JP4094435B2 - Image processing method and image processing apparatus characterized by automatically adjusting environment of optical system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing method and an image processing apparatus for setting an environment of an optical system, which is a condition for photographing a subject to be subjected to image processing.
[0002]
[Prior art]
Conventionally, in a factory production line, when performing solid identification, inspection, position measurement, etc. for products or parts, for example, an image of a subject such as the product or parts is input and input using an imaging means such as a camera. An image processing apparatus that achieves the above-described objects such as solid identification, inspection, and position measurement by processing the processed image is used.
[0003]
The imaging conditions when inputting an image of a subject required for solid identification, inspection, position measurement, etc. of the subject, that is, the environment setting item of the optical system provided in the image processing apparatus is an imaging means. There are camera lens focusing (hereinafter referred to as focus) and diaphragm, camera shutter speed, and illumination light quantity of the illumination means. Lens focus and aperture settings differ depending on the shape of the subject and the amount of light applied to the subject. The setting of the shutter speed of the camera differs depending on whether the subject is moving or stationary, and there is a restriction that the shutter speed cannot be reduced too much when moving. The appropriate amount of light emitted from the illuminating means varies depending on the shape and material of the subject and the portion that is the target of image input.
[0004]
Conventionally, the environment setting of a complex optical system that combines the amount of irradiation light and the focus, aperture, and shutter speed according to the state of the subject is performed by the operator viewing the monitor screen, so experience and skill are required. It is said that. Therefore, when the environment of the optical system once set is forced to change due to external factors such as aging deterioration of the illumination means and the influence of ambient light, it is possible for an inexperienced and less skilled operator to respond. It is impossible, and the actual situation is that an expert has to adjust and re-set in the field. Even if the operator is an experienced operator, the environment setting of the optical system that is determined to be appropriate differs for each operator. There is also a problem that it is different for each.
[0005]
Of the environment setting items of the optical system, the focus and diaphragm of the lens provided in the imaging means are often fixed once by, for example, a screw lock mechanism, so that it is difficult to make a target for automatic adjustment (setting). is there. On the other hand, among the environment setting items of the optical system, the shutter speed of the imaging unit and the irradiation light amount of the illuminating unit are not fixed in the set state, and thus are easy to handle as targets for automatic adjustment (setting).
[0006]
For this reason, in the prior art, the difference between the average density value of the image captured this time by the camera and the average density value of the previously captured image, that is, the amount of change in density is obtained, and the amount of change is preset. A method of automatically setting the shutter speed of a camera is proposed in which the shutter speed is determined based on the amount of change when the threshold value exceeds the threshold value (see Patent Document 1).
[0007]
In another conventional technique, a density histogram of an image taken by a camera is created, a binarization threshold value obtained based on the number of pixels formed in an image to be cut out from a subject, and a dark peak and a bright peak. Has been proposed that automatically adjusts the amount of light emitted from a lighting device having an external dimming function so that the binarization threshold value, which is the density value of the portion with the smallest frequency distribution between the two, coincides (patent) Reference 2).
[0008]
[Patent Document 1]
JP 2001-230967 A
[Patent Document 2]
JP-A-6-139341
[0009]
[Problems to be solved by the invention]
However, in the method disclosed in Patent Document 1, the value to be set for the shutter speed corresponding to the density change amount is automatically obtained. However, in order to actually set the shutter speed to the obtained value, the operator needs You must enter the value that was found. In addition, there is a problem that density change amount data corresponding to all shutter speeds prepared as specifications of the imaging means must be created in advance.
[0010]
In addition, the method disclosed in Patent Document 2 is applied only to a subject that can binarize image information. For example, when there is no distinction between a subject and a background such as a flat panel, or the illuminance of the subject and the illuminance of the background There is a problem that it cannot be applied to cases where and cannot be separated.
[0011]
An object of the present invention is based on the fact that the optical system adjustment variable selected from the shutter speed and the irradiation light quantity among the environment setting items of the optical system and the image density are in a linear relationship, so that the optical system is not operated by the operator. It is an object to provide an image processing method and an image processing apparatus characterized by automatically adjusting an adjustment variable, that is, an environment of an optical system.
[0012]
[Means for Solving the Problems]
  The present invention is an image processing method for photographing an object to be imaged and performing environment setting of an optical system as a photographing condition when performing image processing of the photographed object.
  Obtained by shooting the subjectSet one or more monitoring windows for the part to be monitored in the entire imaging screen,
  The monitoring windowEveryAn average density dav which is an average value of image density is obtained,
  For each monitoring windowDetermining whether the average concentration dav is within a predetermined monitoring concentration range;
  For each monitoring windowThe average density dav is outside a predetermined monitoring density rangeThere is at least one monitoring windowWhen selecting at least one of the shutter speed of the imaging means for photographing the subject or the irradiation light amount of the illumination means for illuminating the subject as an optical system adjustment variable,
  The selected optical system adjustment variable is changed, the image density of the monitoring window that varies with the change of the optical system adjustment variable is obtained, and given as the relationship between the optical system adjustment variable and the image density of the monitoring window. Linear transformation formulaFor each monitoring windowmake,
  Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable Alternatively, the image processing method is characterized in that the environment of the optical system is automatically adjusted by setting the irradiation light quantity.
