, the shape of a ROI can be encrypted and the original object can be decrypted and restored in the compressed domain.

Abstract: The real-time performance in communications networks is improved, especially between a large number of participants, by a server unit having a device for receiving information from at least a client unit, the information including at least part of the state information about a distributed interactive application. The server unit includes a device for storing application state information received from at least one client unit, and a device for forwarding the state information received from the client to at least one other node in the network and for transmitting at least part of the information stored in the state information storing device to the at least one client. In this way, the whole state of the application can be kept in one or more units in the network, which removes the need for each client to store the entire state, thereby reducing memory and bandwidth requirements for each client.

Abstract: In transmission of bit plane coded (23) digitalized moving pictures, which are subject to a motion compensation (19) and an object based segmentation the bit planes are transmitted in order of decreasing significance. An incremental motion estimation (15, 17) and segmentation (11, 13) is performed in the transmitter (1) and the receiver (5) after each transmitted bit plane of a frame of the moving picture. As a result hereof the information, in particular the segmentation information, which must be transmitted is, in particular in the case of a low transmission rate, significantly reduced, due to the heavy reduction of motion parameters which must be transmitted. This method is, in particular, well suited for employment in low rate transmission systems, such as the public telephone network.