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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a video signal processing
circuit used in performing vibration correction for a video camera and,
more particularly, to providing defective pixel compensation and optical
detector window adjustment in accordance with the vibration correction.
2. Description of the Background
In recent years, the realization of a miniature light-weight video camera
has progressed and today such a video camera can be fairly easily handled.
On the other hand, in association with the miniaturization and lowered
weight of the video camera, the video camera can be so easily moved that
the photographing operation is readily influenced by camera movement and
vibration. A video camera, therefore, having a vibration correcting
feature has been proposed and put into practical use.
As a vibration correcting system for a video camera, there has been
proposed a circuit in which an image pickup signal from an image pickup
device is stored in a field memory, and the picture plane is enlarged and
interpolated in the field memory. The reading out operation from the field
memory is controlled in accordance with the vibration of the camera, and
the vibration is corrected. Such a system is disclosed in U.S. patent
application Ser. No. 673,783 assigned to the assignee of the instant
application. Nevertheless, when the picture plane is enlarged and
interpolated as described above, the resolution deteriorates.
There has also been proposed a mechanism in which a variable optical axis
prism is arranged in front of a lens, the prism is moved in accordance
with the vibrations of the camera, the refraction angle of the incident
light is changed, and the vibration is compensated. Such a system is
disclosed in Japanese patent application number Hei 04-016968. According
to such a vibration correcting mechanism, because the picture plane is not
enlarged and interpolated, the picture quality is not deteriorated.
Nevertheless, according to such a vibration correcting mechanism the
variable optical axis prism must be mechanically moved. Therefore, the
required mechanical structure becomes an obstacle to realizing a small
sized and light-weight camera.
Further, there has been proposed a system in which the image pickup device
of the camera has a number of lines greater than the number of lines of
the standard television system, the picture plane is vertically moved by
using the surplus lines which are available, and the vibration is
corrected. This system is disclosed in U.S. patent application Ser. No.
978,366 also assigned to the assignee of the instant application.
In this latter system, for instance, a CCD image pickup device of the PAL
system is used to output the video signal of the NTSC system. When the
video signal of the NTSC system is generated by using the CCD image pickup
device of the PAL system, because the number of lines of the PAL system is
greater than the number of lines of the NTSC system, surplus lines are
provided. The number and location of the lines in the CCD image pickup
device is transferred at a high speed during the vertical blanking period.
By changing the number of lines in the high-speed transfer with respect to
the number of lines before and after the video frame time, the picture
plane can be vertically moved.
Nevertheless, when such a vibration correction using an increase in CCD
lines is executed, the high-speed transfer is executed during the blanking
period, so that considerably large charges must flow from a vertical
transfer register into a horizontal transfer register of the CCD image
pickup device. Consequently, there occurs the problem that when a strong
light is irradiated onto the CCD image pickup device, the charge amount
exceeds the capacity of the horizontal transfer register and the overflow
charges reverse flow into the vertical transfer register side.
Moreover, as a practical matter defective pixels are always included in the
pixels of a CCD image pickup device. Hitherto, position information of the
defective pixels is stored in a memory and processes such as interpolation
and the like are executed at the positions of the defective pixels,
thereby coping with the defective pixels.
As described above, when the image pickup device having a number of lines
greater than the number of lines of the standard television system is used
vibration correction is executed by vertically moving the picture plane by
using the surplus lines which are available. Therefore, because the
defective pixel information is fixed as addresses in a memory, when the
video signal is moved to perform vibration correction the positions of the
defective pixels do not correspond to the positions at which the defect
correction is to be executed.
When the image pickup device in which the number of lines is larger than
the number of lines of the standard television system is used, the
vertical height of the image pickup picture plane is increased. Therefore,
the image pickup signal is stored in a line memory and is time-base
converted in accordance with a magnification ratio. By such time-base
converting the image pickup signal, the picture plane is enlarged in the
horizontal direction. Therefore, by shifting the enlarged picture plane in
accordance with a vibration amount in the horizontal direction, the
vibration in the horizontal direction can be corrected.
In performing the time-base conversion by using the line memory as
mentioned above, there is considered a method whereby a write clock
signal, and a read clock signal are set to the same clock and the same
data is read out a plurality of times in accordance with the magnification
ratio. After such multiple read out, the data is interpolated by an
interpolation filter, however, when the interpolation filter is used the
picture quality deteriorates.