[0013]
  According to the present invention, it is obtained by photographing a subject.Set one or more monitoring windows for the part to be monitored in the entire imaging screen,Surveillance windowEveryIt is determined whether or not the average density dav that is the average value of the image density is within a predetermined monitoring density range, and the average density dav is outside the predetermined monitoring density range.There is at least one monitoring windowSometimes, at least one of the shutter speed and the irradiation light quantity is selected as an optical system adjustment variable, and a linear conversion formula given as a relationship between the selected optical system adjustment variable and the image density of the monitoring window is obtained.For each monitoring windowBased on this linear conversion formula, the shutter speed or irradiation light amount selected as the optical system adjustment variable is automatically adjusted and set so that the value of the optical system adjustment variable is determined in accordance with the average density dav. . In this way, the shutter speed or the amount of irradiation light, which is the environment of the optical system, is quantitatively and automatically set to an appropriate value by the quantification means called the linear conversion formula, so that the operation is not performed by the operator. Therefore, it is possible to set the environment of the optical system with high reproducibility without requiring any skill in the person's skill.
[0014]
  The present invention is also an image processing method for photographing an object to be imaged and performing an environment setting of an optical system as a photographing condition when performing image processing of the photographed object.
  In a state where the shutter speed of the imaging means for photographing the subject and the irradiation light amount of the illuminating means for irradiating the subject with light are provisionally set to predetermined values, the focus and diaphragm of the lens provided in the imaging means are set,
  Set the shutter speed of the imaging unit and the irradiation light amount of the illumination unit to desired values in the set lens focus and aperture environment,
  By the imaging meansSet one or more monitoring windows for the part to be monitored in the entire imaging screen,Surveillance windowEveryAn average density dav which is an average value of image density is obtained,
  For each monitoring windowDetermining whether the average concentration dav is within a predetermined monitoring concentration range;
  For each monitoring windowThe average concentration dav is outside the monitored concentration rangeThere is at least one monitoring windowWhen selecting at least one of the shutter speed and the irradiation light amount as an optical system adjustment variable,
  The selected optical system adjustment variable is changed, the image density of the monitoring window that varies with the change of the optical system adjustment variable is obtained, and given as the relationship between the optical system adjustment variable and the image density of the monitoring window. Linear transformation formulaFor each monitoring windowmake,
  Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable Alternatively, the image processing method is characterized in that the environment of the optical system is automatically adjusted by setting the irradiation light quantity.
[0015]
  According to the invention, by the imaging meansSet one or more monitoring windows for the part to be monitored in the entire imaging screen,Surveillance windowEveryThe suitability of the optical system environment can be diagnosed based on whether or not the average density dav, which is the average value of the image density, is within the monitoring density range that serves as a reference for determining the suitability of the optical system environment. Further, when the diagnosis result is inappropriate, at least one of the shutter speed and the irradiation light amount is selected as an optical system adjustment variable, and linear conversion is given as a relationship between the selected optical system adjustment variable and the image density of the monitoring window. The expressionFor each monitoring windowBased on this linear conversion formula, the shutter speed or irradiation light amount selected as the optical system adjustment variable is automatically adjusted and set so that the value of the optical system adjustment variable is determined in accordance with the average density dav. . In this way, the shutter speed or the amount of irradiation light, which is the environment of the optical system, is quantitatively and automatically set to an appropriate value by the quantification means called the linear conversion formula, so that the operation is not performed by the operator. Therefore, it is possible to set the environment of the optical system with high reproducibility without requiring any skill in the person's skill.
[0016]
In addition, by diagnosing the suitability of the environment of the optical system, it is clear whether the cause of a detection failure in, for example, solid identification or inspection by image processing is due to an inappropriate optical system environment or a subject failure Can be. Therefore, it is possible to reduce the time required for analyzing the cause of the detection failure in the above-described individual identification and inspection.
[0017]
  The present invention also provides an image processing apparatus capable of setting an environment of an optical system, which is a shooting condition, when shooting a subject to be imaged and performing image processing of the shot subject.
  Illumination means capable of irradiating the subject with a variable amount of light;
  An imaging means for photographing a subject, the imaging means capable of shutter speed, aperture and focus adjustment;
  Photographed by the imaging meansOne or more monitoring windows are set for the part to be monitored in the entire image, and the monitoring windowPerform image processing to obtain image density,For each monitoring windowWhile calculating an average density dav which is an average value of image density,For each monitoring windowImage processing means for setting a monitoring density range based on the average density dav;
  Storage means for storing the average concentration dav and the monitored concentration range;
  The monitored concentration range is read from the storage means and photographed by the imaging meansOf the monitoring windowDetermining means for determining whether the density of the image is within the monitored density range;
  Selecting means for selecting at least one of the shutter speed and the irradiation light quantity as an optical system adjustment variable;
  The optical system adjustment variable selected by the selection means is changed, the density of the image that fluctuates with the change of the optical system adjustment variable is obtained, and a linear conversion formula given as the relationship between the optical system adjustment variable and the image density is obtained.For each monitoring windowA linear transformation formula creation means to create;
  Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable Alternatively, the image processing apparatus includes a control unit that controls the amount of irradiation light, and automatically adjusts the environment of the optical system.
