JP2001219546A - Method for inspecting printed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for judging whether a fault exists or not in a density unevenness or a color tone of a printed product outputted from a printer. SOLUTION: The method for inspecting the printed product utilizes that the product fundamentally has sixteen colors (in the case of using four color inks). Colorimetric values of the sixteen colors are previously prepared in an ideal color table. A read image of the product to be inspected is partitioned to many reading blocks. Whether the respective blocks are constituted of only ideal colors or not are judged to inspect the presence or absence of the density unevenness or the fault in the color tone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for inspecting a printed matter output from a printing press.

[0002] Printed matter output from a printing machine needs to be printed in a desired color. However, since the printing operation is affected by a change factor such as a change in the ink component or a change in the printing pressure, the printed matter may deviate from a desired color.

[0003] The present invention relates to an inspection method for inspecting whether a printed matter is printed in a desired color.

[0004]

2. Description of the Related Art Conventionally, "detection of density unevenness" of printed matter has been conventionally performed.
2. Description of the Related Art In a printing apparatus provided with an inspection device for performing "color tone abnormality determination" or the like, inspection is performed as follows.

First, a normal printed matter is output. At this time, a skilled person visually checks the printed matter and checks for “density unevenness” and “color tone abnormality”. When a normal printed matter is obtained, the printed matter is read by the reading means and the read image is stored as a reference image.

After the above preparation, actual printing is performed, and for each print output, a difference in gradation between the read image of the printed matter and the reference image is obtained. If the difference exceeds a predetermined threshold value, It is determined that “density unevenness” and “color tone abnormality” are present.

[0007]

However, this method has the following problems.

A skilled worker is required to obtain a reference image.

[0009] The conditions for reading the reference image and the conditions for reading the printed matter for printed matter determination must match. That is, it is necessary to adjust the reading start position, scanning line, resolution, reading magnification, and the like.

[0010] A fine inspection at a halftone dot level cannot be performed.

[0011]

According to a first aspect of the present invention, there is provided a printed matter inspection method, comprising the steps of: preparing an ideal color table in which an ideal color of a minute portion constituting a printed matter to be inspected is associated with a color specification value; Reading a printed object to be inspected into small parts, reading the printed data of the inspected object, and reading the read data of the printed object to be inspected from the ideal color table; And a determination step of determining whether or not the printed material to be inspected is printed in a desired color according to the result of the comparison.

[0012] If density unevenness or color tone abnormality occurs in a printed matter, the printed matter includes a minute portion of a color different from an ideal color uniquely determined by paper or ink used in the printed matter. According to the present invention, by detecting such a minute portion having a color different from the ideal color, it is possible to easily detect density unevenness and abnormal color tone of a printed matter.

[0013] A printed matter inspection method according to a second aspect of the present invention includes the first aspect.
In the printed matter inspection method according to the invention, the determining step calculates a difference between read data of a minute portion of the printed matter to be inspected and the color specification value of the ideal color, and compares the difference with a predetermined threshold value. And a process.

According to the present invention, it is possible to more easily detect uneven density and abnormal color tone of a printed matter.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <1. Concept of the Present Invention> Printed matter is created by selectively depositing a single color or a plurality of colors of ink on paper. Therefore, when using CMYK four color inks, microscopically, a portion where no color ink is printed, a portion where only one color ink is printed, and a portion where two color inks are overprinted And a portion in which three colors of ink are overprinted and a portion in which four colors of ink are overprinted, and there are 16 combinations. That is, the original is composed of only paper, C, M, Y, K, a mixture of C and M colors,
Mixed color of color and Y, mixed color of C and K, mixed color of M and Y, mixed color of M and K, mixed color of Y and K, C
Mixed color of color, M color and Y color, mixed color of C color, M color and K color,
It is composed of 16 minute portions of a mixed color of C, Y, and K colors, a mixed color of M, Y, and K colors, and a mixed color of C, M, Y, and K colors.

If the output printed matter is printed normally, the color of each minute portion obtained by reading the printed matter at a high resolution (resolution at which dots constituting halftone dots can be read) is the above 16 colors. Converge on either. However, when "density unevenness" or "color tone abnormality" occurs in the output printed matter, a minute portion of a color other than the 16 colors is detected from the printed matter. In other words, a part where dots are formed (a part to which ink is to be attached) is not sufficiently colored due to a poor degree of ink adhesion, or a part where dots are not to be formed (a part to be made the color of paper). If the ink is blurred, a minute portion other than the 16 colors is detected. The output abnormality of the printed matter can be detected by calculating the amount of color difference between the color of the minute part of the printed matter and the 16 colors.

