JPH09107495A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the camera provided with an automatic focusing means which realizes satisfactory automatic focusing and has a simple constitution and a low cost by always surely extracting an evaluation value whether the camera main body is taken in the vertical or the horizontal direction or whether an object consists of vertical lines or horizontal lines. SOLUTION: This camera is provided with a one-dimensional filter 10 which extracts a first focusing evaluation value as a signal component required for focusing from video signals outputted from image pickup means 3 and 4 and a twodimensional filter 6 which extracts a second focusing evaluation value different from the first evaluation value as another signal component required for focusing from video signals outputted from image pickup means 3 and 4. Automatic focusing means 5, 10, 12, 13, and 15 are provided which use the second focusing evaluation value together with the first focusing evaluation value to perform the focusing operation in the case that the focusing operation based on only the first focusing evaluation value extracted by the one- dimensional filter 10 is impossible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera provided with an automatic focus adjustment (autofocus) means which ensures good focusing.

[0002]

2. Description of the Related Art In recent years, at conferences and lectures, information such as characters and figures written on a whiteboard or a blackboard is collectively photographed by a camera incorporating an image pickup device, and the image signal generated by the photographing is reproduced. A portable camera that performs a binarization process and outputs a binarized image having only a white level "0" and a black level "1" has been developed and put into practical use. This camera is called an "OA camera" or a "blackboard camera".

In such a camera, the autofocus function is an essential condition for improving the usability of the user. The autofocus is performed by driving and controlling the focus lens so that the high frequency component of the video signal obtained from the image pickup device incorporated in the camera becomes maximum. Such an autofocus system is mainly used in video cameras, and the extraction of high frequency components of a video signal is realized by a horizontal one-dimensional filter.

23A and 23B are diagrams showing the relationship between the attitude (posture) of the camera body 51 and the scanning direction of the image pickup element 52. In FIG. 23A, the longitudinal direction of the image pickup element 52 is horizontal. The camera posture and the scanning direction (direction indicated by the arrow 53) on the image pickup element surface when the camera body 51 is held horizontally so that the image pickup element 5 is shown in FIG.
2 so that the horizontal direction is horizontal.
3 shows a camera posture in the case of vertically holding and taking a picture and a scanning direction (direction indicated by an arrow 53) on the image pickup element surface at that time.

By the way, it is said that many objects existing in the natural world are composed of vertical lines much more than objects composed of horizontal lines. When shooting with a video camera, in the normal case, the longitudinal direction of the image pickup device 52 is horizontal as shown in FIG.
In most cases, the camera body 51 is held horizontally. Therefore, if the focus adjustment operation using the high frequency component included in the vertical line of the subject is performed, good autofocus can be performed.

[0006]

However, since the "OA camera" described above mainly handles still images,
It is not always necessary to hold the camera horizontally and shoot, and it is possible that the camera body 51 is held vertically as shown in FIG. Therefore, if the high-frequency component of the video signal is performed only by the one-dimensional filter in the horizontal direction, there is a possibility that the high-frequency component cannot be extracted at all depending on the subject.

Therefore, by using a two-dimensional filter,
It has been attempted to extract high frequency components in both vertical directions to perform autofocus. However, when a two-dimensional filter is used, an attempt to improve the probability of focusing by autofocus causes the filter structure to become large in scale, resulting in high cost.

It is an object of the present invention to provide stable and reliable camera body regardless of whether the camera body is held vertically or horizontally or the object is an object constituted by only one of vertical and horizontal lines. It is another object of the present invention to provide a camera equipped with an automatic focus adjusting means that can extract an evaluation value and perform a good autofocus operation, and that has a simple structure and does not cause a large-scale filter structure and a high cost.

[0009]

In order to solve the above problems and achieve the object, the present invention uses the following means.

(1) A camera of the present invention is based on an image pickup means for outputting a video signal corresponding to a subject light through an optical system including a focus adjusting lens, and a video signal outputted from the image pickup means. In a camera equipped with an automatic focus adjusting means for driving and controlling the focus adjusting lens to automatically perform focus adjustment, the automatic focus adjusting means adjusts the focus from a video signal output from the image pickup means. A one-dimensional filter for extracting a first focus adjustment evaluation value, which is a signal component necessary for performing the focus adjustment, and a signal component necessary for performing the focus adjustment from the video signal output from the image pickup means. A two-dimensional filter for extracting a second focus adjustment evaluation value different from the certain first focus adjustment evaluation value, and the first focus adjustment extracted by the one-dimensional filter. When it is detected that the focus adjustment operation based on only the value is impossible, the focus adjustment operation is performed using the second focus adjustment evaluation value together with the first focus adjustment evaluation value. ing.

(2) The camera of the present invention is the camera described in (1) above, wherein the automatic focus adjustment means includes the first focus adjustment evaluation value and the second focus adjustment evaluation value. When using, by inputting the second focus adjustment evaluation value extracted by the two-dimensional filter to the one-dimensional filter to obtain the first focus adjustment evaluation value,
Focus adjustment operation is performed.

(3) The camera of the present invention is the camera described in (2) above, further comprising video processing means for performing a predetermined signal processing on the video signal output from the image pickup means. Thus, the two-dimensional filter also serves as a preprocessing filter for preprocessing the video signal supplied to the video processing means.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a block diagram showing the arrangement of a camera according to the first embodiment of the present invention. As shown in FIG. 1, a subject image X is formed on an image sensor 3 such as a charge-coupled device (CCD) through a diaphragm mechanism 1 for adjusting the amount of light and a lens system 2 including a focus adjusting lens. . The subject image X formed on the image pickup device 3 is photoelectrically converted into an electric signal by the image pickup device 3 and further processed into a video signal by the image pickup circuit 4. The video signal generated by the image pickup circuit 4 is converted into a digital signal by the A / D converter 5 and output. The subsequent processing for the digital signal output from the A / D converter 5 differs depending on the camera mode.

"In the case of the automatic exposure control (abbreviated as AE) mode" When the camera is in the AE mode, the switching contact of the selector switch 11 (SW.Q) is switched to the D terminal side. Therefore, the luminance signal component included in the output of the A / D converter 5 is directly input to the cumulative adder 12 via the D terminal. The cumulative adder 12 cumulatively adds the input luminance signal components to obtain the AE evaluation value, and obtains the obtained A
E evaluation value is a central processing unit (hereinafter abbreviated as CPU)
Send to 13. The CPU 13 performs arithmetic processing based on the sent AE evaluation value, and gives a control signal to the diaphragm mechanism driving unit 14 or the image pickup device driver 16.
Thus, the diaphragm mechanism 1 or the image sensor 3 is drive-controlled,
Appropriate exposure control is performed.

