JPH0951459A - Video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a defect of an image such as a black spot caused by dust adhering to an optical component such as a lens and an optical filter. SOLUTION: A Hall voltage outputted from a Hall element 16b for each iris value of an iris 16 and an address of a pixel corresponding to the Hall voltage are written in a memory 40 as defect information. A microcomputer 22 receives the Hall voltage outputted from the Hall element 16b is given to a microcomputer 22 and an address corresponding to the Hall voltage is read from the memory 40. Then a video signal at an address discriminated to be a correction object is replaced with other video signal being out of correction object for the correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera,
In particular, for example, the present invention relates to a video camera that detects an image defect such as a black spot on an image and corrects the defect.

[0002]

2. Description of the Related Art One example of this type of prior art is Japanese Patent Application Laid-Open No. 61-51670, which was published on March 14, 1986.
No. [G11B 20/18]. In this prior art, regarding abnormal output caused by black or white scratches on a CCD element, the address and level information is input to a storage element by using a CCD tester or the like, and the information and the video signal output from the CCD are arithmetic circuits. By inputting to the CCD, the black and white flaws corresponding to the bit signal level for each CCD and each one bit are corrected to obtain a stable video signal.

[0003]

In the conventional video camera, the pixel defect of the CCD element itself is merely corrected. For example, optical components such as a lens and an optical filter located in front of the CCD sensor are used. When dust adheres, it is impossible to correct black spots (black areas) on the image caused by the dust. In particular, the black spots due to the dust correlate with the iris of the video camera, and when the iris aperture value is large, that is, when the incident light amount entering the CCD sensor is large, the black spots (black regions) appear over a wide range on the image. There was a problem such as.

Therefore, a main object of the present invention is to provide a video camera capable of reproducing a high quality image by detecting and correcting image defects such as black spots caused by dust mixed in during the manufacturing process. is there.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to an iris for adjusting the amount of incident light, a voltage output means for outputting a voltage that changes according to the diaphragm of the iris, and a memory for accumulating the voltage and an image position corresponding to the voltage. , And a defect detection means for reading an image position from a memory based on a voltage, the video camera.

[0006]

For example, in a video camera capable of changing the aperture value of the iris in N stages (N is a natural number), the iris is set in N stages and an all-white pattern for each aperture value is photographed. At this time, the voltage corresponding to the aperture value output from the voltage output means and the address of the pixel corresponding thereto are written in the memory as defect information.

Then, in actual use, the microcomputer is
The voltage changing by the iris is detected, and the address of the image (defect) area corresponding to the voltage is read from the memory. When it is determined that the image area is the correction target area, the image at the address is corrected.

[0008]

According to the present invention, since image defects due to dust contained in optical parts such as lenses and optical filters can be corrected, the image quality can be improved.
In particular, it is possible to effectively correct a black dot (black area) that is greatly affected by the change in iris. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a video camera 10 of this embodiment includes a CCD 12 into which a subject is input via a lens 14. CCD 12 and lens 1
4, an iris 16 is installed, and the iris 16 includes an iris body 16a and a hall element 16b. The iris body 16a adjusts the amount of incident light to be given to the CCD 12 by changing the diaphragm in, for example, 10 steps in accordance with a switching signal output from the iris circuit 20. Further, the Hall element 16b constituting the voltage output means is connected to the Hall element amplifier 24, and the output voltage from the Hall element 16b is input to the amplifier 24.

The optical image projected on the CCD 12 through the lens 14 is converted into an electric signal for each pixel and input to the process amplifier 26. At this time, a clock pulse is applied from the timing generator 28 to the CCD 12, and the charges photoelectrically converted by the V driver 30 are vertically transferred. Then, the process amplifier 26 separates the luminance signal (Y signal) and the color signal (C signal) according to the reference clock from the timing generator 28.
A luminance signal and a chrominance signal are output from the process amplifier 26 to the matrix 32. In the matrix 32, both signals are generated by the reference clock from the timing generator 28 and the horizontal and vertical synchronization signals from the synchronization signal generator 34. It is separated into three signals of R, G and B. Then, these three signals are input to the encoder 36,
A luminance signal and a color signal are formed and converted into a video signal to obtain N
It is output as a TSC signal.

The output voltage from the hall element 16b is amplified by an amplifier 24 and then digitally converted to the microcomputer 22.
Is input to The luminance signal (Y _L ) output from the process amplifier 26 is input to the A / D converter 38 and digitally converted, and then input to the microcomputer 22. The microcomputer 22 uses the Hall element 16b for the memory 40.
The Hall voltage and the address of the pixel corresponding to the Hall voltage are output, and the Hall voltage and the address are written in the memory 40 as defect information. If a threshold value (threshold voltage) is set for the defect level (Hall voltage), only defects having a predetermined level or higher can be targeted for correction.

In actual use, when the Hall voltage output from the Hall element 16b is input to the microcomputer 22,
The microcomputer 22 reads the address corresponding to the Hall voltage from the memory 40 and outputs the address to the timing generator 28. With reference to FIG. 2, the processing operation of the microcomputer 22 when writing the above-described Hall voltage and the address (defect information) of the image area corresponding to the Hall voltage in the memory 40 will be described. In addition, this operation is
It is performed during an inspection process such as a function check before the video camera 10 is shipped.

First, in step S1, a signal for opening the iris is output to the iris circuit 20. In step S3, it is determined whether or not the Hall voltage (V _I ) output from the Hall element 16b when the iris 16 is in an open state exceeds a predetermined threshold voltage (V _TH ). When the Hall voltage (V _I ) exceeds the threshold voltage (V _TH ), it is determined that the image area is the correction target, and in step S5, the Hall voltage corresponding to the correction target area is read. And step S
In 7, the address of the pixel corresponding to the hole voltage is detected, and in step S9, the hole voltage and the address are written in the memory 40 as defect information. Then, in step S11, it is determined whether or not the set value of the iris 16 is N (N is a natural number). Is output. Therefore, the processing operation from step S3 to step S9 is performed N times from the open state of the iris 16 to the light blocking state, and the hall voltage and the address of the defect information according to the iris of N stages are written in the memory 40. Become.

