Television – Camera – system and detail – Unitary image formed by compiling sub-areas of same scene
Reexamination Certificate
1997-07-16
2001-07-24
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Unitary image formed by compiling sub-areas of same scene
C348S208400
Reexamination Certificate
active
06266086
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an imaging apparatus using a solid-state imaging element, and more particularly, to an imaging apparatus furnished with an image shifting mechanism for obtaining a high-resolution image.
BACKGROUND OF THE INVENTION
Conventionally, a solid-state imaging element, such as a CCD (Charge Coupled Device), has been extensively used as a camera element of an image pick up apparatus. The resolution of the solid-state imaging element is generally determined by the number of pixels formed on the photo-receiving surface of the solid-state imaging element. Thus, when a high resolution is desired, only the number of the pixels on the solid-state imaging element has to be increased. However, the conventional techniques can increase the number of the pixels only to the extent that the cost and size permit.
To solve the above problem, Japanese Laid-open Patent Application Nos. 54576/1985 and 284980/1988 (Tokukaisho Nos. 60-54576 and 63-284980, respectively), for example, disclose an imaging apparatus adopting an image shifting mechanism. According to these references, an image with a relatively high resolution can be obtained using a solid-state imaging element having a limited number of pixels thereon.
More specifically, as shown in
FIG. 16
illustrating the feature of the first reference, a tilting angle &thgr; of a plane parallel glass plate
101
is changed, so that incident light on the solid-state imaging element from a subject is shifted by a very small distance &Dgr; when an image is stored into an image memory. For further understanding, a relation between the tilting angle &thgr; of the plane parallel glass plate
101
and a shift amount &Dgr; is expressed as:
&Dgr;=
t·
sin &thgr;(1−1
)
where t is a thickness and n is a refractive index of the plane parallel glass plate
101
.
On the other hand, as shown in
FIG. 17
illustrating the feature of the second reference, light from a subject
200
goes into a photo-receiving surface of a solid-state imaging element
203
through an optical series
201
and a plane parallel glass plate
202
a
when an image is stored into an image memory of an image forming section
204
. Here, the plane parallel glass plate
202
a
is fixed to a driving unit
202
b
, so that the driving unit
202
b
tilts the plane parallel glass plate
202
a
at a certain degree angle with respect to the optical axis.
In the prior art, a plurality of images stored in the image memory in the above manner are synthesized, thereby obtaining a resolution as high as the resolution obtained when the number of the pixels on the solid-state imaging element is increased.
Next, the operation for synthesizing shifted images A and B on the image memory will be explained with reference to
FIGS. 17 through 20
. Since the image synthesizing operations are basically the same, the following description is based on the second reference for convenience.
To begin with, a first image A is stored in the image memory of the image forming section
204
, and the alignment of the image data at this point is illustrated in FIG.
18
(
a
). Note that a capital letter A in the drawing indicates each piece of the image data of the image A and numerical subscripts indicate serial column and row numbers assigned to each piece of the image data. For example, A
12
indicates that it is a piece of the image data of the image A aligned at the first column and second row.
Then, the plane parallel glass plate
202
a
is tilted 45° with respect to the pixel array on the solid-state imaging element
203
both in the horizontal and vertical directions, so that a second image B is obtained by shifting a subject image formed on the solid-state imaging element
203
. The image B thus obtained is also stored in the image memory of the image forming section
204
, and the alignment of the image data at this point is illustrated in FIG.
18
(
b
). Note that a capital letter B in the drawing indicates each piece of the image data of the image B and numerical subscripts indicate serial column and row numbers assigned to each piece of the image data. For example, B
12
indicates that it is a piece of the image data of the image B aligned at the first column and second row.
Here, the alignment of the image data of the image A with those of the image B is illustrated in FIG.
19
. In the drawing, a broken line indicates the image data of the first image data A, while a solid line indicates the image data of the second image data B. The image data of the image B are shifted with respect to the image data of image A by half the pixel pitches Px and Py in X-axis and Y-axis directions of the solid-state imaging element
203
, respectively. Here, the X-axis and Y-axis of the solid-state imaging element
203
refer to the horizontal and vertical directions, respectively.
As shown in
FIG. 20
, the image forming section
204
synthesizes the image data of the two images A and B. In the drawing, positions with a symbol ◯ are empty in the beginning, and new image data, for example, an average value of nearby pixels, are provided therein through interpolation later. The resolution of the synthesized image thus obtained is approximately twice as good as the original resolution of the solid-state imaging element
203
.
As has been explained, to obtain a high-resolution image by an imaging apparatus furnished with the image shifting mechanism, at least two images must be inputted at different times to effect the image shifting. Note that, however, the images A and B are shifted from each other by a time-related factor besides the above image shifting. The cause of this kind of shifting is assumed to be an unstable vibration conveyed to the imaging apparatus when the imaging apparatus is supported by hands (hereinafter, referred to as hand holding), or the displacement of the subject
200
. Since the latter problem is not unique to the imaging apparatus furnished with the image shifting mechanism but common to all types of imaging apparatus, no further discussion is given herein.
Thus, in case that the imaging apparatus, such as a still camera and a movie camera, is not firmly supported on a tripod but supported unstably by hands, the images A and B are shifted from each other by the hand holding in addition to the image shifting, thereby making it impossible to obtain a high-resolution image even when the image shifting is effected. If this kind of unwanted shifting is significant, the resolution of the synthesized image can be hardly improved, and in a worse case, the resolution may be deteriorated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an imaging apparatus which can prevent the deterioration of the resolution caused by the hand holding.
To fulfill the above object, an imaging apparatus of the present invention is characterized by being furnished with:
a solid-state imaging element having thereon a matrix of pixels;
an optical series for entering a subject image into the solid-state imaging element;
an image shifting mechanism for shifting the subject image in 2-D relatively with respect to the solid-state imaging apparatus;
a control circuit for controlling an operation of the image shifting mechanism;
an image synthesizing circuit for synthesizing a plurality of images shifted by the image shifting mechanism;
a moving amount detecting unit for detecting a moving amount of the subject image on the solid-state imaging element; and
a shift amount generating unit for generating an image shift amount of the subject image first, and thence a first correction image shift amount based on the image shift amount and moving amount, based on which the image shifting mechanism shifts the subject image.
According to the above arrangement, the subject image which is incident on the solid-state imaging element through the optical series is shifted in 2-D relatively with respect to the solid-state imaging element by the image shifting mechanism before it is formed thereon. Then, a plurality of images shifted in the above
Iwaki Tetsuo
Okada Hideo
Okuda Tohru
Garber Wendy R.
Nguyen Luong
Sharp Kabushiki Kaisha
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