"In case of automatic focus adjustment (hereinafter abbreviated as AF) mode" When the camera is in AF mode, the changeover contact of the changeover switch 9 (SW.P) is changed over to the A terminal side, and the changeover switch 11 The (SW.Q) switching contact is switched to the C terminal side. Therefore, the output of the A / D converter 5 is the two-dimensional filter 6 and the changeover switch 9
(SW.P) A terminal, one-dimensional filter 10, and changeover switch 11 (SW.Q) C terminal. Therefore, the focus adjustment evaluation value b extracted by the two-dimensional filter 6 and the one-dimensional filter 10,
a, that is, only the high-frequency component necessary for AF is the cumulative adder 1
Enter 2

The cumulative adder 12 cumulatively adds the input high frequency components to obtain an AF evaluation value, and the obtained AF evaluation value is C
Send to PU13. CPU 13 sends the sent AF
The lens drive unit 15 performs the arithmetic processing based on the evaluation value.
To the control signal. In this way, the focus adjustment lens of the lens system 2 is feedback-controlled in the direction in which the high frequency component increases, and focusing is performed.

"In the case of the photographing mode" When the camera is in the photographing mode, the output of the A / D converter 5 is edge-enhanced by the two-dimensional filter 6, and then is output to the binarization processor 7 as a video processor. Supplied. In the binarization processor 7, the input signal is subjected to known simple binarization processing, pseudo-halftone processing, etc. according to the subject. The binarized signal is then output to the printer 8, and the printer 8 prints out an image.

As described above, in this embodiment, the signal path that bypasses only the two-dimensional filter 6 or the signal path that bypasses both the two-dimensional filter 6 and the one-dimensional filter 10 is provided. Thus, depending on the changeover operation of the changeover switch (SW.P) 9 and the changeover switch (SW.Q) 11 which operate according to the situation of the subject, whether to perform filtering by the two-dimensional filter 6 or the one-dimensional filter 10 or to bypass it. It can be appropriately selected.

That is, the changeover switch (SW.P) 9 provided in the preceding stage of the one-dimensional filter 10 switches between the signal filtered by the two-dimensional filter 6 and the signal bypassed by the two-dimensional filter 6 by its switching operation. It is selectively sent to the one-dimensional filter 10. Further, a changeover switch (SW.
The Q) 11 selectively switches the signal filtered by both the two-dimensional filter 6 and the one-dimensional filter 10 or only the one-dimensional filter 10 and the signal bypassed by the two filters 6 and 10 by the switching operation. To the cumulative adder 12.

The two changeover switches (SW.P) 9 and the changeover switch (SW.Q) 11 are both CPUs.
Switching is controlled by a control signal from 13. CPU
In addition to the above-mentioned control, 13 also sets the filter coefficients of the two-dimensional filter 6 and the one-dimensional filter 10.

Next, the camera sequence in the first embodiment having the configuration shown in FIG. 1 will be described with reference to FIG.

FIG. 2 is a flow chart of the camera sequence. The camera sequence will be sequentially described from step S101 with reference to this flowchart.

"S101" It is determined whether or not the power source is ON. If it is determined to be ON, the process proceeds to the next step.

"S102" selector switch (SW.
Q) 11 switches to the D terminal side. Then, A / D
The output of the converter 5 is directly input to the cumulative adder 12.

"S103" The luminance signals are added together in the cumulative adder 12 to obtain the AE evaluation value, and the CPU 13 performs exposure adjustment according to the evaluation value. When the exposures are matched, it is ready to accept the 1st trigger.

[S104] It is determined whether or not the 1st trigger is ON, and if it is determined to be ON, the process proceeds to the next step.

"S105" selector switch (SW.
P) 9 switches to the B terminal side, and the changeover switch (S
W. Q) 11 switches to the C terminal side. Then, A
The output of the / D converter 5 bypasses the two-dimensional filter 6 and is filtered by only the one-dimensional filter 10 and then input to the cumulative adder 12.

"S106" In the cumulative adder 12, the high frequency components are added together to obtain an AF evaluation value, and the CPU 13 performs hill-climbing AF control according to this evaluation value.

[S107] It is determined whether or not the focus is achieved, and if it is determined that the focus is achieved, the second trigger is accepted. In addition, AF of a certain value or more
If there is no peak of the evaluation value and it is determined that the subject is out of focus,
Proceed to step S108.

"S108" Changeover switch (SW.
P) 9 is switched to the A terminal side, and the changeover switch (SW.Q) 11 is switched to the C terminal side. Then, after the output of the A / D converter 5 is filtered by the two-dimensional filter 6, the one-dimensional filter 10 is further added.
It is filtered by and input to the cumulative adder 12. “S109” A signal containing both horizontal and vertical high frequency components is input to the cumulative adder 12, and S1
AF control similar to that in 06 is performed. 2n after focusing
d Triggers will be accepted.

"S110" It is determined whether or not the second trigger is ON, and if it is determined to be ON, the process proceeds to the next step.

"S111" Binary processing, photographing processing such as printout, etc. are performed, and the camera sequence ends.

The present embodiment is characterized in that one type also has two types of two-dimensional filter functions required for completely different purposes.

Here, the two-dimensional filter 6 will be described a little more. The two-dimensional filter 6 used in this embodiment has only to be capable of extracting a high frequency component in the vertical direction, and the number of taps is not particularly limited. In other words, the one-dimensional filter 10 adjusted for AF in the subsequent stage may be used to perform AF using high-frequency components not only in the horizontal direction but also in the horizontal and vertical directions. Therefore, the two-dimensional filter 6 having a smaller circuit scale and a smaller number of taps can be used as compared with the configuration in which it is assumed that AF is performed using the two-dimensional filter alone.

By the way, the two-dimensional filter 6 has different roles and different coefficients set in the AF mode and the photographing mode. That is, the two-dimensional filter 6 is
In the AF mode, a high-pass filter (hereinafter referred to as "H") mainly for extracting high frequency components in the vertical direction.
(Abbreviated as PF). Therefore, the setting coefficient at this time is determined by the frequency characteristic of the one-dimensional filter 10 and the degree of change in the AF evaluation value for controlling the focus lens. Further, the two-dimensional filter 6 operates as a Laplacian filter for the purpose of ensuring the sharpness of the output binary image in the shooting mode. Therefore, the setting coefficient at this time is
It is determined by beauty, and is greatly influenced by the binarization method, paper quality, and printer output characteristics.

As described above, the two-dimensional filter 6 can be operated as an HPF or a Laplacian filter depending on how the coefficients are set, and a low pass filter (hereinafter referred to as LP).
F), a band pass filter (hereinafter abbreviated as BPF), a trap, and the like.

