SYSTEM FOR CAPTURING A DOCUMENT IN AN IMAGE SIGNAL

• US 20140078345A1
• Filed: 12/01/2013
• Published: 03/20/2014
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Showering, Paul Edward
• Granted Patent: US 9,451,132 B2
• Time in Patent Office: Days
• US Class Current: 348/231.99
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/142 using hand-held instruments; Constructional details of the instruments
• CPC Class Codes: G06V 30/1475 Inclination or skew detection or correction of characters or of image to be recognised
• CPC Class Codes: G06V 30/1607 Correcting image deformation, e.g. trapezoidal deformation caused by perspective
• CPC Class Codes: G06V 30/18076 by analysing connectivity, e.g. edge linking, connected component analysis or slices
• CPC Class Codes: H04N 23/00 Cameras or camera modules comprising electronic image sensors; Control thereof
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure

Abstract

Devices, methods, and software are disclosed for capturing a frame of image data having a representation of a feature. In an illustrative embodiment, a device includes an imaging subsystem, one or more memory components, and a processor. The imaging subsystem is capable of providing image data representative of light incident on said imaging subsystem. The one or more memory components include at least a first memory component operatively capable of storing an input frame of the image data. The processor is in communicative connection with executable instructions for enabling the processor for various steps. One step includes receiving the input frame from the first memory component. Another step includes generating a reduced resolution frame based on the input frame, the reduced resolution frame comprising fewer pixels than the input frame, in which a pixel in the reduced resolution frame combines information from two or more pixels in the input frame.

Claims

1. A device, comprising:

an imaging subsystem for generating image data;

a first memory component for storing an input frame of image data; and

a processor configured for;

receiving the input frame from the first memory component;

combining information from two or more pixels in the input frame to generate a pixel in a reduced resolution frame having fewer pixels than the input frame;

attempting to identify, in the reduced resolution frame, transition pairs having differences between the pixels in the pair that exceed a pixel transition threshold; and

attempting to identify, in the reduced resolution frame, a linear feature between two or more identified transition pairs.

2. The device of claim 1, wherein the processor is configured for:

sectioning the input frame into groups of pixels;

for each group of pixels, averaging a property of the pixels;

for each group of pixels, generating an averaged pixel having the averaged property of the pixels for the group; and

generating the reduced resolution frame based on the averaged pixels for the groups of pixels.

3. The device of claim 2, wherein the processor is configured for:

when generating the reduced resolution frame based on the averaged pixels for the groups of pixels, providing a greater number of color data bits in the averaged pixels than in the pixels from the input frame.

4. The device of claim 1, wherein the processor is configured for:

sectioning the input frame into first-stage groups of four pixels in a 2×

2 arrangement;

for each first-stage group, averaging a property of the pixels;

for each first-stage group, generating an averaged pixel having the averaged property of the pixels for the first-stage group;

generating a first-stage reduced resolution frame based on the averaged pixels for the first stage groups of pixels;

sectioning the first-stage reduced resolution frame into second-stage groups of four pixels in a 2×

2 arrangement;

for each second-stage group, averaging a property of the pixels;

for each second-stage group, generating an averaged pixel having the averaged property of the pixels for the second-stage group;

generating a second-stage reduced resolution frame based on the averaged pixels for the second stage groups of pixels.

5. The device of claim 1, wherein:

the imaging subsystem generates image data comprising 16-bit pixels having color data per pixel; and

the processor is configured for, when generating the reduced resolution frame;

averaging four adjacent 16-pixels; and

generating one 24-bit pixel having 24 bits of color data.

6. The device of claim 1, wherein the processor is configured for attempting to identify, in the reduced resolution frame, transition pairs having differences in overall brightness between the pixels in the pair that exceed a pixel transition threshold.

7. The device of claim 1, wherein the processor is configured for attempting to identify, in the reduced resolution frame, transition pairs having differences in individual color brightness between the pixels in the pair that exceed a pixel transition threshold.

8. The device of claim 1, wherein the processor is configured for:

scanning horizontal and/or vertical lines in the reduced resolution frame for transition pairs; and

scanning lines extending from the edges toward the center of the reduced resolution frame for transition pairs.