Some video cameras have a window to detect optical information for
performing automatic exposure control and automatic focus control. For
example, automatic exposure control is executed by detecting a video
signal level using the detection window and by setting an opening amount
of an iris and a gain of an automatic gain control circuit (AGC) in
accordance with the video signal level. As mentioned above, when the image
pickup signal is stored in the line memory, the picture plane is enlarged
in the horizontal direction, the enlarged picture plane is shifted in
accordance with a vibration amount in the horizontal direction, and the
vibration in the horizontal direction is corrected. Thus, the position of
the window is deviated relative to the position of an object to be
photographed. For example, when the position of the window coincides with
the position over the object or is moved away therefrom due to vibration,
although the amount of light in the window changes, the photographed
picture plane is stationary due to the vibration correction. Therefore, a
phenomenon occurs in which the brightness changes in spite of the fact
that the picture plane is stationary.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, one object of the present invention is to provide a video signal
processing apparatus that can prevent the reverse flow of charges to a
vertical transfer register of an image pickup device when performing
vibration correction.
It is another object of the present invention to provide a video signal
processing apparatus that can make the actual positions of defective
pixels in a video camera image pickup device correspond to the position of
defective pixels after an image plane has been shifted due to performing
vibration correction.
It is a still further object of the present invention to provide a video
signal processing apparatus that does not cause deterioration of the
picture quality when a time-base conversion in the horizontal direction is
executed when performing video camera vibration correction.
It is another object of the present invention to provide a video signal
processing apparatus for a video camera in which optical information is
obtained from a window adapted to the picture plane to be actually
photographed.
According to an aspect of the present invention, there is provided a video
signal processing apparatus for correcting vibrations in a video camera,
comprising: an image pickup having a number of lines in vertical direction
that is larger than the number of lines of a television system to be
output; a vibration amount detector for detecting a vibration amount in
the vertical direction; a high-speed transfer control for transferring the
image pickup at a high speed during a blanking period within a range of
the number of surplus lines which is equal to the difference between the
number of lines of the image pickup and the number of lines of the
television system to be output in accordance with the vibration amount in
the vertical direction obtained by the vibration amount detector and for
correcting the vibration in the vertical direction; and a charge backflow
preventing device, arranged in parallel with a horizontal transfer
register of the image pickup, for preventing a back flow of charges to a
vertical transfer register upon high-speed transfer of the charges on the
image pickup.
According to another aspect of the present invention, there is provided a
video signal processing apparatus for correcting vibration in a video
camera, comprising: an image pickup having a number of lines in the
vertical direction which is greater than the number of lines of the
television system to be output; a vibration amount detector for detecting
a vibration amount in the vertical direction; a high-speed transfer
control for transferring charges from the image pickup at high speed
during a video blanking period within a range of the number of surplus
lines that is equal to the difference between the number of lines of the
image pickup and the number of lines of the television system to be output
in accordance with the vibration amount in the vertical direction obtained
by the vibration amount detector and for correcting the vibration in the
vertical direction; a memory for storing pixel defect location formation
for each of the pixels that are arranged in the image pickup; and a defect
corrector for correcting defects in accordance with the defect location
information and the number of lines that are transferred at high speed for
vibration correction, thereby correcting defects.
According to still another aspect of the present invention, there is
provided a video signal processing apparatus for correcting vibrations in
a video camera, comprising: an image pickup having a number of lines in
the vertical direction that is greater than the number of lines of the
television system to be output; a vibration amount detector for detecting
vibration amounts in the horizontal and vertical directions; a high-speed
transfer control for transferring the changes on the image pickup at high
speed during a video blanking period within a range of the number of
surplus lines which is equal to the difference between the number of lines
of the image pickup and the number of lines of the television system to be
output in accordance with the vibration amount in the vertical direction
obtained by the vibration amount detector and for correcting the vibration
in the vertical direction; a line memory into which a video signal after
the vibration in the vertical direction is written and from which the
video signal is read out by a read clock of a frequency lower than that of
the write clock, thereby performing an enlargement in the horizontal
direction of the video signal; and a line memory control for line-locking
the write clock and the read clock, for setting a frequency ratio of the
write clock and the read clock in accordance with a magnification ratio in
the horizontal direction, for shifting the reading position or writing
position of the line memory, thereby correcting the vibration in the
horizontal direction.
