Method and apparatus for three-dimensional shadow lightening

• US 20050093865A1
• Filed: 11/08/2004
• Published: 05/05/2005
• Est. Priority Date: 09/19/2001
• Status: Active Grant

• Current Assignee: Charles Chi Jia
• Original Assignee: Charles Chi Jia
• Inventors: Jia, Charles Chi
• Granted Patent: US 7,483,564 B2
• Time in Patent Office: Days
• US Class Current: 345/426
• CPC Class Codes: H04N 1/38 Circuits or arrangements for blanking or otherwise eliminating unwanted parts of pictures H04N1/387 takes precedence

Abstract

A method of image processing is provided, the method including acquiring a digital image having a three-dimensional shadow, determining a boundary of the three-dimensional shadow, and lightening the three-dimensional shadow within the boundary.

Claims

1. A method of image processing comprising:

acquiring a digital image including a three-dimensional shadow;

determining a boundary of the three-dimensional shadow; and

lightening the three-dimensional shadow within the boundary.

2. The method of claim 1, wherein acquiring the digital image includes scanning two pages of a volume having multiple pages and a binding, the volume having been placed on a scanning surface of an imaging device configured to acquire the digital image;

and wherein the three-dimensional shadow includes a binding shadow associated with the binding of the volume, a perimeter shadow associated with a page perimeter of the volume, and page-fanning shadows associated with page edges of the volume.

9. The method of claim 1, wherein, prior to determining the boundary, processing the digital image further comprises:

determining an image perimeter of the digital image including a perimeter shadow;

determining a skew of the digital image;

de-skewing the digital image;

cropping the digital image at an outer edge of the perimeter shadow; and

determining a content of the digital image.

10. The method of claim 9, wherein determining the content of the digital image includes detecting first portions of the digital image containing text, designating the first portions as text image portions, and designating second portions of the digital image as non-text image portions.

11. The method of claim 9, wherein determining the content of the digital image includes determining the presence of a binding shadow by locating a bisecting shadow portion within the digital image;

and

comparing the bisecting shadow portion with a text orientation of the digital image.

12. The method of claim 11, wherein determining the content of the digital image further includes comparing the perimeter shadow with the bisecting shadow portion and the text orientation.

3. A method of image processing comprising:

acquiring a digital image including a three-dimensional shadow;

determining a boundary of the three-dimensional shadow by performing at least one of a linear analysis and a proximity analysis on the digital image to determine luminosity gradient changes associated with the three-dimensional shadow and establishing the boundary based on the gradient changes; and

lightening the three-dimensional shadow within the boundary.

4. The method of claim 3, wherein the linear analysis includes determining gradient changes by comparing associated luminosity of adjacent pixels of the digital image in at least one of pixel rows of the digital image and pixel columns of the digital image.

5. The method of claim 3, wherein the proximity analysis includes determining gradient changes by comparing associated luminosity of neighboring pixels of the digital image.

6. The method of claim 3, wherein the boundary includes a perimeter shadow boundary associated with a perimeter shadow, the perimeter shadow boundary being determined by establishing an outer edge at a cropped image perimeter for the digital image and establishing an inner edge based on the gradient changes.

7. The method of claim 3, wherein the boundary includes a binding shadow boundary associated with a binding shadow, the binding shadow boundary being determined by:

establishing a centerline of the digital image;

determining gradient changes relative to the centerline;

determining a location of a volume binding within the boundary shadow based on the gradient changes;

establishing a first and a second binding shadow boundary line based on the gradient changes relative to the determined location of the volume binding; and

lightening the binding shadow by applying a lightening function and weighting the lightening function based on a relative distance from the determined location of the volume binding.

8. The method of claim 7, wherein a first lightening function is employed as a result of the digital image having a non-text image portion within a threshold distance of the determined location of the volume binding, and a second lightening function is employed as a result of the digital image having only text image portions within the threshold distance of the determined location of the volume binding.

