US 6020923

US6020923A — Patent Overview

Title: Method and apparatus for coding and recording an image signal and recording medium for storing an image signal

Patent number: US6020923A
Application number: US08/882,889
Inventors: Kazuhisa Hosaka; Yoichi Yagasaki
Assignee: Sony Corporation (original and current assignee listed)
Priority date: 1996-07-01
Filing date: 1997-06-26
Publication/grant date: 2000-02-01
Legal status (as fetched): Expired – Fee Related; anticipated expiration 2017-06-26
Classifications: H04N7/122; H04N19/30 (hierarchical/scalable coding); H04N19/503 (predictive coding with temporal prediction)

Purpose: The patent addresses coding, decoding, and recording of image signals for transmission over various lines (analog/digital telephone, private data lines) at various rates, and for recording onto media such as magnetic disks or RAM of various capacities. It applies hierarchical coding, in which a high resolution image is predicted from a low resolution image; the low resolution image is coded first, then the high resolution image is predicted from it, and the difference between the actual and predicted high resolution image is coded into the same bitstream. This is described as more efficient than coding both images directly. The technique is noted as suitable for hard key signals (bilevel shape signals used to extract an object from a fill image and combine it with a background), which the text says conventional MMR, chain coding, and quad tree techniques cannot code highly efficiently.

Plain-language scope: A coder codes the low resolution image. A judgement unit divides the predicted high resolution image into n×m pixel blocks, detects each block's feature, and outputs a judgement code. A second coder selects a coding table based on that judgement code and codes the corresponding high resolution block using it. A decoder mirrors this: it decodes the low resolution signal, derives the predicted high resolution signal, uses the judgement code to select a coding table, and decodes the coded high resolution signal. The patent also covers coding and decoding methods and a recording medium storing the coded signal.

Source: https://patents.google.com/patent/[US6020923](/patent/US6020923)/en

What the excerpt does not establish: It does not provide the full claims, the complete description (text is marked as excerpted and ends mid-sentence), specific coding tables, block sizes, or figures (e.g., FIGS. 1–21 are not included). No litigation, ownership transfer, validity, or prior-art analysis is presented here.