Methods and systems for detecting regions in digital images

• US 7,889,932 B2
• Filed: 03/02/2006
• Issued: 02/15/2011
• Est. Priority Date: 03/02/2006
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Campbell, Richard John
• Primary Examiner(s): Desire; Gregory M
• Application Number:
  US11/367,244
• Publication Number:
  US 20070206855A1
• Time in Patent Office: 1,811 Days
• Field of Search: 358/462, 358/464, 358/534, 358/540, 382/172, 382/178, 382/190, 382/212, 382/224, 382/232, 382/171, 382/175, 382/176
• US Class Current: 382/212
• CPC Class Codes: G06V 10/507 Summing image-intensity values; Histogram projection analysis
• CPC Class Codes: G06V 30/413 Classification of content, e.g. text, photographs or tables

Abstract

Embodiments of the present invention comprise systems, methods and devices for detection of image regions of various content types using a masking condition and an entropy measure.

Claims

1. A method for calculating an entropy feature in a digital image comprising a plurality of pixels, said method comprising:

a) in a processor, applying a masking condition to said digital image thereby identifying masked pixels that satisfy said masking condition;

b) in a calculator, calculating an entropy measure associated with a center pixel within a block of pixels in said digital image, wherein all masked pixels within said block contribute less to said entropy measure than pixels, within said block, not identified by said masking condition; and

c) assigning a confidence value to a first masked pixel in said block, wherein said confidence value assigned to said first masked pixel reflects a confidence in a mask signature signal at said first masked pixel.

2. A method as described in claim 1 wherein said calculating excludes said all masked pixels within said block.

3. A method as described in claim 1 wherein said contribution of said first masked pixel is related to said assigned confidence value.

4. A method as described in claim 3 wherein said calculating comprises generating a histogram of pixel values.

5. A method as described in claim 1 wherein said calculating comprises generating a histogram of pixel values.

6. A method as described in claim 1 wherein said masking condition comprises edge strength.

7. A system for calculating an entropy feature in a digital image, said system comprising:

a) processor for applying a masking condition to said digital image thereby identifying masked pixels that satisfy said masking condition;

b) a calculator for calculating an entropy measure associated with a center pixel within a block of pixels in said digital image, wherein all masked pixels within said block contribute less to said entropy measure than pixels, within said block, not identified by said masking condition; and

c) a confidence-value assigner for assigning a confidence value to a first masked pixel in said block, wherein said confidence value assigned to said first masked pixel reflects a confidence in a mask signature signal at said first masked pixel.

8. A system as described in claim 7 wherein said calculating excludes said all masked pixels within said block.

9. A system as described in claim 7 wherein said contribution of said first masked pixel is related to said confidence value.

10. A system as described in claim 9 wherein said calculator comprises a histogram generator for generating a histogram of pixel values.

11. A system as described in claim 10 wherein said histogram generator accumulates a pixel value associated with said first masked pixels based on said confidence value.

12. A system as described in claim 7 wherein said calculator comprises a histogram generator for generating a histogram of pixel values.

13. A system as described in claim 12 wherein said histogram generator accumulates pixel values from only pixels, from said block, for which said masking condition is not met.

14. A system as described in claim 7 wherein said masking condition comprises edge strength.

15. A method for detecting a region in a digital image, said method comprising:

a) in a region classifier, applying a masking condition to said digital image thereby identifying masked pixels that satisfy said masking condition;

b) assigning a confidence value to a first masked pixel within a neighbor of said digital image, wherein said confidence value reflects a confidence in a mask signature signal at said first masked pixel;

c) calculating an entropy measure associated with said neighborhood of said digital image, wherein all masked pixels within said neighborhood contribute less to said entropy measure than pixels, within said neighborhood, not identified by said masking condition; and

d) classifying said neighborhood of said digital image based on said entropy measure.

16. A method as described in claim 15 wherein said calculating excludes said all masked pixels within said neighborhood.