JP5395925B2 - Image reading apparatus, image reading apparatus control method, and program - Google Patents

Description

  The present invention particularly relates to an image reading apparatus having a function of automatically determining whether an image of a document is a color image or a monochrome image, a control method for the image reading apparatus, and a program.

  In general, the image reading apparatus switches between storing image data as color or monochrome according to whether the document to be processed is a color document or a monochrome document. In an image reading apparatus having a color / monochrome determination function, scanning may be stopped even during scanning of a document image due to a specific factor such as waiting for processing of a host computer. As a method of reading and scanning a document image, a method of reading and scanning a document image by moving the line sensor along the document while the document is stopped, or a method of moving the document with respect to a fixedly arranged line sensor. There is a method of reading and scanning a document image.

  However, when scanning is stopped during scanning of a document image, the document and the scanning position of the line sensor may shift due to the inertia of the document or the line sensor. For this reason, line omission or line duplication occurs, and even a monochrome original may be tinted in the read image, and the monochrome original may be erroneously determined as a color image.

  Further, a technique for changing the determination condition (Patent Document 1) has been proposed in order to facilitate monochrome determination due to a decrease in scanning speed, but the relative relationship between the document being read and scanned and the line sensor is proposed. A misjudgment caused by speed change cannot be prevented.

Japanese Patent No. 2935505

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mechanism capable of preventing an erroneous determination of color / monochrome determination caused by a relative speed change between a document being scanned and a reading unit in an image reading apparatus. And

In order to achieve the above object, an image reading apparatus of the present invention includes a reading unit that scans and reads an image of a relatively moving document, a driving motor that relatively moves the document and the reading unit, and the reading Determining means for determining whether the image of the original is a color image or a monochrome image based on the image data of the original read by the means, wherein the determining means is a relative moving speed of the original with respect to the reading means, Alternatively, based on the motor speed information of the drive motor indicating either one of the movement speed changes , the color image determination criterion is changed between the acceleration section and the deceleration section to determine whether the document is a color image or a monochrome image. It is characterized by that.

The image reading apparatus of the present invention includes a reading unit that scans and reads an image of a relatively moving document, a drive motor that relatively moves the document and the reading unit, and an image of the document that is read by the reading unit. Based on the data, the determination means for determining whether the image of the document is a color image or a monochrome image, and the determination based on the motor speed information of the drive motor indicating a change in the relative movement speed of the document with respect to the reading means. Determining means for determining whether or not to determine a color image by the means, wherein the determining means determines whether or not a line constituting the read original image is a color line based on the number of color pixels. discriminated, based on the sequential number of the determined color line, when determining whether a color image, the reference and the determines whether or not the color line At least one of the criteria for determining whether the color image, the relative moving speed, or is changed in accordance with either the motor speed information of the drive motor shown one of a change of the moving speed, that characterized And

  According to the image reading apparatus of the present invention, it is possible to prevent erroneous determination of color / monochrome determination caused by a relative speed change between the document being scanned and the reading unit, and to accurately determine whether the document is a color document or a monochrome document. Can be determined.

1 is a perspective view illustrating a state in which an image reading apparatus which is an example of an embodiment of the present invention is connected to a host computer via a communication cable. It is a schematic sectional drawing for demonstrating the internal structure of an image reading apparatus. It is a block diagram for demonstrating the circuit structure of an image reading apparatus. It is a flowchart for demonstrating a timer interruption process in case a stepping motor is constant speed. It is a flowchart for demonstrating a timer interruption process in case the stepping motor is decelerating. It is a flowchart for demonstrating a timer interruption process in case a stepping motor is accelerating. It is a flowchart for demonstrating the processing example of a color / monochrome determination. It is a figure which shows the relationship between the read image of a document, and the motor speed of the stepping motor in the image line position.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an image reading apparatus 1 that is an example of an embodiment of the present invention is connected to a host computer 2 via a communication line such as a communication cable 3.

