Imaging device and imaging method

Patent metadata

Field	Value
Publication number	US-9525856-B2
Application number	US-201514963433-A
Country	US
Kind code	B2
Filing date	Dec 9, 2015
Priority date	Jun 26, 2013
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

An imaging device includes an optics, an image sensor, and a processor including hardware. The optics includes a first pupil and a second pupil. The image sensor includes a first-color filter that has first transmittance characteristics, a second-color filter that has second transmittance characteristics, and a third-color filter that has third transmittance characteristics. The processor is configured to implement a correction process that corrects a pixel value that corresponds to a first color and a pixel value that corresponds to a third color based on a component value that corresponds to the overlapping region of the first transmittance characteristics and the third transmittance characteristics, and a phase difference detection process that detects the phase difference between an image formed by the corrected pixel value that corresponds to the first color and an image formed by the corrected pixel value that corresponds to the third color.

First claim

What is claimed is:

1. An imaging device comprising:
an optics that includes a first pupil that allows light within a first wavelength band to pass through, and a second pupil that allows light within a second wavelength band to pass through, the second wavelength band differing from the first wavelength band;
an image sensor that includes a first-color filter that has first transmittance characteristics, a second-color filter that has second transmittance characteristics, and a third-color filter that has third transmittance characteristics, and acquires a pixel value that corresponds to a first color, a pixel value that corresponds to a second color, and a pixel value that corresponds to a third color; and
a processor comprising hardware,
the processor being configured to implement:
a correction process that corrects the pixel value that corresponds to the first color and the pixel value that corresponds to the third color based on a component value that corresponds to an overlapping region of the first transmittance characteristics and the third transmittance characteristics; and
a phase difference detection process that detects a phase difference between an image formed by the corrected pixel value that corresponds to the first color and an image formed by the corrected pixel value that corresponds to the third color.

2. The imaging device as defined in claim 1 ,
the second color being a color that is longer in wavelength than the first color and is shorter in wavelength than the third color, and
the first wavelength band that passes through the first pupil corresponding to the third color, and the second wavelength band that passes through the second pupil corresponding to the first color.

3. The imaging device as defined in claim 2 ,
the processor being configured to implement the correction process that estimates the component value that corresponds to the overlapping region of the first transmittance characteristics and the third transmittance characteristics based on the pixel value that corresponds to the second color, and reduces the component value that corresponds to the overlapping region from the pixel value that corresponds to the first color and the pixel value that corresponds to the third color.

4. The imaging device as defined in claim 3 ,
the processor being configured to implement the correction process that multiplies the pixel value that corresponds to the second color by a first coefficient based on the first transmittance characteristics and the third transmittance characteristics to calculate the component value that corresponds to the overlapping region.

5. The imaging device as defined in claim 4 ,
the processor being configured to implement a coefficient acquisition process that acquires the first coefficient that maximizes similarity between the second transmittance characteristics multiplied by the first coefficient and the overlapping region.

6. The imaging device as defined in claim 5 ,
the first coefficient that maximizes the similarity being the first coefficient that minimizes a Euclidean distance between a vector that corresponds to the overlapping region and includes transmittance components that respectively correspond to a plurality of wavelengths, and a vector that corresponds to the second transmittance characteristics multiplied by the first coefficient and includes transmittance components that respectively correspond to the plurality of wavelengths.

7. The imaging device as defined in claim 3 ,
the processor being configured to implement the correction process that corrects the pixel value that corresponds to the first color by subtracting the component value that corresponds to the overlapping region from the pixel value that corresponds to the first color, and corrects the pixel value that corresponds to the third color by subtracting the component value that corresponds to the overlapping region from the pixel value that corresponds to the third color.

8. The imaging device as defined in claim 7 ,
the processor being configured to implement the correction process that corrects the pixel value that corresponds to the second color by subtracting the component value that corresponds to the overlapping region, the corrected pixel value that corresponds to the first color, and the corrected pixel value that corresponds to the third color, from the pixel value that corresponds to the second color that is multiplied by a second coefficient based on the first transmittance characteristics and the third transmittance characteristics.

9. The imaging device as defined in claim 8 ,
the processor being configured to implement a coefficient acquisition process that acquires the second coefficient that maximizes similarity of a short-wavelength-side part of the first transmittance characteristics and a long-wavelength-side part of the third transmittance characteristics, with the second transmittance characteristics multiplied by the second coefficient.

10. The imaging device as defined in claim 9 ,
a given wavelength that is shorter than a wavelength that corresponds to a maximum transmittance represented by the first transmittance characteristics being a first wavelength, and a given wavelength that is longer than a wavelength that corresponds to a maximum transmittance represented by the third transmittance characteristics being a second wavelength, and
the second coefficient that maximizes the similarity being the second coefficient that minimizes a Euclidean distance between a vector that corresponds to the first transmittance characteristics and includes transmittance components that respectively correspond to a plurality of wavelengths shorter than the first wavelength, and a vector that corresponds to the second transmittance characteristics multiplied by the second coefficient and includes transmittance components that respectively correspond to the plurality of wavelengths, and a Euclidean distance between a vector that corresponds to the third transmittance characteristics and includes transmittance components that respectively correspond to a plurality of wavelengths longer than the second wavelength, and a vector that corresponds to the second transmittance characteristics multiplied by the second coefficient and includes transmittance components that respectively correspond to the plurality of wavelengths.

11. The imaging device as defined in claim 3 ,
the processor being configured to implement the correction process that calculates an evaluation value that represents similarity of a candidate value for the component value that corresponds to the overlapping region, a value obtained by correcting the pixel value that corresponds to the first color using the candidate value, and a value obtained by correcting the pixel value that corresponds to the third color using the candidate value, with the pixel value that corresponds to the first color, the pixel value that corresponds to the second color, and the pixel value that corresponds to the third color, and calculates the component value that corresponds to the overlapping region by determining the candidate value that maximizes the similarity based on the evaluation value.

12. An imaging method comprising:
forming an image using an optics that includes a first pupil that allows light within a first wavelength band to pass through, and a second pupil that allows light within a second wavelength band to pass through, the second wavelength band differing from the first wavelength band;
capturing the image using an image sensor that includes a first-color filter that has first transmittance characteristics, a second-color filter that has second transmittance characte

Assignees

• Olympus Corp

Inventors

• Imade Shinichi

Classifications

• H04N25/134

  based on three different wavelength filter elements · CPC title

• G03B13/36 Primary

  Autofocus systems · CPC title

• G02B7/365

  by analysis of the spatial frequency components of the image · CPC title

• G02B7/34

  using different areas in a pupil plane · CPC title

• H04N9/646 Primary

  for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters · CPC title