System and method for low light document capture and binarization with multiple flash images
First Claim
1. A method for low light image capture of a document image using a plurality of flash images from a single supplemental light source, the method comprising:
- first capturing a first image of a document with the supplemental light source wherein the first image has a first flash spot in a first flash spot region;
second capturing a second image of the document with the supplemental light source wherein the second image has a second flash spot spaced from a position in the document of the first flash spot by a movement of the supplemental light source from a first position to a second position; and
fusing the first and second images for an alignment of the first and second images to form a fused image, wherein the first flash spot region is replaced in the fused image with a corresponding portion of the second image wherein a boundary of the corresponding portion of the second image is selectively expanded to avoid splitting of characters and words by the fusing.
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Abstract
The embodiments include systems and methods for guiding a user to capture two flash images of a document page, and selectively fuse the images to produce a binary image of high quality and without loss of any content. Each individual image may have an FSR where the content is degraded/lost due to the flash light. The idea is to first guide the user to take two images such that there is no overlap of flash-spots in the document regions. The flash spots in both images are detected and assessed for quality and extent of degradation in both images. The image with lower degradation is chosen as the primary image and the other image as secondary, to minimize fusing artifacts. The region in secondary image corresponding to the FSR in the primary is aligned to the primary region using a multiscale alignment technique. The primary image and aligned FSR are binarized and fused in the vicinity of the flashspot in the primary using an intelligent technique that minimizes fusion boundary artifacts such as cutting of characters and words.
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Citations
18 Claims
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1. A method for low light image capture of a document image using a plurality of flash images from a single supplemental light source, the method comprising:
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first capturing a first image of a document with the supplemental light source wherein the first image has a first flash spot in a first flash spot region; second capturing a second image of the document with the supplemental light source wherein the second image has a second flash spot spaced from a position in the document of the first flash spot by a movement of the supplemental light source from a first position to a second position; and fusing the first and second images for an alignment of the first and second images to form a fused image, wherein the first flash spot region is replaced in the fused image with a corresponding portion of the second image wherein a boundary of the corresponding portion of the second image is selectively expanded to avoid splitting of characters and words by the fusing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A low light image capture system for capturing a document image using a plurality of flash images, the system comprising:
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a capture device including a single supplemental light source for first capturing a first image of a document wherein the first image has a first flash spot in a first flash spot region, and for second capturing a second image of the document with the supplemental light source upon a movement of the supplemental light source from a first position to a second position wherein the second image has a second flash spot spaced from a position in the document of the first flash spot; and a processor for fusing the first and second images for an alignment of the first and second images to form a fused image, wherein the first flash spot region is replaced in the fused image with a corresponding portion of the second image and wherein a boundary of the second image is selectively expanded to avoid splitting of characters and words by the fusing. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification