IMAGE PROCESSING DEVICE AND METHOD, PROGRAM RECORDING MEDIUM, AND IMAGING SYSTEM

• US 20100246991A1
• Filed: 03/25/2010
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Corporation
• Inventors: NAITO, Yukihiro
• Granted Patent: US 8,270,758 B2
• Time in Patent Office: Days
• US Class Current: 382/260
• CPC Class Codes: G06T 2207/20016 Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06V 10/30 Noise filtering

Abstract

A number of invalid pixels at an outer peripheral part is reduced while suppressing an influence on an image quality such as discontinuity by pixel expansion, and suppressing increase in a number of processing pixels. When sequentially generating a plurality of reduced images having resolutions different from each other by sequentially performing a reduction process on an input image when realizing a noise reduction process using multiresolution transformation, the pixel expansion process of expanding the pixels at the outer peripheral part of the image of the reduced image is performed at least once before performing one of the reduction processes, and the reduced image after the pixel expansion process is further reduced to generate the plurality of reduced images.

Claims

1. An image processing device comprising:

a filtering unit of a plurality of stages for filtering an input image;

a plurality of band image signal generating units for generating a plurality of band image signals having different frequency bands from each other from an output image of the filtering unit of a plurality of stages;

a noise reduction processing unit for performing a noise reduction process of reducing a noise component contained in the plurality of band image signals generated by the band image signal generating units; and

a plurality of image synthesizing units for synthesizing the plurality of band image signals subjected to the noise reduction process;

wherein

the image processing device includes a first pixel expansion unit for performing a pixel expansion process of expanding pixels at an outer peripheral part of an image input to one of the plurality of filtering units other than the filtering unit of a first stage, or an image output from one of the plurality of band image signal generating units.

2. The image processing device according to claim 1, further comprising a second pixel expansion unit, arranged on an input side of the filtering unit of the first stage of the plurality of filtering units, for performing the pixel expansion process of expanding the pixels at the outer peripheral part of the input image.

3. The image processing device according to claim 1, wherein at least one of the plurality of filtering units reduces the input image or an output image of the filtering unit arranged at a previous stage.

4. The image processing device according to claim 1, wherein the first pixel expansion unit is arranged on an input side of the filtering unit of a final stage of the plurality of filtering units.

5. The image processing device according to claim 1, further comprising a second pixel expansion unit for performing the pixel expansion process of enlarging the pixels at the outer peripheral part of the image of the band image signal in which at least a band frequency is second lowest of the plurality of band image signals output from the plurality of band image signal generating units.

6. The image processing device according to claim 1, further comprising:

a noise reduction intensity limiting unit for limiting an intensity of noise reduction in the noise reduction processing unit;

wherein

the noise reduction intensity limiting unit includes a mixing part for mixing the band image signal before the noise reduction process by the noise reduction processing unit and the band image signal after the noise reduction process, the noise reduction intensity being controlled by controlling a mixing ratio.

7. The image processing device according to claim 6, wherein the mixing ratio is adjusted so that a mixing proportion of the band image signal after the noise reduction at the outer peripheral part of the image is smaller than that at a portion other than the outer peripheral part of the image.

8. An imaging system comprising:

an imaging unit for acquiring an image; and

the image processing device according to claim 1 for performing an image process with respect to the image signal acquired by the imaging unit.

9. An image processing method comprising the steps of:

performing filtering over plural times with respect to an input image;

generating a plurality of band image signals having different frequency bands from each other from a plurality of output images obtained by the filtering of plural times;

performing a pixel expansion process of expanding pixels at outer peripheral parts of the plurality of output images obtained by the filtering and at least one image of the plurality of band image signals;

performing a noise reduction process of reducing a noise component contained in the plurality of band image signals; and

synthesizing the plurality of band image signals subjected to the noise reduction process.

10. The image processing method according to claim 9, wherein the pixel expansion process of expanding the pixels at the outer peripheral part of the image is performed with respect to the input image.

11. An image processing program recording medium for causing a computer to execute the processes of:

performing filtering over plural times with respect to an input image;

generating a plurality of band image signals having different frequency bands from each other from a plurality of output images obtained by the filtering of plural times;

performing a pixel expansion process of expanding pixels at outer peripheral parts of the plurality of output images obtained by the filtering and at least one image of the plurality of band image signals;

performing a noise reduction process of reducing a noise component contained in the plurality of band image signals; and

synthesizing the plurality of band image signals subjected to the noise reduction process.

12. The image processing program recording medium according to claim 11, causing the computer to execute the pixel expansion process of expanding the pixels at the outer peripheral part of the image with respect to the input image.