  As shown in FIG. 2, the image reading apparatus 1 separates the originals 101 stacked on the original table 102 one by one by a paper feed roller 106 and sends them out to the conveyance path 108. The sent document 101 is transported along a transport path 108 by transport rollers 107, passes through a registration sensor 109 and an image sensor 104, and is discharged to a paper discharge unit 103.

  FIG. 3 is a block diagram for explaining a circuit configuration of the image reading apparatus 1.

  As shown in FIG. 3, the image reading apparatus 1 includes a CPU 202, a RAM 203, a ROM 204, a reading unit 206, a motor driver 207, a stepping motor 208, an external I / F 205, an image sensor 104, and LEDs 210R, 210G, and 210B. These blocks are connected to each other by a system bus 201 on the circuit board 200.

  The light sources 210R, 210G, and 210B include red, green, and blue LEDs, respectively, and sequentially irradiate the reading surface of the document 101 for a predetermined time by the lighting control of the CPU 202.

  The image sensor 104 receives the reflected light of the light irradiated on the reading surface of the original 101 from the light sources 210R, 210G, and 210B, and outputs an analog read image signal corresponding to the received light amount.

  The reading unit 206 performs A / D conversion on analog read image signals of red, green, and blue output from the image sensor 104, performs shading correction, and writes image data to the RAM 203.

  The stepping motor 208 is connected to the conveyance roller 107 by a gear or a belt (not shown), and is controlled by the CPU 202 via the motor driver 207. In the present embodiment, an example will be described in which the document conveyance amount corresponding to one pulse of the pulse signal used to drive the stepping motor 208 is equal to the interval of one line of each color read by the image sensor 104.

  The CPU 202 controls the entire image reading apparatus 1 based on a program stored in the ROM 204.

  Specifically, the CPU 202 executes conveyance control for temporarily stopping the image reading operation of the original 101 by the image sensor 104 and stopping the conveyance roller 107. The CPU 202 determines whether the pixel is a color pixel or a monochrome pixel through all the pixels of the image data temporarily stored in the RAM 203. Further, the CPU 202 detects the conveyance speed (movement speed) of the document 101 at the time of reading each line, stores it in the RAM 203, and performs pixel color / monochrome determination using the pixel data and the conveyance speed in the line.

  The RAM 203 provides a work area to the CPU 202 and functions as a buffer memory that temporarily stores image data obtained from the reading unit 206 when the original 101 is read.

  The ROM 204 stores various programs and initial setting values. In the present embodiment, the ROM 204 stores a program for sequentially turning on the light sources 210R, 210G, and 210B while changing the relative positions of the document 101 and the image sensor 209 by the transport roller 107. The ROM 204 stores a program for reading light reflected from the original 101 by turning on the light sources 210R, 210G, and 210B by the image sensor 104 for each color line by line. Further, the ROM 204 stores a program including a conveyance control program for stopping the conveyance roller 107 when the reading operation for one document 101 is temporarily interrupted.

  Next, an operation example of the image reading apparatus 1 configured as described above will be described.

  When reading the image of the document 101, the CPU 202 controls the stepping motor 208 via the motor driver 207 and transports the document 101 at a predetermined speed in the sub-scanning direction by the transport roller 107.

  Next, when the CPU 202 detects that the conveyed document 101 has passed through the registration sensor 109, the light source 210 </ b> R, 210 </ b> G, 210 </ b> B is sequentially turned on and the image sensor 104 is started after a predetermined time.

  Specifically, the CPU 202 outputs a drive pulse to the stepping motor 208 and simultaneously turns on one of the light sources 210 </ b> R, 210 </ b> G, and 210 </ b> B and reads an image of one line from the image sensor 104. As a result, the image data of the entire conveyed document 101 is read.

  Here, assuming that the lighting order of the light sources 210R, 210G, and 210B is in the order of red, green, and blue, the original 101 is irradiated with light in the order of the light sources 210R, 210G, and 210B. The image sensor 104 receives reflected light from the original 101 each time the original 101 is irradiated with light of each color, and sequentially outputs an analog read image signal of one line corresponding to the received light quantity to the reading unit 206. Output.

