JPH0965172A - Image detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of bits to be invalid at the time of quantizing video signals and to perform highly accurate image detection by extracting only the video signal to be an object from image picked-up video signals and removing unrequired components such as outside light or the like. SOLUTION: A display part 2 where a video image to be the object is not projected is fetched by a camera 1 and inputted through a clamping circuit 3, an amplifier circuit 4 and an A/D converter 5 into an arithmetic processor 6. In the arithmetic processor 6, by controlling the clamping circuit 3, control is performed so as to turn the digital signals of the inputted video signals to zero. After the processing of the arithmetic processor 6 is ended, the video image to be the object is displayed at the display part 2 and fetched by the camera 1, the amplifier circuit 4 is controlled by the arithmetic processor 6, the video signals are turned to an optimum amplitude and A/D converted in the A/D converter 5 and thus, only the video signal to be the object is extracted, the number of the bits to be invalid at the time of A/D conversion is reduced and the quantization accuracy of the video signal is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image detecting device for adjusting an image on a display device.

[0002]

2. Description of the Related Art Conventionally, in an image detecting device for the purpose of image adjustment of a display device, unnecessary components such as black level floating due to the image pickup camera have been dealt with. A change in the image pickup condition at the time of image pickup is not dealt with, and a signal component that is considered unnecessary for adjustment of external light or the like is simultaneously detected and processed.

As a conventional technique, Japanese Patent Laid-Open No. 24490/1993
There is an image detection device described in the publication. This conventional image detecting device will be described with reference to FIG.
FIG. 4 shows a block diagram of a conventional image detection device.

In FIG. 4, 12 is an automatic gain control circuit (hereinafter referred to as AGC), 14 is a CPU, and 16 is an A / D.
Converter, 18 is adder, 20 is clamp level calculation circuit, 46 is first subtractor, 48 is zero clip circuit, 50
Is a low-pass filter (hereinafter referred to as LPF), and 52 is a second subtractor.

The operation of the image detecting apparatus thus configured will be described with reference to FIG. The output signal from the CCD camera is adjusted to the optimum amplitude by the AGC 12,
The signal is converted into a digital signal in the / D converter 16 and C
The offset value set by the PU 14 is added by the adder 18. The output from the adder 18 is clamped by subtracting the clamp level obtained by the clamp level calculation circuit 20 by the first subtractor 46. After the output of the first subtractor 46 is zero clipped by the zero clip circuit 48, the LPF
50, and further, by subtracting the offset value set by the CPU 14 (the same value added by the adder 18) in the second subtractor 52, a video signal without blackening is obtained only by clamping at the input portion. It has gained.

[0006]

However, by including an unnecessary video signal in addition to the video signal targeted for image detection, only the video signal originally targeted in the quantization performed during image processing is quantized. The number of bits to quantize the target video signal by performing image processing by quantizing the video signal that includes unnecessary components such as external light and black level float of the imaging camera, etc. The decrease in the value causes a decrease in the adjustment accuracy.

Further, in the conventional image detecting apparatus, it is possible to obtain a video signal without blackening, but unnecessary components are removed based on the digital signal after the A / D converter. The number of bits of the target video signal portion at the time of conversion is reduced as compared with the case where there is no unnecessary video signal.

This will be described with reference to FIG.
3A shows a video signal of only the target image, whereas FIG. 3B shows an unnecessary component in the target image such as external light or black level floating of the detection camera due to changes in the imaging conditions. Is a video signal including.

In FIG. 3, it is assumed that the images displayed on the display device have the same signal. Further, the synchronization signal portion is not included in the quantization of the video signal.

Now, considering the case where the video signal of FIG. 3A is quantized during image processing, the video signal in the range A is quantized, which is invalid at the time of quantization. There are no bits and there is no loss of precision in quantization. However, considering the case where the video signal of FIG. 3B is quantized during image processing, it is quantized in the range B, and the target video signal is quantized in the quantized bits. The converted range is only C, and an invalid bit is generated in the range of D at the time of quantization, which causes a reduction in adjustment accuracy.

According to the present invention, by extracting only the signal component of interest from the video signal picked up by the image pickup camera, the number of invalid bits at the time of quantization of the video signal is reduced and highly accurate image detection is performed. The purpose is to do.

[0012]

In order to solve the above problems, the present invention provides a circuit configuration in which a component other than a target video signal is regarded as an unnecessary component and removed from a video signal captured by an imaging camera. To take.

