| US 7,463,774 B2 | ||
| Global localization by fast image matching | ||
| Jian Wang, Beijing (China); Yingnong Dang, Beijing (China); Qiang Wang, Beijing (China); Liyong Chen, Beijing (China); and Xiaoxu Ma, Cambridge, Mass. (US) | ||
| Assigned to Microsoft Corporation, Redmond, Wash. (US) | ||
| Filed on Jan. 07, 2004, as Appl. No. 10/752,086. | ||
| Prior Publication US 2005/0147299 A1, Jul. 07, 2005 | ||
| Int. Cl. G06K 9/68 (2006.01) | ||
| U.S. Cl. 382—218 | 21 Claims |
| 1. A method of determining a portion of a document corresponding to a captured image, comprising:
obtaining a captured image of a portion of a document, the document having a pattern that uniquely identifies different positions
in the document;
determining obscured areas of the document in which the pattern is at least partially obscured;
designating a reference pixel in the captured image;
identifying locations in the obscured areas of the document that may correspond with the reference pixel;
comparing the captured image with different portions of the document, such that the reference pixel is compared with one or
more of the identified locations; and
based upon the comparison, determining an identified location in the document that corresponds with the reference pixel,
wherein determining an identified location in the document that corresponds with the reference pixel further includes
warping the captured image so that the scale and rotation of the captured image match the scale and rotation of the document;
rotating the warped captured image at multiples of 90°; and
determining a correlation value for each comparison of the image with a portion of a document.
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