Telefonaktiebolaget Lm Ericsson (publ)

Charilaos Christopoulos

David Nister

Niklas Björk

Göran A P Eriksson

Mathias Larsson

Athanasios Skodras

Jan Höller

Ignacio Mas Ivars

Magnus Jändel

Diego Santa Cruz

Touradj Ebrahmi

Francisco Rivas

Joel Ask&euml;l&ouml;f

Touradj Ebrahimi

Yousri Abdeljaoud

Niklas Bj&ouml;rk

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.

Partial retrieval of images in the compressed domain

A Discrete Cosine Transform (DCT) for an entire original sequence is obtained using the DCT coefficients representing the first half and the second half of the original sequence. This is useful when calculation of DCTs of a certain length is supported by hardware and/or software and different size DCTs must be calculated. Example areas of application include still image and video transcoding and scalable image and/or video coding.

Down scaling of images

A method and system in a heterogeneous environment, capable of locating at least one optimal access area or point for supporting one or more access technologies requested by the user. The determination of the optimal access areas or points is based in part on the location of the device, the specified user preferences, service/application requirements and the capabilities of available access network connections. The optimal access points, and alternative options, are mapped in accordance with the resulting location, combined requirements and service/application requirements of the communication device. This mapping and other information/recommendations related to the access points are then provided to the communication device for action by the user.

Access point discovery and selection

In an embedded DCT-based (EDCT) image coding method, decoded images which give better PSNR over earlier JPEG and DCT-based coders are obtained by a scanning order starting, for each bitplane, from the upper left corner of a DCT block (corresponding to the DC coefficient) and transmitting the coefficients in an order of importance. An embedded bit-stream is produced by the encoder. The decoder can cut the bit-stream at any point and therefore reconstruct an image at a lower bitrate. The quality of the reconstructed image at this lower rate is the same as if the image was coder directly at that rate. Near lossless reconstruction of the image is possible, up to the accuracy of the DCT coefficients. The algorithm is very useful in various applications, like WWW, fast browsing of databases, medical imaging, etc.

Embedded DCT-based still image coding algorithm

In a multimedia environment, end-users are provided with the ability to effectively access, manipulate and share one or more multimedia objects, or select portions thereof, independent of the terminal and/or network capabilities that are associated with the terminals employed by each end-user. This may be accomplished, for example, by identifying a set of multimedia data that is stored in a multimedia database that is accessible by each end-user. The set of multimedia data is then adapted in accordance with an information adaptation service and modified in accordance with a transcoder/scalability service. The functions provided by both of these services are based on a number of user preferences and based on a number of terminal and communication (e.g., network) connection capabilities associated with the terminals corresponding to each of the end-users that are to have access to the modified set of multimedia data.

Interactive access, manipulation, sharing and exchange of multimedia data

In a method and a device for calculation of the Discrete Cosine Transform (DCT) only the DCT coefficients representing the first half and the second half of an original sequence are required for obtaining the DCT for the entire original sequence. The device and the method are therefore very useful when calculations of DCTs of a certain length is supported by hardware and/or software, and when DCTs of other sizes are desired. Areas of application are for example still image and video transcoding, as well as scalable image and/or video coding and decoding.

Efficient down-scaling of DCT compressed images

In a method and a system for encoding and transmission of still images having at least one region of interest (ROI), the ROI coefficients of an image transformed into the frequency domain, preferably using a wavelet transform are encoded so that they are transmitted first and can be decoded by a receiver without transmission of the boundary of the ROI. In a preferred embodiment the coefficients belonging to the ROI are shifted so that the minimum ROI coefficient is larger than the largest background coefficient. A receiver can then perform an opposite procedure and thereby obtain the ROI. By specifying how much the coefficients need to be shifted in order to avoid sending shape information several advantages are achieved. Thus, it is possible to avoid sending shape information and to avoid shape encoding at encoder side. Furthermore, there is no need for a shape decoder at receiver side, and there is no need for the receiver to produce the ROI mask. Also, in another preferred embodiment, the shifting (or scaling operations) required at encoder and decoder are also avoided.

Method and a system for coding rois

In a method and a device for transmission of S&plus;P transform coded digitized images a mask is calculated by means of which a region of interest (ROI) can be transmitted lossless whereby the ROI can be transmitted and received lossless and still maintaining a good compression ratio for the image as a whole. This is possible since no or very few bits can be used for the remaining part of the image. The calculated mask can also be used for transmitting the coefficients needed for a lossless region of interest during any stage of the transmission.

Lossless region of interest coding

An algorithm for video summarization is described. The algorithm combines photometric and motion information. According to the algorithm, the correspondence between feature points is used to detect shot boundaries and to select key frames. Thus, the rate of feature points, which are lost or initiated, is used as an indication if a shot transition occurred or not. Key frames are selected as frames where the activity change is low.

Method and a system for generating summarized video

In a transcoder means are provided for implementing a simultaneous change in rate and in resolution. In a preferred embodiment means are also provided for transferring incoming motion vectors or the like directly to the output encoder. The transcoder architecture is both suited for implementation in the spatial as well as in the frequency domain.

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Sollentuna, Sweden

Charilaos Christopoulos