IMAGE PROCESSING APPARATUS AND IMAGE PROCESSING METHOD

• US 20100177979A1
• Filed: 12/23/2009
• Published: 07/15/2010
• Est. Priority Date: 01/09/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kotani, Takuya
• Granted Patent: US 8,335,393 B2
• Time in Patent Office: Days
• US Class Current: 382/255
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening

Abstract

The invention provides an image processing apparatus which corrects a captured image obtained by capturing an object, the apparatus comprising: an acquiring unit configured to acquire, for each pixel of the captured image, information on an object distance representing a distance to the object; a calculating unit configured to calculate, based on the information on the object distance, a difference in the object distance between a pixel of interest in the captured image and a surrounding pixel of the pixel of interest; a parameter setting unit configured to set a sharpening process parameter for the pixel of interest based on the calculated difference in the object distance; and a sharpening process unit configured to perform a sharpening process for the pixel of interest by using the set parameter.

Claims

1. An image processing apparatus which corrects a captured image obtained by capturing an object, the apparatus comprising:

an acquiring unit configured to acquire, for each pixel of the captured image, information on an object distance representing a distance to the object;

a calculating unit configured to calculate, based on the information on the object distance, a difference in the object distance between a pixel of interest in the captured image and a surrounding pixel of the pixel of interest;

a parameter setting unit configured to set a sharpening process parameter for the pixel of interest based on the calculated difference in the object distance; and

a sharpening process unit configured to perform a sharpening process for the pixel of interest by using the set parameter.

2. The apparatus according to claim 1, wherein said parameter setting unit sets a degree of sharpening and a filter size of the sharpening process as the parameter.

3. The apparatus according to claim 2, wherein said parameter setting unit sets the degree of sharpening larger for a larger difference in the object distance.

4. The apparatus according to claim 2, wherein said parameter setting unit sets the filter size larger for a larger difference in the object distance.

5. The apparatus according to claim 4, wherein said parameter setting unit sets a radius of unsharp masking as the filter size.

6. The apparatus according to claim 1, wherein

said acquiring unit generates a distance map representing the information on the object distance for each pixel of the captured image, and

said calculating unit calculates the difference in the object distance based on the distance map.

7. The apparatus according to claim 6, wherein said acquiring unit generates the distance map by calculating the object distance of each pixel based on a shooting distance of the captured image and contrast information of each pixel.

8. The apparatus according to claim 7, wherein said acquiring unit generates a low-resolution distance map based on a reduced captured image, and enlarges and interpolates the low-resolution distance map to generate the distance map.

9. The apparatus according to claim 1, wherein said calculating unit calculates an average of differences in the object distance between the pixel of interest and a plurality of surrounding pixels of the pixel of interest.

10. The apparatus according to claim 9, wherein said calculating unit calculates the difference in the object distance based on a gradient between a pair of surrounding pixels sandwiching the pixel of interest.

11. The apparatus according to claim 1, further comprising a shooting condition acquiring unit configured to acquire shooting conditions of the captured image,

wherein said parameter setting unit sets the parameter based on the shooting conditions and the difference in the object distance.

12. The apparatus according to claim 11, wherein the shooting conditions include at least one of a shooting distance, a lens F-number, and a lens focal length.

14. A storage medium storing a program for controlling a computer apparatus to function as each unit of an image processing apparatus defined in claim 1.

13. An image processing method of correcting a captured image obtained by capturing an object, the method comprising the steps of:

acquiring, for each pixel of the captured image, information on an object distance representing a distance to the object;

calculating, based on the information on the object distance, a difference in the object distance between a pixel of interest in the captured image and a surrounding pixel of the pixel of interest;

setting a sharpening process parameter for the pixel of interest based on the calculated difference in the object distance; and

performing a sharpening process for the pixel of interest by using the set parameter.