Image pickup apparatus and method of correcting deteriorated pixel signal thereof

• US 6,809,763 B1
• Filed: 07/31/2000
• Issued: 10/26/2004
• Est. Priority Date: 08/02/1999
• Status: Expired due to Fees

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Yoshida, Hideaki
• Primary Examiner(s): Christensen, Andrew
• Assistant Examiner(s): TRAN, NHAN T
• Application Number:
  US09/629,983
• Time in Patent Office: 1,548 Days
• Field of Search: 348/248, 348/241, 348/243, 348/222.1, 348/246, 348/251, 348/256, 358/447, 358/448, 358/450, 358/461, 358/463
• US Class Current: 348/248
• CPC Class Codes: H04N 25/625 for the control of smear

Abstract

An image pickup apparatus is constructed as including: a smear level detecting section for detecting smear components of CCD image pickup device; a smear correcting section for correcting effective pixel signals based on the detected smear components; an output deteriorated pixel determining section for determining corresponding effective signal pixels as output deteriorated pixels when the level of smear component has reached a predetermined value; a compensation condition determining section for determining whether an output deteriorated pixel satisfies predetermined compensation conditions or not; and a data compensating section for performing data compensation of pixels determined as satisfying the compensation conditions by using information of neighboring pixels, the other pixels determined as not satisfying the compensation conditions at the compensation condition determining section being subjected to correction at the smear correcting section.

Claims

1. An image pickup apparatus comprising:

smear level detection means for detecting smear level occurring in effective pixels of an image pickup device on the basis of signals outputted from an optically shielded pixel array of the image pickup device in a vertical blanking period thereof;

deteriorated pixel determination means for, in the case where the smear level detected at said smear level detection means exceeds a predetermined value, determining corresponding effective pixels as output deteriorated pixels;

compensation condition determination means for, when signal from a pixel determined as output deteriorated pixel at said deteriorated pixel determination means is at a predetermined saturation level, determining whether or not the deteriorated pixel satisfies predetermined compensation conditions; and

deteriorated pixel correction means for replacing signals from deteriorated pixels determined as satisfying the compensation conditions at said compensation condition determination means with signals of undeteriorated pixels neighboring the deteriorated pixels.

2. The image pickup apparatus according to claim 1, said deteriorated pixel correction means performs a correction of output level of signals from deteriorated pixels not satisfying said compensation conditions in accordance with the smear level detected at said smear level detection means.

3. The image pickup apparatus according to claim 1, wherein the smear level of the image pickup device detected by said smear level detection means is what is obtained by dividing the sum of signal levels from an optically shielded pixel column having the same horizontal address by the number of pixels in the same column.

4. The image pickup apparatus according to claim 1, wherein said predetermined compensation conditions comprise the condition that at least one undeteriorated pixel column is included within the neighboring four pixel columns at the center of which the pertinent deteriorated pixel column is located.

5. The image pickup apparatus according to claim 2, wherein the correction of output level corresponding to the smear level by said deteriorated pixel correction means comprises the correction that the detected smear level is subtracted from a deteriorated pixel level and the result is multiplied by a coefficient based on the saturation level and the detected smear level.

6. A method of correcting deteriorated pixel signals of image pickup apparatus, including the steps of:

detecting smear level occurring in effective pixels of an image pickup device on the basis of signals outputted from an optically shielded pixel array of the image pickup device in a vertical blanking period thereof;

in the case where the smear level detected at said smear level detecting step exceeds a predetermined value, determining corresponding effective pixels as output deteriorated pixels;

when signal from a pixel determined as output deteriorated pixel at said deteriorated pixel determining step is at a predetermined saturation level, determining whether or not the deteriorated pixel satisfies predetermined compensation conditions; and

correcting deteriorated pixels by means of replacing signals from deteriorated pixels determined as satisfying the compensation conditions at said compensation condition determining step with signals of undeteriorated pixels neighboring the deteriorated pixels.

7. The method of correcting deteriorated pixel signals of image pickup apparatus according to claim 6, said deteriorated pixel correcting step comprises a step of correcting output level of signals from deteriorated pixels not satisfying said compensation conditions in accordance with the smear level detected at said smear level detecting step.

8. The method of correcting deteriorated pixel signals of image pickup apparatus according to claim 6, wherein the smear level of the image pickup device detected at said smear level detecting step is what is obtained by dividing the sum of signal levels from an optically shielded pixel column having the same horizontal address by the number of pixels in the same column.

9. The method of correcting deteriorated pixel signals of image pickup apparatus according to claim 6, wherein said predetermined compensation conditions comprise the condition that at least one undeteriorated pixel column is included within the neighboring four pixel columns at the center of which the pertinent deteriorated pixel column is located.

10. The method of correcting deteriorated pixel signals of image pickup apparatus according to claim 7, wherein the correction of output level corresponding to the smear level at said deteriorated pixel correcting step comprises the correction that the detected smear level is subtracted from a deteriorated pixel level and the result is multiplied by a coefficient based on the saturation level and the detected smear level.