Method and apparatus for locating an acquisition target in two-dimensional images by detecting symmetry in two different directions
First Claim
1. A method of locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
- scanning said stored image along a scanning direction and detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction; and
determining whether said candidate bounded element and associated border area are symmetric along a second direction.
1 Assignment
0 Petitions
Accused Products
Abstract
A system and method are disclosed for locating an acquisition target consisting of a plurality of concentric rings of alternating levels of reflectivity (bull'"'"'s-eye pattern) in two-dimensional images such as optically encoded symbologies. Such targets may be found even if they vary in size and tilt angle with respect to an imaging camera. Symmetry characteristics of the targets are used to locate the targets independent of the threshold level selected for determining transitions between rings of different reflectivity.
-
Citations
29 Claims
-
1. A method of locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
-
scanning said stored image along a scanning direction and detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction; and determining whether said candidate bounded element and associated border area are symmetric along a second direction. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A system for locating an optically readable, two-dimensional acquisition target in a stored image of a symbology in which alphanumeric data is encoded, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising:
-
a light source; a detector comprising an array of pixels positioned to receive light from said light source reflected by said target; a read-out circuit connected to obtain data signals from said pixels and to form in a memory device an image including said target; and a processor configured to locate said key element by; scanning said stored image along a scanning direction to detect a candidate bounded element demonstrating symmetry along said scanning direction; and determining whether said candidate bounded element is symmetric along a second direction. - View Dependent Claims (7, 8, 9, 10, 11)
-
-
12. A method of locating an optically readable, two-dimensional symbology of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
-
deriving a multiple-row image including said symbology from a pixel matrix and storing said image; and locating said key element by; scanning said stored image along a scanning direction and detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction; and determining whether said candidate bounded element and associated border area are symmetric along a second direction. - View Dependent Claims (13, 14)
-
-
15. A system for locating an optically readable, two dimensional symbology of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity completely surrounded by a geometrically symmetric key border area of a second reflectivity, comprising:
-
a light source; a detector comprising an array of pixels positioned to receive light from said light source reflected by said symbology; a read-out circuit connected to obtain data signals from said pixels and to form in a memory device an image including said symbology; and a processor configured to locate said key element by; scanning said stored image along a scanning direction to detect a candidate bounded element and associated border area demonstrating symmetry along said scanning direction; and determining whether said candidate bounded element and associated border area are symmetric along a second direction. - View Dependent Claims (16)
-
-
17. A method of locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
-
scanning said stored image along a scanning direction and detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction; determining whether said candidate bounded element and said associated border area are symmetric along a second direction; determining diameters of said candidate bounded element and said associated border area in said scanning direction and said second direction; and determining whether said diameters are within a predetermined tolerance of each other. - View Dependent Claims (18)
-
-
19. A system for locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising:
-
a light source; a detector comprising an array of pixels positioned to receive light from said light source reflected by said target; a read-out circuit connected to obtain data signals from said pixels and to form in a memory device an image including said target; and a processor configured to locate said key element by; scanning said stored image along a scanning direction to detect a candidate bounded element demonstrating symmetry along said scanning direction; determining whether said candidate bounded element is symmetric along a second direction; determining diameters of said candidate bounded element in said scanning direction and said second direction; and determining whether said diameters are within a predetermined tolerance of each other. - View Dependent Claims (20)
-
-
21. A method of locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
-
scanning said stored image along a scanning direction; run-length coding said image in said scanning direction; detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction by examining said runs for symmetry; and determining whether said candidate bounded element and said associated border area are symmetric along a second direction.
-
-
22. A system for locating an optically readable, two-dimensional acquisition target in a stored image, said target being of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising:
-
a light source; a detector comprising an array of pixels positioned to receive light from said light source reflected by said target; a read-out circuit connected to obtain data signals from said pixels and to form in a memory device an image including said target; and a processor configured to locate said key element by; scanning said stored image along a scanning direction; run-length coding said image in said scanning direction; detecting a candidate bounded element demonstrating symmetry along said scanning direction by examining said runs for symmetry; and determining whether said candidate bounded element is symmetric along a second direction.
-
-
23. A method of locating an optically readable, two-dimensional symbology of the type having a key element, said key element being a geometrically symmetric, bounded element of a first reflectivity surrounded by a geometrically symmetric key border area of a second reflectivity, comprising the steps of:
-
deriving an image including said symbology from a pixel matrix and storing said image; and locating said key element by; scanning said stored image along a scanning direction; run-length coding said image in said scanning direction; detecting a candidate bounded element and associated border area demonstrating symmetry along said scanning direction by examining said runs for symmetry; and determining whether said candidate bounded element and said associated border area are symmetric along a second direction. - View Dependent Claims (24, 25, 26, 27, 28, 29)
-
Specification