  A read image signal of one line of each color of red, green, and blue sequentially output from the image sensor 209 is A / D converted by the reading unit 206, subjected to shading correction, and temporarily stored in the RAM 203.

  The image stored in the RAM 203 is subjected to a series of image processing by the CPU 202 and then transferred to the host computer 2 through the external I / F 205.

  The size of the image data stored in the RAM 203 is managed by the CPU 202, and the size increases as the image data is stored in the RAM 203 at the time of reading, and decreases by transferring the image data to the host computer 2. The image size that can be temporarily stored in the RAM 203 is determined in advance. When the transfer speed of the image data to the host computer 2 is slower than the image reading speed in the reading unit 206, the image data temporarily stored in the RAM 203 increases. However, the free space decreases.

  The CPU 202 uses the timer interrupt to control the driving of the stepping motor 208 via the motor driver 207, and also uses the timer interrupt to turn on the light sources 210R, 210G, and 210B and one line to the image sensor 104. Outputs a read signal. That is, the CPU 202 detects the passage of the document 101 through the registration sensor 109 and, after a lapse of a certain time, starts the lighting control of the light sources 210R, 210G, 210B and the drive control of the image sensor 104 by a timer interruption.

  The CPU 202 determines whether or not the free space in the RAM 203 is greater than or equal to a predetermined value. If the free space in the RAM 203 is equal to or greater than a predetermined value, the CPU 202 continuously drives the stepping motor 208 at a constant speed to rotate the transport roller 107 and continue reading the image of the document 101 by the image sensor 104.

  On the other hand, if the free space in the RAM 203 is less than the predetermined value, the CPU 202 controls the deceleration of the driving of the stepping motor 208, stops the conveyance roller 107, and interrupts the image reading of the document 101 by the image sensor 104. After that, the CPU 202 waits for the free space of the RAM 203 to be equal to or greater than a predetermined value, and then accelerates the driving of the stepping motor 208 to rotate the transport roller 107 and restarts image reading of the document 101 by the image sensor 104. .

  Next, with reference to FIG. 4 to FIG. 6, a timer interruption process executed during image reading of the original 101 by the image sensor 104 will be described. Each process in FIGS. 4 to 6 is executed by the CPU 202 after a program stored in the ROM 204 or the like is loaded into the RAM 203.

  First, as described above, after the image reading of the document 101 by the image sensor 104 is started, when a timer interruption occurs in a section in which an image is read at a constant speed, the “constant speed interruption” in FIG. 4 is called. Set it.

  In FIG. 4, in step S <b> 401, the CPU 202 outputs a drive pulse to the stepping motor 208 via the motor driver 207 to rotationally drive the transport roller 107, and the process proceeds to step S <b> 402.

  In step S402, the CPU 202 outputs a drive pulse for reading one line to the image sensor 104 and controls the lighting of the light sources 210R, 210G, and 210B to be changed, and the process proceeds to step S403. Note that changing the lighting of the light sources 210R, 210G, and 210B means, for example, changing from a state in which the red (R) light source 210R is turned on to a state in which the green (G) light source 210G is turned on.

  In step S403, the CPU 202 stores the current motor speed of the stepping motor 208 in the motor speed table Speed [y] stored in the RAM 203 in advance, and proceeds to step S404. Here, y is the scanning position in the sub-scanning direction read by the image sensor 104 with the image reading start position set to 0.

  In step S404, the CPU 202 sets an interrupt time for the timer interrupt, and proceeds to step S405.

  In step S405, the CPU 202 determines whether or not the free space in the RAM 203 is equal to or greater than a certain amount V. If the free space in the RAM 203 is equal to or greater than the certain amount V, it is determined that the free space in the RAM 203 is sufficient and ends this interrupt processing. To do. On the other hand, if the free capacity of the RAM 203 is less than the predetermined amount V in step S405, the CPU 202 proceeds to step S406.

