JPH0983834A - Image processing unit calculating signal inputted from optical camera and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the identification capability by using a simple circuit and an A/D converter with a few bit number. SOLUTION: The image processing unit and its method convert an analog signal outputted from an optical camera 1 into a digital signal by using an A/D converter 2 and the digital signal is calculated by an arithmetic circuit 3, in which the image is processed. The image processing unit and its method have a level adjustment circuit 4 adjusting the level range of an analog signal converted into a digital signal by the A/D converter 2 between the optical camera 1 and the A/D converter 2. The analog signal whose level is adjusted by the level adjustment circuit 4 is converted into a digital signal at the A/D converter 2 and calculated by the arithmetic circuit 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for converting an analog signal output from an optical camera into a digital signal by an A / D converter and performing image processing.

[0002]

2. Description of the Related Art Image processing apparatuses that calculate signals from optical cameras are used for various purposes. For example, the weight of white powder adhering to a black container can be detected without touching the object to be measured. This image processing device can detect the weight of powder adhering to a container by converting an analog signal output from an optical camera such as a CCD camera into a digital signal and integrating the digital signal by an arithmetic circuit such as a microcomputer. The integrated value of the microcomputer serves as a parameter for calculating the weight of the powder adhering to the container. The integral value is a parameter of weight, because the black container does not reflect light, but the white powder reflects light well, so the part where the powder adheres reflects light well and the output level of the optical camera is large. Because it will be. Furthermore, since the thicker powder adhered to the container is whiter and reflects light better than the lighter powder adheres to the container, the weight of the adhered powder can be calculated by integrating the output of the optical camera. . An optical camera scans the entire projected image, or a specified range, or alternatively, scans the image linearly, proportional to the intensity of the light, so that the microcomputer can integrate the brightness of the entire image. Output an analog signal.

Further, the image processing apparatus for calculating the output of the optical camera is also used for various other purposes. For example, uneven coating or uneven plating can be detected using the same device that detects the amount of powder adhesion. This is because the brightness of the surface changes if there is coating or uneven plating.

An image processing apparatus using an optical camera converts an analog signal output from the optical camera into a digital signal. The digital signal is input to an arithmetic circuit such as a microcomputer, where arithmetic processing such as integration is performed.

[0005]

In this type of device, it is extremely important how to improve the measurement accuracy. However, in reality, even if it can be sufficiently detected by human eyes, it may not be detected by the image processing apparatus. It is effective to use an A / D converter with high resolution in order to increase the measurement accuracy of the image processing apparatus. A / D
The converter has 256 levels of 8 bits and 4 levels of 12 bits.
096 gradations, 16536 bits are 65536 gradations, and the resolution is high. Therefore, there is a feature that the measurement accuracy can be increased. However, if the number of bits output from the A / D converter is increased in order to increase the resolution of the A / D converter, the processing time of the arithmetic circuit becomes longer. The cost of using a high speed microcomputer to increase the processing time is high. If the calculation is simplified to shorten the processing time, accurate image processing cannot be performed.

An A / D converter having a small number of bits is used to adjust the intensity of light radiated on the object to be measured in order to maximize the measurement accuracy. This is because the measurement accuracy changes depending on the intensity of the light with which the measurement object is irradiated. For example, the light intensity is adjusted so that the object to be detected can be identified most clearly. However, by adjusting the light intensity, it may not be possible to make the measurement accuracy high enough. For example, in a device that detects the amount of powder adhered, it may be difficult to identify whether the container is reflected or the powder is reflected. When the intensity of light is increased, both the container and the powder strongly reflect the light, and when the light is weakened, the reflection of the light of both the container and the powder is weakened, and therefore the light intensity cannot be accurately identified. There is an optimum value of light intensity not only for the amount of powder adhered but also for detection of coating unevenness or plating unevenness. Can not.

The present invention was developed to solve these drawbacks, and an important object of the present invention is to identify by using a simple circuit and an A / D converter with a small number of bits. An object of the present invention is to provide an image processing apparatus and method for calculating a signal input from an optical camera, which can remarkably improve the capability.

[0008]

An image processing apparatus according to a first aspect of the present invention converts an analog signal output from an optical camera 1 into a digital signal by an A / D converter 2 and calculates a digital signal. Calculation is performed by the circuit 3. Further, the image processing apparatus for calculating a signal input from the optical camera of the present invention is provided with the level adjusting circuit 4 between the optical camera 1 and the A / D converter 2. The level adjustment circuit 4 is A /
The level range of the analog signal converted into the digital signal by the D converter 2 is adjusted. The analog signal whose level has been adjusted by the level adjusting circuit 4 is converted into a digital signal by the A / D converter 2 and calculated by the arithmetic circuit 3.