[0018]
  According to the present invention, the image processing apparatus is photographed by the imaging means.Of the monitoring window set for the part to be monitored in the entire imageThe suitability of the environment of the optical system can be diagnosed based on whether or not the image density is within a monitoring density range set based on, for example, an average density dav which is an average value of the image density. Further, when the result of the environmental diagnosis of the optical system is inappropriate, the image processing apparatus selects at least one of the shutter speed and the irradiation light amount, which are the environment setting items of the optical system, as the optical system adjustment variable, and the selected optical The linear conversion formula given as the relationship between the system adjustment variable and the image density isFor each monitoring windowThe shutter speed or the amount of irradiation light can be automatically set by the control means so as to be the value of the optical system adjustment variable that is created and determined in accordance with the average density dav of the image based on this linear conversion formula. In this way, an image processing apparatus is realized that can automatically adjust the environment of the optical system with high reproducibility without depending on the operator's operation, and therefore without requiring skill in the operator's skill.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a simplified configuration of an image processing apparatus 1 according to an embodiment of the present invention. The image processing apparatus 1 according to the present embodiment can photograph the subject 2 to be imaged and set the environment of the optical system, which is a photographing condition, when performing image processing of the photographed subject 2. It is provided in a production line of a factory and used for solid identification, inspection, position measurement, etc. for products and parts.
[0020]
The image processing apparatus 1 includes an illuminating unit 3 that can irradiate a subject 2 with a variable amount of light, an imaging unit 4 that captures an image of the subject 2, and an imaging unit 4 that can adjust shutter speed, aperture, and focus, When the person temporarily sets the shutter speed of the image pickup means 4 and the irradiation light quantity of the illumination means 3, the input means 5 used for inputting the set value and the image processing for obtaining the density of the image taken by the image pickup means 4 The image processing means 6 for setting the monitoring density range based on the average density dav, the average density dav and the monitoring density range by the image processing means 6 are stored. Random Access Memory 7 (abbreviated as RAM) which is a storage means to be read out, and the monitor density range is read from the RAM 7 and the density of an image taken by the imaging means 4 is determined. Determination means 8 for determining whether or not it is within the visual density range, selection means 9 for selecting at least one of the shutter speed and the irradiation light quantity as an optical system adjustment variable, and optical system adjustment selected by the selection means 9 A linear conversion formula creating means 10 for creating a linear conversion formula given as a relationship between the optical system adjustment variable and the image density by varying the variable, obtaining the density of the image that fluctuates with the fluctuation of the optical system adjustment variable, and Based on the linear transformation formula created by the linear transformation formula creation means 10, the value of the optical system adjustment variable determined corresponding to the above-mentioned average density dav is obtained, and the value of the obtained optical system adjustment variable is obtained. The control means 11 for controlling the shutter speed or the irradiation light quantity selected as the optical system adjustment variable.
[0021]
The subject 2 is a product or a part that is a target of solid identification, inspection, position measurement, etc. as described above, and includes a semiconductor chip and various other objects. The illumination unit 3 includes a light source 12 that is a light emission source and a power source 13 that can variably supply power to the light source 12. For example, a light-emitting diode (abbreviated LED) or a tungsten lamp is preferably used as the light source 12, and light irradiating the subject 2 is emitted in a variable amount of light according to the amount of power supplied from the power supply 13.
[0022]
The image pickup means 4 includes a CCD camera 14 having a Charge Coupled Device (abbreviated as CCD) element, an analog / digital (abbreviated as A / D) converter 15 that converts an input / output signal to / from the CCD camera 14 into analog / digital, and a CCD. An image display controller 16 that processes image information from the camera 14 and outputs the signal to a processing circuit 20 described later, and outputs a signal for controlling the operation of the CCD camera 14 in response to an output from the processing circuit 20; And a frame memory 17 which is connected to the imaging display controller 16 and is a storage means capable of writing / reading image information at any time by the CCD camera 14.
[0023]
Although not shown, the CCD camera 14 is provided with a lens. Around the lens, a focus mechanism for adjusting the focus of the lens, an aperture mechanism for adjusting exposure, and a shutter mechanism capable of variably setting the speed are provided. It is done. Each of these mechanisms can be adjusted by a control signal from the processing circuit 20 via the imaging display controller 16 and can also be adjusted manually. The imaging unit 4 may include a monitor 18. The monitor 18 is composed of a liquid crystal, a cathode ray tube, or the like. In this embodiment, the monitor 18 is connected to the imaging display controller 16 via a digital / analog (abbreviated as D / A) converter 19, and image information from the CCD camera 14. Is displayed as a visible image.
[0024]
The processing circuit 20 is realized by, for example, a microcomputer equipped with a Central Processing Unit (abbreviated CPU). The processing circuit 20 includes the above-described image processing means 6, determination means 8, selection means 9, linear transformation formula creation means 10 and control means 11. The processing circuit 20 operates according to a program stored in advance in a Read Only Memory 21 (abbreviated ROM), functions as the above-described means, and controls the entire operation of the image processing apparatus 1.
