Image capturing apparatus

• US 20070024738A1
• Filed: 02/23/2006
• Published: 02/01/2007
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Kanai, Kunihiko, Shiraki, Hidenori
• Granted Patent: US 7,583,308 B2
• Time in Patent Office: Days
• US Class Current: 348/335
• CPC Class Codes: G02B 7/34 using different areas in a pupil plane
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67
• CPC Class Codes: H04N 23/672 based on the phase difference signals
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

The present invention provides a digital camera which has a plurality of image capturing optical systems and quickly performs automatic focusing. A digital camera includes a first image capturing optical system formed from a lens 2 and a first image sensor, and a second image capturing optical system formed from a lens 3 and a second image sensor. An image processor detects a phase difference between an image of a single subject formed on the first image sensor and an image of the same formed on the second image sensor, in order to perform phase-difference AF. Since the lenses 2, 3 have different focal lengths, the image processor executes correlation operation after having performed conversion processing for causing a scaling factor of the image formed by the first image sensor to coincide with that of the image formed by the second image sensor, to thus detect a phase difference.

Claims

1. An image capturing apparatus comprising:

a first image capturing optical system;

a second image capturing optical system which is spaced apart from the first image capturing optical system by a predetermined distance and differs from the first image capturing optical system in terms of an angle of field; and

computing means which computes a distance to a subject by means of performing correlation operation of a first image captured by the first image capturing optical system and a second image captured by the second image capturing optical system and which executes correlation operation after performance of conversion operation for causing a scaling factor of the first image to coincide with a scaling factor of the second image.

2. The image capturing apparatus according to claim 1, wherein the computing means causes a resolution of the first image to coincide with a resolution of the second image by means of converting the resolution of at least one of the first and second images.

3. The image capturing apparatus according to claim 1, wherein the first image capturing optical system includes a fixed focus lens, and the second image capturing optical system includes a zoom lens.

4. The image capturing apparatus according to claim 1, wherein each of the first image capturing optical system and the second image capturing optical system includes a zoom lens.

5. The image capturing apparatus according to claim 1, wherein the computing means includes

contrast detection means for detecting contrast of at least one of the first image and the second image;

and

comparison means for comparing the detected contrast with a reference value; and

the image capturing apparatus further comprises

focus adjustment means for adjusting focus until the contrast reaches the reference value when the contrast is less than the reference value, wherein

the computing means executes correlation operation after contrast has reached the reference value.

6. The image capturing apparatus according to claim 1, wherein the computing means executes two-dimensional correlation operation as correlation operation.

7. The image capturing apparatus according to claim 1, wherein the computing means comprises

contrast detection means which divides at least one of the first and second images into a plurality of areas, to thus detect contrast of the respective areas;

comparison means for comparing the detected contrast with a reference value; and

selection means for selecting an area where the detected contrast becomes equal to or greater than the reference value, wherein correlation operation of the area selected by the selection means is executed.

8. The image capturing apparatus according to claim 1, wherein the computing means has

detection means for detecting a characteristic area of a subject from at least one of the first and second images, wherein

conversion operation for causing the scaling factor of the first image to coincide with the scaling factor of the second image is performed such that a scaling factor optimal for a scaling factor of the characteristic area of the subject is achieved.

9. The image capturing apparatus according to claim 8, wherein the characteristic area is a person.