JP2021187110A - Image processing device, image processing method and program, reader and printer - Google Patents

Abstract

To provide an information processing device, an image processing method and program, a reader and a printer for processing gradation information on a read image by using a read image gradation information processing table corresponding to printing or reading.SOLUTION: An image processing device acquires a read image of an image printed on a base material, acquires at least one of printing information including ink color information when the image is printed and a reading condition including lighting information when the image is read, selects at least one read image gradation information processing table from a plurality of read image gradation information processing tables on the basis of at least one of the printing information and the reading condition, and processes gradation information on the read image by using the selected read image gradation information processing table.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image processing device, an image processing method and program, a reading device, and a printing device, and particularly relates to a technique for processing a scanned image obtained by reading a printed substrate.

A printing apparatus that performs inkjet printing on a transparent substrate using process color ink and white ink is known. In order to perform high-quality printing in such a printing apparatus, it is necessary to perform unevenness correction equivalent to that of process color ink and detection and correction of inspection of printed matter, etc. for white ink. However, when handling a transparent base material, the reading result by the reading device is different from that when the base material is paper, so it is necessary to devise even the detection and correction of the process color ink.

Patent Document 1 discloses an inspection device for inspecting a printed image printed on the surface of a transparent base material.

Japanese Unexamined Patent Publication No. 2019-142007

If the reading conditions of the reading device are devised to enable detection and correction, the characteristics of the read image differ greatly depending on the reading conditions, and there is a problem that the detection and correction of the post-process cannot be performed as expected by the common preprocessing. was there. Patent Document 1 does not solve such a problem.

The present invention has been made in view of such circumstances, and provides an image processing device, an image processing method and program, a reading device, and a printing device that process gradation information of a scanned image in response to printing or reading. The purpose.

One aspect of the image processing apparatus for achieving the above object includes a memory for storing an instruction to be executed by a processor and a processor for executing an instruction stored in the memory, and the processor is mounted on a base material. The scanned image of the printed image is acquired, and at least one of the print information including the ink color information when the image is printed and the scanning condition including the illumination information when the image is read is acquired and printed. At least one scanned image gradation information processing table is selected from a plurality of scanned image gradation information processing tables based on at least one of the information and the scanning conditions, and the scanned image is scanned using the selected scanned image gradation information processing table. It is an image processing device that processes the gradation information of.

According to this aspect, the gradation information of the scanned image can be processed according to printing or scanning.

The print information preferably includes information regarding the gradation of the image. This makes it possible to select a scanned image gradation information processing table according to the gradation of the image.

The information regarding the gradation of the image preferably includes at least one of the ink amount and the density. This makes it possible to select a scanned image gradation information processing table according to at least one of the ink amount and the density of the image.

It is preferable that the print information includes the functional information of the post-process using the gradation information processing image processed with the gradation information of the scanned image. This makes it possible to select a scanned image gradation information processing table according to the function of the subsequent process.

The functional information preferably includes at least one of bending amount detection of the nozzle of the inkjet head on which the image is printed, unevenness correction, and inspection of the printed matter. This makes it possible to select a scanned image gradation information processing table according to the amount of bending of the nozzle of the inkjet head, the correction of unevenness, and the inspection of printed matter.

The print information preferably includes information about the substrate. This makes it possible to select a scanned image gradation information processing table according to the substrate.

The substrate is transparent and the information about the substrate preferably includes at least one of thickness and light transmittance. This makes it possible to select a scanned image gradation information processing table according to at least one of the thickness of the transparent substrate and the light transmittance.

The lighting information preferably includes information on either reflected lighting or transmitted lighting. This makes it possible to select a scanned image gradation information processing table according to the reflected illumination and the transmitted illumination.

The processor uses a plurality of scanned image gradation information processing tables for each scanned image to hold a plurality of gradation information processing images processed with gradation information, and uses the plurality of gradation information processing images in a subsequent process. It is preferable to select at least one gradation information processing image. This makes it possible to select a gradation information processing image suitable for the subsequent process.

The processing of the gradation information of the scanned image may include a processing of reducing the number of gradation bits. This aspect is suitable for processing gradation information while reducing the number of gradation bits of the scanned image.

