Television – Camera – system and detail – Camera image stabilization
Reexamination Certificate
1999-10-07
2002-01-29
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Camera image stabilization
Reexamination Certificate
active
06342918
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image-shake preventing device suitable for use in an image pickup apparatus, such as a video camera, and capable of correcting a shake (movement) of an image due to a vibration of the apparatus, or the like.
2. Description of the Related Art:
An electronic correcting system, an optical correcting system and the like have heretofore been known as a system for correcting a shake of an image in this kind of image-shake preventing device. The electronic correcting system is generally arranged to store in a memory an input image which immediately precedes the current input image, detect a shake of an image by detecting a variation of the image from the current input image and the previous input image stored in the memory, and vary an image reading position in the memory from which to read out a cut-out image so as to cancel the shake, thereby correcting the shake of the image. The optical correcting system generally includes a variable angle prism disposed in front of a lens and is arranged to turn the variable angle prism and bend the optical axis thereof so as to cancel a shake of an image, thereby correcting the shake of the image.
FIG. 1
is a block diagram showing the arrangement of a video camera having an image-shake preventing device of the conventional, electronic correction type. The arrangement shown in
FIG. 1
includes an optical system
1
made up of predetermined constituent components, such as a focusing lens group provided for the purpose of focusing, a zooming lens group for varying a focal length of the optical system
1
, a compensation lens group, and an iris for adjusting the amount of light. An image pickup element
2
is made up of, for example, a two-dimensional CCD and is provided for converting an input light signal into an electrical signal and outputting the electrical signal. A sample-and-hold (S/H) circuit is provided for sampling and holding the electrical signal supplied from the image pickup element
2
, at intervals of a predetermined period, and an automatic gain control (AGC) circuit is provided for controlling the gain of the electrical signal outputted from the S/H circuit
3
.
The arrangement shown in
FIG. 1
also includes an analog-to-digital (A/D) converter
5
for converting an analog signal outputted from the AGC circuit
4
into a digital signal, a Y/C separation circuit
6
for generating two kinds of delayed signals, i.e., a 1H delayed signal (H: horizontal synchronizing period) and a 2H delayed signal, from the signal outputted from the A/D converter
5
, and for performing computations on the 1H and 2H delayed signals to separate the signal outputted from the A/D converter
5
into a chrominance signal C and a luminance signal Y. A C process circuit
7
is provided; and for generating the chrominance signal C from the 2H delayed signal outputted from the Y/C separation circuit
6
, and a Y process circuit
8
is provided for generating the luminance signal Y from the 1H delayed signal outputted from the Y/C separation circuit
6
and performing edge enhancement, gamma correction and other predetermined processes on the luminance signal Y.
The arrangement shown in
FIG. 1
also includes a first memory
9
for temporarily storing the chrominance signal C outputted from the C process circuit
7
, a second memory
10
for temporarily storing the luminance signal Y outputted from the Y process circuit
8
, a first digital-to-analog (D/A) converter
11
for converting the output signal (digital signal) of the first memory
9
into an analog signal, a second digital-to-analog (D/A) converter
12
for converting the output signal (digital signal) of the second memory
10
into an analog signal, a first signal output terminal
13
through which to output the signal outputted from the D/A converter
11
, and a second signal output terminal
14
through which to output the signal outputted from the D/A converter
12
.
The arrangement shown in
FIG. 1
also includes a two-dimensional band-pass filter (BPF)
15
which is a spatial-frequency filter for extracting only a signal having a predetermined frequency band useful for detecting a motion vector, from the luminance signal outputted from the Y process circuit
8
, the BPF filter
15
serving to eliminate the high and low spatial frequency components of an image signal which are unsuitable for detecting a motion vector, a motion-vector detecting circuit
16
for detecting a motion vector indicative of movements of an image in horizontal (H) and vertical (V) directions from the output signal of the BPF filter
15
, a third memory
17
for temporarily storing the output signal of the BPF filter
15
, the output signal of the third memory
17
being inputted to the motion-vector detecting circuit
16
, and a memory-reading controlling circuit
18
for controlling the image reading position of each of the first and second memories
9
and
10
on the basis of the output of the motion-vector detecting circuit
16
so that shake of an image in the respective horizontal and vertical directions can be corrected. The image reading position of each of the first and second memory
9
and
10
is shifted in the direction of, and by the amount of a movement indicated by, the motion vector obtained in the motion-vector detecting circuit
16
, whereby the movements, i.e., shake, of the image in the horizontal and vertical directions can be cancelled.
The chrominance and luminance signals C and Y, the image shake of which has been corrected in the above-described manner, are respectively supplied from the first and second memories
9
and
10
to the D/A converters
11
and
12
. The chrominance and luminance signals C and Y are respectively converted by the D/A converters
11
and
12
and outputted through the first and second signal output terminals
13
and
14
.
FIG. 2
is a block diagram showing the arrangement of a video camera having an image-shake preventing device of the conventional, optical correction type. In
FIG. 2
, identical reference numerals are used to denote constituent parts identical to those shown in
FIG. 1
, and description thereof is omitted. Unlike the arrangement shown in
FIG. 1
, the memory-reading controlling circuit
18
is omitted from the arrangement shown in
FIG. 2
, and a variable angle prism (VAP)
19
is instead turnably disposed in front of the optical system
1
and a prism controlling circuit
20
is disposed for driving and controlling the variable angle prism
19
. The variable angle prism
19
has a structure in which a liquid of high refractive index is charged into the sealed space between two parallel flat plates, and is arranged to be able to change the direction of its optical axis, i.e., its apex angle, by varying the angle made by the two parallel flat plates. The prism controlling circuit
20
includes a vertical-direction control part (V-direction VAP controlling part)
20
a
for driving and controlling the variable angle prism
19
to correct a movement of an image in the vertical direction thereof and a horizontal-direction control part (H-direction VAP controlling part)
20
b
for driving and controlling the variable angle prism
19
to correct a movement of the image in the horizontal direction thereof.
A motion-vector detection signal indicative of a motion vector detected by the motion-vector detecting circuit
16
is inputted to the prism controlling circuit
20
, and the variable angle prism
19
is driven and controlled by the prism controlling circuit
20
so that shake of the image in the vertical and horizontal directions thereof can be corrected.
However, in an image-shake preventing device which relies on only a conventional electronic correcting system, shown in
FIG. 1
, which electronically corrects shake in the vertical and horizontal directions, it is necessary to make an image reading area smaller than the picture size of an image stored in the memory and it is, therefore, necessary to perform processing, such as enlargement and interpolation, fo
Inou Kazuya
Kaneda Kitahiro
Garber Wendy R.
Moe Aung S.
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