Photographing apparatus and in-focus position searching method

• US 8,310,586 B2
• Filed: 07/30/2007
• Issued: 11/13/2012
• Est. Priority Date: 08/15/2006
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Sugimoto, Masahiko
• Primary Examiner(s): Tran, Sinh
• Assistant Examiner(s): MONK, MARK T
• Application Number:
  US11/830,501
• Publication Number:
  US 20080043135A1
• Time in Patent Office: 1,933 Days
• Field of Search: 348345-357, 348/370, 248345-356
• US Class Current: 348/349
• CPC Class Codes: G02B 7/365 by analysis of the spatial frequency components of the image
• CPC Class Codes: G03B 3/00 Focusing arrangements of general interest for cameras, projectors or printers
• CPC Class Codes: G06T 2207/30201 Face
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: G06V 40/161 Detection; Localisation; Normalisation
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/695 Control of camera direction for changing a field of view, e.g. pan, tilt or based on tracking of objects

Abstract

The present invention provides a photographing apparatus, in which an object image is formed on an image pickup element through a photographing lens, and a desired frequency component is extracted from an image signal obtained by the image pickup element through a filter so that the extracted frequency component is integrated to calculate a focus evaluation value and, based on the calculated focus evaluation value, an in-focus position of the photographing lens is searched, the apparatus comprising: a scene discrimination section which discriminates a photographing scene of an object image; and a control section which changes either of a searching range of the in-focus position of the photographing lens or the frequency component to be extracted by the filter based on the photographing scene discriminated by the scene discrimination section, and thereafter moves the photographing lens to search an in-focus position.

Claims

1. A photographing apparatus, in which an object image is formed on an image pickup element through a photographing lens, and a desired frequency component is extracted from an image signal obtained by an auto focus (AF) region of the image pickup element through a filter so that the extracted frequency component is integrated to calculate a focus evaluation value and, based on the calculated focus evaluation value, an in-focus position of the photographing lens is searched, the apparatus comprising:

a scene discrimination section which discriminates a backlit photographing scene of an object image;

a control section which restricts a searching range of the in-focus position of the photographing lens within a particular range with reference to a reference position based on the backlit photographing scene discriminated by the scene discrimination section, and thereafter moves the photographing lens to search the in-focus position;

and wherein when no peak of the focus evaluation value is found after restricting the searching range of the in-focus position of the photographing lens within the particular range with reference to the reference position based on the backlit photographing scene discriminated by the scene discrimination section, and thereafter moving the photographing lens to search an in-focus position, the control section does not perform a full range search by which an in-focus position is searched within a full range of the movement of the photographing lens between an end of an infinity side and an end of a nearest side.

2. The photographing apparatus according to claim 1, wherein the control section changes the reference position based on the backlit photographing scene discriminated by the scene discrimination section.

3. The photographing apparatus according to claim 1, wherein

the frequency component to be extracted by the filter may be switched from a predetermined first frequency component to a predetermined second frequency component which is lower than the first frequency component.

5. The photographing apparatus according to claim 1, further comprising a face detecting section, and wherein when the face detecting section detects a face in the image signal, the reference position comprises at least one of a first reference position at a near side focus and a second reference position at an infinity side focus.

6. The photographing apparatus according to claim 1, further comprising a face detection section, and wherein when the face detection section detects a face in the image signal, one reference position is set based on a proportion of the detected face in the image signal and a zoom position.

7. The photographing apparatus according to claim 1, wherein the reference position is determined based on a detected backlight condition.

8. The photographing apparatus according to claim 1, wherein the reference position is determined based on a photographing mode set.

4. An in-focus position searching method, in which an object image is formed on an image pickup element through a photographing lens, and a desired frequency component is extracted from an image signal obtained by an auto focus (AF) region of the image pickup element through a filter so that the extracted frequency component is integrated to calculate a focus evaluation value and, based on the calculated focus evaluation value, an in-focus position of the photographing lens is searched, the method comprising the steps of:

discriminating a backlit photographing scene of an object image;

restricting a searching range of the in-focus position of the photographing lens within a particular range with reference to a reference position based on the backlit photographing scene discriminated by the scene discrimination section, and thereafter moving the photographing lens to search the in-focus position;

and wherein when no peak of the focus evaluation value is found after restricting the searching range of the in-focus position of the photographing lens within the particular range with reference to the reference position based on the backlit photographing scene discriminated by the scene discrimination section, and thereafter moving the photographing lens to search an in-focus position, the control section does not perform a full range search by which an in-focus position is searched within a full range of the movement of the photographing lens between an end of an infinity side and an end of a nearest side.