Further, by calculating the difference between the minute portion and the ideal color in the color space, it is possible to determine which of the four colors of ink for printing is insufficient or excessive.
It can be specified together with the location on the printed matter where the abnormality has occurred. According to this method, it is possible to specify which portion of the printed matter is which ink is insufficient / excess, and it is also possible to automatically control the ink key of the printing press corresponding to that portion. In this way, the printing press can be controlled so that a printed matter without "density unevenness" or "color tone abnormality" is always output.

<2. FIG. 1 shows a system configuration of an output device 1 according to an embodiment of the present invention. Hereinafter, the output device 1 will be described with reference to FIG.

The output device 1 includes a printing machine 10 and a reading device 2
0, a system in which the output abnormality inspection devices 30 are appropriately connected to each other by a bus line BL via an interface (I / F). The printing machine 10 prints and outputs the printed matter 2. The image of the printed matter 2 is read by the reading device 20. The obtained read image data is inspected by the output abnormality inspection device 30 to determine whether the printed matter 2 is printed in a predetermined color and whether there is an output abnormality such as a color tone abnormality or density unevenness. The output abnormality inspection device 30 performs control such as stopping the printing press 10 based on the determination result.

Of these, the output abnormality inspection device 30
U31, ROM3 in which basic programs are stored
2, a RAM 33 for storing a color unevenness detection program, a printing press control program, etc., which will be described later, and a color unevenness detection program and a printing press control program stored on a magnetic disk or CD-RO.
A reading device 34 for reading from a storage medium 34a such as a M, a hard disk for storing programs and data from a keyboard or a mouse (not shown), etc.
/ F) is a device which is realized by executing a color unevenness detection program and a printing press control program by a CPU 31 or the like in a general computer connected by an internal bus line IB via the internal bus line IB. The color unevenness detection program and the printing press control program may be stored in the ROM 32 or the hard disk 37 in advance, and read out and stored in the RAM 33 for use. In that case, the ROM 32 or the hard disk 37 functions as a storage medium. .

The computer system is connected to an external bus line BL, and can communicate with various devices to exchange various data.

The functions described in the first and second embodiments described below are realized by the above-described device configuration.

<3. First embodiment >><< 3-1. Functional Configuration of First Embodiment >> FIG. 2 is a functional block diagram of an output device according to a first embodiment of the present invention. Hereinafter, the function of the output device 1 will be described with reference to FIG.

First, the printing press 10 will be described. The image input I / F unit 101 is an interface for receiving edited base image data before RIP expansion, such as an edited PS format, created by an external image editing layout device (not shown). After being temporarily stored in the image memory 106, it is sent to the RIP developing unit 102. The RIP developing unit 102 performs a tone change such as a screen gradation on the base image data, and then binarizes the data with a group of threshold values distributed at a high resolution in order to convert the tone value into a dot area. Expansion (raster expansion) is performed, and the obtained binary data is output to the beam output unit 103.
Send to Then, the beam output unit 103 performs printing on a plurality of plates for each color by ON / OFF controlling the beam at high resolution according to the binary data.

The printing unit 104 is a device for forming a color image on a printing sheet by sequentially printing a plurality of images on a single printing sheet. The printing unit 104 includes a plate cylinder for holding a plate, an ink key for supplying ink to the plate cylinder, a bracket cylinder, an impression cylinder, and a paper feed mechanism for supplying printing paper to the impression cylinder. A plurality of ink keys are arranged along the axial direction of the plate cylinder. The ink supply amount from each ink key can be individually controlled.

Further, the control system CPU 105 controls each section such as feeding of printing paper, switching of a group of RIP development thresholds, control of ink keys, and the like.

Next, the reading device 20 will be described.

The sensor reading unit 201 illuminates the printed matter 2 extracted from the printed matter output from the printing press 10 or all the printed matter 2 output from the printing press 10, and reads the printed matter 2 with an RGB sensor. Then, the obtained image data is subjected to shading correction and, if necessary, gamma conversion in the image processing unit 202. The image data after the image processing is sent to the output abnormality inspection device 30 through the external bus line BL.

