Encoding of still pictures by a wavelet transform and singular value decomposition
This paper proposes a new scheme for picture compression which decomposes a picture to (3/spl times/3+1) subband pictures using the 2-D discrete wavelet transform three times, and then decomposes a picture block matrix A(16/spl times/16 pixels) of the lowest frequency subband picture to singular values and eigenvectors of AA/sup T/ and A/sup T/A and encode them by PCM. For all other subband pictures, first we encode the 0-level wavelet coefficient run-length by a modified Huffman code and then encode the non-0-level coefficients by PCM with non-linear quantizer.
Image Self-Embedding Technology Research Based on Singular Value Decomposition
Image compression operator based on singular value decomposition was brought up, which enhanced compression ratio while improving recovery quality of tampered image. A securer scrambling locational operator was put forward based on the concept of anti-tamper radius. The basic idea of our algorithm is that it combined image block compression data with its characteristic value first, then scrambled or encrypted and embedded them into least significant bit of corresponding offset block. When carrier image tampering occurred, it could pinpoint tampered image block and tampering type accurately. When tamper occurred within the limits of the anti-tamper radius, it could recover tampered block data with good image quality. It could resist vector quantization and synchronous counterfeiting attacks on self-embedding watermarking schemes effectively.
Point-to-point and point-to-multipoint communications
A network, such as wired and/or wireless LAN, is configured to have both point-to-point and point-to-multipoint connections. The point-to-multipoint connection(s) is used to communicate information between a plurality of the stations (or modem, or transceivers) in the network, whereas the point-to-point connection(s) are used to communicate information between only 2 stations in the network with the ability to, for example, maximize performance (rate/reach/BER/latency/etc) between those two stations. A master station allocates one or more frequency bands to the various point-to-multipoint and point-to-point connections.