  In step S406, the CPU 202 changes the interrupt vector to start the deceleration process for stopping the conveyance of the document 101, thereby changing the process called at the time of the timer interruption to the “deceleration interrupt process”, and ends the process.

  Next, the “deceleration interrupt process” will be described with reference to FIG. Note that steps S501 to S503 in FIG. 5 are the same as steps S401 to S403 in FIG.

  In FIG. 5, in step S504, the CPU 202 determines whether or not the stepping motor 208 cannot decelerate any more, that is, whether it is the minimum speed. If it is not the minimum speed, the process proceeds to step S506, and if it is the minimum speed, the process proceeds to step S505. .

  In step S505, the CPU 202 stops the timer and transitions to a temporarily suspended state. In the temporarily interrupted state, the CPU 202 monitors the availability of the RAM 203, and resets the timer interrupt for starting the acceleration process to start the conveyance of the document 101 when the available capacity becomes equal to or greater than a certain value (V). That is, the CPU 202 changes the interrupt vector to change the process called at the time of the timer interrupt to “accelerated interrupt process”, starts the timer interrupt, and ends the process.

  In step S506, the CPU 202 sets a timer value so that the stepping motor 208 rotates at a lower speed than the current time, and ends the process.

  Next, the “acceleration interrupt process” will be described with reference to FIG. Note that steps S601 to S603 in FIG. 6 are the same as steps S401 to S403 in FIG.

  In FIG. 6, in step S604, the CPU 202 sets a timer value so that the stepping motor 208 rotates at a higher speed than the current time, and the process proceeds to step S605.

  In step S605, the CPU 202 determines whether or not the stepping motor 208 has reached the target speed. If the target speed has been reached, the process proceeds to step S606, and if the target speed has not been reached, the interrupt process is terminated.

  In step S606, the CPU 202 changes from acceleration processing to constant speed processing. That is, the CPU 202 changes the interrupt vector, changes the process called at the time of the timer interrupt to “constant speed interrupt process”, and ends the process.

  In this way, the CPU 202 stores the image data of the original 101 read by the image sensor 104 and the motor speed of the stepping motor 208 in the RAM 203 while accelerating / decelerating the stepping motor 208.

  Next, a color / monochrome determination method will be described.

  The color / monochrome determination method determines that the image of the document 101 is a color image if the number of lines determined to be color lines continues for a fixed line (T). Color line discrimination refers to counting color pixels for each line, and if the counted color pixels are above a certain level, they are determined as color lines. That is, when (color pixel number)> (color line determination threshold), it is determined as a color line. Color determination in pixels for each line means color pixels when (lightness)> (lightness threshold for color pixel determination (reference value)) and (saturation)> (saturation threshold for color pixel determination (reference value)) It is determined.

  However, the brightness and the saturation are calculated by the HSV color space. That is, when the red, green, and blue output values of the pixels are R, G, and B, respectively, (lightness) = MAX (R, G, B), (saturation) = {MAX (R, G, B) -MIN (R, G, B)} / MAX (R, G, B).

  Next, a method for determining whether the image of the document 101 is color or monochrome from the image data temporarily stored in the RAM 203 and the motor speed data of the stepping motor 208 in each line will be described with reference to FIGS. To do. 7 is executed by the CPU 202 after a program stored in the ROM 204 or the like is loaded into the RAM 203.

  FIG. 8 is a diagram illustrating an example of a relationship between an image read from the original 101 by the image sensor 104 and the motor speed of the stepping motor 208 at the image line position.

  In the figure, y indicates the scanning position in the sub-scanning direction in the read image, and Speed [y] is the motor speed of the stepping motor 208 at the scanning position y. In FIG. 8, after the reading of the image of the original 101 is started at a constant motor speed of the stepping motor 208, the image is decelerated in the vicinity of y = 5, temporarily stopped in the vicinity of y = 6 to 7, and then the maximum acceleration is performed. In this example, the speed returns to a constant speed in the vicinity of y = 9.

  In FIG. 7, in step S700, the CPU 202 initializes a variable: cont indicating the number of continuous color lines to 0 when the image sensor 104 starts reading an image of the original 101, that is, when y = 0, and the process proceeds to step S701. move on.