According to yet another aspect of the present invention, there is provided
a video signal processing apparatus for correcting vibration in a video
camera, comprising: a image pickup having a number of lines in the
vertical direction that is greater than the number of lines of the
television system to be output; a vibration amount detector for detecting
vibration amounts in the horizontal and vertical directions; a high-speed
transfer control for transferring the charges on the image pickup at high
speed during a blanking period within a range of the number of surplus
lines which is equal to the difference between the number of lines of the
image pickup and the number of lines of the television system to be output
in accordance with the vibration amount in the vertical direction obtained
by the vibration amount detector and for correcting the vibration in the
vertical direction; a line memory into which a video signal after the
vibration in the vertical direction is written and from which the video
signal is read out by a read clock of a frequency lower than that of the
write clock, thereby performing an enlargement in the horizontal direction
of the video signal; a line memory control for correcting the vibration in
the horizontal direction by shifting a reading position or a writing
position of the line memory; and a window setting circuit for setting a
window to detect optical information and for correcting the position of
the window in accordance with the vibration amount so as not to change the
relative position for the video signal after the vibration has been
corrected.
The above and other objects, features, and advantages of the present
invention will become readily apparent from the following detailed
description thereof, which is to be read in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a general block diagram of a video camera to which the present
invention is applied;
FIG. 2 is a representation of a CCD which is used in a video camera to
which the invention is applied;
FIGS. 3A to 3F are waveform diagrams which are useful in explaining the
video camera to which the present invention is applied;
FIG. 4 is a representation of a CCD which is useful in explaining the video
camera to which the invention is applied;
FIGS. 5A and 5B are representations of a portion of a CCD which are useful
in explaining the video camera to which the invention is applied;
FIG. 6 is a schematic of explain a CCD image pickup device of the video
camera to which the invention is applied;
FIG. 7 is a schematic of explain of a CCD image pickup device of the video
camera according to an embodiment of the present invention;
FIG. 8 is a representation of the CCD image pickup device of the video
camera of FIG. 7 shown in more detail;
FIG. 9 is a block diagram explain the vibration correction system for the
horizontal direction of the video camera according to an embodiment of the
present invention;
FIGS. 10A and 10B are representations of a video frame which useful in
explaining the correction of pixel defects of the video camera according
to an embodiment of the present invention;
FIG. 11 is a block diagram of a system for the correction of defects of the
video camera according to an embodiment of the present invention;
FIG. 12 is a block diagram of a system for setting of a window for optical
detection of the video camera according to an embodiment of the present
invention;
FIGS. 13A to 13D are waveform diagrams which are useful in explaining the
setting of the window for optical detection of the video camera as shown
in FIG. 12; and
FIGS. 14A to 14C are representations of a video frame which are useful in
explaining the setting of the window for optical detection of the video
camera as shown in FIG. 12.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In the video camera of FIG. 1 the light of an object image obtained through
a lens 1 is formed as an image on a photosensitive surface of a CCD image
pickup device 3 after passing through an iris 2. Although the video camera
is selected to perform recording following the NTSC standard system, in
order to perform vibration correction the CCD image pickup device 3 is
provided with a number of lines that is not equal to the number of lines
of the NTSC system but, rather, is equal to the number of lines of the PAL
system. That is, the number of lines of the CCD image pickup device 3 is
selected such that there are 582 effective lines.
The CCD image pickup device 3 is driven by a driver 4 on the basis of a
timing signal from a timing generating circuit 5. A sync signal is
supplied from a sync generating circuit 6 to the timing generating circuit
5 and an output of a vibration correcting controller 20 is also supplied
to the timing generating circuit 5. A high-speed transfer clock signal is
fed to the CCD image pickup device 3 for a period of time equal to the
vertical blanking interval in accordance with the vibration in the
vertical direction of the camera.
According to an embodiment of the invention, pixel defects in the CCD image
pickup device 3 are corrected, and the defect information of the CCD image
pickup device 3 is stored in a defect position memory 31. An output of the
defect position memory 31 is supplied to a defect correction pulse
generating circuit 32 whose output is supplied to a signal processing
circuit 10. At the position of the defective pixel, the output of the CCD
image pickup device 3 is replaced to pixel data formed by interpolating
the data of the adjacent pixels. Due to this, the defect correction is
executed. As will be explained hereinafter in performing defect correction
an address is shifted so that the defect position on the CCD image pickup
device 3 corresponds to the position to correct position after the lines
are shifted to perform vibration correction.
