Image pickup apparatus for preventing linearity defect

• US 20070085917A1
• Filed: 10/11/2006
• Published: 04/19/2007
• Est. Priority Date: 10/14/2005
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Kobayashi, Hirokazu
• Granted Patent: US 7,692,699 B2
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/67 applied to fixed-pattern noise, e.g. non-uniformity of response

Abstract

In an image pickup apparatus for preventing linearity defect at the time of photographing in a high-sensitivity mode, when processing an image signal produced by a solid-state image pickup device under a predetermined condition, such as photographing in a super high-sensitivity mode, at a high temperature or with a long-time exposure, a signal processor increases a clamp level for clamping the image signal. A noise reducer then executes noise reduction for removing noise of random nature from the image signal before correcting the primary black level for the image signal, and thereafter the black level is corrected.

Claims

1. An image pickup apparatus for picking up an imaging field to produce an image signal, said apparatus comprising:

an image pickup device for picking up an imaging field to produce an image signal representative of an image of the imaging field; and

a signal processor for processing the image signal;

said signal processor increasing, when processing the image signal produced under a predetermined exposure condition, a clamp level for clamping the image signal, performing noise reduction for removing noise of random nature from the image signal prior to correcting a primary black level for the image signal, and then correcting the black level.

2. The image pickup apparatus in accordance with claim 1, wherein the predetermined exposure condition is a super high-sensitivity mode of photographing.

3. The image pickup apparatus in accordance with claim 1, wherein the predetermined exposure condition is a high temperature.

4. The image pickup apparatus in accordance with claim 1, wherein the predetermined exposure condition is long-time exposure of photographing.

5. The image pickup apparatus in accordance with claim 1, wherein said signal processor removes high-frequency pattern noise accompanied with correcting the black level, then performs the noise reduction while maintaining the primary black level, and thereafter corrects the primary black level.

6. The image pickup apparatus in accordance with claim 1, wherein said signal processor performs the noise reduction before correcting the black level using light-shielded data.

7. The image pickup apparatus in accordance with claim 5, wherein the high-frequency fixed pattern noise is any one of a spot defect, a vertical line defect and an inter-field step or horizontal defect.

8. The image pickup apparatus in accordance with claim 5, wherein the high-frequency fixed pattern noise includes all of a spot defect, a vertical line defect and an inter-field step or horizontal defect.

9. The image pickup apparatus in accordance with claim 5, wherein the high-frequency fixed pattern noise is removed by compensating for only an offset from data of the primary black level.

10. The image pickup apparatus in accordance with claim 1, wherein, when acquiring cumulative data for executing automatic signal processing based on the image, integration is executed instead of correcting the primary black level, followed by correcting the primary black level.

11. An image pickup apparatus for picking up an imaging field to produce an image signal, said apparatus comprising:

an image pickup device for picking up an imaging field to produce an image signal representative of an image of the imaging field; and

a signal processor for processing the image signal;

said signal processor executing, when an image is picked up under a predetermined exposure condition, noise reduction for removing noise of random nature at least prior to correcting a primary black level, and thereafter correcting the primary black level.

12. The image pickup apparatus in accordance with claim 11, wherein the predetermined exposure condition is a super high-sensitivity mode of photographing.

13. The image pickup apparatus in accordance with claim 11, wherein the predetermined exposure condition is a high temperature.

14. The image pickup apparatus in accordance with claim 11, wherein the predetermined exposure condition is long-time exposure of photographing.

15. The image pickup apparatus in accordance with claim 11, wherein said signal processor removes high-frequency pattern noise accompanied with correcting the black level, then executes the noise reduction while maintaining the primary black level, and thereafter corrects the primary black level.

16. The image pickup apparatus in accordance with claim 15, wherein the high-frequency fixed pattern noise is any one of a spot defect, a vertical line defect and an inter-field step or horizontal defect.

17. The image pickup apparatus in accordance with claim 15, wherein the high-frequency fixed pattern noise includes all of a spot defect, a vertical line defect and an inter-field step defect or horizontal defect.

18. The image pickup apparatus in accordance with claim 15, wherein the high-frequency fixed pattern noise is removed by compensating for only an offset from data of the primary black level.

19. The image pickup apparatus in accordance with claim 11, wherein, when acquiring cumulative data for executing automatic signal processing based on the image, integration is executed instead of correcting the primary black level, followed by correcting the primary black level.