[0025]
The input means 5 is a remote setting key. The input means may be a keyboard or the like, and may be configured to input various setting values from the keyboard. However, if all of the various setting values are entered numerically from the keyboard, the operation becomes complicated and the time required for input becomes longer. In this embodiment, the input means 5 is used as a remote setting key and stored in the RAM 7 as table data, for example. Various setting values stored in advance are read by the processing circuit 20, the read setting values are displayed on the monitor 18, and the selected setting values are selected and input by key operation. The input means 5 is connected to each means of the apparatus including the processing circuit 20 via an input / output (I / O) interface 22. The input / output interface 22 is connected to the power source 13 of the illumination means 3 described above.
[0026]
Hereinafter, operations of the image processing means 6, the determination means 8, the selection means 9, the linear transformation formula creation means 10 and the control means 11 included in the processing circuit 20 will be described.
[0027]
The image processing means 6 sets a monitoring window which is an area formed by forming or dividing the imaging screen on the imaging screen by the imaging means 4, and obtains an average density dav which is an average value of image density for each monitoring window. A monitoring density range serving as a reference for determining the suitability of the environment of the optical system is determined based on the average density dav. The method of determining the monitoring concentration range is not particularly limited, but it is preferable that the initial value is, for example, plus or minus (±) 10% of the average concentration dav. Further, the image processing means 6 can determine the image density and the average density dav of not only the image in the monitoring window but also the entire imaging screen and a region arbitrarily defined in the imaging screen. The average density dav and the monitoring density range for each monitoring window obtained by the image processing means 6 are stored in the RAM 7 as described above.
[0028]
The determining means 8 compares the image density of each monitoring window obtained by the image processing means 6 with the monitoring density range determined for each monitoring window read from the RAM 7 in the set optical system environment. It is determined whether or not it is within the range, that is, the environment of the optical system is diagnosed, and the determination result is output to the selection means 9, the monitor 18, and the output means 24. For the output means 24, for example, an alarm buzzer is used.
[0029]
The selection means 9 responds to the determination result of the determination means 8 and when it is diagnosed that there is even one monitoring window whose image density is outside the monitoring density range, that is, the environment of the optical system is inappropriate, the shutter speed or Either one of the irradiation light amounts is selected as an optical system adjustment variable. This selection can be executed by assigning priorities to the shutter speed and the irradiation light quantity.
[0030]
FIG. 2 is a diagram illustrating a monitoring window setting state and a linear conversion formula. The operation of the linear transformation formula creation means 10 will be described with reference to FIG. FIG. 2 shows a case where the connector 26 with the metal terminal 25 protruding is taken up as a subject. In the present embodiment, the monitoring density range is set to monitor the image density, and four monitoring windows for creating a linear conversion equation are set. The first monitoring window 27 is set to include the metal terminal 25, the second and third monitoring windows 28 and 29 are set to the white resin portion of the connector 26, and the fourth monitoring window 30 has the connector 26 mounted thereon. It is set with respect to the surface of the transfer table to be placed, and the surface of the transfer table is sometimes called the background.
[0031]
For each set monitoring window, when the optical system adjustment variable is, for example, the amount of light irradiated by the illumination means 3, from the minimum to the maximum by the input operation from the input means 5 (for example, from zero (0) in the case of 8-bit dimming) Up to 255). The image processing means 6 determines the density of the monitoring window for each irradiation light quantity at each stage of change. The linear conversion formula creating means 10 obtains the relationship between the volume value of the irradiation light quantity and the concentration for each of the first to fourth monitoring windows 27, 28, 29, 30. The relationship between the volume value of the irradiation light quantity and the concentration can be obtained almost in a linear form. This linear format and a graph of the linear format are referred to herein as a linear conversion formula.
[0032]
When the optical system adjustment variable is, for example, the shutter speed of the image pickup means 4, it is changed from the minimum to the maximum (for example, from 1/10000 to 1/30) by the input operation from the input means 5. The density of the monitoring window for each shutter speed at each stage of change is obtained by the image processing means 6. The linear conversion equation creating means 10 obtains the relationship between the shutter speed value and the density for each of the first to fourth monitoring windows 27, 28, 29, and 30. As described above, the relationship between the shutter speed value and the density can be obtained in a substantially linear form.
[0033]
FIG. 2B shows a linear conversion formula when the optical system adjustment variable is the irradiation light amount. A line 31 shown in FIG. 2B is a linear conversion formula of the image of the first monitoring window 27, that is, the metal terminal portion, and a line 32 and a line 33 indicate the second and third monitoring windows 28, 29, that is, the white resin portion. The line 34 is the fourth monitoring window 30, that is, the linear conversion formula of the background image. The line 32 and the line 33 have a portion where the density does not change on the high concentration side even though the irradiation light amount volume value changes, and this portion is referred to as a “flat portion” for convenience. On the other hand, the portions of the line 32 and the line 33 excluding the “flat portion”, and the lines 31 and 34 are in a linear relationship, and the irradiation light quantity volume value and the density can be converted to each other. This is called a “conversion unit”. The linear conversion formula obtained for each of the environment windows 27, 28, 29, 30 by the linear conversion formula creation means 10 is stored in the RAM 7.
[0034]
The control means 11 uses the average density dav of the image of each monitoring window obtained by the image processing means 6 under the set optical system environment, and adjusts the optical system determined from the linear conversion equation corresponding to the average density dav. Find the value of a variable. Next, the shutter speed or irradiation light amount selected as the optical system adjustment variable is controlled so as to be the value of the obtained optical system adjustment variable. In this way, the control means 11 can automatically adjust the optical system adjustment variable, which is the environment of the optical system, using the linear conversion formula and the average density dav obtained for the image of the monitoring window.