One aspect of the reading device for achieving the above object is an illumination that irradiates an image printed on a substrate with illumination light, an in-line sensor that reads the image printed on the substrate and generates a scanned image, and an in-line sensor. A reading device including the image processing device described above.

According to this aspect, the gradation information of the scanned image can be processed according to printing or scanning by an in-line sensor.

One aspect of the printing apparatus for achieving the above object is a printing apparatus including an inkjet head for applying ink to a substrate to print an image, and the reading apparatus described above.

According to this aspect, the gradation information of the scanned image can be processed according to the printing by the inkjet head or the reading by the inline sensor.

One aspect of the image processing method for achieving the above object is a scanned image acquisition step of acquiring a scanned image of an image printed on a substrate, and printing information including ink color information when the image is printed. , A printing information reading condition acquisition step of acquiring at least one of a reading condition including illumination information when an image is read, and a plurality of scanned image gradation information processing based on at least one of the print information and the reading condition. A table selection step of selecting at least one scanned image gradation information processing table from the table, and a gradation information processing step of processing the gradation information of the scanned image using the selected scanned image gradation information processing table. It is an image processing method to be provided.

According to this aspect, the gradation information of the scanned image can be processed according to printing or scanning.

One aspect of the program for achieving the above object is a program for causing a computer to execute the image processing method described above. A computer-readable non-temporary storage medium on which this program is recorded may also be included in this embodiment.

According to this aspect, the gradation information of the scanned image can be processed according to printing or scanning.

According to the present invention, the gradation information of the scanned image can be processed according to printing or scanning. Therefore, the detection and correction of the post-process can be appropriately carried out.

FIG. 1 is a diagram for explaining conversion of a read gradation value from 10 bits to 8 bits. FIG. 2 is a diagram for explaining the conversion of the read gradation value from 10 bits to 8 bits. FIG. 3 is a diagram showing an example of a scanned image obtained by scanning the same density chart and a scanned gradation value acquired from the scanned image. FIG. 4 is a diagram showing a read image of a density chart printed with white ink. FIG. 5 is a block diagram showing the configuration of the image inspection device 10. FIG. 6 is a flowchart showing an example of the image inspection method according to the first embodiment. FIG. 7 is a process diagram showing the processing of the image inspection device in the image inspection method. FIG. 8 is a flowchart showing an example of the image inspection method according to the second embodiment. FIG. 9 is a process diagram showing the processing of the image inspection device in the image inspection method. FIG. 10 is a flowchart showing an example of the image inspection method according to the third embodiment. FIG. 11 is a process diagram showing the processing of the image inspection device in the image inspection method. FIG. 12 is a schematic diagram of an inkjet printing apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Gradation conversion of scanned image>
The in-line sensor used in the inkjet printing apparatus has a reading gradation value of 10 bits. When linear conversion is performed when converting the read gradation value of this inline sensor from 10 bits to 8 bits, a "blackout" phenomenon occurs in which the read gradation value sticks to 0 in the low gradation region (high density part). ..

FIG. 1 is a diagram for explaining conversion of a read gradation value from 10 bits to 8 bits. F1A shown in FIG. 1 represents an example of the relationship between the reading pixel position and the reading gradation value of 10 bits. F1B shown in FIG. 1 represents a gradation conversion table used for gradation conversion from 10 bits to 8 bits. The horizontal axis of F1B is a 10-bit gradation value which is an input before gradation conversion, and a vertical axis is an 8-bit gradation value which is an output after gradation conversion. The gradation conversion table shown in F1B has linear input / output characteristics. Further, F1C shown in FIG. 1 shows the reading pixel position and the reading gradation at 8 bits when the 10-bit reading gradation value of F1A is gradation-converted to the 8-bit reading gradation value using the F1B gradation conversion table. It shows the relationship with the value.

As shown in F1C, when the gradation conversion from 10 bits (0 to 1023) to 8 bits (0 to 255) is linearly performed, the gradation values of the lower 3 bits of the 10 bits are all 0 in 8 bits.

