JPS63142791A - Image binarization processing device - Google Patents

Abstract

PURPOSE:To always obtain a constant binarization image without being affected by the intensity of illumination by detecting the intensity of illumination in the vicinity of an image pickup device by an illumination intensity sensor, and determining a binarization level based on its illumination intensity signal. CONSTITUTION:The intensity of a reflected light from an object 10 is detected by the illumination intensity sensor 16, and at the same time, the binarization level L is determined based on the illumination intensity signal SS outputted from the illumination intensity sensor 16. Thus, even when an image signal SP varies being accompanied with the variation of the light penetrating from an external part or the change in the lapse of time of the intensity of illumination due to the lighting apparatus, the binarization level L is also changed corresponding to these variations, and the constant binarization image is obtained always without being affected by the intensity of illumination.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an image binarization processing device, and particularly to an image binarization processing device that is not affected by changes in illuminance.

2. Description of the Related Art Imaging devices such as TV cameras are used to, for example, identify the shape of parts or measure the position of workpieces. The determination method described in Japanese Unexamined Patent Publication No. 59-198307 is one example.

Some devices perform image processing such as shape identification and position measurement based on binarized images. That is, the image signal output from the imaging device is converted into a predetermined constant binary signal by the image binarization processing device.
It is binarized into two values depending on whether it is above or below the binarization level compared to the binarization level, and the 2 value expressed by these two values is
Image processing is performed based on the digitized image. Such a binarized image has the advantage that the image processing time is faster than that of a grayscale image that is not binarized, and the apparatus can be constructed simply and inexpensively.

Problems to be Solved by the Invention However, when the image signal from the imaging device changes as the brightness of the object changes, such a binarized image may result in different images even of the same object. It may happen. That is, in the conventional image binarization processing device,
Since the binarization level is set to a constant value in advance, the opposite binarization process is performed for a portion where the image signal changes beyond the binarization level.

Therefore, the binarized image changes due to changes in light entering from the outside, changes in illumination intensity over time, etc., and incorrect shape identification, position measurement, etc. are sometimes performed.

On the other hand, it is possible to use an imaging device that has a function to automatically adjust the aperture in response to the above-mentioned changes in illuminance, but this automatic adjustment of the aperture is generally performed mechanically using a servo mechanism. , it is not possible to obtain sufficient accuracy in image binarization processing.

Means for Solving the Problems The present invention has been made to solve the above problems, and its gist is to compare the image signal output from the imaging device with the binarization level. An image binarization processing device that binarizes an image, comprising: (a) an illuminance sensor that detects illuminance near where the imaging device is placed and outputs an illuminance signal corresponding to the illuminance; and ('b) The present invention further comprises a binarization level determining means for determining the binarization level based on the illuminance signal output from the illuminance sensor.

Operation and Effect of the Invention With this method, the illuminance near the imaging device is detected by the illuminance sensor, and the binarization level is determined based on the illuminance signal output from the illuminance sensor. Even if the image signal changes due to changes in lighting or changes in illumination intensity over time, the binarization level will also change according to the change, resulting in a constant binarized image that is not affected by illuminance. will be obtained.

Note that, since there is a certain relationship between the image signal output from the imaging device and the illuminance, the binarization level determining means may, for example, determine the value represented by the illuminance signal predetermined based on the relationship. The binarization level is determined according to an arithmetic expression using illuminance as a variable.

In addition, when the illuminance signal changes temporarily due to the influence of external light or electrical noise, the
If the digitization level is determined, an incorrect binarization level will be set, so as a binarization level determination means,
It is preferable that the binarization level is determined when variations in illuminance signals sequentially output from the illuminance sensor are equal to or less than a predetermined constant value.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 1 is a block diagram illustrating the configuration of a visual device including an image binarization processing device according to the present invention. In FIG. 1, reference numeral 10 indicates an object supplied to a type discrimination device, an automatic processing machine, etc., and a lighting equipment 1 such as a fluorescent lamp.
Light is irradiated by 2. A TV camera 14 as an imaging device is installed above the object 10, and receives the reflected light of the light irradiated onto the object 10 from the lighting fixture 12, and produces an image proportional to the intensity of the reflected light. Outputs signal SP. Further, an illuminance sensor 16 made of a photodiode, a phototransistor, etc. is provided near the TV camera 14, and similarly receives reflected light from the object IO and generates an illuminance signal proportional to the intensity of the reflected light. Output SS.

The illuminance signal SS output from the illuminance sensor 16 is A/
After being converted into a digital signal by the D converter 18, it is supplied to the CPU 20, while the image signal SP output from the T-camera 14 is supplied to the image binarization comparator 22. The image binarization comparator 22 includes a CPU 2
Level signal SL representing the binarized level L output from 0
is supplied after being converted into an analog signal by the D/A converter 24, and the image binarization comparator 22 compares the image signal SP and the analogized level signal SL and determines the level signal. A binarized image signal SP', which represents the image signal SP with two values depending on whether it is above or below the level signal SL, is output to the CPU 20.

