Image correction according to transmission characteristics of image sensing optical system

• US 20030194143A1
• Filed: 03/24/2003
• Published: 10/16/2003
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Iida, Seiji
• Granted Patent: US 7,190,845 B2
• Time in Patent Office: Days
• US Class Current: 382/241
• CPC Class Codes: G06T 5/008 Local, e.g. shadow enhancement
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 25/61 the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"

Abstract

In an image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by the optical system into an electric signal, a group of correction data, which is calculated on the basis of relative positional information of an optical axis of the optical system and a center of an effective range of the image sensing element, for correcting an image sensed by the image sensing unit is read out from a storage unit, and the image is corrected based upon the group of correction data read out from the storage unit. A minimum value of the group of correction data is associated with a position substantially coinciding with the optical axis position on the image sensing element or a position between the optical axis of the optical system and the center and closer to the optical axis.

Claims

1. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

a storage unit adapted to store relative positional information of an optical axis of said optical system and a reference point of an effective range of said image sensing element and a function representing transmission characteristics of said optical system in advance;

a correction value calculation unit adapted to calculate a correction value for correcting an image sensed by said image sensing unit using the relative positional information and the function; and

an image correction unit adapted to correct the sensed image based upon the correction value.

2. The image processing apparatus according to claim 1, wherein the relative positional information is a distance and a direction from the reference point.

3. The image processing apparatus according to claim 1, wherein the correction is luminance correction for each pixel.

4. The image processing apparatus according to claim 3, wherein the luminance correction is applied to all pixels.

5. The image processing apparatus according to claim 3, wherein the luminance correction is applied to a part of pixels.

13. An image sensing apparatus comprising:

an image sensing unit including an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal; and

the image processing apparatus according to claim 1.

6. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

a storage unit adapted to store in advance a group of correction data, which is calculated on the basis of relative positional information of an optical axis of said optical system and a reference point of an effective range of said image sensing element, for correcting an image sensed by said image sensing unit; and

an image correction unit adapted to correct the sensed image based upon the group of correction data.

7. The image processing apparatus according to claim 6, wherein a minimum value of the group of correction data is associated with a position substantially coinciding with the optical axis position on said image sensing element.

8. The image processing apparatus according to claim 6, wherein a minimum value of the group of correction data is associated with a position between the optical axis of said optical system and the reference point and closer to the optical axis.

9. The image processing apparatus according to claim 6, wherein the relative positional information is a distance and a direction from the reference point.

10. The image processing apparatus according to claim 6, wherein the correction is luminance correction for each pixel.

11. The image processing apparatus according to claim 10, wherein the luminance correction is applied to all pixels.

12. The image processing apparatus according to claim 10, wherein the luminance correction is applied to a part of pixels.

14. An image sensing apparatus comprising:

an image sensing unit including an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal; and

the image processing apparatus according to claim 6.

15. An image processing method for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing method comprising:

reading relative positional information of an optical axis of said optical system and a reference point of an effective range of said image sensing element and a function representing transmission characteristics of said optical system from a storage unit;

calculating a correction value for correcting an image sensed by said image sensing unit using the read relative positional information and the function; and

correcting the image sensed by said image sensing unit based upon the correction value.

19. A storage medium readable by a data processing apparatus, said storage storing a program which is executable by the data processing apparatus and comprises program codes realizing the image processing method described in claim 15.

16. An image processing method for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing method comprising:

reading out a group of correction data, which is calculated on the basis of relative positional information of an optical axis of said optical system and a reference point of an effective range of said image sensing element, for correcting an image sensed by said image sensing unit from a storage unit; and

correcting the image based upon the group of correction data read out from said storage unit.

17. The image processing method according to claim 16, wherein a minimum value of the group of correction data is associated with a position substantially coinciding with the optical axis position on said image sensing element.

18. The image processing method according to claim 16, wherein a minimum value of the group of correction data is associated with a position between the optical axis of said optical system and the reference point and closer to the optical axis.

20. A storage medium readable by a data processing apparatus, said storage storing a program which is executable by the data processing apparatus and comprises program codes realizing the image processing method described in claim 16.

21. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

an acquisition unit adapted to acquire positional deviation information in a manufacturing process between said optical system and said image sensing element;

a storage unit adapted to store image correction values in advance; and

an image correction unit adapted to correct the image based upon said positional deviation information in a manufacturing process and said image correction value.

22. The image processing apparatus according to claim 21, wherein said image correction unit corrects said image correction values based on said positional deviation information, then corrects the sensed image.

23. The image processing apparatus according to claim 21, wherein said image correction unit reads a predetermined image correction value from said storage unit on the basis of said positional deviation information, then corrects the sensed image.

24. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

a storage unit adapted to store correction values for correcting an image sensed by said image sensing unit calculated on the basis of positional deviation information in a manufacturing process between said optical system and said image sensing element; and

an image correction unit adapted to correct the sensed image based upon the correction values.

25. The image processing apparatus according to claim 24, wherein a position corresponding to a minimum value of the correction values in an effective range of said image sensing element is off the center of the effective range.

26. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

a storage unit adapted to store a plurality of different correction values, corresponding to light amount of a subject, for correcting an image sensed by said image sensing unit on the basis of positional deviation information in a manufacturing process between said optical system and said image sensing element,

wherein a position corresponding to a minimum value of the correction values in an effective range of said image sensing element is off the center of the effective range.

27. An image processing apparatus for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing apparatus comprising:

a storage unit adapted to store a first group of correction data for correcting an image sensed by said image sensing unit on the basis of positional deviation information in a manufacturing process between said optical system and said image sensing element; and

a calculation unit adapted to calculate a plurality of second groups of correction data corresponding to a light amount of a object at a time of image sensing operation using said first group of correction data,

wherein a position corresponding to a minimum value of said first group of correction data in an effective range of said image sensing element is off the center of the effective range.

28. An image processing method for processing an image sensed by an image sensing unit which includes an optical system and an image sensing element for converting a subject image formed by said optical system into an electric signal, the image processing method comprising:

acquiring positional deviation information in a manufacturing process between said optical system and said image sensing element;

storing image correction values in advance; and

correcting the image based upon said positional deviation information in a manufacturing process and said image correction values.

29. The image processing method according to claim 28, wherein said image correction values are corrected based on said positional deviation information, then an image sensed by said image sensing unit is corrected.

30. The image processing method according to claim 28, wherein a predetermined image correction value is read from said storage unit on the basis of said positional deviation information, then an image sensed by said image sensing unit is corrected.

31. A storage medium readable by a data processing apparatus, said storage storing a program which is executable by the data processing apparatus and comprises program codes realizing the image processing method described in claim 28.