  In step S701, the CPU 202 scans the image data temporarily stored in the RAM 203 from the upper end of the image and searches for a color line. At this time, if the line of interest is accelerating or decelerating, the CPU 202 skips the color line determination.

  For example, in the present embodiment, the CPU 202 is in an acceleration / deceleration state as compared with the motor speed Speed [y] stored in the RAM 203 for each line and the motor speed Speed [y-2] on two lines. To determine. That is, if Speed [y] ≠ Speed [y-2], the CPU 202 determines an acceleration / deceleration line and proceeds to step S706. If Speed [y] = Speed [y-2], the CPU 202 determines a constant speed line. Then, the process proceeds to step S702.

  In step S702, the CPU 202 determines whether it is a color line by the color line determination process. If it is determined to be a color line, the CPU 202 increments the number of continuous color lines cont in step S703, and proceeds to step S705.

  On the other hand, if it is determined in step S702 that the color is not a color line, the CPU 202 clears the continuous color line number cont in step S704 and proceeds to step S705.

  In step S705, the CPU 202 determines whether or not the color line continuation number cont is equal to or greater than a certain number of lines (T). The CPU 202 proceeds to step S708 when the color line continuation number cont is equal to or larger than the predetermined line number (T), and proceeds to step S706 when the color line continuation number cont is less than the predetermined line number (T).

  In step S708, the CPU 202 determines that the read image of the document 101 is a color image, and ends the process.

  On the other hand, in step S706, the CPU 202 increments the attention line y and proceeds to step S707.

  In step S707, the CPU 202 repeats the above processing until scanning to the lower end of the image data of the image data temporarily stored in the RAM 203. When scanning is performed to the lower end of the image, the read image of the document 101 is a monochrome image in step S709. And the process is terminated.

  As described above, in this embodiment, the color line determination processing of the speed of the stepping motor 208, that is, the acceleration / deceleration line of the conveyance speed of the original 101 or the lines before and after the temporary interruption is skipped. As a result, it is possible to reduce the erroneous determination of the color / monochrome determination due to the color misregistration caused by the unexpected movement of the original 101 due to the inertia force or the like due to acceleration / deceleration of the conveyance speed of the original 101 or temporary interruption of the conveyance.

  Further, by holding the value of the number of continuous color lines cont before and after the conveyance stop period of the original 101, color / monochrome determination can be performed as much as possible even for an image of the original 101 having a relatively small color area.

  In the present embodiment, the case where the color / monochrome determination process is skipped during the acceleration / deceleration line of the stepping motor 208 is exemplified, but the determination criterion for the color / monochrome determination in this section is based on the acceleration or deceleration of the stepping motor 208. May be changed.

  For example, in step 701 in FIG. 7, the color / monochrome determination process is skipped only in the vicinity of the pause section (proceeding in the YES direction). Then, the threshold value is changed between an acceleration section and a deceleration section that are not included in the vicinity of the temporary stop section. That is, in Speed [y−2] <Speed [y], color pixel determination is performed when (lightness)> (acceleration section lightness threshold) and (saturation)> (acceleration section saturation threshold). In Speed [y-2]> Speed [y], color pixel determination is made when (lightness)> (lightness threshold for deceleration zone) and (saturation)> (saturation threshold for deceleration zone). Further, when Speed [y−2] = Speed [y], color pixel determination is made when (lightness)> (constant speed interval lightness threshold) and (saturation)> (constant speed interval saturation threshold). .

  In this embodiment, the brightness threshold for color pixel determination, the saturation threshold for color pixel determination, and the color line determination threshold are changed based on the change in the document conveyance speed, but may be changed depending on the size of the document conveyance speed. Also good.

  Further, without skipping the color / monochrome determination process, the number T of lines used in the determination in step S705 or the color line determination threshold used in the color line determination in step S702 may be changed.

