White balance control amount calculating device

• US 6,958,773 B1
• Filed: 07/14/2000
• Issued: 10/25/2005
• Est. Priority Date: 07/15/1999
• Status: Expired due to Fees

• Current Assignee: PENTAX RICOH IMAGING COMPANY, LTD.
• Original Assignee: Pentax Corporation (Hoya Corporation)
• Inventors: Sato, Koichi
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): GENCO, BRIAN C
• Application Number:
  US09/617,100
• Time in Patent Office: 1,929 Days
• Field of Search: 348/223.1, 348/224.1, 348/275.1
• US Class Current: 348/223.1
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

A white balance control amount calculating device, provided in an electronic still camera, comprises an imaging device by which an image signal of a subject is sensed. Based on the image signal, a single image is divided into three image areas, for example. The first image area contains a first subject which is located at a short distance from the electronic still camera. The second image area contains a second subject which is located at infinity. The third image area contains a third subject which is located at a distance between the first and second subjects. An image area, in which a subject image is in-focus, is extracted from the three image areas. A control amount for a white balance adjustment is obtained based on image data corresponding to the extracted image area.

Claims

1. A device that calculates a white balance control amount for an electronic still camera, comprising:

an image signal generator that generates an image signal corresponding to a first image formed on a light receiving surface of an imaging device;

an image area extractor that extracts at least one image area from said first image, which contains a second image of a subject positioned at a predetermined distance from said electronic still camera, said second image being in-focus; and

a control amount calculator that calculates a control amount for performing a white balance adjustment, based on an image signal relating to a single image area contained in said at least one image area, wherein said image area extractor comprises a three dimensional image data sensing processor that senses three dimensional data indicating a distance from said electronic still camera to each point on a surface of said subject to obtain said second image, and said single image area is formed by selecting pixels from said first image corresponding to points within a predetermined range from said predetermined distance.

2. The device of claim 1, wherein said image area extractor extracts said single image area, and said control amount calculator calculates said control amount, based on said image signal relating to said single image area which is extracted by said image area extractor.

3. The device of claim 1, wherein said control amount calculator extracts a third image composed of an achromatic color from said second image of said image area extracted by said image area extractor, and calculates said control amount based on only said third image.

4. The device of claim 1, wherein said three dimensional image data sensing processor comprises a light source radiating a distance measuring light beam onto said subject, and a three dimensional image signal generator that generates three dimensional data indicating a distance from said electronic still camera to each point on a surface of said subject.

5. The device of claim 4, wherein said three dimensional image signal generator comprises said image signal generator.

6. The device of claim 4, wherein said three dimensional image signal generator comprises:

a plurality of photoelectric conversion elements that receive a reflected light beam from said subject, so that a signal charge corresponding to an amount of said received reflected light beam is accumulated in each of said photoelectric conversion elements;

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

an electric charge discharger that discharges an unwanted charge accumulated in each of said photoelectric conversion elements, so that said accumulation of said signal charge is started in each of said photoelectric conversion elements;

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

a signal charge integrator that alternately drives said electric charge discharger and said signal charge transferor, so that said signal charge is integrated in said signal charge holder.

7. A device that calculates a white balance control amount for an electronic still camera which photographs an image containing at least one subject and at least one portion other than said at least one subject, said white balance control amount calculating device comprising:

an imager by which an image signal corresponding to said image is generated;

an image area extractor that extracts at least one image area from said image, each image area containing one of said at least one subject positioned at a predetermined distance from said electronic still camera, said subject being in-focus; and

a control amount calculator that calculates a control amount for performing a white balance adjustment, based on said image signal relating to a single image area contained in said at least one image area, wherein said image area extractor comprises a three dimensional image data sensing processor that senses three dimensional data indicating a distance from said electronic still camera to each point on a surface of said subject to obtain said at least one image area, and said single image area is formed by selecting pixels from said image corresponding to points within a predetermined range from said predetermined distance.