Therefore, when the gradation conversion from 10 bits to 8 bits is performed, the gradation conversion is performed using a gradation conversion table that relatively increases the resolution of the high density portion.

FIG. 2 is a diagram for explaining the gradation conversion of the read gradation value from 10 bits to 8 bits. F2A shown in FIG. 2 represents an example of the relationship between the reading pixel position and the reading gradation value at 10 bits, and has the same relationship as F1A shown in FIG. F2B shown in FIG. 2 has a gradation having input / output characteristics in which the resolution in the low gradation region is relatively high (the gradation is raised) and the resolution in the high gradation region is relatively low (the gradation is laid down). Represents a conversion table. Further, F2C shown in FIG. 2 shows the reading pixel position and the reading gradation at 8 bits when the 10-bit reading gradation value of F2A is gradation-converted to the 8-bit reading gradation value using the F2B gradation conversion table. It shows the relationship with the value.

As shown in F2C, by using the gradation conversion table as shown in F2B, it is possible to appropriately convert to 8 bits without causing the blackout phenomenon. Since this blackout phenomenon is due to the characteristics of the inline sensor, a common gradation conversion table is used for all the scanned images.

<Technical issues>
When a common gradation conversion table is used, it is not possible to cope with cases where the optimum gradation conversion table differs depending on printing and reading. As an example, it is conceivable that the suitable gradation conversion table differs depending on whether the illumination of the reading device is reflected illumination or transmitted illumination.

FIG. 3 is a diagram showing an example of a scanned image obtained by scanning the same density chart and a scanned gradation value acquired from the scanned image. Here, a scanned image is acquired using a red (R), green (G), and blue (B) color CCD (Charge Coupled Device) linear image sensor, and the scanned gradation value is green (G). Shows the value. F3A in FIG. 3 shows a scanned image read by irradiating the base material with illumination light by reflected illumination. F3B in FIG. 3 shows the reading gradation value acquired from the read image of F3A, the horizontal axis of F3B is the position of the density patch, and the vertical axis is the reading gradation value.

Further, F3C in FIG. 3 shows a scanned image read by irradiating the base material with illumination light by transmitted illumination. F3D in FIG. 3 shows the reading gradation value acquired from the read image of F3C, the horizontal axis of F3B is the position of the density patch, and the vertical axis is the reading gradation value.

Comparing F3B and F3D, it can be seen that the reading gradation values are significantly different even though the density charts are the same, and the reading characteristics are greatly changed. Since the gradation conversion table greatly affects the reading characteristics of the reading device, it can be seen that it is necessary to hold different gradation conversion tables under the two conditions of reflected illumination and transmitted illumination and use them properly.

Further, it is conceivable that the suitable gradation conversion table is similarly different for the image printed with the process color ink and the image printed with the white ink.

FIG. 4 is a diagram showing a read image of a density chart printed with white ink. F4A in FIG. 4 shows the scanned image itself obtained by reading the density chart of the white ink, and F4B shows the scanned image in which the gradation of the scanned image of F4A is inverted. As shown in F4B, the density chart printed with white ink can use the same detection and correction algorithm as the density chart of process color ink by inverting the gradation of the scanned image. Therefore, it is necessary to keep different gradation conversion tables for the image printed with the process color ink and the image printed with the white ink, and use them properly.

Further, functions using the scanned image read by the in-line sensor include detection of bending amount of the nozzle of the inkjet head (NCP: Nozzle Check Print), unevenness correction (ACP: Auto Calibration Print), inspection of printed matter, and the like. However, even in these cases, the suitable gradation conversion table may differ.

For example, since unevenness correction requires a reading value that is particularly effective up to the high density portion, gradation conversion that relatively increases the resolution of the high density portion is effective as described above. On the other hand, in the nozzle bending detection, since the detection is performed in the low to medium density region, the gradation conversion different from the unevenness correction is effective. Further, in the inspection of printed matter, since the inspection is performed on an unspecified number of images, it is effective to use the gradation conversion table properly according to the gradation value used in the inspection image.