The processing operation of the microcomputer 22 when the video camera 10 is actually used by the user will be described with reference to FIG. First, in step S15, the Hall element 1 that changes according to the diaphragm of the iris 16
The Hall voltage output from 6b is detected. Then, in step S17, it is determined whether or not the Hall voltage (V _H ) exists in the memory 40. If it is in the memory 40, the Hall voltage (V _H ) is determined in step S19.
The address corresponding to is read from the memory 40. And
In step S21, the address is output to the timing generator 28. Therefore, process amplifier 2
6, the timing generator 28 no longer outputs the clock pulse at that address. Then, the correction means (not shown) corrects only the address, that is, the pixel (defective area) in which the Hall voltage exceeds the threshold voltage.

FIG. 4 shows an example of a change in a defective area such as a black spot due to a change in the aperture value of the iris 16 and a method of detecting the defective area. As shown in FIG. 4, the aperture of the iris 16 is adjusted from open to light-shielded, for example, in three stages, and the video camera 10 is used to capture an all-white pattern for each aperture.
Then, the Hall voltage corresponding to the aperture value is detected.

In FIG. 4A, the aperture value is F_aSet to
The image condition at the time
Area where addresses are from m to m + 7 and from n to n + 7
For optical components such as lenses and optical filters
Dust contained causes black spots. Video signal at this time
Defect level is V_aIt is represented by Figure 4 (b) shows
Aperture value F of Iris 16_bIs smaller than in the case of (a) in FIG.
(F_a<F_b) Indicates a defective area when the image is taken. So
Is the address of the area of m + 1 to m + 6 and n + 1
And n + 6, and the defect level in the video signal at that time is
V_bIt is represented by FIG. 4C shows the iris 16 further.
(F_a<F _b<F_c) Shows the defective area when
The smaller the iris 16 is, the smaller the defect area becomes.
I understand. At this time, the defect level in the video signal is V
_cExpressed as V_a<V_b<V_cA small aperture value, like
The higher the level, the higher the defect level in the video signal.

In this way, the diaphragm of the iris 16 is set to N (N is a natural number) stages, and the Hall voltage for each diaphragm value and the address indicating the defective area are detected and input to the memory 40. At this time, as described above, by setting the threshold value (threshold voltage) for the defect (black spot) level, it is possible to make the defect information, that is, the correction target, only for the defect of a certain level or higher. That is, for the defect level,
For example, when the threshold voltage V _TH is set, the defect level V _a in the video signal is smaller than the threshold voltage V _TH , so
The defective area shown in FIG. 4A is excluded from the correction target. Further, since the defect level V _b in the video signal exceeds the threshold voltage V _TH , the areas where the defect voltage V _TH exceeds the threshold voltage V _TH , that is, the addresses are m + 2 to m + 5 and n + 2 to n.
The defective area in the range of +5 is detected as the correction target image.
In the case of FIG. 4C, the defect level V _c in the video signal exceeds the threshold voltage V _TH , so that the address m +
Defective areas in the range of 2 to m + 5 and n + 2 to n + 5 are detected as correction target images. And the threshold voltage V
_The hall voltage exceeding _TH and the image area (address) corresponding to the hall voltage are written in the memory 40.

When the user actually uses the iris 1,
The Hall voltage output from the Hall element 16b of No. 6 is detected, and the defect information, that is, the address corresponding to the Hall voltage written in the memory 40 is read from the memory 40. Then, by controlling the timing generator 28 using the defect address determined as the correction target area, the defect correction is performed. That is, for example, as shown in (c) of FIG. 4, when the central 16 pixel area is determined to be the correction target area, the microcomputer 22 sets not to use the data of the 16 pixel, for example, the address m + 2. The video signals at and n + 2 are corrected by being replaced with the video signals of the preceding pixels at addresses m + 1 and n + 2.

As the correction method, interpolation or the like may be used in addition to the above replacement. As described above, the size and the contrast of the black spots on the image generated by the dust contained in the optical component such as the lens mainly depend on the iris 16.
The image position of an image defect such as a black spot can be detected by utilizing the property of changing depending on the aperture of. Further, when this image position is read from the memory 40 during use, and correction is applied only to that region, the iris 16
The defective area that changes depending on the aperture value of can be erased.

The video camera 10 is not limited to the CCD type solid-state image pickup device system as in the above-described embodiment, but may be an M type.
An OS type solid-state imaging device method may be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flow chart showing a defect information detecting means of the embodiment of FIG.

FIG. 3 is a flowchart showing a part of the operation in the use state of the embodiment in FIG. 1;

FIG. 4 is an illustrative view showing an example of a change in the size and contrast of a defect area due to a change in the aperture and a method of detecting the defect area in the embodiment of FIG.

[Explanation of symbols]

 10 ... Video camera 12 ... CCD 16 ... Iris 16b ... Hall element 22 ... Microcomputer 40 ... Memory

Claims (2)

[Claims] 1. An iris for adjusting the amount of incident light, a voltage output means for outputting a voltage that changes according to the diaphragm of the iris, a memory for accumulating the voltage and an image position corresponding to the voltage, and a voltage based on the voltage. A video camera, comprising defect detection means for reading the image position from the memory. 2. A correction means for correcting a defect image detected by the defect detection means is further provided.
The video camera according to claim 1.