Image processing apparatus and method

• US 5,956,432 A
• Filed: 05/31/1996
• Issued: 09/21/1999
• Est. Priority Date: 06/01/1995
• Status: Expired due to Term

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Ohta, Kenichi
• Primary Examiner(s): Tran, Phuoc
• Application Number:
  US08/655,882
• Time in Patent Office: 1,208 Days
• Field of Search: 382/162, 382/167, 382/222, 382/261, 382/263, 382/264, 382/266, 382/272, 382/278, 358/515, 358/518, 358/532
• US Class Current: 382/264
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: H04N 1/58 Edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction H04N1/62 takes precedence

Abstract

In an image processing apparatus and method for effectively removing noise from an input image signal, a mean-value calculation unit calculates the mean value of pixels within a predetermined region in the vicinity of a target pixel, for each color component. A binary-coding unit performs binary-coding processing of the values of pixels within the predetermined region, for each color component, based on the mean value for each color component. A correlation-coefficient calculation unit calculates a correlation coefficient from characteristics between binary image data of respective color components. A smoothing unit performs smoothing processing by adding the value of the target pixel and the mean value using the calculated correlation coefficient, for example as a weight.

Claims

1. An image processing apparatus comprising:

detection means for detecting correlation between color-component signals of an input image signal; and

smoothing means for performing smoothing processing on the image signal inversely proportional to the correlation detected by said detection means.

2. An image processing apparatus according to claim 1, wherein said detection means calculates the mean value of the values of pixels in a predetermined region in the vicinity of a target pixel for each color component, performs binary-coding processing of the values of the pixels in the predetermined region for each color component based on the calculated mean value for each color component, and calculates a correlation coefficient from characteristics between the obtained binary image data of respective color components.

3. An image processing apparatus according to claim 2, wherein the correlation coefficient is calculated from a result of calculation of exclusive OR of the binary image data for respective color components.

4. An image processing apparatus according to claim 3, wherein said smoothing means performs the smoothing processing by adding the value of the target pixel and the mean value using the correlation coefficient as a weight.

5. An image processing apparatus according to claim 2, wherein said smoothing means performs the smoothing processing by adding the value of the target pixel and the mean value using the correlation coefficient as a weight.

6. An image processing method comprising the steps of:

detecting correlation between color-component signals of an input image signal; and

performing smoothing processing on the image signal inversely proportional to the correlation detected in said detection step.

7. An image processing apparatus comprising:

detection means for detecting correlation between color-component signals of an input image signal; and

conversion means for converting spatial-frequency characteristics of the image signal in accordance with the detected correlation,

wherein said conversion means performs sharpening processing when the detected correlation approaches a maximum value and performs smoothing processing when the detected correlation approaches a minimum value.

8. An image processing apparatus according to claim 7, wherein said detection means calculates the mean value of the values of pixels in a predetermined region in the vicinity of a target pixel for each color component, performs binary-coding processing of the values of the pixels in the predetermined region for each color component based on the calculated mean value for each color component, and calculates a correlation coefficient from characteristics between the obtained binary image data of respective color components.

9. An image processing apparatus according to claim 8, wherein the correlation coefficient is calculated from a result of calculation of exclusive OR of the binary image data for respective color components.

10. An image processing apparatus according to claim 8, wherein said conversion means performs the converting by adding the value of the target pixel and the mean value using the correlation coefficient as a weight.

11. An image processing method comprising the steps of:

detecting correlation between color-component signals of an input image signal; and

converting spatial-frequency characteristics of the image signal in accordance with the detected correlations

wherein said converting step includes performing sharpening processing when the detected correlation approaches a maximum value and performing smoothing processing when the detected correlation approaches a minimum value.

12. An image processing apparatus comprising:

detection means for detecting a correlation value between color-component signals of an input image signal; and

smoothing means for performing stronger smoothing when the correlation value detected by said detection means is a low value.

13. An image processing apparatus according to claim 12, wherein said detection means calculates a mean value of pixel values in a predetermined region in a target pixel vicinity for each color component, performs binary-coding processing of the pixel values in the predetermined region for each color component based on the calculated mean value for each color component, and calculates a correlation coefficient from characteristics between an obtained binary image data of respective color components.

14. An image processing apparatus according to claim 13, wherein the correlation value is calculated from a result of an exclusive-OR calculation of the binary image data of respective color components.

15. An image processing apparatus according to claim 14, wherein said smoothing means performs the smoothing processing by adding a value of a target pixel and the mean value using the correlation coefficient a weight.

16. A method for an image processing apparatus, comprising the steps of:

detecting a correlation value between color-component signals of an image signal; and

performing smoothing on the image signal, wherein stronger smoothing is performed when the correlation value is a low value.

17. An image processing apparatus comprising:

detection means for detecting correlation between color-component signals of an input image signal; and

conversion means for converting spatial frequency characteristics of the image signal in accordance with the detected correlation,

wherein said conversion means converts the spatial frequency characteristics by sharpening processing or smoothing processing in accordance with whether the detected correlation is high or low.

18. An image processing apparatus according to claim 17, wherein said detection means calculates a mean value of values of pixels in a predetermined region in a vicinity of a target pixel for each color component, performs binary-coding processing of the values of the pixels in the predetermined region for each color component based on the calculated mean value for each color component.

19. An image processing apparatus according to claim 18, wherein the correlation is calculated from a result of an exclusive-OR calculation of the binary image data for respective color components.

20. An image processing apparatus according to claim 18, wherein said conversion means performs the converting by adding the value of the target pixel and the means value using the correlation value as a weight.

21. A method for an image processing apparatus, comprising the steps of:

detecting correlation between color-component signals of an image signal; and

converting spatial frequency characteristics of the image signal in accordance with the detected correlation,

wherein the spatial frequency characteristics are converted in said converting step by sharpening processing or smoothing processing in accordance with whether the detected correlation is high or low.

22. An image processing apparatus comprising:

detection means for detecting correlation value between color-component signals of an input image signal; and

smoothing means for controlling the strength of smoothing in accordance with correlation value detected by said detection means.

23. A method for an image processing apparatus, comprising the steps of;

detecting correlation value between color-component signals of an image signal; and

controlling the strength of smoothing in accordance with correlation value detected by said detection means.