System and method for whiteboard scanning to obtain a high resolution image
First Claim
1. A computer-implemented process for converting the contents of a planar object into a high-resolution image, comprising the process actions of:
- acquiring a sequence of images of portions of a planar object which have been captured in a prescribed pattern and wherein each subsequent image overlaps a previous image in said pattern;
extracting points of interest in each image;
matching said points of said interest between each pair of successive images wherein the process action of matching said points of said interest between each pair of successive images comprises the process actions of;
for each point of interest in the earlier captured image of the pair of images under consideration, establishing a window of pixels centered on the point of interest;
for each point of interest,comparing said window in said earlier captured image of the pair under consideration with windows of pixels the same size which are centered on the points of interest in the later-captured image of the pair by computing a zero-mean normalized cross correlation between the windows; and
whenever the largest correlation scare computed between the window of the earlier captured image and each of the windows in the later captured image exceeds a prefixed threshold, designating the associated point in the later-captured image as a match candidate for the point under consideration in the earlier-captured image;
computing a projective mapping between each pair of successive images in order to determine corresponding pixel locations in the images; and
generating a composite image from said sequence of images using said projective mapping.
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Accused Products
Abstract
This invention is directed toward a system and method for scanning a scene or object such as a whiteboard, paper document or similar item. More specifically, the invention is directed toward a system and method for obtaining a high-resolution image of a whiteboard or other object with a low-resolution camera. The system and method of the invention captures either a set of snapshots with overlap or a continuous video sequence, and then stitches them automatically into a single high-resolution image. The stitched image can finally be exported to other image processing systems and methods for further enhancement.
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Citations
17 Claims
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1. A computer-implemented process for converting the contents of a planar object into a high-resolution image, comprising the process actions of:
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acquiring a sequence of images of portions of a planar object which have been captured in a prescribed pattern and wherein each subsequent image overlaps a previous image in said pattern; extracting points of interest in each image; matching said points of said interest between each pair of successive images wherein the process action of matching said points of said interest between each pair of successive images comprises the process actions of; for each point of interest in the earlier captured image of the pair of images under consideration, establishing a window of pixels centered on the point of interest; for each point of interest, comparing said window in said earlier captured image of the pair under consideration with windows of pixels the same size which are centered on the points of interest in the later-captured image of the pair by computing a zero-mean normalized cross correlation between the windows; and whenever the largest correlation scare computed between the window of the earlier captured image and each of the windows in the later captured image exceeds a prefixed threshold, designating the associated point in the later-captured image as a match candidate for the point under consideration in the earlier-captured image; computing a projective mapping between each pair of successive images in order to determine corresponding pixel locations in the images; and generating a composite image from said sequence of images using said projective mapping. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for converting markings on a planar object into a high resolution image, the system comprising:
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a general purpose computing device; and a computer program comprising program modules executable by the computing device, wherein the computing device is directed by the program modules of the computer program to, acquire a sequence of images of portions of a planar object having been captured in a prescribed pattern, each subsequent image overlapping a previous image in said pattern; extract points of interest in each image in said sequence; match said points of said interest between two successive images in said sequence;
wherein the program module for matching said points of said interest between two successive images in said sequence comprises sub-modules for,for each point of Interest in the earlier captured image of the set of images under consideration, establishing a window of pixels centered on the point of interest, for each point of interest, comparing said window in said earlier captured image of the set under consideration with windows of pixels the same size which are centered on the points of interest in the later-captured image of the set by computing a zero-mean normalized cross correlation between the windows, and whenever the largest correlation score computed between the window of the earlier captured image and each of the windows in the later captured captured image as a match candidate for the point under consideration in the earlier-captured image; compute a projective mapping between each set of two successive images in said sequence of images in order to determine corresponding pixel locations in the images of each set; and generate a composite image from said images using said projective mapping. - View Dependent Claims (9, 10, 11)
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12. A computer-readable medium having computer-executable instructions for converting a series of low resolution images of portions of a planar object into a high resolution image of said object, said computer executable instructions causing a computer to execute the method comprising:
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acquiring a series of images of the depicting portions of the same scene; extracting points of interest in each image of said series of images; matching said points of interest in each image of said series of images with the image preceding said image in said series of images, wherein said matching said points of interest in each image of said series of images with the preceding said image in said series of images comprises, for each point of interest in the preceding image of a pair of images under consideration, establishing a window of pixels centered on the point of interest; for each point of interest, comparing said window in said preceding image of the pair under consideration with windows of pixels the same size which are centered on the points of interest in the later-captured image of the pair by computing a zero-mean normalized cross correlation between the windows, and whenever the largest correlation score computed between the window of the preceding image and each of the windows in the later captured image exceeds a prefixed threshold, designating the associated point in the later-captured image as a match candidate for the point under consideration in the preceding images; calculating a homography between each image of said series of images with the image preceding said image in said series of images; and stitching each image in said series of images together using said homographies to create a composite image. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification