Granted Patent B2

US 8,879,832 · App. 13/533,459 · Granted Nov 4, 2014

Inventors: Edul N. Dalal (Webster, NY); Wencheng Wu (Webster, NY)

Assignee: Xerox Corporation

Abstract

Claims (76)

1. A method, comprising:

by an imaging device, receiving an image of a color barcode having a plurality of informational elements and a plurality of calibration elements;

by the imaging device, detecting the calibration elements;

by a processor, using the calibration elements to determine one or more color model parameters for assigning a color value to a perceived color;

by the processor, identifying a color model that comprises the determined one or more color model parameters;

by the imaging device, detecting a set of the informational elements, each of which comprises a color data bit;

by the processor, identifying a perceived color value for each of the detected informational elements in the set;

by the processor, applying the one or more color model parameters to the color model to transform the perceived color values for one or more of the detected informational elements and yield one or more adjusted color values; and

by the processor, decoding the color barcode using the one or more adjusted color values.

2. The method of claim 1 , wherein detecting the one or more calibration elements comprises:

detecting one or more position detection pattern locations in the color barcode;

based on the one or more position detection pattern locations, determining a position in the image for the calibration elements; and

identifying the calibration elements as those elements that are located in the determined position.

3. The method of claim 1 , wherein detecting the calibration elements comprises:

recognizing an image of three position detection patterns, each of which is located in a corner of a square;

determining an orientation of the square based on the corners in which the position detection patterns are located; and

determining a calibration element location based on the locations of the position detection patterns and the orientation of the square.

4. The method of claim 1 , wherein determining the one or more color model parameters comprises:

determining a color value for each of the detected calibration elements in the image;

comparing each determined color value to a set of stored color values for each of the detected calibration elements to identify a relationship between them; and

using the relationship to determine the color model parameters.

5. The method of claim 1 , wherein the color model comprises a piecewise linear approximation.

6. The method of claim 1 , wherein the color model comprises a gamma function.

7. The method of claim 1 , wherein the color model comprises a matrix.

8. The method of claim 1 , wherein the color model comprises a polynomial.

9. The method of claim 1 , wherein applying the one or more color model parameters to the color model to yield one or more adjusted color values comprises thresholding the identified color value of at least one of the detected informational elements to the adjusted color value that is nearest to the identified color value of the informational element.

10. The method of claim 1 , wherein each perceived color value and each adjusted color value comprises a set of integers that, for each informational element, provides RGB values for the informational element.

11. A system for decoding a color barcode, comprising:

a processor; and

a non-transitory computer-readable storage medium containing programming instructions that, when executed, instruct the processor to:

receive an image file of a color barcode, the image file having a plurality of informational elements and one or more calibration elements;

use the one or more calibration elements to determine one or more color model parameters for assigning a color value to a perceived color;

identify a color model that comprises the determined one or more color model parameters;

identify a set of the informational elements, each of which comprises a color data bit;

identify a perceived color value for each of the detected informational elements in the set;

apply the one or more color model parameters to the color model to transform the perceived color values for one or more of the detected informational elements and yield one or more adjusted color values; and

decode the color barcode using the one or more adjusted color values.

12. The system of claim 11 , wherein the instructions further comprise instructions that, when executed, cause the processor to:

detect one or more position detection pattern locations in the color barcode;

based on the one or more position detection pattern locations, determine a position in the image for the calibration elements; and

identify the calibration elements as those elements that are located in the determined position.

13. The system of claim 11 , wherein the instructions that, when executed, cause the processor to determine the one or more color model parameters comprise instructions for:

determining a color value for each of the detected calibration elements;

comparing each determined color value to a set of stored color values for each of the detected calibration elements to identify a relationship between them; and

using the relationship to determine the color model parameters.

14. The system of claim 11 , wherein the instructions further comprise instructions that, when executed, cause the processor to:

detect one or more of the calibration elements;

recognize an image of three position detection patterns, each of which is located in a corner of a square;

determine an orientation of the square based on the corners in which the position detection patterns are located; and

determine a calibration element location based on the locations of the position detection patterns and the orientation of the square.

15. The system of claim 11 , wherein the color model comprises a piecewise linear approximation, a gamma function, a matrix, or a polynomial.

16. The system of claim 11 , further comprising an imaging device that receives an image of the barcode and converts the image to the image file.

17. The system of claim 16 , further comprising a display that outputs the barcode to the imaging device.

18. The system of claim 11 , wherein each perceived color value and each adjusted color value comprises a set of integers that, for each informational element, provides RGB values for the informational element.

19. A method of decoding a color barcode, comprising, by one or more processors:

receiving an image file of a color barcode having a plurality of informational elements and a plurality of calibration elements;

detecting a set of the calibration elements by:

detecting one or more position detection pattern locations in the color barcode;

based on the one or more position detection pattern locations, determining a position in the image for the calibration elements; and

identifying the calibration elements as those elements that are located in the determined position;

detecting a set of the informational elements, each of which comprises a color data bit;

using the detected calibration elements to determine one or more color model parameters for assigning a color value to a perceived color;

identifying a color model that comprises one or more color model parameters;

identifying a perceived color value for each of the detected informational elements;

applying the one or more color model parameters to the color model to one or more of the detected informational elements and yield one or more adjusted color values; and

decoding the color barcode using the one or more adjusted color values.

20. The method of claim 19 , wherein determining the one or more color model parameters comprises:

determining a color value for each of the detected calibration elements in the image;

comparing each determined color value to a set of stored color values for each of the detected calibration elements to identify a relationship between them; and

using the relationship to determine the color model parameters.

21. The method of claim 19 , wherein detecting the one or more position detection patterns comprises:

recognizing an image of three position detection patterns, each of which is located in a corner of a square;

determining an orientation of the square based on the corners in which the position detection patterns are located; and

determining a calibration element location based on the locations of the position detection patterns and the orientation of the square.

22. The method of claim 19 , wherein the color model comprises a piecewise linear approximation, a gamma function, a matrix, or a polynomial.

23. The method of claim 19 , wherein each perceived color value and each adjusted color value comprises a set of integers that, for each informational element, provides RGB values for the informational element.

Assignments (9)

Continuity (1)