[0035]
As described above, the shutter speed and the irradiation light amount selected as the optical system adjustment variables in the optical system environment are automatically adjusted. Next, the remaining lens focus and aperture setting in the environment of the optical system will be described. The focus and aperture of the lens are obtained by displaying an image obtained by photographing the subject 2 with the imaging unit 4 on the monitor 18 and the operator adjusting the focus knob and the aperture knob while viewing the screen of the monitor 18. Is set. The focus and stop of the lens may be set based on a quantified index as described below, without relying on an operator's visual judgment.
[0036]
The focus of the lens can be quantified and set by giving the above-mentioned image processing means 6 the following functions. The image processing means 6 performs image processing for first-order differentiation of the density of the image photographed by the imaging means 4 and calculating a difference sum that is a sum of density differences obtained by the first-order differentiation. The difference sum by the first derivative of the image density is obtained in a state where the focus knob is turned and each value is set within a predetermined range. Among the difference sums obtained for each setting value of the focus knob, the position of the focus knob showing the maximum difference sum is selected and set as the optimum focus value.
[0037]
The lens aperture can be quantified and set by providing the image processing means 6 with the following functions. The image processing means 6 obtains the density distribution of the image photographed by the imaging means 4 and further performs an operation for obtaining a density width Dw that is an absolute value difference between the maximum density value Dmax and the minimum value Dmin based on the density distribution. . FIG. 3 is a diagram showing an example in which the image density distribution is obtained by the image processing means 6. In FIG. 3, the density is shown on the horizontal axis, and the frequency of the density is shown on the vertical axis in terms of the number of pixels. The density width Dw is given by the absolute value difference (| Dmax−Dmin |) between the density maximum value Dmax and the density minimum value Dmin given by the line 35 indicating the density distribution. The density width Dw in the image density distribution is obtained in a state where the lens aperture knob of the CCD camera 14 is turned and set to each value within a predetermined range. Among the density widths Dw obtained for each setting value of the aperture knob, the position of the aperture knob showing the maximum density width is selected as the optimum value of the aperture.
[0038]
As described above, in the present embodiment, the focus knob and diaphragm knob are manually adjusted by the operator, but the focus knob and diaphragm knob values are displayed on the monitor 18 as table data, and the input means 5 selects each value. The input may be adjusted via the processing circuit 20 and the imaging display controller 16.
[0039]
FIG. 4 is a flowchart for explaining an image processing method according to an embodiment of the present invention. An image processing method using the image processing apparatus 1 shown in FIG. 1 will be described with reference to FIG. In step s0, the image processing apparatus 1 shown in FIG. 1 and the subject 2 are prepared, and the imaging of the subject 2 can be started. In step s1, a fixed environment is set. Here, the fixed environment means the focus and stop of the lens provided in the image pickup means 4. In the present embodiment, the focus and aperture of the lens are set once by the operator, and then are used without being automatically adjusted by the image processing apparatus 1 and fixed to the set conditions. Call it.
[0040]
FIG. 5 is a flowchart for explaining the fixed environment setting operation. The fixed environment setting operation in step s1 shown in FIG. 4 will be described with reference to FIG. In step s11, the shutter speed of the CCD camera 14 is temporarily set. The shutter speed is set to, for example, 1/60 (1/60) second or 1/100 (1/100) second if the subject 2 is stationary, and the moving speed if the subject 2 is moving. It is set to a value according to. In step s12, the irradiation light quantity of the illumination means 3 is temporarily set. In the present embodiment, the operator temporarily sets the irradiation light amount while observing the image of the subject 2 displayed on the monitor 18.
[0041]
In step s13, the focus of the lens, which is one of the fixed environments, is set. In the present embodiment, the focus setting of the lens, that is, the focus adjustment is performed so that the operator turns the focus knob while observing the image of the subject 2 displayed on the monitor 18 to achieve a suitable focus. The focus adjustment is not limited to a method performed by the operator while observing the monitor 18, and the image including the subject 2 is first-order differentiated by the image processing unit 6 as described above to calculate a density difference sum. Alternatively, a method of setting the focus knob value that maximizes the difference sum as the optimum focus may be used.
[0042]
In step s14, the lens aperture, which is one of the fixed environments, is set. In the present embodiment, the lens aperture setting, that is, the adjustment of image brightness and contrast, is performed by the operator turning the aperture knob while observing the image of the subject 2 displayed on the monitor 18 to obtain a suitable image brightness. And contrast. The aperture adjustment is not limited to a method performed by the operator while observing the monitor 18, and the image processing means 6 calculates the density distribution and the density width Dw of the image including the subject 2 as described above. A method of setting an aperture stop value that maximizes the density width Dw as an optimum aperture may be used.