[0013]

With the above structure, the present invention enables highly accurate image detection that is less affected by the image pickup conditions of the image pickup camera by detecting only the target video signal.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image detecting apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an image pickup camera, 2 is a display device, 3 is a clamp circuit, 4 is an amplifier circuit, and 5
Is an A / D converter, and 6 is an arithmetic processing unit.

The operation of the image detecting apparatus according to the embodiment of the present invention constructed as above will be described with reference to FIGS.

First, the clamp voltage is set.
In the procedure for determining the clamp voltage, first, the image of the display device 2 in which no image is displayed by the imaging camera 1 is captured. Here, when there is no unnecessary component, the video signal output from the imaging camera 1 becomes the video signal c in FIG. 2, and unnecessary components such as external light and black level floating of the imaging camera (hereinafter referred to as background 2), the video signal a in FIG. 2 is obtained. When the image signal a shown in FIG. 2 is output from the image pickup camera 1, the clamp circuit 3 clamps the image signal to the clamp voltage (7 in FIG. 2), and only the image signal having the threshold voltage (8 in FIG. 2) or more is generated, and the amplifier circuit 4 Is variably amplified by the A / D converter 5, converted into digital data by the A / D converter 5, and input to the arithmetic processing unit 6.

In the arithmetic processing unit 6, the clamp voltage (7 in FIG. 2) is varied by controlling the clamp circuit 3 based on the input digital data, and the threshold voltage (8 in FIG. 2) and the background voltage are changed. Voltage (Fig. 2
9) is controlled to be the same voltage, the digital data input to the arithmetic processing unit 6 is reduced, and the threshold voltage (8 in FIG. 2) and the background voltage (FIG. 2) are reduced like the video signal b in FIG. 9) becomes the same voltage and the input digital data becomes zero, the setting of the clamp voltage ends, and the processing ends.

When the setting of the clamp voltage is completed, the target image is detected. First, the target image is displayed on the display device 2 and captured by the image capturing camera 1.

The video signal d in FIG. 2, which is the captured video signal, includes unnecessary components such as external light and black level floating of the image pickup camera in addition to the target video signal. The digital data input to the device 6 is clamped to the clamp voltage (7 in FIG. 2) set by the above method and is the background voltage (9 in FIG. 2) which is an unnecessary component or more. That is, only the target video signal is the digital data converted by the A / D converter 5.

Next, considering the case where the above-mentioned unnecessary components are not clipped, the digital data input to the arithmetic processing unit 6 is obtained by converting the video signal f of FIG. 2 into digital data by an A / D converter. Will be things.

Comparing the case where the unnecessary component is cut and the case where it is not cut, both should be calculated by the arithmetic processing unit 6 if the quantization is performed by the voltage of the full dynamic range in the quantization of the A / D converter. If the effective bit number of the target video signal is not compared with the case where the unnecessary component is cut out, if not compared, it changes with the change of the unnecessary component and it is not only possible to perform detection with constant accuracy, but also becomes the target. When there are more signals that are unnecessary components than video signals, the effective number of bits of the target image among the detected images will be low and the accuracy will be low, so it is necessary to impose restrictions on the imaging conditions at the time of image detection in the imaging camera There is.

[0023]

As is apparent from the above description, in the image detecting apparatus of the present invention, the change of the image pickup condition such as the outside light and the black level floating of the image pickup camera is reflected in advance when the target image is captured. , Unnecessary components caused by the image capturing condition when the image capturing camera detects the image are removed, and the detection accuracy does not change regardless of the image capturing condition when the image capturing camera detects the image, and high-precision image detection is realized. It is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of an image detection apparatus according to an embodiment of the present invention.

FIG. 2 is a video signal waveform diagram for each processing stage of the image detection apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram for explaining an effective bit range when quantizing a video signal.

FIG. 4 is a block diagram of a conventional image detection device.

[Explanation of symbols]

 1 Imaging Camera 2 Display Device 3 Clamp Circuit 4 Amplifying Circuit 5 A / D Converter 6 Arithmetic Processing Device

Claims (1)

[Claims] 1. An image adjustment test pattern generation device for generating an image adjustment test pattern, an image pickup camera for taking in the image adjustment test pattern displayed on a display device as brightness information, and the image pickup camera. An image processing apparatus including an arithmetic processing unit that performs a feedback operation for image detection based on the brightness information captured in.