Television – Camera – system and detail – Optics
Reexamination Certificate
2001-03-20
2004-11-23
Ho, Tuan (Department: 2615)
Television
Camera, system and detail
Optics
C358S302000, C358S461000
Reexamination Certificate
active
06822690
ABSTRACT:
This application is based on Application Ser. No. 2000-81928 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to image processing apparatuses, image pickup apparatuses and image processing methods and, more particularly to an image processing apparatus, image pickup apparatus, and image processing method capable of eliminating an effect of outside light such as light from an interior lamp.
2. Description of the Related Art
Conventionally, image pickup apparatuses such a scanner has been known in which light is directed to a manuscript placed on a base and an image of the manuscript is taken by reading a reflection of the directed light. Such an image pickup apparatus suffers from a problem that the manuscript is illuminated with a light other than that of an illumination lamp in the apparatus, e.g., interior lamp. Thus, the image of the manuscript is affected by outside light such as light from the interior lamp. If such outside light is uneven and a shadow is projected because of an obstacle or the like, in particular, a somewhat strange image is taken which deviates from a desired image.
FIGS. 22A and 22B
are diagrams shown in conjunction with projection of shadows onto the manuscript due to an interior lamp.
FIG. 22A
relates to the case where an image of a manuscript
70
placed on a base is read by an optical head
1
including, for example, a CCD (Charge Coupled Device), when an illumination lamp
2
is off.
FIG. 22B
relates to the case where the image of manuscript
70
is read when illumination lamp
2
is on. Note that an interior lamp
3
is on in either case.
Referring to
FIG. 22A
, when illumination lamp
2
is off, manuscript
70
is illuminated only with light from interior lamp
3
. Since the light from interior lamp
3
is shielded by obstacle
4
, a shadow is projected to manuscript
70
. Thus, there is an illuminance difference between a shadow portion and a portion free from shadow over manuscript
70
. Accordingly, the image read by optical head
1
is subjected to the effect of shadow because of the illuminance difference over the manuscript. Note that, for the shadow portion, an illumination light amount would not be 0 because of scattered light from outside.
Referring to
FIG. 22B
, when illumination lamp
2
is on, manuscript
70
placed on the base is illuminated with uniform light from illumination lamp
2
in addition to light from interior lamp
3
. Accordingly, although manuscript
70
receives a greater amount of light, there still exists an illuminance difference over the manuscript between the shadow portion caused by interior lamp
3
and the portion free from shadow as in the case of FIG.
22
A.
FIG. 23
is a graph showing illuminances of manuscript
70
when illumination lamp
2
in the apparatus is on and off. A solid line {circle around (
1
)} shows an illuminance over manuscript
70
in the case of
FIG. 22A
, that is, in the case where only interior lamp is directed to the manuscript when illumination lamp
2
is off. The shadow region on the left side of the manuscript has lower illuminance than the region free from shadow on the right side. Thus, there is an illuminance difference between the shadow portion and the portion free from shadow.
A solid line {circle around (
2
)} shows an illuminance over manuscript
70
in the case of
FIG. 22B
, that is, in the case where the interior lamp and the light from the illumination lamp are both directed to the manuscript when illumination lamp
2
is on. As compared with {circle around (
1
)}, the illuminance over the manuscript is higher over the entire region by a given amount of light from the illumination lamp. Thus, as in the case where the illumination lamp is off, there still exists an illuminance difference between the shadow region and the region free from shadow.
Accordingly, if the image of the manuscript is read when the illumination lamp is on, i.e., under a general image taking condition, the taken image is affected by the illuminance difference between the shadow region and the region free from shadow as indicated by {circle around (
2
)}. The illuminance difference causes brightness difference over the manuscript.
To eliminate the effect of the shadow caused by the interior lamp or the like, the image when the illumination lamp is off (the image in the case of only interior lamp) i.e., the image that is affected by a shadow or the like may be subtracted from the image when the illumination lamp in the apparatus is on. Namely, the image of the manuscript in the case of
FIG. 22A
is subtracted from that in the case of FIG.
22
B.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image processing apparatus, image pickup apparatus, and image processing method capable of eliminating the effect of outside light caused to a taken image.
Another object of the present invention is to provide an image processing apparatus, image pickup apparatus, and image processing method capable of appropriately correcting any displacement caused to the taken image to eliminate the effect of outside light.
The above objects of the present invention is achieved by providing the image processing apparatus with the following elements. More specifically, according to one aspect of the present invention, an image processing apparatus includes: 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 the object taken under an illuminating condition different from the prescribed illuminating condition; and an eliminating portion eliminating an effect of outside light using the received first and second images. The eliminating portion includes: an adjusting portion adjusting at least one of the first and second images to equalize brightness differences of the first and second images; and a calculating portion calculating a difference between the first and second images that have been adjusted by the adjusting portion to have the same brightness difference.
According to the present invention, at least one of the first and second images taken under different illuminating conditions is adjusted to equalize the brightness differences of the first and second images. After the brightness differences of the images are equalized, a difference between these two images is calculated. Thus, purely the effect of outside light can be eliminated using the first and second images that have been affected by the same outside light.
Accordingly, an image processing apparatus capable of eliminating the effect of outside light caused to the taken image can be provided.
Preferably, the brightness difference adjusted by the adjusting portion is caused by a difference between amounts respectively for said first and second receiving portions when the first and second images are taken.
As such, the brightness difference caused by a difference in exposure amount when the first and second images are taken is eliminated. Thus, even if the images are subjected to different exposure lamps by automatic exposure, for example, such brightness difference is properly adjusted to eliminate the effect of a shadow or the like caused by the outside light.
Preferably, the image processing apparatus is characterized in that it further includes: a first exposure amount receiving portion receiving an exposure amount when the first image is taken; and a second exposure amount receiving portion receiving an exposure amount when the second image is taken. The adjusting portion performs adjustment to equalize the brightness differences of the images based on the exposure amounts respectively received by the first and second exposure amount receiving portions.
Thus, the exposure amounts when the first and second images are taken are received, based on which the images are adjusted. Accordingly, the brightness differences of the first and second images can be precisely and readily equalized.
Preferably, the ima
Ho Tuan
McDermott Will & Emery LLP
Minolta Co. , Ltd.
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