JPH04205385A - Picture processor - Google Patents

Abstract

PURPOSE:To perform proper binarization by setting the threshold value based on the peak value and background value on the indentical line. CONSTITUTION:A sample-and-hold circuit 14 and a binarization part 20 input picture information of the first line in the horizontal scanning direction of the picture information stored in a picture memory 32, and calculates the background level of the line by a background level calculation circuit 25. A threshold value calculation circuit 35 calculates the threshold value based on the calculated background level and the peak value stored in the peak hold circuit 18. On the other hand, a binarization part 20 inputs the identical picture information successively, and decides whether or not the inputted picture information is higher than the threshold value to binarize the picture information. Thus, the binarization of the picture information can be performed with proper threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an image processing system that can appropriately perform binarization processing on an input image regardless of the optical environment in which the subject is placed. It relates to a processing device.

(Prior Art) With the progress of automation technology in recent years, production equipment that performs predetermined operations based on images captured by cameras has come to be used in production factories as well. In production equipment that uses cameras in this way, it is necessary to binarize images captured by the cameras. This binarization has been conventionally performed by various methods. To perform this binarization, it is necessary to calculate a threshold value for setting each point of the image captured by the camera to 0 or 1. If the lighting conditions around the camera are very stable, a fixed value for the second threshold is sufficient, or if the lighting conditions are not stable, the threshold needs to be changed to match the lighting conditions. .

This is because accurate binarization cannot be performed unless the threshold value is changed in accordance with the illumination conditions.

- When using this type of production equipment at a production site for boat fishing, stable lighting conditions cannot be expected.
A device is used that can perform binarization as appropriately as possible regardless of the lighting conditions. An example of a conventional image processing apparatus that performs such binarization has a configuration as shown in FIG.

In the figure, a slit light source 10 is a light source that irradiates a workpiece W with slit-shaped light. An image of the area illuminated by this slit light source 10 and its surroundings is captured by a video camera 12, and the captured image is converted into an image signal of a size corresponding to its brightness by a sample and hold circuit 14. Comparator 16. The signals are output to the peak hold circuit 18 and the binarization section 20, respectively. The sample hold circuit 14 is a circuit that temporarily holds the image signal output from the video camera 12, and the sample hold circuit 14 is a circuit that temporarily holds the image signal output from the video camera 12.
is used to compare the magnitude of the image signal held by the sample and hold circuit 14 with the next image signal held therein. The time delay circuit 22 supplies the sample and hold circuit 1 to the comparator 16 in order to perform such a comparison.
The image signal from 4 is delayed and outputted. Note that the sample hold circuit 14. The comparator 161 and time delay circuit 22 detect the brightness of the background portion of the image captured by the video camera 12 as a background level. The peak hold circuit 18 is a circuit that temporarily holds the image signal with the largest value among the image signals output from the video camera 12, and the storage circuit 24
This retained image signal is stored. Therefore, the image signal stored in the storage unit 24 is the image signal having the maximum value among the image signals output from the video camera 12 last time (one line before).

The background level image signal output from the sample hold circuit 14 and the image signal stored in the storage section 24 are input to the subtraction operation section 26, where the difference between them is calculated. Through this calculation, the difference in brightness between the background brightness and the image signal having the maximum value is calculated. The multiplication operation unit 28 is the subtraction operation unit 26
A certain constant (for example, 0.2~
0°8). The addition calculation unit 30 calculates a threshold value by adding the calculated background level and the value calculated by the multiplication calculation unit 28. The binarization unit 20 binarizes the image signal output from the video camera 12 based on the threshold value output from the addition calculation unit 30.

By performing such processing, a threshold value that takes into account the brightness of the background of the workpiece W is set, and the binarization processing of the image captured by the video camera 12 is appropriately performed. .

(Problem to be Solved by the Invention) However, in such a conventional image processing device, the threshold value is set based on the image signal stored in the storage unit 34 and the background level output from the sample and hold circuit 14. However, the image signal stored in the storage unit 34 is different from the line currently output from the sample hold circuit 14, and the image signal is
This is the largest image signal in the previous line.

