Image processing apparatus, image pickup apparatus, and image processing method capable of eliminating effect of outside light

• US 6,822,690 B2
• Filed: 03/20/2001
• Issued: 11/23/2004
• Est. Priority Date: 03/23/2000
• Status: Expired due to Fees

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Iida, Kentaro
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US09/811,513
• Publication Number:
  US 20010026325A1
• Time in Patent Office: 1,344 Days
• Field of Search: 348/207.99, 348/370, 348/371, 348/362, 348/364, 348/366, 348/222.1, 348/224.1, 348/234, 348/239, 382/274, 382/275, 382/321, 382/312, 382/112, 358/3.26, 358/475, 358/461
• US Class Current: 348/364
• CPC Class Codes: H04N 1/40 Picture signal circuits H04N1/387 takes precedence
• CPC Class Codes: H04N 1/407 Control or modification of tonal gradation or of extreme levels, e.g. background level
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature

Abstract

A pixel value is adjusted to satisfy an exposure condition using a ratio (EV ratio) of exposure amounts of images taken without illumination light and with illumination light. When the pixel value of one of two images is modified, a subtraction process is performed on the pixel values of these two images. By finding a difference between two images that satisfy the exposure condition for pickup, the effect of a shadow or the like due to an interior lamp can be eliminated. Finally, the subtraction result is adjusted. As a result, an image processing apparatus, image pickup apparatus, and image processing method can be provided capable of eliminating the effect of a shadow or the like due to an outside light caused to the taken image.

Claims

1. An image processing apparatus, comprising:

a first receiving portion receiving a first image of an object taken under a prescribed illuminating condition;

a second receiving portion receiving a second image of said object taken under an illuminating condition different from said prescribed illuminating condition; and

an eliminating portion eliminating an effect caused by an outside light using said received first and second images, said eliminating portion including

an adjusting portion adjusting at least one of said first and second images to equalize brightness differences of said first and second images, and

a calculating portion calculating a difference between said first and second images adjusted by said adjusting portion to have the same brightness difference.

2. The image processing apparatus according to claim 1, wherein the brightness difference adjusted by said adjusting portion is caused by a difference between exposure amounts respectively for said first and second receiving portions when said first and second images are taken.

3. The image processing apparatus according to claim 1, further comprising:

a first exposure amount receiving portion receiving an exposure amount when said first image is taken; and

a second exposure amount receiving portion receiving an exposure amount when said second image is taken,

said adjusting portion adjusting said first and second images to have the same brightness difference based on said exposure amounts respectively received by said first and second exposure amount receiving portions.

4. The image processing apparatus according to claim 1, further comprising:

a first brightness difference receiving portion receiving a brightness difference between a maximum brightness portion having a highest brightness and a minimum brightness portion having a lowest brightness of said first image; and

a second brightness difference receiving portion receiving a brightness difference between a maximum brightness portion having a maximum brightness and a minimum brightness portion having a minimum brightness of said second image,

said adjusting portion adjusting said images to have the same brightness difference based on said brightness differences respectively received by said first and second brightness difference receiving portions.

5. The image processing apparatus according to claim 4, wherein said maximum brightness portion having the maximum brightness and said minimum brightness portion having the minimum brightness of each of said first and second data are in an image region other than a region of said object of said first and second images.

6. The image processing apparatus according to claim 4, wherein said maximum brightness portion having the maximum brightness and said minimum brightness portion having the minimum brightness of each of said first and second data are in an image region of said object of said first and second images.

7. The image processing apparatus according to claim 1, further comprising:

an extracting portion extracting an edge region from at least one of said first and second images; and

a controlling portion controlling to eliminate an effect of outside light by said eliminating portion for a region other than said extracted edge region, and eliminate the effect of outside light based on the elimination result of the outside light for the region other than said edge region for said extracted edge region.

8. The image processing apparatus according to claim 7, wherein said controlling portion includes a identifying portion identifying a proximity pixel of a region other than the edge region that corresponds to a target pixel in said extracted edge region, and eliminates elimination of the effect of the outside light of said target pixel based on a pixel value of said identified proximity pixel from which the effect of outside light has been eliminated.

9. The image processing apparatus according to claim 7, wherein said extracting portion extracts said edge region with margin corresponding to a maximum probable width caused by shaking from one of said first and second images.

10. The image processing apparatus according to claim 7, wherein said extracting portion extracts a region determined as an edge region from at least one of said first and second images.

11. An image pickup apparatus, comprising:

an illuminating portion for illuminating an object with light;

a pickup portion for taking an image of said object; and

the image processing apparatus according to claim 1, wherein said first and second images are taken by said image pickup portion under different illuminating conditions of said illuminating portion.

12. The image pickup apparatus according to claim 11, wherein said image processing apparatus further comprises:

an extracting portion extracting an edge region from at least one of said first and second images; and

a controlling portion controlling to eliminate an effect of outside light by said eliminating portion for a region other than said extracted edge region, and eliminate the effect of outside light based on the elimination result of the outside light for the region other than said edge region for said extracted edge region.

13. An image processing method comprising the steps of:

illuminating an object under a first illuminating condition and receiving a first image of thus illuminated object under a first receiving condition;

illuminating the object under a second illuminating condition and receiving a second image of thus illuminated object under a second receiving condition, the second illuminating condition and the second receiving condition being respectively different from the first ones;

modifying the first image data and/or the second image data so that a difference between an effect caused by the first receiving condition on the first image and an effect caused by the second receiving condition on the second image is eliminated; and

detecting a difference between the first and second images modified by said modifying step.

14. The image processing method according to claim 13, wherein one of the first and second illuminating conditions refers to a condition of more intensively applying light than the other, and a factor common to both of the first illuminating condition and the second illuminating condition is eliminated based on the detected difference.

15. The image processing method according to claim 13, further comprising the steps of:

extracting an edge area from at least one of the first image and second image; and

modifying the extracted edge area based on the detected difference.

16. The image processing method according to claim 13, wherein the receiving condition is a product of a shutter releasing time and an aperture opening area.