DUST DETECTION SYSTEM AND DIGITAL CAMERA

• US 20090185716A1
• Filed: 01/21/2009
• Published: 07/23/2009
• Est. Priority Date: 01/23/2008
• Status: Active Grant

• Current Assignee: PENTAX RICOH IMAGING COMPANY, LTD.
• Original Assignee: Hoya Corporation
• Inventors: KATO, Tetsuaki, HORITA, Satoru, KAWANAMI, Naoto
• Granted Patent: US 8,873,881 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06T 2207/10004 Still image; Photographic image
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 23/811 by dust removal, e.g. from surfaces of the image sensor or processing of the image signal output by the electronic image sensor
• CPC Class Codes: H04N 25/68 applied to defects

Abstract

A dust detection system, comprising a receiver, a dust extraction block, a memory and an image correction block, is provided. The receiver receives an image signal. The dust extraction block generates a dust image signal on the basis of the image signal. The memory stores an intrinsic-flaw image signal corresponding to an intrinsic-flaw image including sub-images of dust that the dust extraction block extracts in initializing. The image correction block generates a corrected dust-image signal on the basis of the intrinsic-flaw image signal and a normal dust-image signal. The normal dust-image signal corresponds to a normal dust image including sub-image of dust that the dust extraction block extracts after initializing. The corrected dust image is the normal dust image that sub-images of dust in the intrinsic-flaw image are deleted from.

Claims

1. A dust detection system comprising:

a receiver that receives an image signal, an imaging device generating said image signal according to a captured optical image;

a dust extraction block that generates a dust-image signal by extracting sub-images of dust in said optical image on the basis of said image signal;

a memory that stores an intrinsic-flaw image signal corresponding to an intrinsic-flaw image including sub-images of dust that said dust extraction block extracts in initializing; and

an image correction block that generates a corrected dust-image signal on the basis of said intrinsic-flaw image signal and a normal dust-image signal, said corrected dust-image signal corresponding to a corrected dust image, said normal dust-image signal corresponding to a normal dust image including sub-images of dust that said dust extraction block extracts after said initializing, said corrected dust image being said normal dust image that sub-images of dust in said intrinsic-flaw image are deleted from.

2. A dust detection system according to claim 1, wherein,

an intrinsic-flaw area is determined on the basis of a detected-flaw area, said detected-flaw area being an area where dust is detected in said intrinsic-flaw image, and

said image correction block generates said corrected dust-image signal by deleting sub-images of dust in said intrinsic-flaw area of said normal dust image.

3. A dust detection system according to claim 2, wherein a frame area is determined as said intrinsic-flaw area, a frame enclosing said entire intrinsic-flaw image is located on said frame area, and said frame has a first width.

4. A dust detection system according to claim 2, wherein said intrinsic-flaw area is determined so that said intrinsic-flaw area including said detected-flaw area and said intrinsic-flaw area is larger than said detected-flaw area.

5. A dust detection system according to claim 2, wherein said intrinsic-flaw area is determined so that said intrinsic-flaw area is enlarged more from said detected-flaw area in the direction away from the intersection point of the optical axis of the photographic optical system and said imaging device toward said detected-flaw area for closer distances of the exit pupil of said photographic optical system to said imaging device, said photographic optical system being mounted on the light-receiving surface side of said imaging device.

6. A dust detection system according to claim 3, wherein said frame area is determined so that said first width is broader for closer distance of said exit pupil for said imaging device.

7. A dust detection system according to claim 2, wherein said intrinsic-flaw area is determined so that said intrinsic-flaw area is larger than said detected-flaw area as the diaphragm is opened, said diaphragm being mounted on the light-receiving surface side of said imaging device.

8. A dust detection system according to claim 1, further comprising a first determination block that determines the value of adjustable parameter, said adjustable parameter affecting the visibility of a sub-image of a subject in an entire image captured by said imaging device, said subject being located in the peripheral area of the surface of said imaging device, said adjustable parameter being determined so that said visibility upon capturing said normal dust image is reduced more than when said intrinsic-flaw image is captured.

9. A dust detection system according to claim 8, wherein said adjustable parameter is the size of aperture of the diaphragm mounted on the light-receiving surface side of said imaging device, said first determination block determining said size so that said size upon capturing said normal dust image is larger than upon capturing said intrinsic-flaw image.

10. A dust detection system comprising:

a receiver that receives an image signal, an imaging device generating said image signal according to a captured optical image;

a second determination block that determines on the basis of said image signal whether or not partial areas which said entire optical image consist of includes a sub-image of dust;

a memory that stores an intrinsic-flaw area signal corresponding to said partial area which said second determination block has determined includes a sub-image of dust on the basis of said image signal generated on initialization; and

a controller that orders said second determination block to suspend the determination of whether said partial areas corresponding to said intrinsic-flaw area signal includes said sub-image of dust.

11. A digital camera comprising:

a receiver that receives an image signal, an imaging device generating said image signal according to a captured optical image;

a dust extraction block that generates a dust-image signal by extracting sub-images of dust in said optical image on the basis of said image signal;

a switch for commanding said dust extraction block to generate said dust-image signal;

a memory that stores an intrinsic-flaw image signal corresponding to an intrinsic-flaw image including sub-images of dust that said dust extraction block extracts in initializing; and

an image correction block that generates a corrected dust-image signal on the basis of said intrinsic-flaw image signal and a normal dust-image signal, said corrected dust image signal corresponding to a corrected dust image, said normal dust-image signal being said dust-image signal generated by said dust extraction block upon to the operation of said switch, said corrected dust image being a normal dust image from which sub-images of dust in said intrinsic-flaw image are deleted from, said normal dust image corresponding to said normal dust-image signal.