In the image processing method according to the second aspect of the present invention, the analog signal output from the optical camera 1 is converted into a digital signal by the A / D converter 2, and the digital signal is processed by the arithmetic circuit 3. Calculate Further, in the method of the present invention, the level adjusting circuit 4 is provided between the optical camera 1 and the A / D converter 2, and the level adjusting circuit 4 is used to
The level range of the analog signal converted into the digital signal by the / D converter 2 is adjusted. Level adjustment circuit 4
The analog signal whose level has been adjusted in step 1 is converted into a digital signal in the A / D converter 2 and is calculated in the calculation circuit 3.

The level adjusting circuit 4 includes an A / D converter 2
1 and 2 show a state in which the level range of an analog signal converted into a digital signal by is adjusted. FIG. 1 shows an analog signal output by the optical camera 1. As shown in this figure, the optical camera 1 outputs an analog signal proportional to the intensity of the received light. The image processing apparatus and method of the present invention do not A / D convert the analog signal output from the optical camera 1 in all level ranges. A / D converter 2 is A /
The level range of the analog signal to be D converted is, for example,
It is adjusted within the range indicated by A, B, or C. A
The range of A / D conversion by the / D converter 2 is adjusted by the level adjusting circuit 4. The level adjusting circuit 4 is, for example,
With the input / output characteristics shown by A, B, and C in FIG. 2, the analog signal level output from the optical camera 1 is converted and output. The level adjusting circuit 4 can adjust the curve of the input / output characteristic. When the level adjusting circuit 4 is adjusted to the input / output characteristic of the curve A in FIG. 2, the A / D converter 2 for A / D converting this output converts the analog signal in the level range shown in A in FIG. 1 into a digital signal. Convert. When the input / output characteristic of the level adjusting circuit 4 is adjusted to B or C, A / D
The converter 2 converts an analog signal in the B or C level range of FIG. 1 into a digital signal.

As described above, the level adjusting circuit 4 operates as an A / D converter.
Since the level range of the analog signal converted into the digital signal by the converter 2 is adjusted, the image processing apparatus and method of the present invention can perform image processing with high accuracy by using the A / D converter 2 having a small number of bits. For example, when an 8-bit A / D converter 2 is used, an analog signal in the level range of A, B or C can be converted into a digital signal of 256 gradations. Since the level adjusting circuit 4 can freely adjust the level range of the analog signal to be digitally converted, if the level adjusting circuit 4 narrows the level range to be A / D converted by the A / D converter 2, the difference in brightness and color difference. Very small range with high accuracy, eg 2
Can be digitally converted to 56 gradations. Therefore, according to the image processing apparatus and the method thereof of the present invention, the level adjusting circuit 4 adjusts the range of converting an analog signal into a digital signal to a range capable of performing image processing in an ideal state, and the A / D converter 2 Even if an inexpensive one is used, image processing can be performed with high accuracy. This is because unnecessary information can be cut and necessary information can be expanded and extracted.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify an image processing apparatus and an image processing method for calculating a signal input from an optical camera for embodying the technical idea of the present invention, and the present invention relates to an image. Processors and methods are not specified below.

Further, in this specification, in order to facilitate understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claims column" and "to solve the problems. It is added to the members shown in the column of "means". However, the members shown in the claims are not limited to the members of the embodiment.

An image processing apparatus for calculating a signal input from the optical camera shown in FIG. 3 is an apparatus for detecting the amount of powder adhering to the container 5, and includes a light source 6, an optical camera 1, and a level adjusting circuit 4. , A monitor 7, an A / D converter 2, and an arithmetic circuit 3.

The light source 6 is a lamp such as a ring-shaped fluorescent lamp that uniformly irradiates the container 5, which is the object to be measured, with light. The light source 6 emits light so as to minimize the shadow formed on the measured object. Further, the container 5 and the powder adhering to the container 5 are irradiated with light at an intensity that maximizes the contrast.

The optical camera 1 is a CCD camera having a lens arranged at the center of the light source 6. As the optical camera 1, for example, a monochrome or color video camera can be used. Like the video camera, the optical camera 1 scans the entire image to be projected, converts the intensity of light into an electric signal which is an analog signal, and outputs the electric signal. The optical camera 1, for example, decomposes one screen into 100,000 to 400,000 pixels, converts the light intensity of each pixel, that is, the brightness, into an electric signal which is an analog signal, and outputs the electric signal in order. The optical camera 1 outputs an analog signal having a voltage proportional to the brightness, as shown in FIG.

