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Robert J. Safranek
Researcher at Bell Labs
Publications - 23
Citations - 1465
Robert J. Safranek is an academic researcher from Bell Labs. The author has contributed to research in topics: Image quality & Image compression. The author has an hindex of 14, co-authored 23 publications receiving 1446 citations. Previous affiliations of Robert J. Safranek include AT&T.
Papers
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Signal compression based on models of human perception
TL;DR: It is proposed that fundamental limits in the science can be expressed by the semiquantitative concepts of perceptual entropy and the perceptual distortion-rate function, and current compression technology is examined in that framework.
Patent
Hdtv encoder with forward estimation and constant rate motion vectors
Scott C. Knauer,Kim Nigel Matthews,Arun Narayan Netravali,Eric D. Petajan,Robert J. Safranek,Peter H. Westerink +5 more
TL;DR: In this paper, the authors propose a motion compensated encoder where motion vectors are selected based on the prediction error generated in localized areas of the encoded image and based on an available bit budget.
Patent
Adaptive non-linear quantizer
James D. Johnston,Scott Carroll Knauer,Arun Kim Nigel Matthews,Arun N. Netravali,Eric D. Petajan,Robert J. Safranek,Peter H. Westerink +6 more
TL;DR: In this article, a quantizer with quantization control that is sensitive to input signal characteristics and to output buffer fullness responds to an input signal that is divided into blocks and DCT transformed.
Patent
A high definition television coding arrangement with graceful degradation
James D. Johnston,Scott Carroll Knauer,Kim Nigel Matthews,Arun Narayan Netravali,Eric D. Petajan,Robert J. Safranek,Peter H. Westerink +6 more
TL;DR: In this paper, the authors proposed a graceful degradation for digitally encoded HDTV signals by appropriately coding the image to provide a controllable degradation of chosen image characteristics, such as temporal degradation, spatial degradation, and dynamic range degradation.
Patent
Adaptive leak hdtv encoder
TL;DR: In this paper, the problem of error perpetuation is solved by leaking a changing, rather than a fixed, fraction of the input signal to the differential PCM, sensitive to the characteristics of the signal.