Selective local transient improvement and peaking for video sharpness enhancement

• US 7,668,387 B2
• Filed: 12/29/2005
• Issued: 02/23/2010
• Est. Priority Date: 06/20/2005
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Ali, Walid S. Ibrahim
• Primary Examiner(s): Couso; Jose L
• Application Number:
  US11/321,690
• Publication Number:
  US 20060285766A1
• Time in Patent Office: 1,517 Days
• Field of Search: 382/191, 382/232, 382/240, 382/254, 382/260, 382/263, 382265-266, 382/274, 348/398.1, 3484031-4041, 3484081-4091, 348/424.2, 348/431.1, 375/240.02, 375/240.18, 375/240.19
• US Class Current: 382/254
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20016 Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform
• CPC Class Codes: G06T 2207/20064 Wavelet transform [DWT]
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/10 using non-spatial domain filtering
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 5/208 for compensating for attenuation of high frequency components, e.g. crispening, aperture distortion correction

Abstract

A method of selectively sharpening an image may include, for at least some pixels in the image, determining a frequency content associated with a pixel value in the image. The pixel may be linearly sharpened if the frequency content exceeds a threshold. The pixel may be non-linearly sharpened if the frequency content does not exceed the threshold. In some implementations, the non-linear sharpening may include wavelet decomposition of the image and enhancement of decomposed components.

Claims

1. A method comprising:

using a computer to locate edges in an image using wavelet decomposition modules in horizontal, vertical, and diagonal directions; and

using a computer to selectively sharpen pixels at said edges in an amplifier by altering components of said wavelet decomposition of different frequencies differently.

2. The method of claim 1 including using three levels of wavelet decomposition.

3. The method of claim 2 including using wavelet decomposition in horizontal, vertical, and diagonal directions at each of said three levels.

4. The method of claim 3 including boosting higher frequency components at each of said levels.

5. The method of claim 4 including boosting said higher frequency components differently at each level.

6. The method of claim 5 including boosting said higher frequency components by different factor at each level.

7. The method of claim 6 including using a threshold value to distinguish higher and lower frequency components.

8. The method of claim 7 including using different threshold values at each level.

9. The method of claim 8 including using different threshold values for horizontal, vertical, and diagonal directions.

10. A computer readable medium storing instructions that are executed by a computer to:

selectively sharpen pixels at edges using wavelet decomposition in horizontal, vertical, and diagonal directions to locate edges in an image; and

enhance the edges in the horizontal, vertical, and diagonal directions, said amplifiers coupled to said sharpener, and to alter components of said wavelet decomposition of different frequencies differently.

11. The medium of claim 10, further storing instructions to use three levels of wavelet decomposition.

12. The medium of claim 11, further storing instructions to use wavelet decomposition in horizontal, vertical, and diagonal directions at each of said three levels.

13. The medium of claim 12, further storing instructions to boost higher frequency components at each of said levels.

14. The medium of claim 13, further storing instructions to boost said higher frequency components differently at each level.

15. The medium of claim 14, further storing instructions to boost said higher frequency components by a different factor at each level.

16. The medium of claim 15, further storing instructions to use a threshold value to distinguish higher and lower frequency components.

17. The medium of claim 16, further storing instructions to use different threshold values at each level.

18. The medium of claim 17, further storing instructions to use different threshold values for horizontal, vertical, and diagonal directions.