The level adjusting circuit 4 includes an A / D converter 2
Adjust the level range of the analog signal converted into a digital signal with. The level adjusting circuit 4 shows the input / output characteristics as shown in FIG.
It is converted to A, B or C curve and output.
FIG. 4 shows a level adjusting circuit 4 that realizes this. The level adjusting circuit 4 in this figure includes a comparator 4A that shifts the 0 level of an input analog signal, and a variable amplification factor amplifier 4B that adjusts the level width for A / D converting the output of the comparator 4A. Equipped with.

The comparator 4A changes the 0 level of the input signal as shown in FIG. The comparator 4A shifts the minimum value of the analog signal A / D converted by the A / D converter 2 to 0 level. All analog signal levels that are not A / D converted are set to 0 level. The comparator 4A that realizes this is a differential amplifier having an amplification factor of 1. In the comparator 4A, the reference voltage conversion circuit 8 is connected to the-side input terminal, and the analog signal is input to the + side input terminal.

The reference voltage conversion circuit 8 determines the 0 level of the input analog signal. The comparator 4A is
All voltages lower than the signal input from the reference voltage conversion circuit 8 are output as 0 level, and analog signals higher than the reference voltage conversion circuit 8 are shifted and output as shown in FIG. The reference voltage conversion circuit 8 includes a reference power source 8A and a variable resistor 8B connected to the reference power source 8A. By adjusting the variable resistor 8B, the voltage of the negative side input terminal of the differential amplifier which is the comparator 4A can be changed.

The analog signal whose 0 level is shifted by the comparator 4A is amplified by the variable amplification factor amplifier 4B. The variable amplification factor amplifier 4B amplifies and outputs an analog input signal, as shown in FIG. The A / D converter 2 converts an analog signal having a level equal to or lower than the level indicated by the chain line in this figure into, for example, an 8-bit, 256-gradation digital signal. Further, the variable amplification factor amplifier 4B having the input / output characteristic shown in this figure is set to 0 level in order to ignore an analog signal having an A / D conversion level or more shown by a chain line. However, a signal having an A / D conversion level or higher may not be set to 0 level depending on the processing method. As shown in FIG. 6, the variable amplification factor amplifier 4B includes a variable resistor 9 for changing the amplification factor in order to adjust the gradient of the input / output characteristic. The variable resistor 9 adjusts the amplification factor by adjusting the negative feedback amount of the amplification factor variable amplifier 4B, for example. The variable amplification factor amplifier 4B adjusts the amplification factor to be small when the level range of the analog signal to be A / D converted is increased, as shown by the input / output characteristic C in FIG. On the contrary, the input / output characteristics B in this figure
As shown in, when the level range of the analog signal to be A / D converted is reduced, the amplification factor is increased and the gradient is made steep.

The level adjusting circuit 4 shown in FIG. 4 is characterized in that the level range of the analog signal A / D converted by the A / D converter 2 can be converted in real time. Furthermore, FIG.
The level adjusting circuit 4 shown in is realized by a separate circuit, a comparator 4A and a variable amplification factor amplifier 4B.
The level adjusting circuit 4 can also realize the comparator 4A and the variable amplification factor amplifier 4B by a single amplifier. Furthermore, in the image processing apparatus and method of the present invention, the level adjusting circuit can be realized by a digital circuit instead of the analog circuit. The level adjustment circuit of the digital circuit converts the input analog signal into a digital signal, calculates the digital signal with a microcomputer, and then performs A / D at the next stage.
The converter adjusts the level range of the analog signal to be A / D converted, and the D / A converter again converts the adjusted digital signal into an analog signal for output. The level adjusting circuit realized by the digital circuit makes the resolution of the built-in A / D converter higher than that of the A / D converter in the next stage.

The level adjusting circuit 4 does not necessarily need to adjust the A / D conversion level by linearly amplifying. For example, as shown in FIG. 7, the amplification factor can be gradually reduced by the lower limit and the upper limit of A / D conversion. Also, the analog signal can be amplified by an exponential function to adjust the A / D conversion level.

The monitor 7 is connected to the level adjusting circuit 4 and displays a signal input from the optical camera 1 to the level adjusting circuit 4 or a signal level-adjusted by the level adjusting circuit 4.

The A / D converter 2 includes a level adjusting circuit 4
The analog signal whose level has been adjusted by is converted into a digital signal. As the A / D converter 2, for example, an 8-bit output having a resolution of 256 gradations or a 10-bit output having a resolution of 1024 gradations is used.