[0043]
Returning to FIG. 4, in step s2, an adjustment environment is set. Here, the adjustment environment means the shutter speed of the CCD camera 14 provided in the imaging unit 4 and the amount of light irradiated by the illumination unit 3. Since the shutter speed and the irradiation light amount are automatically adjusted in the image processing apparatus 1 based on the linear conversion formula by the above-described linear conversion formula creation means 10 when the image density is outside the monitoring density range under the set environment. Called the adjustment environment. However, in this step s2, the shutter speed and the amount of irradiation light are set by the operator without any automatic adjustment yet.
[0044]
FIG. 6 is a flowchart for explaining the adjustment environment setting operation. The adjustment environment setting operation in step s2 shown in FIG. 4 will be described with reference to FIG. In step s21, in a state where the fixed environment is set, the operator finely adjusts and resets the shutter speed temporarily set in the previous step s1. At this time, if the subject 2 is in a moving state, care must be taken not to exceed the limit of the slower shutter speed with respect to the moving speed of the subject 2 in order to prevent the image from blurring. In step s22, in a state where the fixed environment is set, the irradiation light amount temporarily set in the previous step s1 is adjusted and set while the operator observes the image displayed on the monitor 18.
[0045]
Returning to FIG. 4, in step s3, environmental monitoring is set. In this step, a monitoring window and a monitoring concentration are set in order to monitor the environment of the optical system set in steps s1 and s2 during actual operation such as solid identification and inspection. FIG. 7 is a flowchart for explaining the environment monitoring setting operation. The environment monitoring setting operation in step s3 shown in FIG. 4 will be described with reference to FIG.
[0046]
In step s31, in the imaging screen obtained including the subject 2, a monitoring window as illustrated in FIG. 2A is provided at a site where the environment of the optical system is to be monitored. In step s32, the image processing means 6 obtains the set average density dav of the monitoring window. In step s33, a monitoring density range is set based on the average density dav obtained for the monitoring window. In the present embodiment, the monitoring concentration range is set to ± 10% of the average concentration dav obtained for the monitoring window, that is, a range of 0.90 dav to 1.10 dav.
[0047]
In step s34, it is determined whether or not a predetermined number of monitoring windows are set according to the type of subject 2. In this determination, the number of monitoring windows to be set for each type of subject 2 is stored in the RAM 7 as table data, and is set as an initial value “0”, and each time one monitoring window is provided, This can be done by adding “1” to the initial value and comparing the result of the addition with the number of monitoring windows read from the RAM 7 described above. When the determination result is negative and the number of set monitoring windows is less than the value read from the RAM 7, the process returns to step s31, and the steps after setting the monitoring window are repeated. When the determination result is affirmative and the number of set monitoring windows matches the value read from the RAM 7, the process proceeds to the main flow.
[0048]
Returning to FIG. 4, in step s4, automatic adjustment and setting of the optical system environment are performed. The environment of the optical system that is subject to automatic adjustment in this step is the shutter speed and the amount of irradiation light, which are the adjustment environment described in step s2. In this step, either shutter speed or irradiation light quantity is selected as an optical system adjustment variable, a linear conversion formula between the selected optical system adjustment variable and the image density is created, and the image density in the monitoring window is monitored. When there is a monitoring window in which the image density is outside the monitoring density range, the shutter speed or irradiation light amount selected as the optical system adjustment variable is automatically adjusted and set based on the linear conversion formula.
[0049]
FIG. 8 is a flowchart for explaining the operation of creating a linear transformation equation. With reference to FIG. 8, the linear transformation formula creation operation in the optical system environment automatic adjustment setting operation in step s4 of FIG. 4 will be described. In step s411, the selection unit 9 selects, as an optical system adjustment variable, one of the environmental factors of the optical system, which is the shutter speed or the irradiation light amount, which is the adjustment environment.
[0050]
When the illumination unit 3 has only a function of manually adjusting the amount of irradiation light, the shutter speed is inevitably selected as the optical system adjustment variable. When the moving speed of the subject is high, the shutter speed is set to a short time according to the moving speed, and the adjustment range can hardly be set. Therefore, the irradiation light quantity is necessarily selected as the optical system adjustment variable. .
[0051]
In step s412, it is determined whether or not the selected optical system adjustment variable is a shutter speed. When the determination result is affirmative and the shutter speed is selected, the process proceeds to step s413. When the determination result is negative and the irradiation light amount is selected, the process skips to step s414. In step s413, when the subject is in a moving state, a lower limit value (slower limit value) is set for the shutter speed. This prevents over processing time and video blur. When adjustment is not possible within a range equal to or higher than the lower limit value of the shutter speed defined as the specification of the imaging means 4 and adjustment is performed in a moving state taking into account processing time and image blurring, “no adjustment” is selected. Select “with adjustment” to obtain an adjustment variable by making it stand still.
[0052]
In step s414, it is determined again whether or not the optical system adjustment variable is the shutter speed. When the determination result is affirmative and the optical system adjustment variable is the shutter speed, the process proceeds to step s415. When the determination result is negative and the optical system adjustment variable is the irradiation light amount, the process proceeds to step s416. In step s415, the shutter speed is changed to all shutter speeds within a predetermined change range, and the image density in the monitoring window at each shutter speed is obtained. On the other hand, in step s416, the irradiation light amount is changed to the total irradiation light amount within a predetermined fluctuation range, and the image density in the monitoring window at each irradiation light amount is obtained.
