JPH0682234A - Image binary coding processor - Google Patents

Abstract

PURPOSE:To achieve higher image processing accuracy in binary coding by providing a camera with a filter which transmits the color complementary to the background color. CONSTITUTION:An image binary coding processor has a monochromatic TV camera 1 provided with a filter which transmits the color complementary to the background color. The density distribution of pixels corresponding to a background part 3 is separated from the density distribution of the pixels corresponding to a work 2, thereby, improving the accuracy in binary coding image processing.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image binarization processing apparatus, and more particularly to an image binarization processing apparatus for image processing a monochrome image.

[0001]

2. Description of the Related Art Conventionally, as an image processing apparatus for identifying the shape of an article or measuring the position of a workpiece by using an image pickup apparatus such as a television camera, image processing based on a binary image. For example, Japanese Patent Laid-Open No. 63-1427
It is proposed as disclosed in Japanese Patent No. 91. The conventional technique disclosed in the above publication will be described below.

FIG. 3 is a block diagram showing the configuration of a conventional image binarization processing apparatus. In FIG. 3, reference numeral 11 denotes an object to be measured, which is illuminated by a lighting device 12 such as a fluorescent lamp. A television camera 14 as an imaging device is installed above the target object 11, receives reflected light of the light emitted from the lighting fixture 12 to the target object 11, and produces an image proportional to the intensity of the reflected light. The signal SP is output. An illuminance sensor 16 is provided in the vicinity of the television camera 14, similarly receives the reflected light from the object 11 and outputs a signal SS proportional to the intensity of the reflected light.

The illuminance signal SS output from the illuminance sensor 16 is sent to a CPU (Central Processing Unit) 20 which is a binarization level determining means, and the CPU 2
At 0, the binarization level is calculated based on the data stored in advance in the ROM (Read Only Memory) 26 and the illuminance signal SS, and is output to the image binarization comparator 22 as the binarization level signal SL. Image binarization comparator 22
Compares the image signal SP with the binarized level signal SL, and outputs a binarized image signal SP ′ represented by two values depending on whether the image signal SP is above or below the binarized level signal SL. Output to the CPU 20. In the CPU 20, the ROM
After performing predetermined signal processing according to a program stored in advance in 26, the output signal is output to an external device such as an automatic processing machine.

In the above-mentioned prior art, in order to prevent a binary image from being changed due to a change of light entering from the outside or a change of illumination illuminance with time, an incorrect image processing is performed in the vicinity of the image pickup device. A sensor for detecting illuminance is provided, and the binarization level is changed based on the illuminance signal from the sensor.

[0005]

However, in the monochrome binarized image processing apparatus, image processing is performed by utilizing the difference in density. Therefore, an accurate binary image cannot be obtained unless there is a difference in the density value between the measurement object and the background on which the measurement object is placed. Therefore,
Even if the binarization level is changed depending on the illuminance as in the above-mentioned conventional technique, if there is an overlapping region in the density distribution of the reflected light between the background and the measurement object, the binarization level is close to the level. There is a possibility that the determination in step 1 will be an erroneous determination, and it may be difficult to obtain an accurate binary image. Even if the color of the measurement object and the background color are different, the difference in color is not necessarily the difference in the density in a monochrome image, so even if the color of the background and the measurement object is changed, binarization is performed. It may be difficult to improve the accuracy of the.

The present invention has been made in view of the above problems, and its object is to provide a density distribution of pixels corresponding to a background portion and a density distribution of pixels corresponding to an object to be measured. Is to improve the accuracy of the binarized image processing.

[0007]

In order to achieve the above object, the image binarization processing apparatus of the present invention irradiates an object to be imaged placed in the background with light by means of light irradiating means, and the reflected light thereof. In the image binarization processing apparatus for binarizing the image signal output from the imaging device with the imaging device, a background of the reflected light from the light irradiating means of the object to be captured by the imaging device. It is characterized in that a filter capable of transmitting only light of a color complementary to the color of is provided.

[0008]

Next, the operation of the above configuration will be described. An object to be imaged, such as shape identification, is placed in the background, and light is emitted toward the imaged object by the light irradiation means. The radiated light strikes and is reflected by the image-captured object, and the reflected light is input to the image-capturing device, whereby the image-captured object is imaged. At this time, the reflected light of the background exists together with the reflected light of the object to be imaged, but the reflected light of the background is reflected by the filter provided in the image pickup apparatus and capable of transmitting only the light of the color having the complementary color relationship with the background color. It is blocked by the filter. Therefore, the reflected light that can pass through the filter of the image pickup object is taken into the image pickup device, and the density value of the pixel in the background portion is distributed near zero and is almost separated from the distribution of the density value of the pixel in the image pickup portion. Will be done. Then, the density signal of the light input to the image pickup device is sent to the binarized image processing means, and the binarized image processing is performed by comparing the density value for each pixel with the density value of the binarized level. .

[0009]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is an overall view of an apparatus showing an example of an image binarization processing apparatus of the present invention. Reference numeral 2 in the figure denotes a workpiece for which measurement such as shape identification is to be performed. 3 is a table on which the work 2 is placed, and the color of the upper surface, that is, the background color is blue.
The work 2 has a color other than blue. Reference numeral 4 denotes a fluorescent lamp which is an illumination device that irradiates the work 2 and the table 3 with light. In addition, it is preferable that the illumination device does not emit light having a bluish wavelength. A monochrome television camera 1, which is an image pickup device, is installed above the work 2 by a support tool (not shown). The reflected light of the light emitted from the fluorescent lamp 4 to the work 2 is received, and the density of the brightness of the light is received. 25 proportional to the value
The digital density signal S of 6 gradations (0 to 255) is output. Further, the lens of the monochrome television camera 1 has a wavelength of 500 to 700, which is complementary to the background color of blue.
A bandpass filter 5 capable of transmitting yellow light of mμ is provided.

