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Patent metadata

Field	Value
Publication number	US-9558401-B2
Application number	US-201514861586-A
Country	US
Kind code	B2
Filing date	Sep 22, 2015
Priority date	Sep 10, 2013
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

Embodiments are provided for content item classification. In some embodiments, an image for classification is received, a compact representation for the image having values indicative of pixel values within the received image is generated, a plurality of angle measurements for possible edges of at least one potential document within the received image are determined, and the image is classified using said compact representation and said plurality of angle measurements.

First claim

What is claimed is:

1. A method for content item classification, comprising:
receiving a digital image;
identifying, by at least one processor, a plurality of angle measurements for possible page edges of at least one potential document within the received image, wherein identifying the plurality of angle measurements comprises:
identifying, by the at least one processor, a plurality of edge candidates of the at least one potential document; and
calculating an angle measurement for each edge candidate of the plurality of edge candidates based on a plurality of vectors, each vector of the plurality of vectors extending orthogonally from a selected origin to a point corresponding to a given edge candidate of the plurality of edge candidates;

determining, based on the identified plurality of angle measurements, whether the image contains a document; and
in response to determining that the image contains a document, classifying the image as a document-containing image.

2. The method as recited in claim 1 , further comprising converting the plurality of angle measurements to polar coordinates.

3. The method as recited in claim 2 , further comprising determining, based on the polar coordinates, a location for each page edge of the document within the received digital image.

4. The method as recited in claim 1 , wherein identifying the plurality of edge candidates of the at least one potential document comprises calculating gradient values for a plurality of points within the received digital image.

5. The method as recited in claim 4 , wherein identifying the plurality of edge candidates of the at least one potential document further comprises identifying a location for each of the plurality of edge candidates within the received digital image based on the gradient values.

6. The method as recited in claim 4 , wherein calculating the plurality of angle measurements comprises calculating polar coordinates for the plurality of points within the received image.

7. The method as recited in claim 6 , further comprising eliminating at least one of the plurality of edge candidates as a page edge for the document based on the plurality of angle measurements.

8. The method as recited in claim 6 , further comprising confirming at least one of the plurality of edge candidates as a page edge for the document based on the plurality of angle measurements.

9. A non-transitory computer-readable medium containing storing instructions that, when executed by at least one processor of a computing device, cause the computing device to:
receive a digital image;
identify a plurality of angle measurements for possible page edges of at least one potential document within the received image, wherein identifying the plurality of angle measurements comprises:
identifying a plurality of edge candidates of the at least one potential document; and
calculating an angle measurement for each edge candidate of the plurality of edge candidates based on a plurality of vectors, each vector of the plurality of vectors extending orthogonally from a selected origin to a point corresponding to a given edge candidate of the plurality of edge candidates;

determine, based on the identified plurality of angle measurements, whether the image contains a document; and
in response to determining that the image contains a document, classify the image as a document-containing image.

10. The non-transitory computer-readable medium of claim 9 , further comprising instructions that, when executed by the at least one processor of the computing device, cause the computing device to convert the plurality of angle measurements to polar coordinates.

11. The non-transitory computer-readable medium of claim 10 , further comprising instructions that, when executed by the at least one processor of the computing device, cause the computing device to determine, based on the polar coordinates, a location for each page edge of the document within the received digital image.

12. The non-transitory computer-readable medium of claim 9 , wherein identifying the plurality of edge candidates of the at least one potential document comprises calculating gradient values for a plurality of points within the received digital image.

13. The non-transitory computer-readable medium of claim 12 , wherein identifying the plurality of edge candidates of the at least one potential document further comprises identifying a location for each of the plurality of edge candidates within the received digital image based on the gradient values.

14. The non-transitory computer-readable medium of claim 12 , wherein calculating the plurality of angle measurements comprises calculating polar coordinates for the plurality of points within the received image.

15. A system for content item classification, the system comprising:
one or more processors; and
memory containing instructions thereon that, when executed, cause the one or more processors to:
receive a digital image;
identify a plurality of angle measurements for possible page edges of at least one potential document within the received image, wherein identifying the plurality of angle measurements comprises:
identifying a plurality of edge candidates of the at least one potential document; and
calculating an angle measurement for each edge candidate of the plurality of edge candidates based on a plurality of vectors, each vector of the plurality of vectors extending orthogonally from a selected origin to a point corresponding to a given edge candidate of the plurality of edge candidates;

determine, based on the identified plurality of angle measurements, whether the image contains a document; and
in response to determining that the image contains a document, classify the image as a document-containing image.

16. The system of claim 15 , further comprising instructions that, when executed, cause the one or more processors to convert the plurality of angle measurements to polar coordinates.

17. The system of claim 16 , further comprising instructions that, when executed, cause the one or more processors to determine, based on the polar coordinates, a location for each page edge of the document within the received digital image.

18. The system of claim 15 , wherein identifying the plurality of edge candidates of the at least one potential document comprises calculating gradient values for a plurality of points within the received digital image.

19. The system of claim 18 , wherein identifying the plurality of edge candidates of the at least one potential document further comprises identifying a location for each of the plurality of edge candidates within the received digital image based on the gradient values.

20. The system of claim 18 , wherein calculating the plurality of angle measurements comprises calculating polar coordinates for the plurality of points within the received image.

Assignees

• Dropbox Inc

Inventors

• Chajed Tej
• Welinder Peter
• Babenko Boris
• Simeonov Dimitar

Classifications

• G06V30/413

  Classification of content, e.g. text, photographs or tables · CPC title

• G06V10/48 Primary

  by mapping characteristic values of the pattern into a parameter space, e.g. Hough transformation · CPC title

• G06V10/243

  by compensating for image skew or non-uniform image deformations · CPC title

• G06T7/0085

  Physics · mapped topic

• G06K9/4633

  Physics · mapped topic