[0053]
In step s417, a linear conversion formula is created from the relationship between the shutter speed and the image density, or the relationship between the irradiation light quantity and the image density. In step s418, a boundary value between the “flat part” and “conversion unit” in the created linear conversion equation is obtained, and the boundary value is stored in the RAM 7 together with the linear conversion equation. In the case where a “flat part” does not occur in the linear transformation equation, there may be no boundary value. In step s419, it is determined whether or not a linear conversion formula has been created for a number of monitoring windows that are predetermined according to the type of subject 2. If the determination result is negative, the process returns to step s414 to perform the subsequent steps. When the determination result is affirmative, the process proceeds to the main flow.
[0054]
FIG. 9 is a flowchart for explaining the operation of automatically adjusting and setting the optical system adjustment variable based on the linear conversion equation. At the start of step s420, a start step is provided so as to overlap with step s0 in the main flow. The operation of monitoring and diagnosing the image density in the monitoring window and automatically adjusting the optical system adjustment variable in response to the diagnosis result may be performed at all times during the production operation of the line. It is not preferable from the viewpoint of production efficiency because it is in a state of adjusted operation rather than production operation. Diagnosis and automatic adjustment of the optical system environment can be performed after the line has been stopped for a long period of time, and after the line operating conditions have been adjusted due to solid identification defects or inspection defects using the image processing device. It is preferable to be executed only when raising the machine. Therefore, a step for instructing the execution start is provided. In step s420, a signal instructing the monitoring of the optical system environment and the start of the automatic adjustment operation is input by operating a predetermined key on the input means 5.
[0055]
In step s421, the image including the subject is captured by the imaging unit 4. In step s422, the density of the image in the monitoring window (monitoring image density) is obtained. This monitoring image density is the average density dav of the image in the monitoring window. In step s423, the determination unit 8 compares the monitoring image density with the monitoring density range read from the RAM 7, that is, diagnoses the image density, and stores the diagnosis result in the RAM 7. In step s424, it is determined whether image density diagnosis has been performed for a predetermined number of monitoring windows depending on the type of subject. If the determination result is negative and the number of diagnosed monitoring windows is less than a predetermined number, the process returns to step s422 to perform the subsequent steps. If the determination result is affirmative and the number of diagnosed monitoring windows matches the predetermined number, the process proceeds to step s425.
[0056]
In step s425, the determination means 8 reads the diagnosis results for all the predetermined number of monitoring windows from the RAM 7, and determines whether there is a monitoring window whose monitoring image density is outside the monitoring density range. If the determination result is negative and the monitoring image density of all the monitoring windows is within the monitoring density range, the optical system environment is appropriate, and the process proceeds to step s431. In step s431, the determination unit 8 displays “monitoring OK” on the monitor 18 and outputs it to the output unit 24. The process proceeds to step s432 (s5), and the automatic adjustment operation of the optical system environment ends.
[0057]
On the other hand, when the determination result is affirmative and there is at least one monitoring window whose monitoring image density is outside the monitoring density range, “monitoring NG (No Good)” is displayed on the monitor 18 by the output signal from the determination means 8. It is displayed and output to the output means 24. At this time, the number of monitoring windows that are outside the monitoring density range of the monitoring image density is displayed at the same time.
[0058]
In step s427, the control unit 11 reads the linear conversion formula corresponding to the monitoring window stored in the RAM 7, and based on the linear conversion formula, the optical system adjustment variable corresponding to the average density dav that is the monitoring image density. Find the value. In step s428, the control unit 11 further automatically adjusts and sets the selected optical system adjustment variable so that the value of the optical system adjustment variable obtained in the previous step is obtained.
[0059]
In step s429, it is determined whether or not the adjustment of the optical system adjustment variable for the monitoring window in which the monitoring image density is outside the monitoring density range is completed for both the optical system adjustment variable, that is, the irradiation light amount and the shutter speed. . Note that when the irradiation light quantity is manually adjusted, or when the subject moving speed is fast and the shutter speed setting range is narrow, what can be used as an optical system adjustment variable is the irradiation light quantity or shutter speed. When only one of them is present, this step s429 is not executed and the process proceeds to the next step.
[0060]
When the determination result is negative, the process returns to step s421 and the subsequent steps are repeated. When the determination result is affirmative, that is, when the adjustment is completed for the monitoring window whose monitoring image density is outside the monitoring density range, but the output of “monitoring OK” is not obtained, the process proceeds to step s430. In step s430, the determination unit 8 displays “optical system environment abnormality” on the monitor 18 and outputs it to the output unit 24, and proceeds to step s432 (s5) to complete the optical system environment automatic adjustment operation.
[0061]
When “optical system environment abnormality” is output, it is determined whether the entire area of the imaging screen is abnormal or the specific area is abnormal depending on the number of monitoring windows that are “monitoring NG”. Check the items according to the order of items such as ball breakage, shutter speed abnormality, and other external environment abnormality. As a result of the inspection, for example, if the light source 12 is out of the ball, the lens is replaced, and then the environment of the optical system is reconstructed to execute diagnosis and automatic adjustment.
[0062]
【The invention's effect】
According to the present invention, among the environment setting items of the optical system, the shutter speed or the amount of irradiation light is set to an appropriate value quantitatively and automatically by a quantification means called a linear conversion formula. Therefore, it is possible to set the environment of the optical system with high reproducibility without requiring skill in the operator's skill.
