Method and apparatus for decoding bar code symbols using byte-based searching
First Claim
Patent Images
1. A method for reading a bar code symbol in a binary image, comprising the steps of:
- (a) selecting a first scan line in said image;
(b) byte-based quiet-zone searching along said first search line to identify a candidate quiet zone;
(c) byte-based transition searching along said first search line to identify a plurality of candidate bars and spaces;
(d) determining whether said candidate quiet zone and said candidate bars and spaces correspond to said symbol; and
(e) decoding said symbol in accordance with the determination of step (d), wherein step (c) comprises the steps of;
(1) selecting a byte of said image, wherein said byte corresponds to two or more consecutive pixels of said image along said first scan line;
(2) accessing a look-up table using the byte as an index to determine how many bright/dark transitions correspond to the byte; and
(3) determining whether said bright/dark transitions correspond to said plurality of candidate bars and spaces.
0 Assignments
0 Petitions
Accused Products
Abstract
A bar code reader locates and decodes a bar code symbol in a pixel image by searching along a selected scan line for a candidate quiet zone and then counting the bright/dark transitions that correspond to candidate bars and spaces. The reader determines whether the candidate quiet zone and candidate bars and spaces correspond to a bar code symbol, and, if so, decodes the symbol. When processing binary pixel images, the reader searches for candidate quiet zones and counts bright/dark transitions by analyzing the image one byte of pixels at a time.
49 Citations
40 Claims
-
1. A method for reading a bar code symbol in a binary image, comprising the steps of:
-
(a) selecting a first scan line in said image; (b) byte-based quiet-zone searching along said first search line to identify a candidate quiet zone; (c) byte-based transition searching along said first search line to identify a plurality of candidate bars and spaces; (d) determining whether said candidate quiet zone and said candidate bars and spaces correspond to said symbol; and (e) decoding said symbol in accordance with the determination of step (d), wherein step (c) comprises the steps of; (1) selecting a byte of said image, wherein said byte corresponds to two or more consecutive pixels of said image along said first scan line; (2) accessing a look-up table using the byte as an index to determine how many bright/dark transitions correspond to the byte; and (3) determining whether said bright/dark transitions correspond to said plurality of candidate bars and spaces. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A method for reading a bar code symbol in a binary image, comprising the steps of:
-
(a) selecting a first search line in said image; (b) selecting a byte of said image, wherein said byte comprises two or more pixels along said first search line; (c) determining whether said byte corresponds to said symbol; and (d) decoding said symbol in accordance with the determination of step (c), wherein step (c) comprises the steps of; (1) accessing a look-up table using the byte as an index to determine how many bright/dark transitions correspond to the byte; and (2) determining whether said bright/dark transitions correspond to a plurality of candidate bars and spaces. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. An apparatus for reading a bar code symbol in a binary image, comprising:
-
(a) means for selecting a first search line in said image; (b) means for byte-based quiet-zone searching along said first search line to identify a candidate quiet zone; (c) means for byte-based transition searching along said first search line to identify a plurality of candidate bars and spaces; (d) means for determining whether said candidate quiet zone and said candidate bars and spaces correspond to said symbol; and (e) means for decoding said symbol in accordance with the determination of means (d), wherein means (c) comprises; (1) means for selecting a byte of said image, wherein said byte corresponds to eight consecutive pixels of said image along said first scan line; (2) means for accessing a look-up table using the byte as an index to determine how many bright/dark transitions correspond to the byte; and (3) means for determining whether said bright/dark transitions correspond to said plurality of candidate bars and spaces. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
-
-
29. An apparatus for reading a bar code symbol in a binary image, comprising:
-
(a) means for selecting a first search line in said image; (b) means for selecting a byte of said image, wherein said byte comprises two or more pixels along said first search line; (c) means for determining whether said byte corresponds to said symbol; and (d) means for decoding said symbol in accordance with the determination of means (c), wherein means (c) comprises; (1) means for accessing a look-up table using the byte as an index to determine how many bright/dark transitions correspond to the byte; and (2) means for determining whether said bright/dark transitions correspond to a plurality of candidate bars and spaces. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
Specification