US 5,917,945 AGranted

Recognizing dataforms in image areas

AssigneeMetanetics Corporation

InventorRobert Stanley Cymbalski

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Abstract

Dataforms, such as bar codes and matrix codes, are recognized by analysis of histogram type data derived for a plurality of window sections of an image area. Typically, an image area 512 pixels high by 480 pixels wide is divided into 240 window areas, each including 1024 pixels in a 32 by 32 pixel square. A histogram for a window section overlying a portion of the dataform may typically exhibit two peaks representing the two principal reflective values (black and white, for example) of the elements and spaces of a dataform. A background (quiet zone) window section histogram exhibits one principal peak representing the background value (white, for example). The background window sections and the dataform window sections are assigned to two different groups. One or both groups are then used for one or more of the following: recognizing the presence of a dataform; determining whether the dataform is darker or lighter than the background; and locating the dataform within the image area. Also, a single histogram is used to identify the type of dataform, based upon the histogram signature of the dataform.

Claims23

Dependent claims

A method of recognizing a dataform, including elements and spaces having different reflective values, which may be present in an image area including a background area having primarily a single reflective value distinct from the reflective value of said elements, comprising the steps of:

(a) storing pixel data including pixel values representing reflection from said image area which may include said dataform;
(b) sampling pixel values, each representative of a reflective value of an incremental part of a window section of said image area which may include a portion of said dataform, to determine the number of occurrences of discrete pixel values representative of reflective values within said window section;
(c) categorizing said window section in one of the following groups (i) a first group for which said determined number of occurrences indicates the presence of at least two principal reflective values, including a relatively higher value and a relatively lower value, (ii) a second group for which said determined number of occurrences indicates the presence of one principal reflective value, representative of said background area, and (iii) a third group for other window sections;
(d) repeating steps (b) and (c) for a plurality of additional window sections of said image area;
(e) utilizing at least one of said first and second groups of window sections, with said determined number of occurrences as relevant, for carrying out at least one of the following steps:
(x) recognizing the presence of said dataform in said image area;
(y) determining whether said elements have a reflective value higher or lower than said background area reflective value;
and
(z) determining the location of said dataform within said image area;
and
(f) providing the results of step (e) for use in activating reading of said dataform.

8 more elements

A method of recognizing a dataform, including elements and spaces having two different reflective values, positioned on a background area primarily characterized by a single reflective value, comprising the steps of:

(a) selecting an image area which may include said dataform;
(b) storing pixel values each representative of a reflective value of an incremental part of one window section of said image area, each said window section comprising a portion of said image area large enough to be able to encompass at least portions of a plurality of said elements of said dataform;
(c) sampling step (b) pixel values for each of a plurality of said window sections to determine, for individual ones of said window sections, the number of occurrences of discrete pixel values representative of reflective values in an individual window section;
(d) analyzing said derived data to identify at least one of (i) a first group of said window sections for which said determined number of occurrences is indicative of at least two principal reflective values, (ii) a second group of said window sections for which said determined number of occurrences is indicative of one principal reflective value and (iii) a third group of other window sections;
(e) utilizing at least one of said first and second groups of window sections, with step (c) data as relevant, for at least one of the following (i) recognizing the presence of said dataform, (ii) determining whether the reflective value of said dataform elements is higher or lower than said single reflective value corresponding to said background area, and (iii) locating said dataform relative to said image area;
and
(f) providing the results of step (e) for use in activating reading of said dataform.

4 more elements

Dependencies are inferred from the claim text.