Next, the output abnormality inspection device 30 will be described. This apparatus determines whether or not an abnormality such as “density unevenness” or “color unevenness” (hereinafter, collectively referred to as “output abnormality”) has occurred in the printed material 2 read by the reading device 20 (determination). Process), a process of notifying the operator of the determination result (warning process), a process of identifying a portion in the printed matter 2 where an output abnormality has occurred (abnormal location identifying process), a determination process and / or an abnormal location identifying process. This is a device that performs processing (control signal generation processing) for generating a control signal for controlling the printing press, such as stopping the printing press 10 or adjusting a desired ink key in the printing press 10.

As shown in FIG.
Is mainly based on the theoretical color database 301, RGB → Lab
Conversion section 302, peak coordinate calculation section 303, diffusion degree calculation section 304, determination section 305, printing press control signal generation section 306,
A display unit 307 is provided.

The ideal color database 301 has a plurality of tables having contents as shown in FIG. 3, for example. The table shown in FIG. 3 associates 16 colors (ideal colors of minute portions) reproducible in minute portions of the printed matter with the colorimetric values thereof. This table is for printing four specific colors of ink in a specific order on a specific color paper. For example, C, M, Y, K
, The colorimetric values of 16 colors reproduced when printing in the following order are held. So if you use different paper or ink,
Alternatively, when printing in a different order, the color tone of the minute portion on the printed matter also changes, so a table storing different colorimetric values is required. The ideal color database 301 includes a plurality of such tables.

The RGB → Lab converter 302 converts the RGB signal of each read pixel output from the reading device 20 into a CIE-
This is a means for converting into a lightness index L and chromaticity indices a and b in the Lab color space.

The peak coordinate calculator 303 is means for calculating one or a plurality of peak coordinates included in each read block (described later) of the printed matter 2.

The diffusivity calculating unit 304 is a means for calculating the diffusivity of the color of the minute portion constituting the printed matter for each reading block based on the peak coordinates calculated by the peak coordinate calculating unit 303.

The determination unit 305 includes a peak coordinate calculation unit 303
Is a means for judging whether or not the read block is printed in a normal color based on the peak coordinates of each read block calculated by and / or the diffusion degree of each read block calculated by the diffusion degree calculation unit 304. .

The printing press control signal generation unit 306 determines the judgment unit 3
This is a means for generating a control signal for controlling the printing press 10 by, for example, calculating the type and amount of ink required based on the determination result of step 05.

The display unit 307 is a device such as a CRT.
This is a means for notifying the operator of the determination result of the determination unit 305 and inputting necessary input information to the output abnormality inspection device 30.

<<< 3-2. Processing of First Embodiment >>
Hereinafter, the output abnormality inspection process according to the present invention will be described with reference to the flowchart of FIG.

First, an ideal color database 301 as shown in FIG. 3, for example, is prepared (step S.10).
It is desirable that the ideal color database 301 be prepared in advance for each type of paper and ink, and for each printing order. The ideal color database 301 is prepared by selecting a table that matches the conditions under which the printed material 2 to be inspected is printed from a plurality of tables prepared as described above.

Next, printing by the printing machine 10 is started (step S.20). The printed matter 2 is printed from the printing press 10 and output outside the printing press. Part of the printed matter is extracted from the printed matter 2 output from the printing press 10 and read by the sensor reading unit 201 at a high resolution. The obtained read image data is subjected to shading correction and, if necessary, gamma conversion and color conversion in the image processing unit 202 and sent to the output abnormality inspection device 30 via the external bus BL.

FIG. 5 illustrates a read block which is a unit of processing in the output abnormality inspection device 30. The ultimate purpose of the output abnormality inspection is to detect what portion of the printed matter 2 has an output abnormality.
In the output abnormality inspection device 30, the output abnormality is detected in units of the size of the read block. That is, if an output abnormality occurs even in a part of the read block, it is determined that the entire read block is abnormal.

The horizontal size (size in the axial direction of the plate cylinder) of each reading block is substantially the same as the width of the ink key.
The reading blocks are numbered consecutively from the lower left to the upper right.

Printed matter 2 sent to output abnormality inspection device 30
Is converted into Lab values (lightness index L and chromaticity indices a and b in the CIE-Lab color space) by RGB → Lab conversion means 302.

Based on the Lab value, the peak position calculator 303 calculates the peak coordinates of each read block, and the spread degree calculator 304 calculates the spread degree of each read block. On the other hand, the determination unit 305 determines eligibility / non-eligibility for all read blocks of the printed material 2 based on the peak coordinates and / or the degree of diffusion (step S.60).