As the arithmetic circuit 3, a microcomputer can be used. When the arithmetic circuit 3 integrates the output signal of the A / D converter 2, an integrating circuit can be used instead of the microcomputer. The microcomputer, which is the arithmetic circuit 3, integrates the digital signal A / D converted by the A / D converter 2 with respect to time to calculate, for example, the amount of powder adhering to the container. The arithmetic circuit 3 does not necessarily need to integrate the light intensity (brightness) of the entire container to calculate the powder adhesion amount. In the simplest case, as shown in FIG.
It is also possible to calculate the amount of powder adhering by integrating the intensity of light along the measurement line 10 on a straight line passing through the center of. In FIG. 8, the portion where the powder adheres is shown by hatching. However, with this calculation method, powder that is not on a straight line cannot be detected. Therefore, for example, as shown in FIG. 9, light intensities on a plurality of lines are integrated, or as shown in FIG. It is also possible to calculate the amount of adhered powder by integrating the intensities of light on a plurality of lines.

The above image processing apparatus and method calculate the signal input from the optical camera as follows. As an example, a method for measuring the weight of the powder adhering to the container will be shown. The optical camera 1 converts the reflected light of the container 5 with which the light source 6 is irradiated into an analog signal and outputs it. The optical camera 1
As shown in FIG. 1, an analog signal proportional to the intensity of the received light is output.

The analog signal output from the optical camera 1 is level-adjusted by the level adjustment circuit 4 and then A /
D conversion is performed. According to the image processing method of the present invention, the signal whose level is adjusted by the level adjusting circuit 4 is A / D converted by the A / D converter 2.
D-convert. In other words, the level adjustment circuit 4 is A /
Adjust the level of A / D conversion by the D converter. The level adjusting circuit 4 adjusts the level range, which is an analog signal output from the optical camera 1 and is A / D by the A / D converter, to a range indicated by A, B, or C in FIG. 1, for example. . The level adjusting circuit 4 converts the analog signal level output from the optical camera 1 with the input / output characteristics shown by A, B, and C in FIG. Since the level adjusting circuit 4 is configured to adjust the input / output characteristic curve, the A / D converter 2 for A / D converting this output when the input / output characteristic of the curve A in FIG. 2 is adjusted. , The analog signal in the level range shown by A in FIG. 1 is converted into a digital signal. When the input / output characteristic of the level adjusting circuit 4 is adjusted to B or C, the A / D converter 2 converts an analog signal in the level range of B or C in FIG. 1 into a digital signal.

The output of the level adjusting circuit 4 is converted into a digital signal by the A / D converter 2. The A / D converter outputs an analog signal in the level range of A, B, or C, for example, 8-bit 256 gradation, 10-bit 10
It is converted into a digital signal of 24 gradations or the like. When the level adjustment circuit 4 narrows the level range for A / D conversion of the A / D converter 2 as shown by B in FIG. 1, the range of extremely small difference in brightness and color difference is converted into a digital signal with high accuracy. Can be converted.

In the arithmetic circuit 3, the A / D converter
The / D-converted digital signal is integrated over time to calculate the amount of powder adhering to the container. The arithmetic circuit 3 is, for example,
As shown in FIG. 8, the intensity of light is integrated along a straight measurement line 10 passing through the center of the container 5 to calculate the amount of powder adhered.

The image processing apparatus described above integrates the output signal of the A / D converter 2 to detect the amount of powder adhering to the container. However, the image processing apparatus and method of the present invention can be used for this purpose. Not specified. This is because, for example, uneven coating and uneven plating can be detected by the same method. Further, in the method of scanning the entire surface of one screen, the size of the solid matter and the like can be calculated.

[0031]

According to the image processing apparatus and the image processing method for calculating a signal input from the optical camera of the present invention, the discrimination ability can be remarkably improved by using a simple circuit and an A / D converter having a small number of bits. There are features. This is because the image processing apparatus and method of the present invention include the level adjustment circuit between the optical camera and the A / D converter. In particular, the image processing apparatus and method of the present invention uses an A / D converter for an analog signal output from an optical camera using a level adjusting circuit.
Adjust the level range to be converted. The analog signal output from the optical camera is adjusted to the level range most suitable for image processing, converted into a digital signal by the A / D converter, and calculated. The apparatus and method for adjusting the level range of the analog signal to be A / D converted by the level adjusting circuit have a high accuracy which cannot be realized by adjusting the intensity of the light illuminating the DUT, and are suitable for various applications. The feature is that it can process images. This is because the level adjustment circuit can cut unnecessary portions and expand the required signal level for calculation.