13. An article comprising:

a storage medium having a plurality of machine-readable instructions, wherein when the instructions are executed, the instructions provide for;

processing a digital image including a three-dimensional shadow, wherein the processing includes determining a boundary of the three-dimensional shadow; and

lightening the three-dimensional shadow within the boundary.

14. The article of claim 13, wherein determining the boundary includes performing at least one of a linear analysis and a proximity analysis on the digital image to determine luminosity gradient changes associated with the three-dimensional shadow;

and

establishing the boundary based on the gradient changes.

15. The article of claim 14, wherein the linear analysis includes determining gradient changes by comparing associated luminosity of adjacent pixels of the digital image in at least one of pixel rows of the digital image and pixel columns of the digital image;

and

the proximity analysis includes determining gradient changes by comparing associated luminosity of neighboring pixels of the digital image.

16. The article of claim 14, wherein the boundary includes a perimeter shadow boundary associated with a perimeter shadow, the perimeter shadow boundary being determined by establishing an outer edge at a cropped image perimeter for the digital image and establishing an inner edge based on the gradient changes.

17. The article of claim 16, wherein the perimeter shadow boundary includes page-fanning shadows associated with page edges of an original source for the digital image.

18. The article of claim 14, wherein the boundary includes a binding shadow boundary associated with a binding shadow, the binding shadow boundary being determined by:

establishing a centerline of the digital image;

determining gradient changes relative to the centerline;

determining a location of a volume binding within the boundary shadow based on the gradient changes;

establishing a first and a second binding shadow boundary line based on the gradient changes relative to the determined location of the volume binding; and

lightening the binding shadow by applying a lightening function and weighting the lightening function based on a relative distance from the determined location of the volume binding.

19. The article of claim 18, wherein a first lightening function is employed as a result of the digital image having a non-text image portion within a threshold distance of the determined location of the volume binding, and a second lightening function is employed as a result of the digital image having only text image portions within the threshold distance of the determined location of the volume binding.

20. An image processing system comprising:

a computing system having a processor coupled with one or more input/output devices and an imaging device capable of providing a digital image including a three-dimensional shadow to the computing system for determining a boundary of the three-dimensional shadow and lightening the three-dimensional shadow within the boundary.

21. The image processing system of claim 20, wherein determining the boundary includes performing at least one of a linear analysis and a proximity analysis on the digital image to determine luminosity gradient changes associated with the three-dimensional shadow, and establishing the boundary based on the gradient changes.

22. The image processing system of claim 20, wherein lightening includes modifying luminosity of pixels included in the three-dimensional shadow based on one or more lightening functions and one or weighting factors.

23. The image processing system of claim 20, wherein the imaging device includes a flatbed scanner.

24. The image processing system of claim 21, wherein the imaging device includes a line scanner.

25. An image processing system comprising:

a computing system having a processor coupled with one or more input/output devices and an imaging device capable of providing a digital image including a three-dimensional shadow to the computing system for processing, the processing including;

determining a boundary of the three-dimensional shadow wherein determining the boundary includes performing at least one of a linear analysis and a proximity analysis on the digital image to determine luminosity gradient changes associated with the three-dimensional shadow and establishing the boundary based on the gradient changes; and

lightening the three-dimensional shadow within the boundary wherein lightening includes modifying luminosity of pixels included in the three-dimensional shadow based on one or more lightening functions and one or weighting factors.

26. A method of image processing comprising:

acquiring a digital image including a three-dimensional shadow;

determining luminosity gradient changes within the digital image;

establishing a boundary of the three-dimensional shadow based on the luminosity gradient changes; and

lightening the three-dimensional shadow within the boundary.

27. An article comprising:

a storage medium having a plurality of machine-readable instructions, wherein the instructions are executed, the instructions provide for processing a digital image including a three-dimensional shadow, wherein the processing includes determining luminosity gradient changes within the digital image, establishing a boundary of the three-dimensional shadow based on the luminosity gradient changes and lightening the three-dimensional shadow within the boundary.