The output of the CCD image pickup device 3 is supplied to an
analog-to-digital (A/D) converter 9 through a sample-and-hold circuit 7
and an automatic gain control (AGC) circuit 8. The image pickup signal is
converted into a digital signal by the A/D converter 9 and an output of
the A/D converter 9 is supplied to the signal processing circuit 10 and is
also supplied to an optical detector circuit 11.
The signal processing circuit 10 executes necessary camera signal
processing and forms a luminance signal and a chrominance signal
corresponding to the NTSC system from the image pickup signal from the CCD
image pickup device 3. The luminance signal and the chrominance signal
from the signal processing circuit 10 are supplied to a horizontal
correcting circuit 14.
The optical detector circuit 11 is provided to obtain information which is
necessary for optical controls such as exposure control, focus control,
white balance control, and the like. A window for obtaining this
information is set by the optical detector 11 and a light level in the
window is detected and a corresponding signal is supplied to a camera
controller 13. The camera controller 13 controls the gain of the AGC
circuit 8 and the opening size of the iris 2 in accordance with the light
level signal, so that automatic exposure control is performed. The
detection window is set by the optical detector 11 and an edge component
level of the image pickup signal in the window is detected and supplied to
the camera controller 13. The camera controller 13 controls the position
of the lens 1, the lens position control mechanism is not shown, so that
the edge component level is maximized. In this way, the automatic focus
control is executed. The position of the window of the optical detector 11
can be moved by a window correction circuit 12.
According to an embodiment of the invention, the lines in the horizontal
direction are enlarged by the line memory of the horizontal correcting
circuit 14 and the reading position, or the writing position, in the line
memory is shifted, thereby performing the vibration correction in the
horizontal direction. When such a method is used, however, the position of
the picture plane which is output does not coincide with the position of
the picture plane photographed by the CCD image pickup device. Therefore,
when the position of the window does not coincide with the position of the
object due to the vibration correction, the light amount in the window
changes but the photographed picture plane appears stationary due to the
vibration correction. Thus, a phenomenon occurs in which the brightness
changes in spite of the fact that the picture plane is stationary. To
overcome this, the invention provides a system whereby the position of the
window of the optical detector 11 is shifted in accordance with a
vibration correction amount.
The luminance signal and the chrominance signal from the signal processing
circuit 10 are supplied to the horizontal correcting circuit 14, and the
horizontal correction circuit 14 enlarges a signal of one line and shifts
the reading position, thereby correcting the effects of vibration in the
horizontal direction of the camera. The horizontal correcting circuit 14
is constructed by a line memory. A PLL 15 provides a synchronized read
clock and write clock for the line memory. The reading and writing
positions of the line memory forming the horizontal correction circuit 14
are controlled by the vibration correcting controller 20.
The luminance signal and chrominance signal from the horizontal correcting
circuit 14 are supplied respectively to D/A converters 16A and 16B and the
analog luminance signal and chrominance signal are generated by the D/A
converters 16A and 16B and output from output terminals 17A and 17B.
The shaking of the video camera is detected by pitch and yaw angular
velocity sensors 21A and 21B. That is, shaking in the vertical direction
is detected by the pitch angular velocity speed sensor 21A, and an output
of the pitch angular velocity speed sensor 21A is supplied to an A/D
converter 23A through an amplifier 22A. An output of the A/D converter 23A
is supplied to the vibration correcting controller 20. Shaking in the
horizontal direction is detected by the yaw angular velocity sensor 21B
and an output of the yaw angular velocity sensor 21B is supplied to an A/D
converter 23B through an amplifier 22B. The output of the A/D converter
23B is also supplied to the vibration correcting controller 20.
The vibration correcting controller 20 controls a high-speed transfer of
the CCD image pickup device 3 by a signal fed to timing generator 5 on the
basis of shaking in the vertical direction as detected by the pitch
angular velocity sensor 21A, thereby executing the vibration correction in
the vertical direction. On the basis of shaking in the horizontal
direction as detected by the yaw angular velocity sensor 21B, the read
position (or writing position) of the line memory constructing the
horizontal correcting circuit 14 is shifted, thereby performing the
vibration correction in the horizontal direction.
More specifically, as shown in FIG. 2A according to the embodiment of the
invention the CCD image pickup device 3 is formed of a device in which the
number of lines is in accordance with the PAL system, so that the number
of effective lines is equal to 582. On the other hand, the number of
effective lines of the NTSC system is usually taken to be 494 lines.
Therefore, 494 lines are selected from among the 582 effective lines of
one picture plane that are available in the CCD image pickup device 3. As
shown by the upper and lower hatched regions in FIG. 2A, outputs of these
extraneous lines are not used. The picture plane can be moved in the
vertical direction by changing the start position ST. Therefore, by moving
the start position ST so as to eliminate the shake in the vertical
direction of the picture plane the vibration correction in the vertical
direction can be executed.
FIGS. 3A-3F show the waveforms of the various signals applied to the CCD
image pickup device 3. More specifically, a field identification pulse FLD
(FIG. 3A), a vertical sync pulse VD (FIG. 3B), a horizontal sync pulse HD
(FIG. 3C), sensor gate pulses XG1 and XG2 (FIGS. 3D and 3E), and a
transfer clock CK (FIG. 3F) are supplied to the CCD image pickup device 3.
A sensor gate pulse is supplied at a time point t1 and charges are
transferred from each pixel of the CCD image pickup device 3 to the
vertical transfer register by the sensor gate pulse. The charges are
transferred by the transfer clock shown in FIG. 3F. In this instance, the
signals of two pixels in the vertical direction are mixed and sent to the
vertical transfer register. The reading position can be shifted by
one-half line by a combination of the sensor gate pulses XGS1 and XGS2.
As shown by the frequency of the clock pulses in FIG. 3F, N lines of the
CCD image pickup device 3 are transferred at a high speed. Although these
N lines of the CCD image pickup device 3 are transferred at a high speed,
the other lines of the CCD image pickup device 3 are transferred at the
normal transfer speed starting from time point t2. The CCD image pickup
device 3 is then again transferred at a high speed from time point t3. The
total number of lines which have been transferred for a period of time
from time point t1 to time point t4 corresponds to the number of lines of
the PAL system, as represented in FIG. 2. The number of lines for a period
of time from time point t2 to time point t3 corresponds to the number of
lines of the NTSC system, as represented by the middle open area in FIG.
2. The position in the vertical direction of the picture plane can be
changed by the number N of lines which are transferred at a high speed. By
setting the number N of lines which are vertically transferred in
accordance with the shake in the vertical direction of the video camera,
the vibration correction in the vertical direction is executed.
Among the 582 effective lines of the CCD image pickup device 3 according to
the PAL system, the charges of the 494 effective lines according to the
NTSC system are transferred at a normal speed. The charges of remaining
lines are transferred at a high speed. As a consequence of this two-speed
charge transfer, a circular object A1 will be displayed as a vertically
elongated circular image A2, as shown in FIG. 4.
In regard to the horizontal vibration correction, a signal SL of one line
is stored in the line memory 14, as shown in FIG. 5A. As shown in FIG. 5B,
the time base of such a signal is converted and the resultant signal is
read out. By performing this time base conversion, a ratio of the vertical
and lateral lengths of the image which is displayed is corrected and the
picture plane is enlarged in the horizontal direction. By shifting the
reading position of the line memory in accordance with the shake of the
video camera in the horizontal direction the vibration correction can be
performed.
In the video camera to which the invention is applied, as mentioned above,
the CCD image pickup device 3 transfers the charges at a high speed during
the vertical blanking period and sweeps out at a high speed. Therefore,
considerably large charges flow from the vertical transfer register into
the horizontal transfer register of the CCD image pickup device 3.
Therefore, when a strong light is irradiated onto the CCD image pickup
device 3, the charge amount will exceed the capacity of the horizontal
transfer register and the overflow charges can easily flow in reverse to
the vertical transfer register side.
This is shown in FIG. 6, in which the photoelectric converting devices 41
are two-dimensionally arranged to form the pixels of the ordinary CCD
image pickup device. In each of the photoelectric converting devices 41,
the incident light is photoelectrically converted and the charges are
supplied from the photoelectric converting devices 41 to a vertical
transfer register 42. As represented by arrow a1, the charges are
transferred by the vertical transfer register 42 and sent to a horizontal
transfer register 43. The charges are transferred, as represented by arrow
c1, by the horizontal transfer register 43 and are output to the
appropriate circuitry of the video camera.
When a large amount of charges are sent to the horizontal transfer register
43 through the vertical transfer register 42, the charges of the
horizontal transfer register 43 will overflow. As represented by arrow b1,
these overflow charges then flow in reverse from the horizontal transfer
register 43 to the vertical transfer register 42.
According to an embodiment of the present invention, as shown in FIG. 7, a
drain device 44 is provided in parallel with the horizontal transfer
register 43. In operation of this embodiment, the charges from the
photoelectric converting device 41 of each pixel are supplied to a
vertical transfer register 42 and the charges are transferred from the
vertical transfer register 42, as represented by arrow a2 to a horizontal
transfer register 43. The charges are transferred from the horizontal
transfer register 43, as represented by arrow c2, and output to the other
circuitry of the video camera.
Now, assuming that a large amount of charges are transferred to the
horizontal transfer register 43 through the vertical transfer register 42,
the charges of the horizontal transfer register 43 will overflow as
explained above. In this embodiment, however, the overflow charges flow
into the drain 44 arranged in parallel with the horizontal transfer
register 43, as shown in FIG. 8. Therefore, it is possible to prevent the
overflow charges from flowing in reverse from the horizontal transfer
register 43 to the vertical transfer register 42.
According to the embodiment of the invention, as shown in FIGS. 5A and 5B,
the time base in the horizontal direction is changed by the horizontal
correcting circuit 14 and the picture plane in the horizontal direction is
enlarged. In such a time-base conversion, the same data is repetitively
read out from the line memory without changing the write clock and read
clock and the data during such a period of time can be easily interpolated
by management of the clock signals. When such a method is used, however,
because interpolation of the data is necessary a deterioration of the
picture quality due to the interpolation filter occurs.
According to an embodiment of the present invention, time-base conversion
is executed by changing the frequencies of the clocks in the writing and
reading operation. FIG. 9 shows an example of the horizontal correcting
circuit 14 to which the invention is applied. in FIG. 9, a video signal
(luminance or chrominance) is supplied to an input terminal 51 and fed to
a line memory 52. An output of the line memory 52 is supplied to a
terminal 53A of a switching circuit 53.
A horizontal clock signal of frequency fH is supplied to an input terminal
54 and fed to a write clock generating circuit 55 and to a 1/N frequency
dividing circuit 56. The output of the 1/N frequency dividing circuit 56
is supplied to a phase comparing circuit 57 that produces an output fed to
a voltage controlled oscillator (VXO) 58 through a low pass filter 61. The
output of the VXO 58 is supplied to a read clock generating circuit 59 and
to a sync generating circuit 62 and is also supplied to a 1/M frequency
dividing circuit 60. The output of the 1/M frequency dividing circuit 60
is supplied to the other input of the phase comparing circuit 57. In the
phase comparing circuit 57, the phase of the clock signal that has been
frequency divided by 1/N is compared with the phase of the output of the
VXO 58 that has been frequency divided by 1/M. On the basis of this phase
comparison, the oscillating frequency of the VXO 58 is controlled.
A phase-locked loop (PLL) is constructed by the frequency dividing circuits
56 and 60, the VXO 58, and the phase comparing circuit 57. The write clock
and read clock of different frequencies can be formed by the PLL and,
moreover, because the PLL is constructed as described above, the write
clock and read clock are line-locked.
The output of the write clock generating circuit 55 and the output of the
read clock generating circuit 59 are supplied to a memory controller 64. A
shift amount in the horizontal direction is also supplied to an input
terminal 65 of the memory controller 64. The memory controller 64 controls
the writing and reading operations of the line memory 52 by the write
clock signal from the write clock signal generating circuit 55 and the
read clock from read clock generating circuit 59. A frequency ratio of the
write clock and read clock is determined by the frequency dividing ratio N
of the frequency dividing circuit 56 and the frequency dividing ratio M of
the frequency dividing circuit 60. Therefore, the time-base conversion is
realized, and the line in the horizontal direction is enlarged. The
reading position, or writing position, of the enlarged line is changed in
accordance with a shift amount from the input terminal 65. Thus, the
vibration correction in the horizontal direction is executed.
The output of the sync generating circuit 62 is supplied to a fixed
terminal 53B of a switching circuit 53. The switching circuit 53 is
switched to the other fixed terminal 53A connected to the output of line
memory 52 for a video signal period of time. More specifically, the
switching circuit 53 is switched from the terminal 53A side to the
terminal 53B side at a timing of a sync signal and an output of the
switching circuit 53 is taken out from an output terminal 63.
Defective pixels are almost invariably included in the large number of
pixels forming the CCD image pickup device 3. As described above, the
position information of the defective pixels is accumulated into the
defect position memory 31 and processes, such as interpolation and the
like, are executed at the positions of the defective pixels, thereby
coping with the defective pixels.
