Image pickup apparatus, signal processing method, and signal processing program

Patent metadata

Field	Value
Publication number	US-10491840-B2
Application number	US-201715825969-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	Jul 13, 2015
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

An image pickup apparatus of the present invention includes: an image pickup optical system configured to form a subject image; an image pickup device configured to photoelectrically convert the subject image formed by the image pickup optical system, wherein part of pixels in a region provided with image formation pixels arranged in a matrix are arranged as focus detection pixels; an optical influence estimation unit configured to use output signals from the image formation pixels, output signals from the focus detection pixels, and two-dimensional pixel position information of the focus detection pixels to estimate a level of influence of vignetting caused by the image optical system according to an image height; and an optical influence correction unit configured to execute image processing with different details that vary according to an estimation result of the optical influence estimation unit.

First claim

What is claimed is:

1. An image pickup apparatus comprising:
an image pickup optical system configured to form a subject image;
an image pickup device configured to photoelectrically convert the subject image formed by the image pickup optical system, wherein part of pixels in a region provided with image formation pixels arranged in a matrix are arranged as focus detection pixels;
an optical influence estimation circuit configured to use output signals from the image formation pixels, output signals from the focus detection pixels, and two-dimensional pixel position information of the focus detection pixels to estimate a level of influence of vignetting caused by the image optical system according to an image height; and
an optical influence correction circuit configured to execute image processing with different details that vary according to an estimation result of the optical influence estimation circuit,
wherein the optical influence estimation circuit further comprises:
a ratio computation processing circuit configured to calculate a ratio of the output signals from the image formation pixels and the output signals from the focus detection pixels according to the image height;
a vignetting influence determination circuit configured to judge a magnitude of influence of vignetting from a change in the ratio according to the image height calculated by the ratio computation processing circuit; and
a region division processing circuit configured to divide an inside of an image pickup region into a plurality of regions according to the level of influence of vignetting caused by the image pickup optical system according to the image height,

wherein the vignetting influence determination circuit further comprises:
a change statistics processing circuit configured to statistically determine whether the change in the ratio according to the image height calculated by the ratio computation processing circuit is a close change; and
an influence change detection circuit configured to determined that the influence of vignetting is changed at an image height position where a tendency of the change is different,

wherein the optical influence correction circuit executes the image processing with different details that vary in each of the regions divided by the region division processing circuit.

2. The image pickup apparatus according to claim 1 , wherein
the region division processing circuit of the optical influence estimation circuit divides the inside of the image pickup region, as a region with a different influence of vignetting, the image height position with the different tendency of the change outputted by the influence change detection circuit.

3. The image pickup apparatus according to claim 1 , wherein
the optical influence correction circuit further comprises:
a region adaptive gain calculation circuit configured to calculate each amount of gain to be applied to the image formation pixels and the focus detection pixels according to an output of the optical influence estimation circuit, for each image height position of the influence of vignetting at a similar level; and
a region adaptive gain correction circuit configured to execute a gain correction process according to the amount of gain of each image height position calculated by the region adaptive gain calculation circuit.

4. The image pickup apparatus according to claim 1 , wherein
the optical influence correction circuit further comprises a region adaptive parameter calculation processing circuit configured to calculate each image processing parameter to be applied to both the image formation pixels and the focus detection pixels according to the output of the optical influence estimation circuit, for each image height position of the influence of vignetting at the similar level.

5. The image pickup apparatus according to claim 4 , wherein
the region adaptive parameter calculation processing circuit comprises:
a region adaptive noise reduction calculation circuit configured to calculate a parameter of an edge enhancement process according to the image height position; and
a region adaptive edge enhancement calculation circuit configured to calculate a parameter of an edge enhancement process according to the image height position.

6. A signal processing method of processing an output signal from an image pickup device configured to photoelectrically convert a subject image formed by an image pickup optical system, wherein part of pixels in a region provided with image formation pixels arranged in a matrix and arranged as focus detection pixels in the image pickup device, the signal processing method comprising:
an optical influence estimation process of using output signals from the image formation pixels, output signals from the focus detection pixels, and two-dimensional pixel position information of the focus detection pixels to estimate a degree of influence of vignetting caused by the image optical system according to an image height; and
an optical influence correction process of executing image processing with different details that vary according to the degree of influence of vignetting estimated in the optical influence estimation process,
wherein the optical influence estimation process further comprises:
a ratio computation process of calculating a ratio of the output signals from the image formation pixels and the output signals from the focus detection pixels according to the image height;
a vignetting influence determination process of judging a magnitude of influence of vignetting from a change in the ratio according to the image height calculated by the ratio computation process; and
a region division process of dividing an inside of an image pickup region into a plurality of regions according to the level of influence of vignetting caused by the image pickup optical system according to the image height,

wherein the vignetting influence determination process further comprises:
a change statistics process of statistically determining whether the change in the ratio according to the image height calculated by the ratio computation process is a close change; and
an influence change detection process of determining that the influence of vignetting is changed at an image height position where a tendency of the change is different,

wherein the optical influence correction process executes the image processing with different details that vary in each of the regions divided by the region division process.

7. A non-transitory computer-readable medium storing a signal processing program for a computer of an image pickup apparatus, the signal processing program comprising:
an optical influence estimation step of estimating a degree of influence of vignetting caused by an image optical system according to an image height by using output signals from image formation pixels, output signals from focus detection pixels, and two-dimensional pixel position information of the focus detection pixels; and
an optical influence correction step of executing image processing with different details that vary according to the degree of influence of vignetting estimated in the estimating,
wherein the optical influence estimation step further comprises:
a ratio computation step of calculating a ratio of the output signals from the image formation pixels and the output signals from the focus detection pixels according to the image height;
a vignetting influence determination step of judging a magnitude of influence of vignetting from a change in the ratio according to the image height calculated by the ratio computation step; and
a region division step of dividing an inside of an image pickup region into a plurality of regions according to the level of influence of vignetting caused by th

Assignees

• Olympus Corp

Inventors

• Okazawa Atsuro

Classifications

• H04N25/704

  Pixels specially adapted for focusing, e.g. phase difference pixel sets · CPC title

• H04N23/672

  based on the phase difference signals · CPC title

• G02B7/34 Primary

  using different areas in a pupil plane · CPC title

• H04N25/61 Primary

  the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4" · CPC title

• H04N23/76

  by influencing the image signals · CPC title