[0063]
In addition, by diagnosing the suitability of the environment of the optical system, it is clear whether the cause of a detection failure in, for example, solid identification or inspection by image processing is due to an inappropriate optical system environment or a subject failure Can be. Therefore, it is possible to reduce the time required for analyzing the cause of the detection failure in the above-described individual identification and inspection.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a simplified configuration of an image processing apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a monitoring window setting state and a linear conversion equation;
FIG. 3 is a diagram illustrating an example in which an image density distribution is obtained by the image processing unit 6;
FIG. 4 is a flowchart illustrating an image processing method according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a fixed environment setting operation.
FIG. 6 is a flowchart illustrating an adjustment environment setting operation.
FIG. 7 is a flowchart illustrating an environment monitoring setting operation.
FIG. 8 is a flowchart illustrating an operation for creating a linear transformation equation.
FIG. 9 is a flowchart for explaining an operation of automatically adjusting and setting an optical system adjustment variable based on a linear conversion equation.
[Explanation of symbols]
1 Image processing device
2 Subject
3 lighting means
4 Imaging means
5 input means
6 Image processing means
7 RAM
8 Judgment means
9 Selection means
10 Linear transformation formula creation means
11 Control means
12 Light source
13 Power supply
14 CCD camera
15 A / D converter
16 Imaging display controller
17 frame memory
18 Monitor
19 D / A converter
20 Processing circuit
21 ROM
22 I / O interface

Claims (3)

An image processing method for setting an environment of an optical system that is a shooting condition when shooting a subject to be imaged and performing image processing of the shot subject,
One or more monitoring windows are set in the part to be monitored in the entire imaging screen obtained by photographing the subject ,
An average density dav which is an average value of image density is obtained for each monitoring window,
Determining whether the average density dav for each monitoring window is within a predetermined monitoring density range;
When there is at least one monitoring window in which the average density dav for each monitoring window is outside a predetermined monitoring density range, the shutter speed of the imaging unit that captures the subject or the illumination unit that irradiates the subject with light Select at least one of the light quantities as the optical system adjustment variable,
The selected optical system adjustment variable is changed, the image density of the monitoring window that varies with the change of the optical system adjustment variable is obtained, and given as the relationship between the optical system adjustment variable and the image density of the monitoring window. Create a linear transformation formula for each monitoring window ,
Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable An image processing method characterized by automatically adjusting the environment of an optical system by setting an irradiation light quantity. An image processing method for setting an environment of an optical system that is a shooting condition when shooting a subject to be imaged and performing image processing of the shot subject,
In a state where the shutter speed of the imaging means for photographing the subject and the irradiation light amount of the illuminating means for irradiating the subject with light are provisionally set to predetermined values, the focus and diaphragm of the lens provided in the imaging means are set,
Set the shutter speed of the imaging unit and the irradiation light amount of the illumination unit to desired values in the set lens focus and aperture environment,
One or two or more monitoring windows are set in a region to be monitored in the entire imaging screen by the imaging unit, and an average density dav that is an average value of image density is obtained for each monitoring window,
Determining whether the average density dav for each monitoring window is within a predetermined monitoring density range;
When there is at least one monitoring window in which the average density dav for each monitoring window is outside the monitoring density range, at least one of the shutter speed and the irradiation light amount is selected as an optical system adjustment variable,
The selected optical system adjustment variable is changed, the image density of the monitoring window that varies with the change of the optical system adjustment variable is obtained, and given as the relationship between the optical system adjustment variable and the image density of the monitoring window. Create a linear transformation formula for each monitoring window ,
Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable An image processing method characterized by automatically adjusting the environment of an optical system by setting an irradiation light quantity. In an image processing apparatus capable of setting an environment of an optical system, which is a photographing condition, when photographing a subject to be imaged and performing image processing of the photographed subject,
Illumination means capable of irradiating the subject with a variable amount of light;
An imaging means for photographing a subject, the imaging means capable of shutter speed, aperture and focus adjustment;
One or two or more monitoring windows are set in a region to be monitored in the entire image captured by the imaging means, image processing for obtaining the image density of the monitoring window is performed, and an average value of image density for each monitoring window Image processing means for calculating an average density dav and setting a monitoring density range based on the average density dav for each monitoring window ;
Storage means for storing the average concentration dav and the monitored concentration range;
Determining means for reading out the monitoring density range from the storage means and determining whether or not the density of the image of the monitoring window imaged by the imaging means is within the monitoring density range;
Selecting means for selecting at least one of the shutter speed and the irradiation light quantity as an optical system adjustment variable;
The optical system adjustment variable selected by the selection means is changed, the density of the image that fluctuates with the change of the optical system adjustment variable is obtained, and a linear conversion formula given as the relationship between the optical system adjustment variable and the image density is obtained. A linear conversion formula creating means for creating each monitoring window ;
Based on the linear conversion formula, the value of the optical system adjustment variable determined corresponding to the average density dav is obtained, and the shutter speed selected as the optical system adjustment variable so as to be the value of the obtained optical system adjustment variable Alternatively, an image processing apparatus comprising: a control unit that controls the amount of irradiation light, and automatically adjusting the environment of the optical system.

Images