The calculation of the peak coordinates, the calculation of the degree of diffusion, and the determination step will be described in detail with reference to the flowchart of FIG.

First, at step S. In 601, by setting the variable n to 1, the read block to be processed is set as the first block. Next step S. In step 603, a Lab value of a read pixel belonging to the first block is obtained. Next step S. At 605, the Lab value of the incorrect pixel is removed from the Lab values of all the pixels of the first block. Here, an incorrect pixel is, for example, a pixel that covers the edge of a halftone dot.

FIG. 7 schematically shows reading of the printed matter 2, in which one of the halftone dots constituting the printed matter 2 is enlarged. One halftone dot is composed of a plurality of dots. Each dot develops color when ink adheres to the printing paper. Since the read pixel 1 does not overlap any dot, only the paper color is detected from the read pixel 1. The color of the paper is
It belongs to one of the 16 ideal colors described above. On the other hand, since the read pixel 2 that reads the dot at the edge of the halftone dot reads both the paper color and the dot color at a time, a color that does not belong to any of the aforementioned 16 ideal colors is obtained from this read pixel. Is detected. If the determination is made based on the data of the read pixel 2, an inaccurate result will be obtained. Therefore, the read pixel data for reading the edge of the halftone dot should not be the basis for the output abnormality determination.
Such a read pixel that reads the edge of a halftone dot is determined to be a pixel whose difference in RGB value or Lab value from the eight surrounding pixels is extremely large.

Next, at step S. In step 606, a histogram is created for the remaining read pixels from which the read pixels for reading the edges of the halftone dots have been removed.

FIG. 8 shows step S. FIG. 6 is a schematic diagram of a histogram created in 606. The Lab value of the read pixel belonging to the processing target block is associated with the number of appearances. That is, the horizontal axis represents the Lab value, and the vertical axis represents the number of read pixels having the Lab value. Although the Lab value is originally a three-dimensional value, it is illustrated here as a one-dimensional value for ease of explanation. Since the printed matter eventually converges to 16 colors, 16 peaks are formed as shown.

The coordinates (Lab value) of the first peak are P1,
The coordinates (Lab value) of the second peak are referred to as P2, and the respective peaks are hereinafter referred to as P3 to P16.

A range of Lab values of a predetermined number of read pixels appearing around each peak coordinate is called a set. Each set is referred to as S1 to S16 in association with each peak P1 to P16.

FIG. 9 is a diagram showing a state in which the read pixels of the first block after the incorrect read pixels have been removed are plotted in a three-dimensional color space. The read pixel of the first block is
Distributed in a plurality of sets on the color space. Note that, as described above, the distribution is actually divided into 16 sets, but for simplicity, only five sets are shown in this figure.

Step S. At 607 (FIG. 6), peak coordinates P1 to P16 are detected.

Next step S. In step 608 (FIG. 6), step S. The ranges of the sets S1 to S16 are determined based on the histogram created in 606. The range of each set is determined by selecting a predetermined number of read pixels from those having values close to each peak coordinate.

As shown in FIG. 9, Lab values (Lab1 to Lab5) of ideal colors exist inside or near each of the sets S1 to S5. For example, the ideal color Lab1 is located inside the set S1. Near the outside of the set S2,
An ideal color Lab2 exists. Some peak coordinates have a small color difference from the ideal color (for example, peaks P1, P3, P
5) There are also peak coordinates far from the ideal color (for example, peaks P2 and P4). In this output abnormality inspection device 30,
The determination unit 305 calculates the separation distance between the peak coordinates and the ideal color in the color space, thereby detecting the abnormal coloring of the printed matter (step S.611). Specifically, peaks P1 to P1
A color abnormality is detected based on whether the difference (color difference ΔE) between the color coordinate value of No. 6 and the color coordinate value of the nearest ideal color is equal to or smaller than a predetermined threshold value. The color difference ΔE is calculated by Expression 1. (Equation 1) Here, d1 is a difference between two colors for the lightness index L, da
Is the difference between the two colors for the chromaticity index a, and db is the chromaticity index b
Is the difference between the two colors.

If it is determined that the read block to be processed includes peak coordinates that do not approximate any of the ideal colors, the determination unit 305 determines that the block is ineligible (step S.619). ).

Conversely, if it is determined that all the peak coordinates in the read block to be processed approximate one of the ideal colors, step S. Proceeding to 613, the diffusion degree calculation unit 3
04 is performed to detect the degree of diffusion.

