US 6,389,175 B1Granted

Method for encoding digital information

AssigneeAT&T Laboratories

InventorsKenneth Robert Wood, Tristan John Richardson

Life of this patent

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Abstract

A method for encoding digital information to be transmitted from a first device to a second device, wherein the digital information is mapped according to a map of n rows and m columns which define a plurality of cells (n×m) and wherein each of said cells has a pixel value. The method is useful for compressing bitmapped images to be rendered by the simplest of graphics engines. Thus the method is particularly suited to the transmission of images to a relatively slow client on which the images are to be rendered in real time and on which any complex decompression would be too costly for such rendering. Raw compression ratios are comparable to those obtained with standard runlength encoding, but the number of drawing primitive calls required to render the compressed images directly is substantially less. If the size of the largest area exceeds predetermined limits it is subdivided into smaller areas automatically without having to specify the size and position.

Claims5

Dependent claims

A method for encoding digital information to be transmitted from a first device to a second device, wherein said digital information is mapped according to a map of rows and columns which define a plurality of cells and wherein each of said cells has a pixel value, said method being characterised by the following steps:

from a predetermined first cell having a certain pixel value, determining the largest area of cells, adjacent to said first cell, having the same pixel value as said first cell;
generating a code indicative of the row-column position of said first cell, of the dimensions of said largest area, and of said pixel value common to all the cells of said area;
proceeding to a second cell, adjacent to said area and having a pixel value different from the pixel value of said first cell;
from said second cell, determining another largest area of cells, adjacent to said second cell, having the same pixel value as said second cell;
generating a code indicative of the row-column position of said second cell, of the dimensions of said largest area, and of said pixel value common to all the cells of said area;
and
repeating said steps until all said cells have been encoded,
characterised by the step of determining whether the dimensions of said largest area exceed predetermined limits and if the result of the determination is that said limits are exceeded, subdividing said largest area into smaller areas, the dimensions of which are less than said predetermined limits and in that the step of subdividing the largest area comprises subdividing the area in a predetermined order without explicitly specifying the size and position of each smaller area.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/619,709Filed 19 Jul 2000 · continuation
Priority: GB 962635919 Dec 1996
Granted: 14 May 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H04N 19/00
Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
G06T 9/20
Image coding: contour coding, e.g. using detection of edges
G06V 10/421
Global feature extraction by analysis of the whole pattern, e.g. using frequency domain transformations or autocorrelation: by analysing segments…
H04N 19/93
Using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals: run-length coding

Family

Application08/994,132Parent of this continuation-in-part · filed 19 Dec 1997
PCT/GB99/00204Parent of this continuation · filed 21 Jan 1999
US 6,192,159 B1Parent of this continuation-in-part · filed 20 Feb 2001
PCT/GB99/00204Parent of this continuation-in-part
US 6,389,175 B1This patent

From the US filing history. Foreign family members aren’t listed.