It is necessary to use a common gradation conversion table at the time of calibration for sensitivity correction for correcting the sensitivity difference between a plurality of light receiving elements of the inline sensor.

<Configuration of image inspection device>
The image inspection device 10 will be described. The image inspection device 10 is a device for acquiring a scanned image of an image printed on a base material and correcting and detecting the printing device that printed the image from the acquired scanned image.

FIG. 5 is a block diagram showing the configuration of the image inspection device 10. As shown in FIG. 5, the image inspection device 10 includes a higher-level system 12, a reading system 16, and an image processing unit 24.

The host system 12 includes an input device 14 and a display (not shown). The input device 14 includes an operation button, a keyboard, a touch panel, and the like. The host system 12 controls the reading system 16 and the image processing unit 24 according to the user from the input device 14.

Further, the host system 12 is provided with a communication interface (not shown) and is communicably connected to a printing device (not shown).

The reading system 16 acquires a scanned image of the image printed on the base material. Here, the image printed on the substrate is printed using at least one of a color ink and a white ink. The reading system 16 includes an in-line sensor 18, a reflective illumination 20, and a transmitted illumination 22.

The in-line sensor 18 includes an imaging device that captures an image printed on a substrate, converts it into an electrical signal, and generates a scanned image. A color CCD linear image sensor can be used as the image pickup device. A color CMOS (Complementary Metal Oxide Semiconductor) linear image sensor can also be used instead of the color CCD linear image sensor.

The reflected illumination 20 is a light source that irradiates the illumination light from the in-line sensor 18 side of the substrate toward the substrate. The reflective illumination 20 may be ring illumination that irradiates light toward the base material in a ring shape.

The transmitted illumination 22 is a light source that irradiates the substrate with illumination light from the side opposite to the in-line sensor 18 of the substrate.

The image processing unit 24 (an example of an image processing device) performs image processing including gradation conversion processing on the scanned image output from the scanning system 16, and corrects and detects the printing device based on the image after the image processing. And so on.

The image processing unit 24 includes a processor 26, a memory 28, a read image gradation information control unit 30, and a correction detection processing unit 34.

The processor 26 executes an instruction stored in the memory 28. The memory 28 stores an instruction for the processor 26 to execute. The processor 26 and the memory 28 cause the image processing unit 24 to perform desired image processing on the scanned image.

The hardware structure of the processor 26 is various processors (processors) as shown below. Various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) and functions as various processing units, and a GPU (Graphics Processing Unit), which is a processor specialized in image processing. Dedicated to execute specific processing such as programmable logic device (PLD), ASIC (Application Specific Integrated Circuit), which is a processor whose circuit configuration can be changed after manufacturing FPGA (Field Programmable Gate Array), etc. A dedicated electric circuit or the like, which is a processor having a designed circuit configuration, is included.

The processor 26 may be composed of one of these various processors, or may be composed of two or more processors of the same type or different types (for example, a plurality of FPGAs, or a combination of a CPU and an FPGA, or a CPU and a GPU). It may be composed of a combination).

Further, the hardware-like structure of these various processors is, more specifically, an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

The scanned image gradation information control unit 30 includes a scanned image gradation conversion table storage unit 32. The scanned image gradation conversion table storage unit 32 stores a plurality of scanned image gradation conversion tables (an example of a scanned image gradation information processing table) in association with at least one of print information and scanning conditions, respectively. .. The scanned image gradation information control unit 30 processes the gradation information of the scanned image using the scanned image gradation conversion table.

The correction detection processing unit 34 performs correction and detection regarding the printing device. For example, the correction detection processing unit 34 calculates the density correction value of the inkjet head (not shown) provided in the printing apparatus. Further, the correction detection processing unit 34 detects defective nozzles such as ejection failure nozzles from a plurality of nozzles (not shown) of the inkjet head. The calculated density correction value and the detected defective nozzle information are output to the printing apparatus via the host system 12.

Here, the image processing unit 24 includes the scanned image gradation information control unit 30, but the present invention is not limited to this configuration, and the scanning system 16 may include the scanned image gradation information control unit 30. Further, the processor 26 may perform the processing of the scanned image gradation information control unit 30 and the correction detection processing unit 34. Further, instead of the scanned image gradation conversion table storage unit 32, the memory 28 may store a plurality of scanned image gradation conversion tables.

