Method and subsystem for identifying document subimages within digital images
First Claim
1. An image-processing subsystem to identify a document sub-image within a digital image, the image-processing subsystem comprising:
- a memory; and
a processor, operatively coupled to the memory, being configured to;
receive the digital image;
identify contours corresponding to intensity edges within the digital image;
generate four contour sets that each includes either predominantly vertically oriented or predominantly horizontally oriented contours selected from the identified contours, wherein to generate the four contour sets, the processor is to partition the identified contours into a first set of predominantly vertically oriented contours and a second set of predominantly horizontally oriented contours, select contours from the first set of predominantly vertically oriented contours to add to right and left contour sets, and select contours from the second set of predominantly horizontally oriented contours to add to upper and lower contour sets;
generate hypotheses, each comprising data that describes a four-sided polygon positioned and oriented with respect to the received digital image, by combining contours selected from each of the right, left, upper, and lower contour sets from the four contour sets;
score the generated hypotheses;
select a hypothesis among the generated hypotheses based on the generated scores; and
store the selected hypothesis in memory as an indication of boundaries of the document sub-image.
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Abstract
The current document is directed to automated methods and systems, controlled by various constraints and parameters, that identify document sub-images within digital images. Certain of the parameters constrain contour identification and document-subimage-hypothesis generation. The currently described methods and systems identify contours within the digital image, partition the identified contours into four contour sets corresponding to four different regions of the original digital image, construct hypotheses based on these contours for the edges or boundaries of a digital sub-image, and evaluate the hypotheses in order to select a most highly scored hypotheses as a representation of the borders of a digital sub-image within the original received digital image.
51 Citations
19 Claims
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1. An image-processing subsystem to identify a document sub-image within a digital image, the image-processing subsystem comprising:
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a memory; and a processor, operatively coupled to the memory, being configured to; receive the digital image; identify contours corresponding to intensity edges within the digital image; generate four contour sets that each includes either predominantly vertically oriented or predominantly horizontally oriented contours selected from the identified contours, wherein to generate the four contour sets, the processor is to partition the identified contours into a first set of predominantly vertically oriented contours and a second set of predominantly horizontally oriented contours, select contours from the first set of predominantly vertically oriented contours to add to right and left contour sets, and select contours from the second set of predominantly horizontally oriented contours to add to upper and lower contour sets; generate hypotheses, each comprising data that describes a four-sided polygon positioned and oriented with respect to the received digital image, by combining contours selected from each of the right, left, upper, and lower contour sets from the four contour sets; score the generated hypotheses; select a hypothesis among the generated hypotheses based on the generated scores; and store the selected hypothesis in memory as an indication of boundaries of the document sub-image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method that identifies a document sub-image within a digital image, the method comprising:
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receiving the digital image; identifying contours corresponding to intensity edges within the digital image; generating four contour sets that each includes either predominantly vertically oriented or predominantly horizontally oriented contours selected from the identified contours by partitioning the identified contours into a first set of predominantly vertically oriented contours and a second set of predominantly horizontally oriented contours, selecting contours from the first set of predominantly vertically oriented contours to add to right and left contour sets, and selecting contours from the second set of predominantly horizontally oriented contours to add to upper and lower contour sets; generating hypotheses, each comprising data that describes a four-sided polygon positioned and oriented with respect to the received digital image, by combining contours selected from each of the right, left, upper, and lower contour sets from the four contour sets; scoring the generated hypotheses; selecting a hypothesis among the generated hypotheses based on the generated scores; and storing the selected hypothesis in memory as an indication of boundaries of a document sub-image within the received digital image. - View Dependent Claims (15, 16, 17, 18)
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19. A non-transitory computer-readable medium for identifying a document sub-image within a digital image, the non-transitory computer-readable medium having recorded thereon instructions that when executed by one or more computer processors, perform operations comprising:
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receiving the digital image; identifying contours corresponding to intensity edges within the digital image; generating four contour sets that each includes either predominantly vertically oriented or predominantly horizontally oriented contours selected from the identified contours by partitioning the identified contours into a first set of predominantly vertically oriented contours and a second set of predominantly horizontally oriented contours, selecting contours from the first set of predominantly vertically oriented contours to add to right and left contour sets, and selecting contours from the second set of predominantly horizontally oriented contours to add to upper and lower contour sets; generating hypotheses, each comprising data that describes a four-sided polygon positioned and oriented with respect to the received digital image, by combining contours selected from each of the right, left, upper, and lower contour sets from the four contour sets; scoring the generated hypotheses; selecting a hypothesis among the generated hypotheses based on the generated scores; and storing the selected hypothesis in memory as an indication of boundaries of the document sub-image.
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Specification