Enhancement of Blurred Image Portions

• US 20080025628A1
• Filed: 10/21/2005
• Published: 01/31/2008
• Est. Priority Date: 10/26/2004
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: De Haan, Gerard
• Application Number:
  US11/577,743
• Publication Number:
  US 20080025628A1
• Time in Patent Office: Days
• US Class Current: 382/255
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening

Abstract

This invention relates to a method for image enhancement, comprising a first step (41) of distinguishing blurred and non-blurred image portions of an input image, and a second step (42) of enhancing at least one of said blurred image portions of said input image to produce an output image. Said blurred and non-blurred image portions are for instance distinguished by comparing (416) the differences (415) between a linearly up-scaled (414) version of the down-scaled (411) input image and the input image, and the differences (413) between a non-linearly up-scaled (412) representation of the down-scaled input image and the input image. Said blurred image portion is for instance enhanced by replacing (42) it with a portion of a non-linearly up-scaled representation of the down-scaled input image. The invention also relates to a device, a computer program, and a computer program product.

Claims

1. A method for image enhancement, comprising:

a first step (41) of distinguishing blurred and non-blurred image portions of an input image, and

a second step (42) of enhancing at least one of said blurred image portions of said input image to produce an output image.

2. The method according to claim 1, wherein said non-blurred image portions are not enhanced.

3. The method according to claim 1, wherein said first step (41) comprises:

transforming (411) at least a portion of said input image according to a first transformation to obtain a transformed input image portion;

enhancing (412) a representation of said transformed input image portion to obtain an enhanced transformed input image portion; and

processing (413, 415, 416) at least said portion of said input image, said enhanced transformed input image portion, and one of said transformed input image portion and an image portion, which is obtained by transforming (414) said transformed input image portion according to a second transformation, to distinguish said blurred and non-blurred image portions of said input image.

4. The method according to claim 3, wherein said processing (413, 415, 416) to distinguish said blurred and non-blurred image portions of said input image comprises:

determining (413) first differences between said enhanced transformed input image portion and said portion of said input image;

determining (415) second differences between said transformed input image portion or said image portion, which is obtained by transforming (414) said transformed input image portion according to said second transformation, and said portion of said input image; and

comparing (416) said first and second differences to distinguish blurred and non-blurred image portions of said input image.

5. The method according to claim 3, wherein said first transformation (411) causes a reduction or elimination of spectral components of said portion of said input image, and wherein said enhancing (412) aims at a restoration or estimation of spectral components of said representation of said transformed input image portion.

6. The method according to claim 5, wherein said first (41) and second (42) steps are repeated at least two times, and wherein in each repetition, a different spectral component is concerned, respectively.

7. The method according to claim 3, wherein said first transformation (411) causes a blurring of said portion of said input image, wherein said enhancing (412) aims at a de-blurring of said representation of said transformed input image portion, wherein said second differences are determined (415) between said transformed input image portion and said portion of said input image, and wherein image portions where said first differences are larger than said second differences are considered as blurred image portions.

8. The method according to claim 3, wherein said first transformation (411) causes a down-scaling of said portion of said input image, wherein said enhancing (412) causes a non-linear up-scaling of said representation of said transformed input image portion, wherein said second differences are determined (415) between said image portion, which is obtained by transforming (414) said transformed input image portion according to said second transformation, and said portion of said input image, wherein said second transformation (414) causes a linear up-scaling of said transformed input image portion, and wherein image portions where said first differences are larger than said second differences are considered as blurred image portions.

9. The method according to claim 3, wherein said at least one blurred image portion is enhanced in said second step (42) by replacing it with an enhanced transformed input image portion obtained in said first step (41).

