Strokes localization by m-array decoding and fast image matching
First Claim
1. A method for determining a path of a pen tip within a document, the method comprising:
- (A) decoding extracted bits associated with a captured image to determine location coordinates of the captured image, by;
(A)(i) obtaining the extracted bits that are associated with a captured array;
(A)(ii) processing the extracted bits to determine whether the extracted bits contain at least one error bit and to determine the location coordinates if no error bits are detected; and
(A)(iii) if the at least one error bit is detected, further processing the extracted bits to determine the location coordinates from a portion of the extracted bits, by;
(A)(iii)(1) if an error bit is detected, selecting a different subset from the extracted bits, wherein at least one bit of the different subset is not one of previously correctly decoded bits;
(A)(iii)(2) decoding associated bits of the different subset;
(A)(iii)(3) in response to (2), determining whether another decoding iteration shall be performed;
(A)(iii)(4) if another decoding iteration shall be performed, selecting another subset from the extracted bits wherein at least one bit of the other subset is selected from a set of wrongly decoded bits of each previous iteration and repeating (2); and
(A)(iii)(5) if another decoding iteration shall not be performed, determining the location coordinates of the captured array, wherein the location coordinates are consistent with a local constraint;
(B) in response to (A), if the location coordinates of the captured image cannot be determined by decoding, matching the captured image with image information of the document; and
(C) mapping the path of the pen tip from the location coordinates of the captured image to the location coordinates of the tip of the pen.
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Accused Products
Abstract
Systems and methods that determine a path of a pen tip as the pen tip is moved across a document are described. The document is watermarked with a maze pattern from which encoded position information is determined. A sequence of images is captured by a camera that is located in a pen. The path of the pen tip is determined by decoding the associated maze pattern and by matching the captured images with document images. If the position coordinates of any frame that is associated with a stroke cannot be determined from m-array decoding, the frames are transformed and then matched with an area of a document image. Once the position coordinates of at least one frame is determined, the position coordinates of other frames are determined by matching the frames in a neighboring area.
48 Citations
33 Claims
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1. A method for determining a path of a pen tip within a document, the method comprising:
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(A) decoding extracted bits associated with a captured image to determine location coordinates of the captured image, by; (A)(i) obtaining the extracted bits that are associated with a captured array; (A)(ii) processing the extracted bits to determine whether the extracted bits contain at least one error bit and to determine the location coordinates if no error bits are detected; and (A)(iii) if the at least one error bit is detected, further processing the extracted bits to determine the location coordinates from a portion of the extracted bits, by; (A)(iii)(1) if an error bit is detected, selecting a different subset from the extracted bits, wherein at least one bit of the different subset is not one of previously correctly decoded bits; (A)(iii)(2) decoding associated bits of the different subset; (A)(iii)(3) in response to (2), determining whether another decoding iteration shall be performed; (A)(iii)(4) if another decoding iteration shall be performed, selecting another subset from the extracted bits wherein at least one bit of the other subset is selected from a set of wrongly decoded bits of each previous iteration and repeating (2); and (A)(iii)(5) if another decoding iteration shall not be performed, determining the location coordinates of the captured array, wherein the location coordinates are consistent with a local constraint; (B) in response to (A), if the location coordinates of the captured image cannot be determined by decoding, matching the captured image with image information of the document; and (C) mapping the path of the pen tip from the location coordinates of the captured image to the location coordinates of the tip of the pen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for determining a path of a pen tip within a document, the method comprising:
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(A) decoding extracted bits associated with a captured image to determine location coordinates of the captured image; (B) in response to (A), if the location coordinates of the captured image cannot be determined by decoding, matching the captured image with image information of the document, by; (B)(i) matching the captured image with an area of an image of the document, wherein the area is estimated by analyzing the image of the document or a corresponding location of a neighbor image frame, and wherein the corresponding location is determined by m-array decoding or global localization; (B)(ii) in response to (i), if the location coordinates cannot be determined, warping the captured image, by; (B)(ii)(
1) scaling and rotating a captured image by applying an affine transform obtained from maze pattern analysis;(B)(ii)(2) aligning the captured maze pattern to a select point of a search region; and (B)(ii)(3) matching the warped frame with a document image, wherein the warped frame corresponds to a largest cross-correlation value; and (B)(iii) matching the captured image with an area of the document, wherein an x-y position cannot be uniquely determined by m-array decoding; and (C) mapping the path of the pen tip from the location coordinates of the captured image to the location coordinates of the tip of the pen. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for determining a path of a pen tip within a document, the method comprising:
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(A) decoding extracted bits associated with a captured image to determine location coordinates of the captured image; (B) in response to (A), if the location coordinates of the captured image cannot be determined by decoding, matching the captured image with image information of the document, by; (B)(i) matching the captured image with an area of an image of the document, wherein the area is estimated by analyzing the image of the document or a corresponding location of a neighbor image frame, and wherein the corresponding location is determined by m-array decoding or global localization; (B)(ii) in response to (i), if the location coordinates cannot be determined, warping the captured image; and (B)(iii) matching the captured image with an area of the document, wherein an x-y position cannot be uniquely determined by m-array decoding; (C) mapping the path of the pen tip from the location coordinates of the captured image to the location coordinates of the tip of the pen; and (D) determining the area of the document, wherein the area is occluded by content of the document, and wherein the document is watermarked, by; (D)(i) obtaining a document image, wherein the document image is watermarked; (D)(ii) determining whether a neighboring window of a pixel only contains maze pattern cells, wherein the document image is represented by a plurality of sub-windows; and (D)(iii) if the sub-window does not contain only the maze pattern, differentiating a measure of visible maze pattern cells. - View Dependent Claims (29, 30, 31, 32, 33)
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Specification