An integrated adaptive spatial-temporal system and method for controlling narrowband and wideband sources of interference. The system includes an N element antenna array which receives a spread spectrum signal and interference signals, each element receiving a different phase shifted version of the spread spectrum and interference signals; a spatial filter including an antenna pattern former responsive to the antenna array which combines the phase shifted spread spectrum and interference signals according to controlling weights to null N-1 of the interference signal; an adaptive narrow band, e.g., temporal filter, responsive to the spatial filter for filtering any remaining narrowband interference signals from the combined signal; and feedback subsystem responsive to the narrow band filter for adjusting the controlling weights of the antenna pattern former until the operation of the spatial filter is optimized and nulls wideband interference signals before narrowband interference signals.

Integrated adaptive spatial-temporal system for controlling narrowband and wideband sources of interferences in spread spectrum CDMA receivers

A method and apparatus for transcoding digital video data, for example, at the headend of a cable or satellite television network A generic multi-functional transcoder architecture has a “post-pre-processing engine” that provides a number of processing functions for implementing desired format conversions according to a user selection signal or an automatically generated selection signal The processing functions can change frame size, frame rate, color space sampling format, interlaced or progressive scan format, resolution, and provide noise/deblocking filtering, for example The system also allows the control of several transcoders to convert several bit streams with different formats into corresponding bit streams with a common format Furthermore, the transcoder avoids the need for motion estimation

Multi-functional transcoder for compressed bit streams

The invention is an image transmitting method and system including receiving encoded images, decoding those images and post-processing the decoded images. The post-processing reduces visual artifacts, such as blocking artifacts and mosquito noise, through separate detection, mapping and smoothing operations while avoiding many of the complexities associated with existing techniques. In detecting blocking artifacts, the inventive method employs DCT-domain detection rather than edge detection in the pixel domain. Also, the interior of a detected block is updated based on the surrounding blocks without disturbing the surrounding blocks. In reducing mosquito noise, the inventive method smooths the non-edge pixels within blocks containing edge pixels rather than smoothing the edge pixels. Also, distortion-induced false edge pixels are distinguished from true edge pixels and heavily smoothed. The post-processing method and system is generally applicable to Block DCT based compression systems, either intrinsically or extrinsically.

Method and apparatus for post-processing images

A filter that filters in the spatial and temporal domain in a single step with filtering coefficients that can be varied depending upon the complexity of the video and the motion between the adjacent frames comprises: a IIR filter, a threshold unit, and a coefficient register. The IIR filter and threshold unit are coupled to receive video data. The IIR filter is also coupled to the coefficient register and the threshold unit. The IIR filter receives coefficients, a, from the coefficient register and uses them to filter the video data received. The IIR filter filters the data in the vertical, horizontal and temporal dimensions in a single step. The filtered data output by the IIR filter is sent to the threshold unit. The threshold unit compares the absolute value of the difference between the filtered data and the raw video data to a threshold value from the coefficient register, and then outputs either the raw video data or the filtered data. The present invention is advantageous because it preserves significant edges in video sequence; it preserves motion changes in video sequences; it reduces noise; and it uses minimal memory storage and introduces minimal processing delay. The present invention also includes methods for filtering in parallel the pixel data in one step for the horizontal, vertical and temporal dimensions.

System and method for spatial temporal-filtering for improving compressed digital video

A post-processor for a decoded video sequence includes a digital noise reduction unit and an artifact reduction unit which significantly reduce blocking artifacts and mosquito noise in a video image. The post-processor uses both temporal and edge characteristics of the video image to enhance the displayed image. A coding parameter from a decoder is used in a coding parameter adaptive filter unit within an artifact unit to further enhance the perceived quality of the displayed image. The coding parameter for a particular macroblock is selected using a characteristic of that macroblock. The post-processor operates on a current frame of pixel data using information from the immediately preceding post-processed frame that is stored in a frame memory of the post-processor. The post-processor uses artifact reduction only on portions of the image that are not part of an edge, and are not part of a texture or fine detail area. Since artifact reduction is not utilized on these areas, the post-processed image is not softened in regions where it is easily noticed by the human eye.

Coding parameter adaptive transform artifact reduction process

A 3D nonlinear postprocessing system and method are utilized to reduce coding artifacts produced by block-based motion-compensated transform coding. In the system and method, a separable 3D filtering structure is used: space-variant FIR-Median Hybrid filtering (in 106) is used in the spatial domain, followed by a motion-compensated (on 112) nonlinear filtering in the temporal domain (in 110). By using this structure and method, the coding artifacts in a reconstructed image sequence can be effectively reduced without blurring edges or moving objects in the image sequence. Significant improvement in the picture quality of low bit-rate coded video sequences (111) is thereby achieved.

Li Yan

Papers

Adaptive spatial-temporal postprocessing for low bit-rate coded image sequences