Subject selection device and in-focus portion indicating device

• US 6,765,618 B1
• Filed: 10/08/1999
• Issued: 07/20/2004
• Est. Priority Date: 10/19/1998
• Status: Expired due to Fees

• Current Assignee: PENTAX RICOH IMAGING COMPANY, LTD.
• Original Assignee: Pentax Corporation (Hoya Corporation)
• Inventors: Sato, Koichi
• Primary Examiner(s): Christensen, Andrew
• Assistant Examiner(s): TRAN, NHAN T
• Application Number:
  US09/414,608
• Time in Patent Office: 1,747 Days
• Field of Search: 348/345-356, 396/72, 396/79-82, 396/87-89, 396/125, 396/93, 396/100
• US Class Current: 348/348
• CPC Class Codes: G03B 13/00 Viewfinders; Focusing aids for cameras; Means for focusing for cameras; Autofocus systems for cameras
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/635 Region indicators; Field of view indicators
• CPC Class Codes: H04N 23/671 in combination with active ranging signals, e.g. using light or sound signals emitted toward objects
• CPC Class Codes: H04N 5/2226 Determination of depth image, e.g. for foreground/background separation determining depth by image analysis in general G06T7/50; segmentation by image analysis in general G06T7/10

Abstract

A subject selection device comprises a light source and an imaging device, such as a CCD, having a plurality of photo-diodes. The light source radiates a distance measuring light beam toward a plurality of objects. A reflected light beam, generated by the objects due to the distance measuring light beam, is received by the, photo-diodes. A signal charge is integrated in each of the photo-diodes, so that three-dimensional information, which includes distances from the camera to each point on a surface of the objects, is obtained. A histogram indicating a distribution of the distances is generated. Based on a peak value of the histogram, a subject to be photographed is selected from the objects. An in-focus portion indicating device indicates a portion of the subject, which is in focus, based on the peak value.

Claims

1. A subject selection device for a camera, said device comprising:

a light source that radiates a distance measuring pulse light beam having a predetermined pulse width toward a plurality of objects to be photographed, each of said objects reflecting said distance measuring pulse light beam to generate a reflected light beam;

an imaging device that has a plurality of photoelectric conversion elements that detect a part of said reflected light beam, so that a signal charge corresponding to an amount of said detected reflected light beam is accumulated in each of said photoelectric conversion elements;

a three-dimensional information sensor that integrates said signal charge in each of said photoelectric conversion elements, whereby three-dimensional information indicating distances from said camera to points on a surface of each of said objects is obtained;

a histogram generator that generates a histogram indicating a distribution of said distances; and

a subject selector that selects, based on said histogram, a subject of photography, from said objects,

wherein said subject selector selects said subject based on a ratio of peak values included in said histogram.

2. A device according to claim 1, wherein said three-dimensional information sensor comprises:

a signal charge holder disposed adjacent to each of said photoelectric conversion elements;

an electric charge discharging processor that discharges unwanted charge accumulated in each of said photoelectric conversion elements, so that an accumulating operation of signal charge is started in each of said photoelectric conversion elements;

a signal charge transfer processor that transfers said signal charge accumulated in said photoelectric conversion elements to said signal charge holder; and

a signal charge integrating processor that drives said electric charge discharging processor and said signal charge transfer processor alternately, so that said signal charge is integrated in said signal charge holder.

3. A device according to claim 2, wherein said photoelectric conversion elements are provided on a substrate, and said electric charge discharging processor discharges said unwanted charge to said substrate.

4. A device according to claim 2, wherein said signal charge holder is provided in a vertical transfer unit that outputs said signal charge from said three-dimensional information sensor.

5. A device according to claim 2, wherein said photoelectric conversion elements and said signal charge holders are formed as a vertical overflow drain type of interline CCD.

6. A device according to claim 2, wherein said electric charge discharging processor outputs an electric charge discharging signal to discharge said unwanted charge, and said signal charge transfer processor outputs an electric charge transfer signal to transfer said signal charge to said signal charge holder, said electric charge discharging signal and said electric charge transfer signal being pulse signals.