For example, as shown in FIG.
Assuming that a signal as shown in the figure is output as the horizontal scanning line signal of the n-th line, the background level of the n-th line is output in synchronization with this signal. Further, the peak value of the n-th horizontal scanning line signal is stored in the storage section 24. Although not shown, the threshold at the beginning of the n line is determined from the peak value of the horizontal scanning line signal at the (n-1) line and the horizontal scanning line signal at the beginning of the n line. Therefore, if the slit light source 10
When the horizontal scanning line signal of line n+1 was taken in, the brightness of the line 1 and 1 became much lower than the brightness when the scanning line signal was taken underwater in line 1 and 1. A background level is set for the horizontal scanning line signal at the level shown. The threshold for "n+3 line 1" is set based on the peak value at the beginning of the n line and the background level of the n-(1 line). Therefore, as shown in the figure, the threshold level is set to be high. As a result, appropriate binarization cannot be performed.

The present invention has been made to solve these conventional problems, and even when the lighting conditions suddenly change, it is possible to follow the change and perform appropriate binarization processing. The purpose is to provide an image processing device that can perform

(Means for solving the problem) The present invention to achieve the above object includes a camera that inputs an image of a subject and outputs an image signal according to the illuminance of the image, and a camera that stores the image signal as a digital value. storage means for storing the maximum digital value of any one line of the image signals stored in the storage means; peak value storage means for storing the maximum digital value of any one line of the image signals stored in the storage means; 1-background value calculation means for calculating a digital value corresponding to the background part of the image of the line; and a peak value and background value of the same line stored in the peak value storage means and the background value storage means. A threshold calculation means for calculating a threshold for binarizing the image signal of the line based on the ground value, and a threshold calculation means for calculating the threshold for binarizing the image signal of the line based on the ground value, and a It is characterized by comprising a binarization processing means for performing binarization processing on the image signal stored in the storage means.

(Operation) In the present invention having the above configuration, the threshold value calculation means sets the threshold value based on the peak value and background value for the same line.

Therefore, a threshold value that matches the illuminance of the image input from the camera is calculated, and the binarization processing means can perform appropriate binarization.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 is a block diagram of the image processing device of the present invention;
The figure is a flowchart showing the operation of the device, and FIG.
FIG. 3 is an explanatory diagram of threshold values calculated by the device. It should be noted that parts of the apparatus shown in FIG. 1 that are common to those shown in FIG.

In the configuration of the image processing device shown in this embodiment and the configuration of the conventional image processing device shown in FIG. 32 is provided, and a storage section 24 for storing the image signal held by the peak hold circuit 8 is not provided. Note that the configuration other than this is completely the same, and the functions of the respective constituent parts are also the same.

The image memory 32 shown in FIG. 1 stores an image signal around the workpiece W output from the video camera 2 as digital data. This image memory 32 stores image information for four screens captured by the video camera 1-2, and functions as a storage means 7. Sample and hold circuit 14. A background level calculation circuit 25 composed of a comparator]-6 and a time delay circuit 22 calculates the background level of an arbitrary line based on the image information of the line stored in the image memory 32. This functions as a background value calculation means. Subtraction calculation unit 26
A threshold calculation circuit 35 composed of a 1 multiplication calculation unit 28 and an addition calculation unit 30 calculates an optimal value from the image information stored in the Beekholt circuit 8 and the background level output from the background level calculation circuit 25. There is a device that calculates a threshold value, and functions as a threshold value calculation means. The peak hold circuit 18 is used as a peak value storage means, and the binarization section 2o is used as a binarization processing means 7.
function respectively.

The image processing apparatus of the present invention having such a configuration operates as shown in the flowchart shown in FIG. This operation will be explained below.

First, in response to a processing start command, the sample and hold circuit 14. The peak hold circuit 18 and the binarization unit 20 each set the value of the counter n provided in those circuits to 1.
(Step 1).

