EP0396368A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Perceptually-adapted image coding system
Assignee: AT&T Inc
•
Filing: 1990-04-30
•
Granted: —
•
Expires: 2010-04-30
Abstract
Abstract An image-coding system reduces image data redundancies and perceptual irrelevancies through progressive sub-band coding. The image is separated into plurality of sub-bands ((0,0) to (3,3)). From this sub-band information, a perceptual metric, based on the properties of the sub-band filters, quantizer error distribution, and properties of the human visual system, is determined (28) which provides the maximum amount of coding noise that may be introduced to each pixel in every sub-band without causing perceptible degradation of the coded image. This perceptual metric is used to adjust the quantizer (25) used in encoding each sub-band signal. In addition, redundancy in the output of the quantizer is reduced using a multidimensional Huffman compression scheme (27).
Inventors
- 👤 James D. Johnston
- 👤 Robert J. Safranek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 18:23
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N1/00; H04N1/41; H04N1/4105; H04N19/60; H04N19/61; H04N19/63; H04N19/90; H04N19/94; H04N5/00; H04N5/76; H04N5/91; H04N5/92; H04N5/926; H04N5/9261; H04N19/13; H04N5/84; H04N5/85
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
56 words
A method for encoding two-dimensional information, comprising analyzing said information in a plurality of sub-bands to determine the amount of quantizing noise which would be just imperceptible, including adapting said analysis for each pixel in response to a major parameter of said information in said pixel and encoding the information with quantizing noise approaching said amount.
Claim 2
Independent Claim
56 words
A method for encoding two-dimensional information, comprising analyzing said information in a plurality of sub-bands to determine the amount of quantizing noise which would be just imperceptible, including adapting said analysis for each pixel in response to a major parameter of said information in said pixel and encoding the information with quantizing noise approaching said amount.
Claim 3
Independent Claim
49 words
A method for encoding two-dimensional information, comprising analyzing said information in a plurality of sub-bands to determine the amount of quantizing noise which would be just imperceptible in terms of effect upon the local texture content of the information, and encoding said information with quantizing noise approaching said amount.
Claim 4
Independent Claim
49 words
A method for encoding two-dimensional information, comprising analyzing said information in a plurality of sub-bands to determine the amount of quantizing noise which would be just imperceptible in terms of effect upon the local texture content of the information, and encoding said information with quantizing noise approaching said amount.
Claim 5
Dependent Claim
17 words
The method according to claim 1 or claim 2 wherein the analyzing and encoding steps are reversible.
Claim 6
Dependent Claim
27 words
The method according to claim 1 or claim 2 wherein the analyzing step includes filtering the information into a plurality of sub-bands in at least one dimension.
Claim 7
Dependent Claim
50 words
The method according to claim 1 or claim 2 wherein the analyzing step includes filtering the information into a plurality of sub-bands in both of said dimensions and the encoding step includes allocating the quantization noise predominantly to sub-bands other than the sub-band containing lowest frequencies for row and column.
Claim 8
Dependent Claim
32 words
The method according to claim 5 wherein the encoding step further includes spreading the quantization noise away from brightness levels of maximum contrast sensitivity and toward brightness levels of lesser contrast sensitivity.
Claim 9
Dependent Claim
58 words
The method according to claim 2 wherein the analyzing step includes determining texture as the degree of variation from a flat field within each sub-band in nearby-pixels in both directions from a selected pixel, and the encoding step includes adapting the allowed degree of quantizing noise for said selected pixel in direct relation to said degree of variation.
Claim 10
Dependent Claim
48 words
The method according to claim 7 wherein the analyzing step includes filtering the information into a plurality of sub-bands in both dimensions, and the encoding step includes spreading the quantization noise toward frequencies higher than those of the (0,0) sub-band and toward brightness levels of lesser contrast sensitivity.
Claim 11
Dependent Claim
20 words
The method according to claim 8 wherein the encoding step further includes encoding the analyzed information substantially noiselessly with compression.
Claim 12
Dependent Claim
42 words
The method according to claim 8 wherein the encoding step further comprises encoding each sub-band with differential PCM coding with a variable uniform mid-riser quantizer responsive to the allowable level of quantizing noise, and then channel coding the encoded sub-bands with compression.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.