Noise reduction pre-preocessor for digital video using previously generated motion vecotrs and adaptive spatial filering

Abstract

Noise is reduced in a video system by applying motion compensated temporal filtering using previously generated motion vectors and adaptive spatial filtering at scene change frames. Various types of noise can be introduced into video prior to compression and transmission. Artifacts arise from recording and signal manipulation, terrestrial or orbital communications, or during decoding. Noise introduced prior to image compression interferes with performance and subsequently impairs system performance. While filtering generally reduces noise in a video image, it can also reduce edge definition leading to loss of focus. Filtering can also tax system throughput, since increased computational complexity often results from filtering schemes. Furthermore, the movement of objects within frames, as defined by groups of pixels, complicates the noise reduction process by adding additional complexity. In addition to improvements made to FIR spatial filtering, the present invention improves on previous filtering techniques by using Infinite Impulse Response (IIR) temporal filtering to reduce noise while maintaining edge definition. It also uses motion vectors previously calculated as part of the first-pass image encoding or alternatively by trans coding to reduce computational complexity for P-frame and B-frame image preprocessing. Single stage P-frame temporal noise filtering and double stage B-frame temporal noise filtering are presented.

Description

technical field [0001] The present invention relates to an apparatus and method for noise reduction in video systems by applying motion compensated temporal filtering using pregenerated motion vectors and applying adaptive spatial filtering at scene change frames. Background technique [0002] Digital television provides high-quality video entertainment to viewers with features such as pay-per-view, electronic program guides, video-on-demand, weather and stock information, and Internet access. Video images are packaged in information streams and transmitted to users via broadband communication networks based on satellite, cable or land-based transmission media. Due to bandwidth and power constraints, efficient transmission of film and video requires extensive use of compression and formatting techniques. Protocols such as MPEG1 and MPEG2 maximize the bandwidth utilization of film and video information transmission by adding a temporal component to the spatial domain compres...

AI Technical Summary

Problems solved by technology

Noise introduced prior to image compression can be problematic as it monopolizes data bandwidth while degrading image quality, thereby interfering with the performance of subsequent compression systems

Also, quantization in the discrete cosine transform (DCT) domain tends to amplify the effects of noise, leading to increased signal degradation

[0006] Filtering reduces the noise in the video image, which may also reduce the resolution (such as sharpness) of the image, resulting in imprecise edge transitions, thereby reducing the apparent focus (apparent focus)

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