The degree of diffusion refers to the degree of unity of the color of the read pixel. When the printed matter is properly printed, the Lab values of all read pixels are close to the Lab values of any of the ideal colors. On the other hand, when the printed matter is improperly printed, the Lab values of the read pixels are diffusely distributed. The output abnormality inspection device 30 calculates the diffusion degree for each set, and if at least one set having a diffusion degree equal to or greater than the threshold is included in the read block to be processed, the read block is invalid. Judge that there is.

The degree of diffusion will be described with reference to FIG.
The output abnormality inspection device 30 determines the diffusion degree based on the so-called half width. FIG. 10 shows the read pixels and La in the set S1.
9 is a histogram showing a relationship with a b value. The horizontal axis is Lab
The chromaticity index a is one component of the value, and the vertical axis indicates the number of read pixels in the set S1 indicating the chromaticity index a.

Since the Lab values of the read pixels in the set S1 are distributed around the peak coordinates P1 (Lab values: L1, a1, b1), the number of read pixels is the largest in the chromaticity index a1 of the peak coordinates P1. In many cases, the number of read pixels decreases as the distance from the chromaticity index a1 increases. Let N be the number of read pixels showing the chromaticity index a1. The chromaticity index (a0 and a0) of the read pixel that appears by the number N / 2 obtained by multiplying N by ２
2) is detected. Next, a difference | a0−a2 | between the chromaticity index a0 and the chromaticity index a2 is obtained. This value indicates the degree of diffusion for the chromaticity index a of the read pixels in the set S3.

Next, step S. In step 615, the diffusion degree | a0-a2 | is compared with a predetermined threshold value. If the threshold value is exceeded, the block is determined to have a high diffusion degree. Proceed to 619. On the other hand, if the diffusion degree is within the threshold value, the same processing as when the diffusion degree related to the chromaticity index a is obtained is performed for the Lab value components (the lightness index L or the chromaticity index b) other than the chromaticity index a. It is determined whether the degree of diffusion for the lightness index L or the chromaticity index b is within a predetermined threshold.

In the above example, the difference between the chromaticity index a0 and the chromaticity index a2 was obtained.
1 and / or chromaticity index a1 and chromaticity index a2
May be calculated to calculate the diffusion degree.

If it is determined that the diffusion degree is within the threshold for all the components of the Lab value, step S. Proceeding to 617, the block is determined to be eligible. Next step S. In step 621, it is determined whether all read blocks of the printed material to be processed have been processed. If there are undetermined blocks, the next processing block is obtained (step S.623), and step S.623 is performed again. The processing from 603 is started.

When the eligibility / non-eligibility of all the blocks is determined, the printing press control signal generator 306 calculates the amount of excess or insufficient ink for the non-eligible block (step S shown in FIG. 4). .80). If the number of unqualified blocks is too large, or if the unqualified blocks cannot be corrected, the printing machine 10 (FIG. 1) is stopped and the display unit 307 of the reading device 20 (FIG. 2).
May be displayed to notify the operator that the printing press has been stopped due to an output error.

The type and amount of excess / insufficient ink for the ineligible blocks are:

In the color space, the L of the ideal color is calculated from the peak coordinates.
It can be determined based on the magnitude and direction of the vector subtracted toward the ab value. If this vector is oriented in the L-axis plus direction, the type and amount of ink that can reduce only the brightness without changing the hue are calculated. Alternatively, the required type and amount of ink may be calculated from the degree of diffusion shown in FIG.

Next, at step S. Go to step S.90, and select the ink key corresponding to the unqualified block. Control is performed based on the type and amount of the excess / insufficient ink determined at 80 so that a print of a desired color is obtained.

<4. Second Embodiment> A second embodiment of the present invention will be described below. The difference between the second embodiment and the first embodiment lies in whether or not an ideal color database is prepared in advance.

Hereinafter, description will be made with reference to the flowchart of FIG.

First, an ideal image is prepared (step S.1). An ideal image is an image of a printed material without “density unevenness” or “color tone abnormality”. Most of each minute portion of the ideal image is printed in the ideal color.

The ideal image is read at a high resolution (resolution at which the dots constituting the halftone dots can be read) (step S.1).
3).

The pixel data of the read image is converted into uniform color space data (step S.5).

The peak coordinates are calculated for all the read blocks of the read image (step S.7). Each read block has 16 peak coordinates.