As described above, in the present embodiment, one two-dimensional filter 6 is used as an HPF for extracting high frequency components during AF, and during image capture, the image sharpness is used as a pre-process for the binarization process. It is used as a Laplacian filter for measuring. However, there are many other situations where a two-dimensional filter is used as a video signal processing for an electronic camera. Hereinafter, some examples of sharing a two-dimensional filter will be given.

For example, the resolution of the obtained image is MTF (Modulation T) of the lens system 2 including the focus adjusting lens.
ransfer funstion), the aperture ratio of the pixels of the image sensor 3, the frequency characteristics of the optical LPF and the electric circuit, and the like. In order to correct this, the two-dimensional filter 6 is used as a Laplacian filter, and the contour emphasis signal is added to the original signal. Since the amount of decrease in frequency characteristics is added to the video signal in advance, it is possible to obtain an image whose resolution is not impaired.

FIG. 3A is a diagram showing operation waveforms for resolution correction, and FIG. 3B is a diagram showing frequency characteristics after resolution correction. It is possible to use the two-dimensional filter for resolution correction as shown here and the two-dimensional filter for extracting the high frequency component in the vertical direction for AF, and the circuit scale can be reduced by sharing the two-dimensional filter.

Further, when outputting an image to a monitor or an EVF (electronic viewfinder) or compressing image data, a contour enhancement signal is added using a Laplacian filter so as not to impair the resolution. Things are done. Two-dimensional filter for this edge enhancement and AF
It is possible to share a two-dimensional filter for extracting the vertical high-frequency component for use, and by sharing it, the circuit scale can be reduced.

In the storage / reproduction of the magnetic tape in the FM (Frequency Modulation) system, the noise becomes larger and the S / N becomes worse as the frequency becomes higher when the signal is demodulated. Since noise is generated during demodulation, if only the high-frequency signal is emphasized using the Laplacian filter before that, and after demodulation, it is restored to the original level. Can be made smaller without changing the shape of.

FIG. 4 is a waveform diagram showing the mechanism of high frequency noise removal by video emphasis. It is possible to share the above-mentioned two-dimensional filter for high-frequency emphasis and the two-dimensional filter for vertical high-frequency component extraction for AF, and by sharing the two-dimensional filter, the circuit scale can be reduced.

There are some situations where a two-dimensional filter is used as an LPF. For example, it is used as an LPF for reducing noise in a video signal. Also AE (Auto Exposur
To obtain the evaluation value for e), it is not necessary to know the details of the image, but the average brightness of the entire image, that is, the low frequency component of the image. Therefore, it is also used as an LPF for AE. Furthermore, in the simple binarization processing, the image of a character or figure has many high-frequency components in the character part,
The fluctuation of the background level of the original due to the “illumination unevenness” has a low frequency component. Therefore, it is also used as an LPF for extracting a background level which is a threshold for binarization.

It is possible to share the two-dimensional filter for constructing these LPFs and the two-dimensional filter for extracting the high frequency component in the vertical direction for AF, and by sharing them, the circuit scale can be reduced. .

A trap is used to remove the aliasing component of the color signal in complementary color imaging.

FIG. 5A is a diagram showing an example of the complementary color mosaic filter. In the complementary color mosaic method as shown in the figure, two pixels are repeated in the horizontal direction. Normally, after the white balance is adjusted so that the output of the signals read side by side in the horizontal direction is equal to the achromatic color,
The luminance signal is generated by switching every pixel. By doing so, sampling points can be obtained for the achromatic color by the number of pixels in the horizontal direction. However, for chromatic colors, the output of the two colors is not always equal, so
Luminance carriers are generated at a frequency that is ½ of the pixel sampling frequency, and aliasing from this causes moiré with respect to luminance, degrading image quality. Further, since color carriers are also generated at the same position, a subject having a frequency component in the vicinity of the color carrier is colored even if it is an achromatic color. This is a phenomenon in which the aliasing component of the color signal becomes moire within the band. A trap is required to remove these folding components.

FIG. 5B shows the characteristics of the complementary color mosaic filter. As shown in the figure, a trap is required so that the positions of the luminance carrier and the color carrier with respect to the chromatic color, that is, the response at 1/2 of the pixel sampling frequency fs become zero. It is possible to share the two-dimensional filter for forming the trap and the two-dimensional filter for extracting the high frequency component in the vertical direction for AF, and by sharing the two-dimensional filter, the circuit scale can be reduced.

In the present embodiment, the two-dimensional filter 6 is set to A
Although it is used for extracting the vertical direction high frequency component at the time of F, it can also be used as a BPF for extracting the middle frequency component of the video signal.

FIG. 6 is a diagram showing the evaluation value change characteristics of the high frequency component and the mid frequency component. "Bokeh" only with high frequency components
Since there is little change in the evaluation value of A, it is better to use the mid-range component as well.
This is advantageous in improving the probability of focusing of F. As described above, the two-dimensional filter used in AF is
It can be used as a PF or the like.

(Second Embodiment) FIG. 7 is a block diagram showing the configuration of the second embodiment of the present invention. The second embodiment is an embodiment showing an example in which the two-dimensional filter 6 necessary for AF described above is shared with electronic devices having various functions. As shown in FIG. 7, the subject image X is formed on the image sensor 3 via a diaphragm system 1 for adjusting the amount of light and a lens system 2 including a focus adjusting lens. The subject image X formed on the image pickup device 3 is photoelectrically converted into an electric signal by the image pickup device 3, and further converted into a digital signal by the A / D converter 5. This digital signal is processed by the digital imaging process 4'and becomes a video signal.

When performing resolution correction on the generated video signal, a coefficient is set by the control signal from the CPU 13 so that the two-dimensional filter 6 operates as a Laplacian filter. The contour enhancement signal is supplied from the two-dimensional filter 6 to the imaging process 4 ′. Therefore, in the imaging process 4 ′, the contour emphasis signal is added to the signal from the A / D converter 5.

In the case of outputting the edge-enhanced signal to the monitor 21 and the EVF 22, in the case where the data is compressed by the compressor 17 and then recorded in the memory 18, and after the binarization processor 7 performs simple binarization, the printer. In the case of outputting to 8 as well, in each case of
Are set to operate as a Laplacian filter. Thus, the contour enhancement is performed in the same procedure as above.

When the aliasing component of the color signal is removed in the complementary color image pickup, the control signal from the CPU 13 sets the coefficient so that the two-dimensional filter 6 operates as a trap. For this reason, the signal filtered by the two-dimensional filter 6 has no aliasing of the color signal.

When recording on the magnetic tape 20, a CP
The control signal from U13 sets the coefficient of the two-dimensional filter 6 so that it operates as a Laplacian filter. The signal pre-emphasized by the two-dimensional filter 6 is FM-modulated by the recording preprocessor 19 and then recorded on the magnetic tape 20.

When performing AE, a coefficient is set by the control signal from the CPU 13 so that the two-dimensional filter 6 operates as an LPF. The signal filtered by the two-dimensional filter 6 is input to the AE controller 24.
In the AE controller 24, the input signals are cumulatively added, and the obtained AE evaluation value is sent to the CPU 13. CPU
In 13, the arithmetic processing based on the sent AE evaluation value is performed. A control signal from the CPU 13 is given to the diaphragm mechanism drive unit 14 or the image pickup device driver 16.
Thus, the diaphragm mechanism 1 or the image sensor 3 is drive-controlled,
Appropriate exposure control is performed.

When performing AF, a coefficient is set by the control signal from the CPU 13 so that the two-dimensional filter 6 operates as a desired HPF or BPF. The signal filtered by the two-dimensional filter 6 is further filtered by the one-dimensional filter 10 to extract only high-frequency components necessary for AF and input to the AF controller 23. However, when the two-dimensional filter 6 is used as the BPF, the one-dimensional filter 10 may be bypassed. In the AF controller 23, high frequency components are cumulatively added to obtain an AF evaluation value. The obtained AF evaluation value is CPU1.
It is sent to 3. The CPU 13 performs arithmetic processing based on the input AF evaluation value. The control signal from the CPU 13 is given to the lens driving unit 15. In this way, the lens system 2 including the focus adjusting lens is drive-controlled, and focusing is performed while feedback-controlling in the direction in which the high frequency component increases.

Here, the structure of the two-dimensional filter 6 will be further described. The two-dimensional filter 6 is mainly composed of a line buffer (delay line), a multiplier, an adder, and a divider. In the present embodiment, the sharing of the 3 × 3 two-dimensional filter is described, but the effect to be obtained and the circuit scale greatly change depending on which part is shared.

FIG. 8 is a block diagram showing a first structural example of the two-dimensional filter 6 in which all parts are shared. In FIG. 8, 31 and 32 are line buffers, 33 is a flip-flop group, 34 is a multiplier group, 35 is an adder, and 36 is a divider. As shown in FIG. 8, when all parts are shared, only one type of filter characteristic can be obtained at a time. Therefore, when the two-dimensional filter 6 is shared for another purpose, it is impossible to output two types of outputs at the same time, and therefore it is necessary to reset the coefficients by time division and use them. However, since all of them are shared, the circuit scale can be very small.

FIG. 9 is a block diagram showing a second configuration example of the two-dimensional filter 6 which shares the line buffer and the multiplier. In FIG. 9, 31 and 32 are line buffers and 3
3 is a flip-flop group, 34 is a multiplier group, 35A, 3
5B is an adder, 36A and 36B are dividers, 37A and 37
B is a changeover switch group.

Set the changeover switch groups 37A and 37B to 0N /
By turning it off, the coefficient "0" is set, so that the combination to be added becomes arbitrary and the characteristics can be slightly changed. Therefore, two or more outputs having slightly different characteristics can be output at the same time. Line buffers 31 and 32 with large circuit scale and multiplier group 3
Since 3 and 3 are shared, the circuit scale can be extremely small.

FIG. 10 is a block diagram showing a third configuration example of the two-dimensional filter 6 that shares only the line buffer. It is possible to simultaneously realize the filter characteristics suitable for each application. Although the circuit scale is slightly larger than that of FIG. 9, the expensive line buffer 3
Since 1 and 32 are shared, there are sufficient merits.

The configuration of the two-dimensional filter 6 in this embodiment has been described using the case of 3 × 3, but it is also possible to add a line buffer to 4 × 4 or more.
However, in order to simplify the configuration of the two-dimensional filter 6 as much as possible, about 3 × 3 is sufficient as described above. Also, a second configuration example of the two-dimensional filter 6 shown in FIG.
In the third configuration example of the two-dimensional filter 6 shown in FIG. 10, it is possible to have three or more outputs.

As described above, the two-dimensional filter 6 required for AF can be shared with an electronic device having various functions, but hereinafter, a case where it is shared with the binarization processor 7 is a typical example. explain.

(Third Embodiment) This third embodiment is an embodiment in which the switching of the filter is performed not by the switching operation by the changeover switch but by setting the coefficient. The configuration will be described below with reference to the block diagram shown in FIG.

The subject image X has a diaphragm mechanism 1 for adjusting the amount of light.
An image is formed on the image sensor 3 via the lens system 2 including the focus adjustment lens. The subject image X formed on the image pickup element 3 is photoelectrically converted by the image pickup element 3 into an electric signal, and further processed by the image pickup circuit 4 into a video signal.
The generated video signal is converted into a digital signal by the A / D converter 5. The converted digital signal is processed differently depending on the mode of the camera. Therefore, in the two-dimensional filter 6 and the one-dimensional filter 10,
A control signal from the filter controller 38 sets a coefficient according to the mode of the camera.

"In case of AE mode" The coefficients are set so that the two-dimensional filter 6 and the one-dimensional filter 10 have the same function as the bypass function described above. Therefore, the output of the A / D converter 5 is directly input to the cumulative adder 12. The cumulative adder 12 cumulatively adds the input luminance signal components to obtain an AE evaluation value, and sends this to the CPU 13. The CPU 13 performs arithmetic processing based on the sent AE evaluation value, and gives a control signal to the diaphragm mechanism driving unit 14 or the image pickup device driver 16. Thus, diaphragm mechanism 1
Alternatively, the image sensor 3 is driven and controlled, and appropriate exposure control is performed.

[In the case of AF mode] A coefficient or AF that causes the two-dimensional filter 6 to have a function equivalent to the bypass function.
The coefficient for use is set, and AF is applied to the one-dimensional filter 10.
The coefficient for is set. Then, only the high frequency component necessary for AF is extracted from the digital signal output from the A / D converter 5, and this is input to the cumulative adder 12. Switching of the coefficient setting of the two-dimensional filter 6 will be described later in detail.

The cumulative adder 12 cumulatively adds the high frequency components to obtain the AF evaluation value, and sends this to the CPU 13.
The CPU 13 performs arithmetic processing based on the sent AF evaluation value, and gives a control signal to the lens driving unit 15. Thus, the lens system 2 including the focus adjustment lens is feedback-controlled in the direction in which the high frequency component increases, and focusing is performed.

[In case of photographing mode] A coefficient for binarization is set in the two-dimensional filter 6. The output of the A / D converter 5 is edge-enhanced by the two-dimensional filter 6 and then input to the binarization processor 7. The binarization processor 7 subjects the input signal to simple binarization processing or pseudo halftone processing according to the subject. The binarized signal is then printed out as an image by the printer 8.