The peak hold circuit 18 inputs the image information of the first line in the horizontal scanning direction of the image information stored in the image memory 32 based on the value of this counter n, and selects the largest value of this image information. Temporarily stores the image information, that is, the peak value.

Having a large value as image information is equivalent to being photographed as a relatively bright image (steps 2 and 3).

Next, the sample hold circuit 14 and the binarization section 20,
Based on the value of this counter n, the image information of the first line in the horizontal scanning direction of the image information stored in the image memory 32 is input, and the background level of that line is calculated by the background level calculation circuit 25 ( Step 4). Then, the threshold calculation circuit 35 calculates a threshold based on the calculated background level and the peak value stored in the peak hold circuit 18.

The method of calculating this threshold is exactly the same as before, so
A detailed explanation thereof will be omitted (step 5).

On the other hand, the binarization unit 20 also inputs the same image information as the sample and hold circuit 14 one after another, and the input image information is
It is determined whether the image information is larger or smaller than a threshold value, and the image information is binarized. Specifically, if the input image information is larger than the threshold, set it to 1, if it is smaller, set it to 0,
The binary signal thus set is output to an external device (steps 6 and 7). In this way the first
After completing the binarization process for the line image information,
Sample and hold circuit 14. The peak hold circuit 18 and the binarization unit 20 each increment the value of the counter n provided in these circuits by 1, and perform the processing from step 1 in the same manner (step 8). When the above process has been performed for all lines (N+1 lines) stored in the image memo 1J32, the binarization process ends (step 9).

To summarize, in the image processing apparatus of this embodiment, first, the peak hold circuit 18 extracts, for example, the first line of image information, detects the peak value of the image information, and stores the value. Then, the background level calculation circuit 25 takes out the image information of the first line again in order and sets the background level of the taken out image information of the first line, and at the same time, the threshold calculation circuit 35
The set background level and the memorized first
A threshold value is set based on the peak value of the line. Furthermore, at the same time, the binarization circuit 20 uses the threshold value and the extracted first
It compares the image information with the image information of the line and outputs a binarized signal. Therefore, as shown in FIG. 3, the threshold value for the nth line is determined based on the peak value of the image information on the nth line and the background level of the nth line, that is, the peak value and background level of the same line. Since the value is determined based on the value, there is no possibility that the binarization process will not be performed properly due to differences in lighting conditions.

(Effects of the Invention) As is clear from the above description, according to the present invention, even when the illumination conditions suddenly change, it is possible to perform the binarization process of image information using an appropriate threshold value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the image processing device of the present invention, FIG. 2 is a flowchart showing the operation of the device, FIG. 3 is an explanatory diagram of threshold values calculated by the device, and FIG. 4 is a conventional image processing device. FIG. 5 is a block diagram of the image processing device of FIG. 5, which is an explanatory diagram of threshold values calculated by the conventional device. 12... Video camera (camera), 18... Peak hold circuit (peak value storage means) 2
0... Binarization unit (binarization processing means), 25... Background level calculation circuit (background value calculation means), 32... Image memory (storage means), 35... Threshold value calculation Circuit (threshold calculation means). Patent applicant Nissan Motor Co., Ltd. agent Patent attorney 8 1) Mikio (and 1 other person) Figure 2

Claims (1)

[Scope of Claims] A camera that inputs an image of a subject and outputs an image signal according to the illuminance of the image, a storage device that stores the image signal as a digital value, and an image stored in the storage device. any one of the signals
Peak value storage means for storing the maximum digital value of the line; and any one of the image signals stored in the storage means.
a background value calculation means for calculating a digital value corresponding to a background portion of the image of a line; and a background value calculation means based on the peak value and background value of the same line stored in the peak value storage means and the background value storage means. a threshold calculation means for calculating a threshold for binarizing the image signal of the line; and based on the threshold calculated by the threshold calculation means,
Binarization processing is performed on the image signal stored in the storage means on the same line as when calculating this threshold value.
An image processing device comprising: a value conversion processing means.