Method and apparatus for locating and decoding machine-readable symbols
First Claim
1. A method of locating within a two-dimensional stored image and decoding a machine-readable symbol representing encoded information in two-dimensions, the symbol including a plurality of selectively spaced two-dimensional geometric shapes, the shapes and spaces between the shapes having at least a first width in at least one dimension, the symbol having a predetermined location pattern of shapes and spaces identifying the symbol, the method comprising the steps of:
- producing a reflectance signal from the two-dimensional stored image based on light reflected from the symbol, the reflectance signal having valleys and peaks that represent the reflectance of the shapes and spaces, respectively, comprising the symbol, the signal including a regular series of peaks and valleys corresponding to the predetermined location pattern;
identifying a plurality of portions in the reflectance signal that correspond to the valleys and peaks of the shapes and spaces;
measuring distances between the plurality of portions in the reflectance signal, including an approximately regular series of measured distances corresponding to the regular series of peaks and valleys;
identifying the predetermined location pattern based on the approximately regular series of measured distances in the reflectance signal;
determining a location orientation of the symbol based on the identified predetermined location pattern; and
decoding the information encoded in the symbol based on the location of the symbol.
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Accused Products
Abstract
A method and apparatus for locating and decoding machine-readable symbols is provided. In a preferred embodiment, an image of the symbol is stored and a sampling path through the stored image is selected. The sampling path represents a reflectance signal profile formed through the symbol. Characteristic or critical points are selected along the profile, including minimum and maximum points of peaks and valleys in the profile. Distances between the centers of peaks and valleys are determined. The present invention locates a defined portion of the symbol, such as a finder pattern, by locating a predetermined series of measured distances, such as a series of adjacent, substantially equal distances. After having located the finder pattern, the present invention determines the location of the symbol within the stored image, and thereafter decodes the symbol.
93 Citations
24 Claims
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1. A method of locating within a two-dimensional stored image and decoding a machine-readable symbol representing encoded information in two-dimensions, the symbol including a plurality of selectively spaced two-dimensional geometric shapes, the shapes and spaces between the shapes having at least a first width in at least one dimension, the symbol having a predetermined location pattern of shapes and spaces identifying the symbol, the method comprising the steps of:
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producing a reflectance signal from the two-dimensional stored image based on light reflected from the symbol, the reflectance signal having valleys and peaks that represent the reflectance of the shapes and spaces, respectively, comprising the symbol, the signal including a regular series of peaks and valleys corresponding to the predetermined location pattern; identifying a plurality of portions in the reflectance signal that correspond to the valleys and peaks of the shapes and spaces; measuring distances between the plurality of portions in the reflectance signal, including an approximately regular series of measured distances corresponding to the regular series of peaks and valleys; identifying the predetermined location pattern based on the approximately regular series of measured distances in the reflectance signal; determining a location orientation of the symbol based on the identified predetermined location pattern; and decoding the information encoded in the symbol based on the location of the symbol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of locating a data collection symbol representing encoded information, the symbol including a plurality of spaced two-dimensional shapes and having a selected pattern of shapes and spaces between the shapes, the method comprising the steps of:
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receiving a signal based on light reflected from the symbol, the signal representing a reflectance of at least some of the shapes and spaces of the symbol, wherein the shapes and spaces of the symbol represent information encoded in two dimensions; identifying a plurality of portions in the signal that correspond to at least portions of the shapes and spaces represented in the signal; measuring distances between the plurality of portions in the signal including a selected pattern of measurements; identifying the selected pattern based on the measured selected pattern of measurements in the signal; and determining a location of the symbol based on the identified selected pattern. - View Dependent Claims (15, 16, 17, 18)
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19. An apparatus for locating a machine-readable symbol representing encoded information in two-dimensions, the machine-readable symbol including a plurality of selectively spaced two-dimensional shapes, and having a selected pattern of shapes and spaces between the shapes, the apparatus comprising:
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a sensor that receives light that is reflected from the machine-readable symbol and produces an output signal therefrom that represents the reflectance of the shapes and spaces comprising the symbol; a receiver that receives the output signal and produces a reflectance signal indicative of at least some of the shapes and spaces; and a processor for processing the reflectance signal and producing a signal indicative of the information encoded in the symbol, the processor (i) identifying a plurality of portions in the reflectance signal that correspond to at least portions of the shapes and spaces, (ii) measuring distances between the plurality of portions in the reflectance signal, including an approximately regular series of measured distances, (iii) identifying the selected pattern based on the regular series of measured distances in the reflectance signal, and (iv) determining a location of the symbol based on the identified selected pattern. - View Dependent Claims (20, 21, 22, 23)
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24. An apparatus for locating and decoding a machine-readable symbol representing encoded information in two-dimensions, the machine-readable symbol including a plurality of selectively spaced two-dimensional shapes, and having a selected pattern of shapes and spaces between the shapes, the apparatus comprising:
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a sensor that receives light that is reflected from the machine-readable symbol and produces an output signal therefrom that represents the reflectance of the shapes and spaces comprising the symbol; a receiver that receives the output signal and produces a reflectance signal indicative of at least some of the shapes and spaces; a detection circuit that identifies a plurality of portions in the reflection signal that correspond to portions of at least some of the shapes and spaces, including an approximately regular series of measured distances; a measuring circuit that generates a distance signal indicating distances between the plurality of portions in the reflectance signal; and a decoding circuit that identifies a location of the selected pattern in the machine-readable symbol based on the distance signal, including the regular series of measured distances, and therefrom produces a signal indicative of the information encoded in the machine-readable symbol.
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Specification