FIG. 12 is a flow chart of a camera sequence when the filter is switched by setting the coefficient. The camera sequence will be sequentially described from step S201 with reference to this flowchart.

"S201" It is determined whether or not the power supply is ON. If it is determined to be ON, the process proceeds to the next step.

"S202" Coefficients are set in the two-dimensional filter 6 and the one-dimensional filter 10 so that a function equivalent to the bypass function is exerted. FIG. 13A is a diagram showing a filter state when the two-dimensional filter 6 (3 × 3 spatial filter) is set with a coefficient such that a function equivalent to the bypass function is set, and FIG. (B) is a diagram showing a filter state when a coefficient is set in the one-dimensional filter 10 (two-dimensional IIR filter) so that the same function as the bypass function is exhibited. Thus, the A / D converter 5
Is directly input to the cumulative adder 12.

[S203] The luminance signals are added together in the cumulative adder 12 to obtain the AE evaluation value, and the CPU 13 adjusts the exposure according to the evaluation value. When the exposures are matched, it is ready to accept the 1st trigger.

[S204] It is determined whether or not the 1st trigger is ON, and if it is determined to be ON, the process proceeds to the next step.

"S205" AF is applied to the one-dimensional filter 10.
A coefficient for setting a dedicated HPF is set.

"S206" The output of the A / D converter 5 is
The two-dimensional filter 6 is bypassed, and after being filtered only by the one-dimensional filter 10, it is input to the cumulative adder 12. In the cumulative adder 12, the high frequency components are added together to obtain the AF evaluation value. The CPU 13 performs hill-climbing AF control according to the input AF evaluation value.

[S207] It is determined whether or not the subject is in focus. When it is determined that the subject is in focus, the second trigger is accepted. In addition, AF of a certain value or more
If there is no peak of the evaluation value and it is determined that the subject is out of focus,
It proceeds to step S208.

"S208" The AF coefficient is set in the two-dimensional filter 6. FIG. 13C is a diagram showing a filter state when the coefficient weighted in the vertical direction is set in the two-dimensional filter 6 (3 × 3 spatial filter). Thus, after the output of the A / D converter 5 is filtered by the two-dimensional filter 6 to extract the high frequency component in the vertical direction, it is further filtered by the one-dimensional filter 10 and input to the cumulative adder 12.

[S209] A signal containing both horizontal and vertical high frequency components is input to the cumulative adder 12, and the same AF control as in S206 is performed. After focusing, the second trigger is accepted.

"S210" It is determined whether or not the second trigger is ON. If it is determined to be ON, the process proceeds to the next step.

[S211] The binarization coefficient is set in the two-dimensional filter 6. FIG. 13D is a diagram showing a filter state when weighting coefficients are set in both the horizontal direction and the vertical direction in the two-dimensional filter 6 (3 × 3 spatial filter). In this way, the digital signal is subjected to the edge enhancement most suitable for the binarization process.

[S212] Binarization processing, photographing processing such as printout, etc. are performed, and the camera sequence ends.

By the way, as a result of conducting an AF experiment on various subjects using the camera having the structure described in this embodiment, it was found that the following phenomenon occurs. That is, when the video signal has a lot of noise, if filtering is performed by the two-dimensional filter 6, the noise is emphasized and the signal originally required for AF is buried in the noise.
This is a phenomenon in which good AF cannot be performed.
An embodiment including means for solving this problem will be described below.

(Fourth Embodiment) The hardware configuration of the fourth embodiment is the same as the block diagram shown in FIG. The camera sequence is as shown in the flowchart of FIG. Hereinafter, the camera sequence will be sequentially described from step S301 using the flowchart of FIG.

"S301" It is determined whether or not the power supply is ON. If it is determined to be ON, the process proceeds to the next step.

"S302" selector switch (SW.
Q) 11 switches to the D terminal side. Then, A / D
The output of the converter 5 is directly input to the cumulative adder 12.

[S303] The luminance signals are added together in the cumulative adder 12 to obtain the AE evaluation value, and the CPU 13 adjusts the exposure according to the evaluation value. When the exposures are matched, it is ready to accept the 1st trigger.

"S304" It is determined whether or not the 1st trigger is ON. If it is determined to be ON, the process proceeds to the next step.

[S305] The brightness of the subject is determined based on the result of AE. If it is determined that the brightness is equal to or higher than the reference, the process proceeds to step S306, and if it is determined that the brightness is lower than the reference, step S308.
Proceed to.

"S306" Changeover switch (SW.
P) 9 switches to the A terminal side, and the changeover switch (S
W. Q) 11 switches to the C terminal side. Then, A
The output of the / D converter 5 is filtered by the two-dimensional filter 6, then further filtered by the one-dimensional filter 10, and input to the cumulative adder 12. S3
The changeover switch (SW.P) 9 is changed over to the A terminal side at 06 because the subject is bright and it is considered that the video signal has little noise.

"S307" The cumulative adder 12 is supplied with a signal containing high-frequency components in both the horizontal and vertical directions. High-frequency components are added together in the cumulative adder 12 to obtain an AF evaluation value, and the CPU 13 performs hill-climbing AF control according to this evaluation value. After focusing, the second trigger is accepted.

[S308] Changeover switch (SW.
P) 9 switches to the B terminal side, and the changeover switch (S
W. Q) 11 switches to the C terminal side. Therefore A /
The output of the D converter 5 bypasses the two-dimensional filter 6,
After being filtered only by the one-dimensional filter 10, it is input to the cumulative adder 12. The changeover switch (SW.P) 9 is changed over to the B terminal side in S308 because it is considered that the image signal has a lot of noise because the subject is dark.

"S309" In the cumulative adder 12, S30
AF control is performed in the same manner as in 7, and after focusing, the second trigger is accepted.

[S310] It is determined whether or not the second trigger is ON, and if it is determined to be ON, the process proceeds to the next step.

[S311] Binarization processing, photographing processing such as printout, etc. are performed, and the camera sequence ends.

(Fifth Embodiment) The fifth embodiment is an embodiment in which the setting of the coefficient of the two-dimensional filter is variable according to the brightness of the subject. The hardware configuration of this embodiment is the same as that shown in the block diagram of FIG. 11 (configuration diagram of the third embodiment). The camera sequence is as shown in the flowchart of FIG. Hereinafter, the camera sequence will be sequentially described from step S401 using the flowchart of FIG.

"S401" It is determined whether or not the power is on. If it is determined to be ON, the process proceeds to the next step.

"S402" Coefficients are set in the two-dimensional filter 6 and the one-dimensional filter 10 so that a function equivalent to the bypass function is exerted. Then, the A / D converter 5
Is directly input to the cumulative adder 12.

