IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0845584
(2007-08-27)
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등록번호 |
US-7570813
(2009-08-24)
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발명자
/ 주소 |
- Wang, Jian
- Dang, Yingnong
- Wang, Qiang
- Chen, Liyong
- Ma, Xiaoxu
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출원인 / 주소 |
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대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
11 인용 특허 :
216 |
초록
▼
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 th
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.
대표청구항
▼
We claim: 1. A method for determining a path of a pen tip of a pen within a document, the method comprising: (A) calibrating the pen in order to obtain a calibration parameter; (B) analyzing a watermarked document image in order to determine areas where x-y positions cannot be uniquely determined b
We claim: 1. A method for determining a path of a pen tip of a pen within a document, the method comprising: (A) calibrating the pen in order to obtain a calibration parameter; (B) analyzing a watermarked document image in order to determine areas where x-y positions cannot be uniquely determined by m-array decoding; (C) segmenting a maze pattern from an obstruction component of a captured image, wherein the obstruction component comprises document content that occludes the maze pattern; (D) analyzing the maze pattern to extract bits from the maze pattern of the captured image; (E) in response to (D), determining a transform that transforms image position coordinates to actual position coordinates, wherein the actual position coordinates identify a location of the pen tip in relation to the document; (F) decoding the extracted bits associated with the captured image; (G) in response to (F), if the image position coordinates of the captured image cannot be determined, matching the captured image with image information, comprising: (i) warping the captured image to create a warped image; and (ii) matching the warped image with an area of the document, where a corresponding x-y position cannot be uniquely determined by m-array decoding; (H) determining image position coordinates of other image frames that are associated with a pen stroke, comprising: (i) matching a corresponding captured image with a neighboring area of the image position coordinates of an image whose image position coordinates have been determined previously; and (ii) repeating (i) until all image frames of the pen stroke are processed; and (I) mapping the path of the pen tip from the transform, the calibration parameter, and the image position coordinates. 2. The method of claim 1, wherein the transform is a perspective transform obtained from local localization. 3. The method of claim 1, wherein calibrating the pen tip comprises: fixing the pen tip at a contact point on the document; changing a position of a pen camera center; and mapping the position of the pen camera center to the contact point. 4. The method of claim 1, wherein the calibration parameter is indicative of a virtual pen tip position. 5. The method of claim 1, further comprising, processing the extracted bits to determine whether the extracted bits contain at least one error bit. 6. The method of claim 1, wherein the document is a paper document. 7. The method of claim 1, wherein the document is an electronic document. 8. A computer-readable storage medium having computer-executable instructions for performing a method for determining a path of a pen tip of a pen within a document, the method comprising: calibrating the pen in order to obtain a calibration parameter; analyzing a watermarked document image in order to determine areas where x-y positions cannot be uniquely determined by m-array decoding; segmenting a maze pattern from an obstruction component of a captured image, wherein the obstruction component comprises document content that occludes the maze pattern; analyzing the maze pattern to extract bits from the maze pattern of the captured image; in response to analyzing the maze pattern, determining a transform that transforms image position coordinates to actual position coordinates, wherein the actual position coordinates identify a location of the pen tip in relation to the document; decoding the extracted bits associated with the captured image; in response to decoding the extracted bits, if the image position coordinates of the captured image cannot be determined, matching the captured image with image information, comprising: warping the captured image to create a warped image; and matching the warped image with an area of the document, where a corresponding x-y position cannot be uniquely determined by m-array decoding; determining image position coordinates of other image frames that are associated with a pen stroke, comprising: matching a corresponding captured image with a neighboring area of the image position coordinates of an image whose image position coordinates have been determined previously; and repeating the matching of the corresponding captured image with neighboring areas until all image frames of the pen stroke are processed; and mapping the path of the pen tip from the transform, the calibration parameter, and the image position coordinates. 9. The computer-readable storage medium of claim 8, wherein the transform is a perspective transform obtained from local localization. 10. The computer-readable storage medium of claim 8, wherein calibrating the pen tip comprises: fixing the pen tip at a contact point on the document; changing a position of a pen camera center; and mapping the position of the pen camera center to the contact point. 11. The computer-readable storage medium of claim 8, wherein the calibration parameter is indicative of a virtual pen tip position. 12. The computer-readable storage medium of claim 8, further comprising, processing the extracted bits to determine whether the extracted bits contain at least one error bit. 13. The computer-readable storage medium of claim 8, wherein the document is a paper document. 14. The computer-readable storage medium of claim 8, wherein the document is an electronic document.
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