The CPU 20 is connected to an R bus line via a data bus line.
OM26. RAM28. Together with the video RAM 30 and the external device I/F 32, it constitutes a so-called microcomputer, and uses the temporary storage functions of the RAM 28 and the video RAM 30 to perform signal processing according to a program stored in advance in the ROM 26, and processes the level signal SL.
is supplied to the D/A converter 24, and is also supplied from the external device I/F 32 to the parallel I/F 34. Serial I/F
An output signal is supplied to the above-mentioned type discrimination device, automatic processing machine, etc. via 36.

The visual device configured as described above has the functions shown in the block diagram of FIG.

That is, the binarization level determination block 38 to which the illuminance signal SS is supplied from the illuminance sensor 16 binarizes the illuminance by multiplying the illuminance represented by the illuminance signal SS by a preset proportionality constant according to the following equation (1). While continuously calculating the level L7, when the dispersion of the binarization levels L, -L, of a constant valence a is smaller than the constant value R, the average value of the a number of binarization levels L1 is calculated. is determined as a binarization level, and a level signal S representing the determined binarization level L is determined.
L is supplied to the image binarization comparator 22.

The above proportionality constant is based on the relationship between the image signal SP output from the TV left camera 4 and the illuminance, and is calculated as follows:
It is experimentally or logically set in advance so that the value image is always constant. Furthermore, the constant valence a can be set to any value depending on the purpose using a setting device (not shown). In this embodiment, this binarization level determination block 3
8 corresponds to the binarization level determining means.

Illuminance = (illuminance) x (proportionality constant) ... (1) Image 2
The value comparator 22 compares the image signal sp supplied from the TV left camera 4 with the level signal SL and outputs a binary image signal SP'. This image binarization comparator 2
The binarized image signal SP' outputted from the block 2 is stored in the video RAM 30 as a binarized image, and is read out from the video RAM 30 in response to a request from the image processing block 40. Then, the image processing block 40
performs image processing such as shape identification 1 position measurement based on the read binarized image, and sends an output signal representing the result of the image processing from the external device I/F 32 to the parallel I/F 34.
It is supplied to a type discrimination device, automatic processing machine, etc. via the serial I/F 36.

FIG. 3 shows the ROM2
6 is a flowchart of a program stored in FIG. A more specific explanation will be given below according to this flowchart.

When a power switch (not shown) is turned on, step S1 is first executed, and it is determined whether an image measurement start signal has been input from a type discrimination device, an automatic processing machine, or the like. Since the image measurement start signal is not yet input at the beginning of startup when the power switch is turned on, step S2 is subsequently executed and the content of the counter C is set to O. Thereafter, in step S3, the illuminance represented by the illuminance signal SS is read, and in step S4, based on the read illuminance, the binarization level L is set according to the above equation (1).
is calculated. Then, in step S5, 1 is added to the contents of the counter C, and in step S6, it is determined whether the contents of the counter C have reached a certain value a. This constant value a corresponds to the constant valence a.

The execution from step 83 onward is repeated until the content of the counter C reaches a certain value a, and when it reaches the certain value a,
In other words, when a certain number a of binarization levels L7 are successively calculated in step S4, then step S7
is executed. In step S7, the calculated a
It is determined whether the dispersion of the binarization levels L, -L, is smaller than a predetermined constant value R, and if the dispersion is greater than the predetermined value 8, the execution from step 82 onwards is repeated. , a new binarization level L of a certain number a, ~L
1 is calculated. Further, if the dispersion of the binarization levels L, ~L, is smaller than the constant value R, step S8 is executed, and the average value of the binarization levels L, ~L, of the constant valence a is calculated. , the average value is determined and stored as the final binarization level.

Thereafter, the step S1 is executed again, and the binarization level L is sequentially updated to the latest value by repeating the steps until the image measurement start signal is input. These steps 82 to S8 represent the specific contents of the binarization level determination block 38.

Then, when the image measurement start signal is input and the determination in step S1 becomes YES, steps S9 and subsequent steps are executed to perform image measurement. That is, first, step S
In step 9, the level signal SL representing the latest binarization level L determined in step S8 is output to the image binarization comparator 22, and in step 310, the level signal SL representing the latest binarization level L determined in step S8 is outputted to the image binarization comparator 22. Read the digitized image signal SP' and convert it to the binarized image signal SP'
The 2(a) image represented by An output signal representing this is output. This step Sll corresponds to the image processing block 40.

When the image measurement for one object 10 is completed in this way, the steps from step 81 onward are executed again, a new binarization level L is determined, and the image measurement for the object 10 to be supplied subsequently is performed. This is performed based on the new binarization level L.

In this way, the visual device of this embodiment detects the intensity of reflected light from the object 10 using the illuminance sensor 16, and also determines the binarization level L based on the illuminance signal SS output from the illuminance sensor 16. is determined, so even if the image signal SP changes due to a change in light entering from the outside or a change over time in the illuminance of the lighting fixture 12, the binarization level L is also changed in accordance with the change. As a result, a constant binarized image can always be obtained without being affected by illuminance.