  In this embodiment, an example in which the color / monochrome determination is processed in the image reading apparatus 1 has been described. However, the image data and the motor speed table Speed [y] are transferred to the host computer 2 to perform the color / monochrome determination. You may make it process by 2 sides. In that case, a system in which the image reading apparatus 1 and the host computer 2 are connected corresponds to the image reading apparatus of the present invention, and a control method and program executed in the host computer 2 correspond to the control method and program of the present invention.

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in the above-described embodiment, the case where the document 101 is moved with respect to the fixedly arranged line sensor 104 is illustrated. However, the document image is read and scanned by moving the line sensor along the document while the document is stopped. In this case, the present invention can be applied. In this case, the motor speed of the stepping motor 208 is replaced with the motor speed of the drive motor that moves the line sensor.

  Moreover, in the said embodiment, since it is suitable to change both a lightness threshold value and a saturation threshold value, although both are changed, you may make it not change a lightness threshold value.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Host computer 3 Communication cable 101 Original 102 Original stand 103 Paper discharge part 104 Image sensor 106 Paper feed roller 107 Conveyance roller 108 Conveyance path 109 Registration sensor 200 Circuit board 201 System bus 202 CPU
203 RAM
204 ROM
205 External I / F
206 Reading unit 207 Motor driver 208 Stepping motor 210R Light source (red LED)
210G Light source (green LED)
210B Light source (blue LED)

Claims (6)

Reading means for scanning and reading an image of a relatively moving document;
A drive motor for relatively moving the document and the reading unit;
Determination means for determining whether the image of the document is a color image or a monochrome image based on the image data of the document read by the reading unit;
The determination unit is configured to display a color image in an acceleration section and a deceleration section based on motor speed information of the driving motor indicating either a relative movement speed of the document with respect to the reading section or a change in the movement speed. An image reading apparatus characterized by changing a determination criterion to determine whether a document is a color image or a monochrome image. A calculation unit that calculates saturation and brightness from image data of the document read by the reading unit;
The image reading apparatus according to claim 1, wherein the determination unit determines that the image of the document is a color image based on the saturation and brightness calculated by the calculation unit. Reading means for scanning and reading an image of a relatively moving document;
A drive motor for relatively moving the document and the reading unit;
Determining means for determining whether the image of the original is a color image or a monochrome image based on the image data of the original read by the reading means;
Determination means for determining whether or not to determine a color image by the determination means based on motor speed information of the drive motor indicating a change in the moving speed of the document relative to the reading means;
The determination means determines whether or not a line constituting the read image of the original is a color line based on the number of color pixels, and whether or not the line is a color image based on the number of consecutive color lines determined. In determining
At least one of the reference for determining whether or not the color line is the color image and the reference for determining whether or not the color image is the motor of the drive motor indicating either the relative movement speed or the change in the movement speed An image reading apparatus that is changed according to speed information.   The image reading apparatus according to claim 3, wherein the determination unit changes a determination criterion for a color image based on the relative moving speed or a change in the moving speed. A control method for an image reading apparatus, comprising: a reading unit that scans and reads an image of a relatively moving document; and a driving motor that relatively moves the document and the reading unit.
A determination step of determining whether the image of the document is a color image or a monochrome image based on the image data of the document read by the reading unit;
In the determination step, based on the motor speed information of the drive motor indicating either the relative movement speed of the document with respect to the reading unit or the change in the movement speed , the color image is detected in the acceleration section and the deceleration section. A control method for an image reading apparatus, characterized in that a determination criterion is changed to determine whether a document is a color image or a monochrome image. A program for controlling an image reading apparatus, comprising: a reading unit that scans and reads an image of a relatively moving document; and a drive motor that relatively moves the document and the reading unit, and is read by the reading unit. A determination step for determining whether the original image is a color image or a monochrome image based on the original image data;
Based on the motor speed information of the driving motor indicating either the relative moving speed of the document with respect to the reading means or the change in the moving speed, the color image in the determination step is determined in the acceleration section and the deceleration section . A program for causing a computer to execute a changing step for changing a determination criterion.

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