[S403] The luminance signals are added together in the cumulative adder 12 to obtain the AE evaluation value, and the CPU 13 adjusts the exposure according to the evaluation value. When the exposures are matched, it is ready to accept the 1st trigger.

"S404" It is determined whether or not the 1st trigger is ON. If it is determined to be ON, the process proceeds to the next step.

"S405" A coefficient for AF that is variable according to the brightness is set in the two-dimensional filter 6 according to the result of AE. 16A, 16B, and 16C are diagrams showing the relationship between the brightness of the subject and the coefficient of the two-dimensional filter 6. When the brightness level is low, the video signal contains a lot of noise, and therefore edge enhancement should not be applied. Further, when the luminance level is high, the video signal has less noise, so edge enhancement is strongly applied so that high-frequency components in the vertical direction can be more sufficiently extracted.

Further, the one-dimensional filter 10 has an HPF for AF.
Is set. Then, the output of the A / D converter 5 is filtered by the two-dimensional filter 10 and the one-dimensional filter 6 and input to the cumulative adder 12.

"S406" A signal containing high-frequency components in both the horizontal and vertical directions is input to the cumulative adder 12, and the high-frequency components are added together to obtain an AF evaluation value. According to the evaluation value, the CPU 13 climbs the mountain A
F control is performed. After focusing, the second trigger is accepted.

"S407" It is determined whether or not the second trigger is ON, and when it is determined to be ON, the process proceeds to the next step.

"S408" Binary processing, photographing processing such as printout are performed, and the camera sequence ends.

In this embodiment, the case where the setting of the coefficient of the two-dimensional filter 6 is made variable according to the brightness of the subject has been described, but the frequency of the one-dimensional filter 10 is changed according to the frequency characteristic of the two-dimensional filter 6. If you change the characteristics,
Even better autofocus can be achieved.

(Sixth Embodiment) This sixth embodiment can be realized by the configuration shown in the block diagram of FIG. 11 and the processing procedure shown in the flowchart of FIG. 11 and 15
Since it has already been described in the description of the fifth embodiment, here, in terms of how to change the frequency characteristic of the one-dimensional filter 10 according to the frequency characteristic of the two-dimensional filter 6, An example will be described.

FIG. 17A shows the frequency characteristic of a one-dimensional filter, FIG. 17B shows the frequency characteristic of a two-dimensional filter, and FIG. 17C shows the frequency characteristic when two filters are connected in cascade. The frequency characteristic shown in (a) is the cutoff frequency f.
It is the HPF characteristic of c, and the frequency characteristic shown in (b) is a characteristic in which the Nyquist frequency fN rises in a mountain shape. Therefore, the frequency characteristic obtained by superimposing the above two characteristics naturally has the Nyquist frequency f as shown in (c).
It is a mountain-shaped bulge centered on N. If this mountain-shaped swell is large, the data will overflow and correct results cannot be obtained.

Therefore, as shown in FIG. 17 (d), the frequency characteristic of the one-dimensional filter 10 is set in advance to the lower right in consideration of the frequency characteristic of the two-dimensional filter 6.
Then, the frequency characteristics when the two filters are connected in cascade are as shown in (f), the Nyquist frequency fN
The shape of the mountain-shaped bulge centered on is suppressed.

As described above, it is understood that the frequency characteristic of the two-dimensional filter 6 can be corrected by the frequency characteristic of the one-dimensional filter 10. Therefore, it is not necessary to finely set the coefficients of the two-dimensional filter 6 and the one-dimensional filter 10. For example, even when the coefficient can be set only roughly because the configuration of the two-dimensional filter 6 is simplified, the one-dimensional filter Even if the coefficient of 10 is set finely, a desired frequency characteristic can be obtained accurately.

FIG. 18 is a diagram showing the structure of the one-dimensional filter 10 in which the coefficient can be finely set. One-dimensional filter 10
Originally, the coefficient can be finely set in order to maintain the accuracy of AF. Since it has a group of five multipliers as shown in the figure, various amplitude frequency characteristics can be realized.

FIG. 19 is a block diagram showing the structure of the two-dimensional filter 6 with simplified coefficients. In FIG. 19, 3
Reference numeral 9 is an adder group, and 40 is a bit shift processor. FIG.
As shown in FIG. 9, the two-dimensional filter 6 is a small-scale one in which the flip-flops are two-dimensionally arranged in “3 × 3”, and has eight adder groups 39. In this example, all eight pixels around the pixel of interest have the same coefficient, and bit shift processing is performed by the bit shift processor 40 without using a multiplier. Therefore, the filter is more simplified. In the configuration as shown in FIG. 19, the coefficient that can be set is shifted by 1 bit to the right by a bit shift process to "0.5" (= 1/2), and further shifted to the right by 2 bits by "0.25". (= 1/4), and by further shifting to the right by 3 bits, "0.125" (= 1/8),
Further shift to the right by 4 bits to "0.0625".
(= 1/16) ... It will be quite rough. However, since the one-dimensional filter 10 can supplement the frequency characteristic as described above, the total desired amplitude frequency characteristic is always obtained. Further, the configuration of the two-dimensional filter 6 itself is simplified as much as possible.

By the way, when the video signal contains a large amount of high frequency components as described above, the output of the two-dimensional filter 6 increases. In that case, the circuit in the subsequent stage has to have a multi-bit bus structure accordingly. An embodiment taking this point into consideration is shown below.

(Seventh Embodiment) FIG. 20 is a block diagram showing the main parts of the seventh embodiment. The configuration shown in FIG. 20 is almost the same as the main part of the block diagram shown in FIG. 11, but a bit shift processor 41 is additionally inserted between the one-dimensional filter 10 and the cumulative adder 12.
When the coefficient in the two-dimensional filter 6 is set by the control signal from the filter controller 38, the two-dimensional filter 6 converts the digital signal, which was n bits at the input, into n + m.
Increase to a bit. Information on how many bits (n + m) the output of the two-dimensional filter 6 has increased from the coefficient set in the two-dimensional filter 6 is given from the filter controller 38 to the bit shift processor 41. Therefore, the bit shift processor 41 is set to shift rightward by the increased bits (m bits) based on the given information. Shifting to the right corresponds to truncating the lower bit side by the shifted amount.
Therefore, in the bit shift processor 41, the digital signal is converted into n bits again, and the cumulative adder 12 in the subsequent stage can always process with n bits.

FIG. 21 is a diagram showing how the bit width is increased by the two-dimensional filter 6. As shown in FIG. 21B, the target pixel data is G, and the peripheral pixel data is S1 to S.
8 and each is 8-bit data. Therefore, first, as shown in FIG. 21B, the peripheral pixel data S1
Since the addition is performed three times to add ~ S8, the data is increased to 11 bits. However, the numerical value itself does not always have to be 11 bits. The reason for using 11 bits is because the value being handled is a binary number, so add 1
This is because there is always a possibility of carrying a digit with respect to the number of times, and the hardware must be configured beforehand to have a bit width that is one bit larger. In other words, since the addition is done 3 times,
This is because it is necessary to increase the bit width by 3 bits as hardware, that is, the bit width of 11 bits. Since the two-dimensional filter 6 further adds the peripheral pixel data S1 to S8 and the target pixel data G, a bit width of 12 bits is required. In FIG. 21A, USB indicates the upper bit side, and LSB indicates the lower bit side.

Even if the data is increased to 12 bits by the two-dimensional filter 6, if it is shifted by 4 bits to the right by the bit shift processing by the bit shift processor 41, the lower 4
Since the bits have been truncated, the data reverts to 8 bits. If this is done, the accuracy of the data will be reduced, but since only the relative size of the data is important in autofocus data processing, there is no problem due to a decrease in the data accuracy.

(Eighth Embodiment) FIG. 22 is a block diagram showing the main parts of the eighth embodiment. Like the configuration shown in FIG. 20, the configuration shown in FIG. 22 is almost the same as the main part of the block diagram shown in FIG.
Is additionally inserted between the two-dimensional filter 6 and the one-dimensional filter 10.

With this configuration, both the one-dimensional filter 10 and the cumulative adder 12 in the subsequent stage can always perform processing with n bits. The camera sequence in this embodiment is similar to the sequence shown in the flow chart of FIG. However, in step S405, when setting the coefficient of the two-dimensional filter 6, it is only necessary to add the shift amount of the bit shift processor 41 at the same time.

(Summary of Embodiments) The following is a summary of the configuration and effects of the camera shown in the above embodiment.

[1] The camera shown in the embodiment is an image pickup means (3, 4) for outputting a video signal corresponding to the subject light through the lens system (1, 2) including the focus adjusting lens.
And an automatic focus adjusting means (5, 1) for automatically controlling the focus by driving and controlling the focus adjusting lens based on a video signal output from the image pickup means (3, 4).
0, 12, 13, 15), and the automatic focusing means (5, 10, 12, 13, 15)
Is a one-dimensional filter (for extracting the first focus adjustment evaluation value (a), which is a signal component necessary for performing the focus adjustment, from the video signal output from the image pickup means (3, 4). 10) and a second focus adjustment evaluation value (a) which is a signal component necessary for performing the focus adjustment from the video signal output from the image pickup means (3, 4). A two-dimensional filter (6) for extracting the focus adjustment evaluation value (b), and the one-dimensional filter (1
When it is detected that the focus adjustment operation based only on the first focus adjustment evaluation value (a) extracted in 0) is impossible, the second focus adjustment value (a) and the second focus adjustment operation are performed. The focus adjustment operation is also performed by using the focus adjustment evaluation value (b).

The camera has the following operational effects. In order to focus on both an object without vertical lines and an object without horizontal lines, a filter capable of extracting high frequency components in both horizontal and vertical directions is required. Originally, the purpose can be achieved only by the two-dimensional filter (6), but if the probability of focusing is increased, the configuration becomes complicated, resulting in a large scale and high cost. However, in the above camera, the object can be achieved by using the one-dimensional filter (10) adjusted for autofocus and the two-dimensional filter (6) having a simple structure, so that the structure is simple and the scale is small. It is possible to avoid increasing the size, cost and cost.

[2] The camera shown in the embodiment is the camera described in [1], and the automatic focus adjusting means (5, 10, 12, 13, 15) is the same as the first camera. When using the second focus adjustment evaluation value (b) together with the focus adjustment evaluation value (a), the second focus adjustment evaluation value (b) extracted by the two-dimensional filter (6) is used as described above. The focus adjustment operation is performed by inputting it to the one-dimensional filter (10) to obtain the first focus adjustment evaluation value (a).

The camera has the following operational effects. Instead of using a dedicated AF filter,
Since the two-dimensional filter (6) and the one-dimensional filter (10) are connected in cascade, the configuration of the two-dimensional filter (6) is simplified and the preceding two-dimensional filter (6) is used.
Can also be used for other purposes.

[3] The camera shown in the embodiment is the camera described in [2] above, and performs predetermined signal processing on the video signal output from the image pickup means (3, 4). The image processing means (7) for applying is further provided, and the two-dimensional filter (6) also serves as a pre-processing filter for pre-processing the video signal supplied to the video processing means (7). It is supposed to do.

In the above camera, the following operational effects can be obtained. Since the two-dimensional filter 6 is used for both AF and image processing, it is possible to reduce the number of circuits and memories and reduce the cost.

[4] The camera shown in the embodiment is the camera described in [3], and the two-dimensional filter (6) uses the second focus adjustment evaluation value (b). Different filter coefficients are set when extracting and performing the focus adjustment operation and when performing filter processing as preprocessing for the video processing means (7).

The camera has the following operational effects. Since different coefficients are set for AF and image processing, a two-dimensional filter (6) suitable for each processing is provided.
Can be realized.

[5] The camera shown in the embodiment is the camera described in [4], and the two-dimensional filter (6) uses the second focus adjustment evaluation value (b). The filter coefficient at the time of extracting and performing the focus adjustment operation is set so as to weight the image pickup screen in the vertical direction, and an edge as a preprocessing for the binarization processing means (7) as a video processing means. The filter coefficient for performing the enhancement processing is configured to be weighted in both the horizontal and vertical directions with respect to the image pickup screen.

The camera has the following operational effects. Since the original purpose of extracting high-frequency components in the vertical direction can be achieved during AF, and edge enhancement can be applied in both horizontal and vertical directions during binarization processing, an adaptive two-dimensional filter suitable for each process can be used. realizable.

[6] The camera shown in the embodiment is the camera described in the above [2], and includes a subject brightness detecting means (4,5, 12, 1) for detecting the brightness of the subject.
3) is further provided, and the subject brightness detecting means (4,
When it is determined that the brightness of the object detected in (5, 12, 13) is below a predetermined level, the automatic focus adjusting means (6, 10, 12, 13, 15) causes the one-dimensional filter (10). First focus adjustment evaluation value (a) extracted in
The focus adjustment operation is performed by itself.

The camera has the following operational effects. When the subject is dark, that is, when the amount of noise in the video signal is large, the two-dimensional filter (6) is not applied, so that the influence of noise is not significantly affected.