7. A device according to claim 6, wherein said light beam is output for an accumulating period, which commences at an output of said electric charge discharging signal and concludes at an output of said electric charge transfer signal, so that said signal charge corresponding to said three-dimensional information is integrated in said signal charge holder.

8. A device according to claim 1, wherein said subject selector selects said subject based on the larger peak value included in said histogram.

9. A device according to claim 1, wherein said subject selector selects one of said objects, corresponding to one of a plurality of peak values included in said histogram, as said subject.

10. A device according to claim 1, further comprising an automatic focusing adjustment processor that performs an automatic focusing adjustment for said subject.

11. A device according to claim 1, further comprising an automatic exposure control processor that performs an automatic exposure control for said subject.

12. An in-focus portion indicating device for a camera, said device comprising:

a light source that radiates a distance measuring pulse light beam having a predetermined pulse width toward an object to be photographed, said object reflecting said distance measuring pulse light beam to generate a reflected light beam;

an imaging device that has a plurality of photoelectric conversion elements that detect a part of said reflected light beam, so that a signal charge corresponding to an amount of said detected reflected light beam is accumulated in each of said photoelectric conversion elements;

a three-dimensional information sensor that integrates said signal charge in each of said photoelectric conversion elements, whereby three-dimensional information indicating distances from said camera to points on a surface of said object is obtained;

a histogram generator that generates a histogram indicating a distribution of said distances; and

an in-focus portion indicator that indicates an in-focus portion of said object, based on a depth of field of said object and said histogram,

wherein said in-focus portion indicator indicates said in-focus portion based on a ratio of peak values included in said histogram.

13. A device according to claim 12, wherein said three-dimensional information sensor comprises:

a signal charge holder disposed adjacent to each of said photoelectric conversion elements;

an electric charge discharging processor that discharges unwanted charge accumulated in each of said photoelectric conversion elements and allows an accumulating operation of signal charge in each of said photoelectric conversion elements;

a signal charge transfer processor that transfers said signal charge accumulated in said photoelectric conversion elements to said signal charge holder; and

a signal charge integrating processor that drives said electric charge discharging processor and said signal charge transfer processor alternately, so that said signal charge is integrated in said signal charge holder.

14. A device according to claim 13, wherein said photoelectric conversion elements are provided on a substrate, and said electric charge discharging processor discharges said unwanted charge to said substrate.

15. A device according to claim 13, wherein said signal charge holder is provided in a vertical transfer unit that outputs said signal charge from said three-dimensional information sensor.

16. A device according to claim 13, wherein said photoelectric conversion elements and said signal charge holders are formed as a vertical overflow drain type of interline CCD.

17. A device according to claim 13, wherein said electric charge discharging processor outputs an electric charge discharging signal to discharge said unwanted charge, and said signal charge transfer processor outputs an electric charge transfer signal to transfer said signal charge to said signal charge holder, said electric charge discharging signal and said electric charge transfer signal being pulse signals.

18. A device according to claim 17, wherein said light beam is output for an accumulating period, which commences at an output of said electric charge discharging signal and concludes at an output of said electric charge transfer signal, so that said signal charge corresponding to said three-dimensional information is integrated in said signal charge holder.

19. A device according to claim 12, wherein said in-focus portion indicator indicates said in-focus portion based on the larger peak value included in said histogram.

20. A device according to claim 12, wherein said in-focus portion indicator indicates a portion, corresponding to one of a plurality of peak values included in said histogram, as said in-focus portion.

21. A device according to claim 12, wherein said in-focus portion indicator comprises a liquid crystal monitor, which indicates said in-focus portion with a luminance which is different from other portions.

22. A device according to claim 12, wherein said in-focus portion indicator comprises a liquid crystal display panel provided in an optical path of an optical view finder of said camera, said liquid crystal display panel being controlled in such a manner that said in-focus portion is in a transparent state.