9. The device of claim 1, wherein the processor is configured for attempting to identify, in the reduced resolution frame, transition pairs having differences between the pixels in the pair that exceed two or more pixel transition thresholds.

10. The device of claim 1, wherein the processor is configured for:

scanning horizontal and/or vertical lines in the reduced resolution frame;

scanning lines extending from the edges toward the center of the reduced resolution frame; and

scanning each of the scanned lines for two transition pairs per line.

11. The device of claim 1, wherein the processor is configured for:

scanning horizontal and/or vertical lines in the reduced resolution frame;

scanning lines extending from the edges toward the center of the reduced resolution frame;

scanning each of the scanned lines in an attempt to identify two transition pairs per line; and

if two transition pairs are not identified in a given scanned line, re-scanning the given line and attempting to identify transition pairs having differences between the pixels in the pair that exceed another pixel transition threshold.

12. The device of claim 1, wherein the processor is configured for:

connecting consecutive identified pixel transitions into identified line segments;

identifying sets of line segments that are approximately in-line with each other; and

merging identified sets of in-line line segments into identified linear features.

13. The device of claim 1, wherein the processor is configured for:

measuring angles between identified linear features;

evaluating whether the measured angles are within a constrained skew value around 90 degrees; and

if the measured angles are within a constrained skew value around 90 degrees, identifying intersections of the linear features as identified corner points.

14. The device of claim 1, wherein the processor is configured for:

attempting to identify four corner points in the reduced resolution frame; and

if four corner points cannot be identified, generating a prompt signal via an output component.

15. The device of claim 1, wherein:

the imaging subsystem continuously generates image data;

the first memory component buffers the input frames of the image data; and

the processor is configured for processing the input frames until a rectangle in three dimensions is identified in a reduced resolution frame.

16. A device, comprising:

an imaging subsystem for generating image data;

a first memory component for storing an input frame of image data; and

a processor configured for;

receiving the input frame from the first memory component;

generating a reduced resolution frame having fewer pixels than the input frame;

attempting to identify four corner points in the reduced resolution frame;

if four corner points cannot be identified, generating a prompt signal via an output component; and

if four corner points are identified, attempting to calculate a conversion of a two-dimensional quadrilateral defined by the four corners into a rectangular form in three dimensions.

17. The device of claim 16, wherein the processor is configured for:

converting an image portion defined by the rectangular form in three dimensions into a corresponding two-dimensional rectangular image portion; and

saving the two-dimensional rectangular image portion in a memory component.

18. The device of claim 16, wherein the processor is configured for:

after calculating a conversion of a two-dimensional quadrilateral defined by the four corners into a rectangular form in three dimensions, converting a high-resolution quadrilateral image portion in the input frame corresponding to the quadrilateral defined by the four corners in the reduced resolution frame into a high-resolution two-dimensional rectangular image portion.

19. The device of claim 16, comprising an illumination source, wherein the processor is configured for:

compensating pixels of an image portion representing the rectangular form for vignetting by both an imaging lens of the imaging subsystem and by an offset of the illumination source from the imaging lens.

20. A method, comprising:

receiving, with a processor, an input frame of image data generated by an imaging subsystem from a first memory component;

combining, with a processor, information from two or more pixels in the input frame to generate a pixel in a reduced resolution frame having fewer pixels than the input frame;

attempting, with a processor, to identify, in the reduced resolution frame, transition pairs having differences between the pixels in the pair that exceed a pixel transition threshold; and

attempting, with a processor, to identify, in the reduced resolution frame, a linear feature between two or more identified transition pairs

21. The method of claim 20, comprising:

sectioning, with a processor, the input frame into groups of pixels;

for each group of pixels, averaging a property of the pixels with a processor;

for each group of pixels, generating, with a processor, an averaged pixel having the averaged property of the pixels for the group; and

generating, with a processor, the reduced resolution frame based on the averaged pixels for the groups of pixels.

22. The method of claim 20, comprising:

attempting to identify four corner points in the reduced resolution frame with a processor; and

if four corner points are identified, attempting to calculate a conversion of a two-dimensional quadrilateral defined by the four corners into a rectangular form in three dimensions.