In the device for adjusting the light intensity, the level of the analog signal output from the optical camera changes as a whole.
On the other hand, in the apparatus and method of the present invention, as shown in FIG. 1, the signal level converted into a digital signal by the A / D converter and operated by the arithmetic circuit can be freely adjusted by the level adjusting circuit. The level adjusting circuit can adjust the width and size of the analog signal level to be A / D converted, and adjust the range to the most accurate image processing range. In the image processing with a small lightness difference, the analog signal level range for A / D conversion is narrowed, the part with a small lightness difference is analyzed with high accuracy, and the image processing is performed. A / D
The analog signal level range to be converted is widened, and the object to be measured can be detected in the bright area, or the object to be measured can be detected in the dark area. Has the feature that A / D conversion can be performed and image processing can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a graph showing a level range for A / D converting an analog signal output from an optical camera in an image processing apparatus and method according to the present invention.

FIG. 2 is a graph showing the output of the level adjustment circuit with respect to the output of the optical camera.

FIG. 3 is a block diagram showing an example of an image processing apparatus that calculates a signal input from the optical camera of the present invention.

FIG. 4 is a circuit diagram showing an example of a level adjustment circuit.

5 is a graph showing the input / output characteristics of the comparator of the level adjustment circuit shown in FIG.

6 is a graph showing input / output characteristics of a variable gain amplifier of the level adjustment circuit shown in FIG.

FIG. 7 is a graph showing input / output characteristics of another level adjusting circuit provided in the image processing apparatus of the present invention.

FIG. 8 is a graph showing an analog signal level of a portion where the arithmetic circuit performs arithmetic processing.

FIG. 9 is a plan view showing a portion in which an arithmetic circuit performs arithmetic processing.

FIG. 10 is a plan view showing a portion where an arithmetic circuit performs arithmetic processing.

[Explanation of symbols]

1 ... Optical camera 2 ... A / D converter 3 ... Arithmetic circuit 4 ... Level adjusting circuit 4A ... Comparator 4B ... Amplification factor variable amplifier 5 ... Container 6 ... Light source 7 ... Monitor 8 ... Reference voltage conversion circuit 8A ... Reference power supply 8B ... Variable resistance 9 ... Variable resistance 10 ... Measurement line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nio Takada 14-5 Shimokita-machi, Neyagawa-shi, Osaka Kurashiki Spinning Co., Ltd. Technical Research Institute (72) Masaru Otsuka 14-5 Shimokita-machi, Neyagawa-shi, Osaka No. 14 within the Technical Research Laboratory of Kurashiki Spinning Co., Ltd. (72) Akio Kurosawa 14-5 Shimokita-cho, Neyagawa-shi, Osaka Prefecture Within the Technical Research Center of Kurashiki Spinning Co., Ltd. (72) Noboru Yamazaki 14 Shimokita-cho, Neyagawa-shi, Osaka Prefecture No. 5 Inside the Technical Research Laboratory, Kurashiki Spinning Co., Ltd. (72) Inventor Kazunori Sakatsuji 178, Shinkai, Hamamachi, Tokushima City, Tokushima Prefecture (72) Inventor, Hiroshi Abe 16th Kitakita, Nishibanashi, Itano-gun, Tokushima Prefecture Of 2

Claims (2)

[Claims] 1. An apparatus for converting an analog signal output from an optical camera (1) into a digital signal by an A / D converter (2) and computing the digital signal by an arithmetic circuit (3) to perform image processing. A level adjustment circuit (4) is provided between the camera (1) and the A / D converter (2) to adjust the level range of the analog signal converted into a digital signal by the A / D converter (2). The analog signal whose level is adjusted by the level adjusting circuit (4) is converted into a digital signal by the A / D converter (2) and is operated by the operating circuit (3). An image processing device that calculates a signal input from an optical camera. 2. A method of converting an analog signal output from an optical camera (1) into a digital signal by an A / D converter (2) and computing the digital signal by an arithmetic circuit (3) to perform image processing. Between the camera (1) and the A / D converter (2), a level adjusting circuit (4) for adjusting the level range of the analog signal converted into the digital signal by the A / D converter (2) is provided, and the level adjusting circuit (4) is provided. A signal input from an optical camera, which is characterized in that an analog signal whose level is adjusted by the adjusting circuit (4) is converted into a digital signal by the A / D converter (2) and the digital signal is calculated by the arithmetic circuit (3). Image processing method.