In addition, in this embodiment, a fixed number a of binarization levels L1 to L
, and if the variations in these are smaller than a constant value R, in other words, when the variations in the illuminance signals SS sequentially supplied from the illuminance sensor 16 are below a predetermined constant value, Binarization level L Since the final binarization level L is determined by averaging the I-L-, external light.

Alternatively, even if the illuminance signal SS changes temporarily due to the influence of electrical noise, etc., an incorrect binarization level L will not be set due to this, and high reliability can be obtained. .

,Furthermore, in this embodiment, not only the initial startup of the device, but also the
When image measurement is not being performed, the illuminance signal SS is constantly read and the binarization level L is updated, so the image binarization process is always performed based on the optimal binarization level L. For example, it has the advantage of being able to adequately respond to changes in illumination throughout the day.

Furthermore, since the binarization level L is set before starting image measurement, the image measurement time is shortened compared to the case where the binarization level L is determined after starting image measurement.

Next, another embodiment of the present invention will be described. In the following embodiments, parts common to those in the first embodiment are designated by the same reference numerals, and explanations thereof will be omitted.

First, in the embodiment shown in FIG. 4, compared to the first embodiment, an illuminance sensor 16 is provided on the object 10 side, and the irradiation light from the lighting fixture 12 is directly detected. Also,
In the embodiment shown in FIG. 5, a lighting fixture 44 is arranged on the back side of the object 10.

In these cases as well, the binarization level determination block 38
By appropriately setting the arithmetic expression in (2) through experiments or the like, it is possible to always obtain a constant binary image regardless of changes in illuminance, as in the first embodiment.

Although the embodiments of the present invention have been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the embodiment, there are a number of binarization levels L1 to L1.
is calculated and the final binarization level L is determined when the variation is smaller than a constant value R. However, when determining the binarization level L, it is not necessary to take into account the variation. There is no need to make a judgment. Alternatively, the final binarization level L may be determined by determining the average of the illuminance represented by the illuminance signal SS within a certain period of time, and multiplying the average by the proportionality constant of equation (1) above. Of course. Note that even if one binarization level is only calculated according to equation (1) without calculating a number of binarization levels L, -L, and it is set as the final binarization level L, The effects of the present invention can be obtained.

Further, in the embodiment described above, the binarization level L, , is calculated according to the arithmetic expression (1), but this arithmetic expression is changed as appropriate based on the relationship between the image signal SP and the illuminance. Yes, and the binary level L7 is used instead of the arithmetic expression.
It is also possible to use a data map or the like that represents the relationship between the brightness and the illuminance.

Further, in the embodiment described above, the binarization level determination block 38 is constituted by a so-called microcomputer, but it may also be constituted by a hard logic circuit. Note that it is of course possible to configure the image binarization comparator 22 using a microcomputer.

Further, in the embodiment described above, the binary conversion level L is determined before starting the image measurement from step 89 onwards, but the binary conversion level L is determined during the image measurement. There is no problem.

Furthermore, in the embodiment described above, when image measurement is not being performed, the illuminance signal SS is constantly read and the binarization level L is updated, but the binarization level L determined at the beginning of startup remains unchanged. The binarization level L
There is no problem in updating the .

Furthermore, in the above embodiment, the binarization level L is determined and stored when the power switch is turned on, but a fixed binarization level L may be set in advance based on environmental illumination conditions, etc. It is also possible to correct this and determine a new binarization level L when the illuminance changes.

Although other examples are not given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the configuration of an example of a visual device equipped with an image binarization processing device according to the present invention. Second
The figure is a block diagram illustrating the functions of the visual device of FIG. 1. FIG. 3 is a flowchart for explaining the functional block diagram of FIG. 2 in more detail. FIG. 4 is a block diagram illustrating the main parts of another embodiment of the present invention. FIG. 5 is a block diagram illustrating the main parts of yet another embodiment of the present invention. 14: TV camera (imaging device) 16: Illuminance sensor Applicant: Toyota Motor Corporation, Figure 4, page 9

Claims (3)

[Claims] (1) An image binarization processing device that binarizes an image signal output from an imaging device by comparing it with a binarization level, which detects the illuminance near where the imaging device is placed and an illuminance sensor that outputs an illuminance signal corresponding to illuminance;
An image binarization processing device comprising a binarization level determining means for determining a binarization level. (2) The binarization level determining means determines the binarization level according to an arithmetic expression that is predetermined based on the relationship between the image signal and the illuminance and uses the illuminance represented by the illuminance signal as a variable. An image binarization processing apparatus according to claim 1. (3) The binarization level determining means determines the binarization level when variations in illuminance signals sequentially output from the illuminance sensor are equal to or less than a predetermined constant value. Image 2 described in Section 1 or Section 2
Value processing device.