According to an embodiment of the present invention, as represented by the
CCD image pickup device in FIG. 10A, the addresses of the defective pixels
P.sub.1, P.sub.2, P.sub.3 are stored in the defect position memory 31. The
addresses (Hn, Vn) are set to the absolute addresses (H.sub.1, V.sub.1)
with respect to the first defect P1 and are set to the absolute addresses
(H.sub.2, H.sub.3) with respect to the horizontal direction with regard to
the subsequent defects P2 and P3, respectively, and are set in the
relative addresses (V.sub.2, V.sub.3) from the positions of the preceding
defect pixels with regard to the vertical direction.
As shown in the circuit of FIG. 11, the addresses (Hn, Vn) of the defect
positions are output from the defect position memory 31. The addresses
(Hn, Vn) are supplied to the defect correction pulse generating circuit
32. A vibration amount .DELTA.V in the vertical direction is supplied from
the vibration correction controller 20 to the minus input of a signal
summer 30 where it is subtracted from the vertical address Vn before being
fed to the defect correction pulse generating circuit 32. Thus, the
addresses (Hn, Vn-.DELTA.V) which have been shifted in accordance with the
vibration amount are formed.
A defect correction pulse is generated at each position corresponding to
the addresses (Hn, Vn -.DELTA.V) and a switching circuit 71 in the signal
processing circuit 10 is controlled by the defect correcting pulses. That
is, in case of a normal pixel, the switching circuit 71 is set to a
terminal 71A side. When the defect correction pulse is generated, the
switching circuit 71 is switched to a terminal 71B side, and the pixel
data that has been interpolated by a delay circuit 72 is output from the
switching circuit 71. By adjusting the vertical addresses of all defective
pixels by the amount of shift needed to correct for camera vibrations, as
mentioned above, as shown in FIGS. 10B and 10C, the pixel defects can be
accurately corrected along with the vibration correction.
As described above, the position of the window of the optical detector 11
can be moved by the window correcting circuit 12 in correspondence to a
shift amount of the picture plane in the horizontal direction. That is, as
shown in FIG. 12, a horizontal sync pulse HD (FIG. 13A) is fed in at an
input terminal 81 to a load signal generating circuit 82, which generates
a load pulse signal as shown in FIG. 13B, that is supplied to the counter
83. The counter 83 loads a value M in response to the pulses in load
signal. The value M is set in accordance with the vibration amount in the
horizontal direction and is counted by the counter 83 and the count output
of the counter 83 is supplied to a decoder 84. The position of a window W
is determined by the decoder 84 on the basis of an output of the counter
83. The position of the window W is shifted in accordance with the value M
which is loaded into the counter 83, namely, in accordance with the
vibration amount as shown in FIGS. 13A and 13B.
As described above, because the position of the window of the optical
detector 11 is shifted in accordance with the vibration correction amount,
there is a problem such that a phenomenon occurs in which the brightness
is changed in spite of the fact that the picture plane is stationary. If
it is assumed that, as shown in FIG. 14A, that vibration occurs in a state
in which the position of an object Q coincides with the position of the
window WD, and the position on the picture plane is corrected by
performing vibration correction in accordance with an embodiment of the
present invention. In this example as shown in FIG. 14B, the actual
picture plane does not move to perform the necessary vibration correction,
however, the result of the vibration correction is that the position of
the window WD does not coincide with the position of the object Q.
Therefore, the light amount in the window changes, although the
photographed picture plane is stationary, due to the vibration correction
and the whole brightness changes, thereby affecting the automatic focus
control, the automatic exposure controls and the white balance control.
To solve the problem according to an embodiment of the present invention,
as shown in FIG. 14C, the position of the window WD is shifted in
accordance with the vibration amount, so that the position of the object Q
coincides with the position of the window WD. Thus, the brightness
detected in window WD does not change.
Having described a specific preferred embodiment of the present invention
with reference to the accompanying drawings, it is to be understood that
the invention is not limited to that precise embodiment, and that various
changes and modifications may be effected therein by one skilled in the
art without departing from the scope or the spirit of the invention as
defined in the appended claims.
For example, according to an embodiment of the present invention, the image
pickup signal of the NTSC system is output by using a CCD image pickup
device that has the number of lines corresponding to the PAL system.
Nevertheless, a | | |