Next, the average of the uniform color space data values of the corresponding peak coordinates between the read blocks is obtained. For example, in the example of FIG. 9, the peak coordinates corresponding to the peak coordinates P1 of the first block are considered to be calculated in another read block (for example, the second block). The average of such corresponding peak coordinates is obtained. That is, the first
Block peak coordinates P1 (Lab values (L1, a1, b
1)), the peak coordinate P1 of the second block (Lab value (12, a2, b2), and the peak coordinate P of the third block).
1,. . . , The average value of the peak coordinates P1 (Lab values (Ln, an, bn)) of the n-th block for each Lab value component, that is, the lightness index L of the calculated average Lab value
Is (L1 + L2 + ... + Ln) / n, the chromaticity index a is (a1 + a2 + ... + an) / n, and the chromaticity index b is (b1 + b2 + ... + bn) / n.

The coordinates indicated by the average value are La of a specific ideal color.
It almost matches the b value. When such processing is performed for all peak coordinates, 16 average values are calculated. These are stored as an ideal color database of 16 ideal colors.

Thereafter, the process proceeds to step 20 in FIG. 4, and printing by the printing machine 10 is started. With respect to all or a part of the first output printed matter, the eligibility / non-eligibility of the inspection target image is determined by the same method as in the first embodiment, and the printing press 10 is controlled according to the determination result.

In the first and second embodiments, C
Although the IE-Lab color system has been described as an example, another uniform color space or a color system other than the uniform color space (eg, an RGB color system or an XYZ color system) may be used. However, in the uniform color space, since the three-dimensional color difference is guaranteed to be equal, the above-described calculation of the shift amount of the peak coordinates and the diffusion degree can be easily performed. When a color system other than the uniform color space is used, since the color difference differs depending on the color space position occupied by the color to be compared, the deviation amount of the peak coordinates from the ideal color Lab value and the magnitude of the diffusion degree are described above. In the eligibility / non-eligibility determination process based on, it is necessary to change the size of the threshold value according to the color space position.

In addition, the operation of judging eligibility / non-eligibility is described in RG
When performing based on the B color system, the sensor reading unit 201
It is desirable that the image processing unit 202 adds gamma conversion to extend the gradation of the shadow part to the RGB signal obtained in step (1). This is because the characteristics of the signal output from the sensor reading unit 201 are different from the human eye's relative luminous efficiency characteristics, and the RGB color space is pseudo-equalized by extending the gradation of the shadow part in advance. This is to enable use as a color space.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an output device according to a first embodiment.

FIG. 2 is a functional block diagram of the output device according to the first embodiment.

FIG. 3 is a diagram in which ideal colors of minute parts and colorimetric values are associated with each other in the first embodiment.

FIG. 4 is a flowchart illustrating an output abnormality inspection process according to the first embodiment.

FIG. 5 is a diagram illustrating a read block which is a processing unit in the output abnormality inspection device according to the first embodiment.

FIG. 6 is a flowchart illustrating a peak coordinate calculation, a diffusion degree calculation, and a determination process according to the first embodiment.

FIG. 7 is an enlarged view of a halftone dot in the first embodiment.

FIG. 8 is a schematic diagram of a histogram created in the first embodiment.

FIG. 9 is a drawing in which colorimetric values of read pixels are plotted in a color space in the first embodiment.

FIG. 10 is a histogram for explaining a method of calculating a diffusion degree in the first embodiment.

FIG. 11 is a flowchart illustrating an output abnormality inspection process according to the second embodiment.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C250 EB31 EB40 EB43 2G020 AA08 DA02 DA03 DA04 DA12 DA43 5B057 AA11 CE18 DA03 DB02 DB06 DB09 DC19 DC25 DC33

Claims (2)

[Claims] A step of preparing an ideal color table in which an ideal color of a minute portion constituting a printed matter to be inspected is associated with a color specification value; A reading step of acquiring read data of the printed matter; comparing the read data of the printed matter to be inspected with a color specification value of an ideal color read from the ideal color table; and, according to a result of the comparison, the printed matter to be inspected is A determination step of determining whether or not a print is performed in a desired color. 2. The method according to claim 1, wherein the determining includes calculating a difference between read data of a minute portion of a printed material to be inspected and the color specification value of the ideal color, and comparing the difference with a predetermined threshold value. The printed matter inspection method according to claim 1, further comprising: