Methods and systems for noise reduction and image enhancement involving selection of noise-control parameter

• US 8,532,429 B2
• Filed: 09/28/2010
• Issued: 09/10/2013
• Est. Priority Date: 09/28/2010
• 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: Segall, Christopher A.
• Primary Examiner(s): Drennan, Barry
• Assistant Examiner(s): MOYER, ANDREW M
• Application Number:
  US12/892,803
• Publication Number:
  US 20120076430A1
• Time in Patent Office: 1,078 Days
• Field of Search: None
• US Class Current: 382/275
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20028 Bilateral filtering
• CPC Class Codes: G06T 5/75 Unsharp masking

Abstract

Aspects of the present invention are related to systems and methods for image enhancement, wherein an input image may be separated into two images: a first image comprising image content, from the input image, which may be sharpened; and a second image comprising image content, from the input image, which may be attenuated. One aspect of the present invention relates to determining a value for a noise-control parameter that controls the amount of attenuation applied to the second image.

Claims

1. A system for enhancing an input image, said system comprising:

an edge-preserving filter for generating, from an input image, a first image comprising image content, from said input image, to sharpen and a second image comprising image content, from said input image, to attenuate; and

a noise-control-parameter selector for selecting a value for a noise-control parameter that controls the amount of attenuation applied to said second image, wherein said noise-control-parameter selector selects said value based on a first noise estimate of an additive noise in said input image and a second noise estimate of a compression noise in said input image, and wherein said value is a scalar value.

2. The system as described in claim 1, wherein said edge-preserving filter comprises a bi-lateral filter.

3. The system as described in claim 1, wherein said value is proportional, by a proportionality constant, to the ratio of the first noise estimate and the sum of the first noise estimate and the second noise estimate.

4. The system as described in claim 3, wherein said value is determined by accessing a look-up-table using said first noise estimate and said second noise estimate as indices into said look-up-table.

5. The system as described in claim 3, wherein said proportionality constant is a beta preference parameter associated with no compression in said input image.

6. The system as described in claim 1 further comprising a noise estimator for estimating said first noise estimate and said second noise estimate.

7. The system as described in claim 6, wherein said noise estimator comprises:

an image-noise statistic estimator for estimating at least one of grain noise, sensor noise and thermal noise in said input image, thereby producing an image-noise statistic for generating said first noise estimate; and

a codec-noise statistic estimator for estimating compression noise in said input image, thereby producing a codec-noise statistic for generating said second noise estimate.

8. The system as described in claim 7, wherein said codec-noise statistic estimator estimates said codec noise statistic from said input image.

9. The system as described in claim 7, wherein said codec-noise statistic estimator estimates said codec-noise statistic from coding parameters associated with said input image.

10. The system as described in claim 9, wherein said codec-noise statistic estimator comprises a plurality of look-up tables, wherein each look-up table in said plurality of look-up tables is associated with a codec and at least one codec coding parameter.

11. The system as described in claim 1 further comprising a decoder for decoding a bitstream associated with said input image.

12. The system as described in claim 1 further comprising:

a sharpener for sharpening said first image;

an attenuator for attenuating said second image; and

an image combiner for combining said sharpened first image and said attenuated second image.

13. The system as described in claim 12 further comprising an up-sampler for up-sampling said combined image.

14. The system as described in claim 12, wherein said sharpener comprises an un-sharp masking filter.

15. The system as described in claim 12, wherein said noise-control parameter controls said attenuator.

16. The system as described in claim 1, wherein said noise-control-parameter selector comprises a noise-control-parameter-value calculator.

17. The system as described in claim 16, wherein said noise-control-parameter-value calculator calculates a first value for said noise-control parameter based on a first noise estimate of an additive noise in said input image and a second noise estimate of a compression noise in said input image.

18. The system as described in claim 17, wherein said first value for said noise-control parameter calculated by said noise-control-parameter-value calculator is combined with a previously stored value for said noise-control parameter.

19. A method for calculating a value for a noise-control parameter for controlling the amount of attenuation of a first image, said method comprising:

receiving a first noise estimate of the additive noise present in a first image;

receiving a second noise estimate of the compression noise present in said first image;

calculating a first value for said noise-control parameter based on said first noise estimate and said second noise estimate, wherein said first value is a scalar value; and

combining said first value for said noise-control parameter with a previously stored value for said noise-control parameter.