10. The method according to claim 3, wherein said first (41) and second (42) steps are repeated in N iterations to produce a final output image from an original input image, wherein in each iteration n=1, . . . ,N, an N−

n fold transformed version of at least a portion of said original input image obtained from N−

n fold application of said first transformation to said portion of said original input image is used as said portion of said input image, wherein in the first iteration n=1, an N fold transformed version of said portion of said original input image obtained from N fold application of said first transformation to said portion of said original input image is used as said representation of said transformed input image portion, wherein in each other iteration n=2, . . . ,N, at least a portion of said output image produced by the preceding iteration n−

1 is used as said representation of said transformed input image portion, and wherein the output image produced in the last iteration n=N is said final output image.

11. The method according to claim 10, wherein N equals 3.

12. The method according to claim 8, wherein said non-linear up-scaling (314) is performed according to the PixelPlus, Digital Reality Creation or Digital Emotional Technology technique.

13. A computer program with instructions operable to cause a processor to perform the method steps of claim 1.

14. A computer program product comprising a computer program with instructions operable to cause a processor to perform the method steps of claim 1.

15. A device (10;

30) for image enhancement, comprising;

first means (101, 102, 103, 104;

301, 302, 304) arranged for distinguishing blurred and non-blurred image portions of an input image, and

second means (105;

305) arranged for enhancing at least one of said blurred image portions of said input image to produce an output image.

16. The device (10) according to claim 15, wherein said first means comprises:

means (101) arranged for transforming at least a portion of said input image according to a first transformation to obtain a transformed input image portion;

means (102) arranged for enhancing a representation of said transformed input image portion to obtain an enhanced transformed input image portion;

means (103) arranged for transforming said transformed input image portion according to a second transformation; and

means (104) arranged for processing at least said portion of said input image, said enhanced transformed input image portion and an image portion, which is obtained by transforming said transformed input image portion according to said second transformation, to distinguish said blurred and non-blurred image portions of said input image.

17. The device according to claim 16, wherein said means (104) arranged for processing at least said portion of said input image, said enhanced transformed input image portion and said image portion, which is obtained by transforming said transformed input image portion according to said second transformation, comprises:

means (104) arranged for determining first differences between said enhanced transformed input image portion and said portion of said input image;

means (104) arranged for determining second differences between said image portion, which is obtained by transforming said transformed input image portion according to said second transformation, and said portion of said input image; and

means (104) arranged for comparing said first and second differences to distinguish blurred and non-blurred image portions of said input image.

18. The device (30) according to claim 15, wherein said first means comprises:

means (301) arranged for transforming at least a portion of said input image according to a first transformation to obtain a transformed input image portion;

means (302) arranged for enhancing a representation of said transformed input image portion to obtain an enhanced transformed input image portion; and

means (304) arranged for processing at least said portion of said input image, said enhanced transformed input image portion and said transformed input image portion to distinguish said blurred and non-blurred image portions of said input image.

19. The device according to claim 18, wherein said means (304) arranged for processing at least said portion of said input image, said enhanced transformed input image portion and said transformed input image portion comprises:

means (304) arranged for determining first differences between said enhanced transformed input image portion and said portion of said input image;

means (304) arranged for determining second differences between said transformed input image portion and said portion of said input image; and

means (304) arranged for comparing said first and second differences to distinguish blurred and non-blurred image portions of said input image.

20. The device according to claim 16, wherein said first (101, 102, 103, 104) and second (105) means form a unit (10, 10′

-1, 10′

-2), wherein N of these units are interconnected as a cascade (20) that produces a final output image from an original input image, wherein in each unit n=1, . . . ,N, an N−

n fold transformed version of at least a portion of said original input image obtained from N−

n fold application of said first transformation to said portion of said original input image is used as said input image, wherein in the first unit n=1, an N fold transformed version of said portion of said original input image obtained from N fold application of said first transformation to said portion of said original input image is used as said representation of said transformed input image portion, wherein in each other unit n=2, . . . ,N, at least a portion of said output image as produced by the preceding unit n−

1 is used as said representation of said transformed input image portion, and wherein the output image produced in the last unit n=N is said final output image.