[7] The camera shown in the embodiment is the camera according to the above [2], and includes a subject brightness detecting means (4,5, 12, 1) for detecting the brightness of the subject.
3) is further provided, and the two-dimensional filter (6) changes its frequency characteristic according to the brightness level of the subject detected by the subject brightness detecting means (4,5, 12, 13). It is configured as follows.

The camera has the following operational effects. Since the coefficient of the two-dimensional filter (6) can be changed according to the brightness of the subject, that is, the amount of noise in the video signal, it is possible to realize optimal AF according to the brightness of the subject.

[8] The camera shown in the embodiment is the camera described in [7] above, and the two-dimensional filter is the subject luminance detecting means (4,5, 12, 13).
The higher the brightness level of the subject detected in step 3, the higher the edge enhancement degree to the input video signal.

The camera has the following operational effects. Since the coefficient of the two-dimensional filter (6) can be changed according to the brightness of the subject, that is, the amount of noise in the video signal, it is possible to realize optimal AF according to the brightness of the subject.

[9] The camera described in the embodiment is the camera described in [2] above, and the frequency characteristic of the one-dimensional filter is set according to the frequency characteristic of the two-dimensional filter. It has become one.

The camera has the following operational effects. Even if the coefficient of the two-dimensional filter (6) can be set only roughly, if the coefficient of the one-dimensional filter (10) can be set thin, the final frequency characteristic obtained by adding both filters (6, 10) can be freely changed. be able to. Therefore, the two-dimensional filter (6) has a simple structure and is advantageous.

[10] The camera shown in the embodiment is the camera described in [2] above, and the camera is
The image pickup means (3, 5) further comprises an A / D conversion means (5) for converting a video signal into a digital video signal, and the two-dimensional filter (6) comprises the A / D conversion means ( 5) Extracting a second focus adjustment evaluation value (b) from the digital video signal converted in 5), the bit width of the extracted second focus adjustment evaluation value (b) or the extraction. The frequency characteristic of the two-dimensional filter (6) having the bit width of the first focus adjustment evaluation value extracted by the one-dimensional filter (10) for inputting the selected second focus adjustment evaluation value (b). By changing the setting according to
It is provided with means for making the bit width of the cumulative addition value based on the focus adjustment evaluation value (a).

The camera has the following operational effects. That is, since the bit width is constant, it is sufficient for the circuit in the subsequent stage to have the necessary minimum bit width. Therefore, the circuit scale is reduced, leading to cost reduction.

[0140]

According to the present invention, since a simple two-dimensional filter and a one-dimensional filter are combined and the features of both filters are skillfully utilized, the camera can be placed in either a vertical or horizontal orientation. Even if you hold the camera at the same position, or if the subject consists of only one of the vertical and horizontal lines, you can always reliably extract the evaluation value and perform good autofocus operation.
It is possible to provide a camera having an automatic focus adjusting means which is simple in structure and does not cause cost increase.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a camera according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a camera sequence according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of resolution correction of the camera of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a high frequency noise removing unit of the camera according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram relating to a complementary color mosaic filter of the camera of the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing changes in evaluation values of a high frequency component and a mid frequency component of the camera of the first embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of a camera according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a first configuration example of a two-dimensional filter of a camera according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a second configuration example of the two-dimensional filter of the camera according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a third configuration example of the two-dimensional filter of the camera according to the second embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a camera according to a third embodiment of the present invention.

FIG. 12 is a flowchart showing a camera sequence of a camera according to a third embodiment of the present invention.

FIG. 13 is a diagram showing operating states of a two-dimensional filter and a one-dimensional filter of the camera of the third embodiment of the present invention.

FIG. 14 is a flowchart showing a camera sequence according to a fourth embodiment of the present invention.

FIG. 15 is a flowchart showing a camera sequence according to the fifth embodiment of the present invention.

FIG. 16 is a diagram showing the relationship between the brightness of a subject and the coefficient of the two-dimensional filter according to the fifth embodiment of the present invention.

FIG. 17 is a waveform diagram showing frequency characteristics of the one-dimensional filter according to the sixth embodiment of the present invention.

FIG. 18 is a diagram showing a configuration of a one-dimensional filter capable of setting a thin coefficient according to a sixth embodiment of the present invention.

FIG. 19 is a block diagram showing the configuration of a simplified two-dimensional filter according to a sixth embodiment of the present invention.

FIG. 20 is a block diagram showing a configuration of a main part of a camera of a seventh embodiment of the present invention.

FIG. 21 is a diagram showing how the bit width of the two-dimensional filter according to the seventh embodiment of the present invention increases.

FIG. 22 is a block diagram showing a configuration of a main part of a camera of an eighth embodiment of the present invention.

FIG. 23 is a diagram showing a relationship between a camera posture and a scanning direction of an image sensor, which is shown for explaining a problem of the conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Aperture mechanism 2 ... Lens system including a lens for focus adjustment 3 ... Image sensor which consists of a charge-coupled device (CCD) 4 ... Imaging circuit 5 ... A / D converter 6 ... Two-dimensional filter 7 ... Binarization processor 8 ... Printer 9 ... Changeover switch (SW.P) 10 ... One-dimensional filter 11 ... Changeover switch (SW.Q) 12 ... Cumulative adder 13 ... CPU (Central processing unit) 14 ... Aperture mechanism drive unit 15 ... Lens drive unit 16 ... Image sensor driver

Claims (3)

[Claims] 1. An image pickup means for outputting a video signal corresponding to a subject light through an optical system including a focus adjustment lens, and driving the focus adjustment lens based on the video signal output from the image pickup means. In a camera equipped with an automatic focus adjusting means for controlling the focus automatically, the automatic focus adjusting means is a signal necessary for performing the focus adjustment from a video signal output from the image pickup means. A one-dimensional filter for extracting a first focus adjustment evaluation value, which is a component, and the first focus adjustment, which is a signal component necessary for performing the focus adjustment from the image signal output from the image pickup means. A two-dimensional filter for extracting a second focus adjustment evaluation value different from the focus evaluation value, and a focus based only on the first focus adjustment evaluation value extracted by the one-dimensional filter. When it is detected that the adjustment operation is impossible, the focus adjustment operation is performed by using the second focus adjustment evaluation value together with the first focus adjustment evaluation value. camera. 2. The automatic focus adjustment means uses the second evaluation value for focus adjustment together with the first evaluation value for focus adjustment in order to use the second focus adjustment value extracted by the two-dimensional filter. The camera according to claim 1, wherein the focus adjustment operation is performed by inputting an evaluation value to the one-dimensional filter to obtain the first focus adjustment evaluation value. 3. A video signal supplied to the video processing means, further comprising video processing means for performing a predetermined signal processing on the video signal output from the imaging means. The camera according to claim 2, which also functions as a pre-processing filter for performing pre-processing for.