Reference numeral 6 denotes a binarized image processing device, which is a CPU
(Central processing unit) ROM (read only memory) 9 in which image processing calculation programs such as shape identification and binarization level signal value L are stored, density signal S from monochrome television camera 1 and ROM 9 '0' or '1' by comparing with the binary level signal L
The image binarization comparator 7 for outputting the binarized image signal SC to the CPU 8 and the binarized image signal SC from the image binarization comparator 7 are temporarily stored, and the CPU 8 outputs the binary image signal SC to the CPU 2 if necessary. It is composed of a ROM (random access memory) 10 capable of extracting the binarized image signal SC. The CPU 8 performs image processing such as shape identification based on the binarized image signal SC extracted from the ROM 10 by an arithmetic program in the ROM 9, and outputs the result to an external device such as a type determination device.

Next, the image 2 of this embodiment having the above-mentioned structure
The operation of the digitization processing device will be described. First, the work 2 and the table 3
The fluorescent lamp 4 irradiates the workpiece 2 with light. The irradiated light hits the work and is reflected,
Further, it hits the background table 3 and is reflected. The reflected light reaches the monochrome television camera 1, but only the yellow light having a wavelength of 500 to 700 mμ is received by the monochrome television camera 1 by the bandpass filter 5. That is, the blue light having a wavelength of 400 to 500 mμ which is the reflected light of the background is blocked by the bandpass filter 5. Therefore, in the monochrome television camera 1, the density value is set to 0 to 256 gradations, and as shown in FIG. 2, the density values of the pixels corresponding to the background portion are distributed around 0, and the pixels corresponding to the work 2 are distributed. The density value of is distributed to the high density side, and the density distribution of the background portion and the work 2 portion is separated.

The density signal S corresponding to each pixel is input from the monochrome television camera 1 to the image binarization comparator 7 in the binarization image processing device 6, while the binarization level signal L stored in the ROM 9 is stored. Is input via the CPU 8. The image binarization comparator 7 compares the density signal S corresponding to each pixel with the binarization level signal L, and if it is larger than the binarization level signal L, it is "1", and if it is smaller, it is "0". The binarized image signal SC represented by one value is sent to the CPU
Output to 8. The output binary image signal SC is temporarily stored in the RAM 10, and then the CPU 8 causes the RAM 1 to operate.
The binarized image signal SC is read out from 0 as appropriate and stored in the ROM 9
Image processing is performed based on an image processing calculation program such as shape identification, and the result is output to an external device 13 such as a type determination device.
Output to.

In this embodiment, the background color is blue, and the bandpass filter 5 is selected to be able to transmit yellow light, which is a complementary color of blue, for the reason described below.

When the light of the three primary colors, red, green and blue, is converted into a density value of 256 gradations (0 to 255) of black and white by a monochrome television camera (black is 0, white is 255) The coefficients are LR = 1.0 for red, LG = 4.5907 for green, and LB = 0.0601 for blue, and the blue light with the smallest luminosity factor is converted to low density, that is, black. Therefore, if a filter that blocks red or green light is blocked, the light that is converted to high density is blocked, and the density value of the entire image is reduced, and the pixel density distribution is in the 0 direction side (low density). Side), and it becomes difficult to determine the binarization level. On the other hand, when the blue light is blocked by using the yellow filter, the light (yellow light) converted into high density is transmitted through the filter, and the density distribution of the pixels corresponding to the work 2 portion is on the low density side. Therefore, the density distribution of pixels corresponding to the background portion and the density distribution of pixels corresponding to the work 2 portion are largely separated, and the binarization level can be easily determined. Therefore, it is preferable to use a filter capable of transmitting yellow light and use a blue color corresponding to the complementary color of yellow for the background color.

According to the present embodiment, since the yellow bandpass filter 5 is used in the monochrome television camera 1 and the binary image processing with high accuracy can be performed with a simple structure using the blue background, it is possible to realize the conventional method. As described above, the binarized image processing device 6 does not have to be complicated, and maintenance of the binarized image processing device 6 is facilitated.

[0017]

As described above, according to the present invention, a filter capable of transmitting only light of a color complementary to the background color is provided in the image pickup device, and the density distribution of the pixels corresponding to the background, Since the density distribution of the pixels for the object to be imaged is separated, accurate binary image processing can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image binarization processing apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram showing a density distribution state of pixels with and without a filter.

FIG. 3 is a block diagram showing a configuration of a conventional image binarization processing device.

[Explanation of symbols]

 1 ... Monochrome TV camera 2 ... Work 3 ... Stand 4 ... Fluorescent lamp 5 ... Bandpass filter 7 ... Image binarization comparator 8 ... CPU (Central Processing Unit) 9・ ・ ・ ROM (Read Only Memory) 10 ・ ・ ・ RAM (Random Access Memory)

Claims (1)

[Claims] 1. An object to be imaged placed in the background is irradiated with light by a light irradiating means, the reflected light is imaged by an image pickup device, and an image signal output from the image pickup device is subjected to binary image processing. In the image binarization processing device, the image pickup device is provided with a filter capable of transmitting only light of a color complementary to the background color of the light reflected by the light irradiation means of the object to be imaged. A characteristic image binarization processing device.