PHOTOGRAPHING APPARATUS AND IN-FOCUS POSITION SEARCHING METHOD

• US 20080043135A1
• Filed: 07/30/2007
• Published: 02/21/2008
• 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
• Granted Patent: US 8,310,586 B2
• Time in Patent Office: Days
• US Class Current: 348/345
• 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 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.

2. 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, and

a control section which performs an in-focus position searching procedure depending on the photographing scene discriminated by the scene discriminating section.

13. The photographing apparatus according to claim 2, wherein

the scene discrimination section detects a backlight condition, and

the control section compares two tentative in-focus positions calculated for two different focus-evaluation-value calculation target region in response to a detection of a backlight condition by the scene discrimination section and, when the difference between the two tentative in-focus positions is within a predetermined range, lets the two tentative in-focus positions detected for either one of the two focus-evaluation-value calculation target regions be the final in-focus position.

14. The photographing apparatus according to claim 13, further comprising:

a face detection section which detects a face region based on an image signal, and

a region determination section which determines at least any one of a neck region, a chest region, an abdomen region, and a leg region depending on the face region detected by the face detection section, wherein

the two different focus-evaluation-value calculation target regions may include any two of a face region, a neck region, a chest region, an abdomen region, a leg region and any region combining all or part thereof.

17. The photographing apparatus according to claim 14, 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.

3. 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 tentative in-focus position calculation section which calculates a first tentative in-focus position and a second tentative in-focus position respectively through a first procedure for calculating a focus evaluation value based on a signal output from a filter and a second procedure which is different from the first procedure; and

a control section which judges whether or not the difference between the first tentative in-focus position and the second tentative in-focus position is within a predetermined range and, in response to a judgment that the difference is within the predetermined range, moves the photographing lens to the first tentative in-focus position as a final in-focus position.

4. The photographing apparatus according to claim 3, wherein

the tentative in-focus position calculation section changes at least either one of a focus-evaluation-value calculation target region of the first tentative in-focus position and the frequency component to be extracted by the filter in response to a judgment that the difference is not within the predetermined range, and thereafter calculates the first tentative in-focus position again, and

the control section judges whether or not the difference between the redetected first tentative in-focus position and the second tentative in-focus position is within a predetermined range and, in response to a judgment that the difference is within the predetermined range, moves the photographing lens to the first in-focus position as a final in-focus position.

5. The photographing apparatus according to claim 4, wherein

the control section repeats the recalculation of the first tentative in-focus position until a judgment is made that the difference within the predetermined range.

6. The photographing apparatus according to claim 3, wherein

the control section, in response to an event that the number of the calculation of the first tentative in-focus position becomes more than a predetermined number which is one or more, moves the photographing lens to the reference position as a final in-focus position.

7. The photographing apparatus according to claim 5, wherein

the control section, in response to an event that the number of the calculation of the first tentative in-focus position becomes more than a predetermined number which is one or more, moves the photographing lens to the reference position as a final in-focus position.

8. The photographing apparatus according to claim 3, further comprising a scene discrimination section which discriminates a photographing scene, wherein

the control section changes at least one of the predetermined range and the predetermined reference position based on the photographing scene discriminated by the scene discrimination section.

9. The photographing apparatus according to claim 4, further comprising a scene discrimination section which discriminates a photographing scene, wherein

the control section changes at least one of the predetermined range and the predetermined reference position based on the photographing scene discriminated by the scene discrimination section.

10. The photographing apparatus according to claim 5, further comprising a scene discrimination section which discriminates a photographing scene, wherein

the control section changes at least one of the predetermined range and the predetermined reference position based on the photographing scene discriminated by the scene discrimination section.

11. The photographing apparatus according to claim 6, further comprising a scene discrimination section which discriminates a photographing scene, wherein

the control section changes at least one of the predetermined range and the predetermined reference position based on the photographing scene discriminated by the scene discrimination section.

12. The photographing apparatus according to claim 7, further comprising a scene discrimination section which discriminates a photographing scene, wherein

the control section changes at least one of the predetermined range and the predetermined reference position based on the photographing scene discriminated by the scene discrimination section.

15. The photographing apparatus according to claim 4, further comprising:

a face detection section which detects a face region based on the image signal, and

a region determination section which determines at least either one of a neck region, a chest region, an abdomen region, and a leg region depending on the face region detected by the face detection section, wherein

the focus-evaluation-value calculation target region may include any one of a face region, a neck region, a chest region, an abdomen region, a leg region, and any region combining all or part thereof.

16. The photographing apparatus according to claim 4, 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.

18. 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 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 photographing scene of an object image; and

changing at least either one of the searching range of the in-focus position of the photographing lens and the frequency component to be extracted by the filter, and thereafter moving the photographing lens so as to search the in-focus position.

19. 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 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 photographing scene, and

performing an in-focus position searching procedure depending on the discriminated photographing scene.

20. 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 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:

calculating a first tentative in-focus position and a second tentative in-focus position respectively through a first procedure for calculating a focus evaluation value based on a signal output from the filter and a second procedure which is different from the first procedure; and

judging whether or not the difference between the first tentative in-focus position and the second tentative in-focus position is within a predetermined range and, in response to a judgment that the difference is within the predetermined range, moving the photographing lens to the first tentative in-focus position as a final in-focus position.