<First Embodiment>
FIG. 6 is a flowchart showing an example of the image inspection method according to the first embodiment. Further, FIG. 7 is a process diagram showing the processing of the image inspection device 10 in the image inspection method. The image inspection method may be configured as a program realized by a computer. Further, the program may be recorded on a non-temporary information storage medium such as a CD-ROM (Compact Disc read-only memory). The program may be provided as a download service using a communication network such as the Internet.

In the first embodiment, an example of performing gradation conversion processing according to print information on a scanned image read by using reflected illumination will be described. The processing order, communication path, and the like are not limited to the examples of FIGS. 6 and 7.

In step S1, the user inputs the ink color of the image as an example of the print information using the input device 14. The host system 12 determines the ink color according to the input from the input device 14. Here, it is assumed that the determined ink color is white.

In step S2, the host system 12 transmits the determined ink color to the scanned image gradation information control unit 30. Here, the host system 12 transmits to the scanned image gradation information control unit 30 that the ink color is white.

In step S3 (an example of the print information reading condition acquisition process and an example of the table selection process), the scanned image gradation information control unit 30 acquires the ink color from the host system 12. Further, the scanned image gradation information control unit 30 has a scanned image gradation associated with the ink color acquired from a plurality of scanned image gradation conversion tables stored in the scanned image gradation conversion table storage unit 32. Select a conversion table. Here, the scanned image gradation information control unit 30 selects the scanned image gradation conversion table B associated with the white ink color.

In step S4, the host system 12 instructs the reading system 16 to read the image. Here, the host system 12 instructs the reading of the image using the reflective illumination 20. This image is an image printed on a substrate with white ink.

In step S5 (an example of the scanned image acquisition step), the scanning system 16 acquires the scanned image. That is, the reading system 16 irradiates the base material with the illumination light by the reflected illumination 20, and reads the image printed on the base material by the in-line sensor 18. I ₁ shown in FIG. 7 is an example of a scanned image reading system 16 has acquired. Here, the read image is data having 10-bit gradation information.

In step S6, the reading system 16 _{transmits the acquired read image I 1} to the image processing unit 24.

In step S7 (an example of the gradation information processing process), the scanned image gradation information control unit 30 of the image processing unit 24 has the scanned image gradation selected in step S3 with respect _{to the scanned image I 1 acquired in step S6.} The gradation conversion process is performed using the conversion table B. _{I 2} shown in FIG. 7 is an example of an image (an example of a gradation information processing image) after the gradation conversion process. The gradation conversion process includes a process of reducing the number of gradation bits. Here, the image after the gradation conversion process is data having 8-bit gradation information.

Finally, in step S8, the correction detection processing unit 34 performs image processing on the _{image I 2.} Here, since the image printed on the base material is a density correction chart, the correction detection processing unit 34 performs a process of calculating the density correction value for each nozzle based on _{the image I 2.}

With the above, the image inspection method is completed. The steps S2 to S7 of the image inspection method constitute an image processing method.

As described above, the print information of the image is acquired from the host system 12, the scanned image gradation conversion table associated with the acquired print information is selected from the plurality of scanned image gradation conversion tables, and the selected scanned image scale is selected. Since the gradation conversion of the scanned image obtained by scanning the image printed with the print information using the key conversion table is performed, the optimum gradation conversion processing can be performed on the scanned image, and the gradation can be performed. Post-processes such as high-quality detection and correction can be performed using the image after the conversion process.

According to the present embodiment, the ink color information is used as the print information, and the scanned image gradation conversion table associated with the color ink and the scanned image gradation conversion table associated with the white ink can be selected. It is possible to apply an original gradation conversion even to an ink having reading characteristics different from those of other color inks such as, and it is possible to share the image processing algorithm of the post-process with other color inks.

The host system 12 may acquire print information from the printing device via a communication interface (not shown).

The print information may include information about the gradation of the image, may include information about the base material, and include functional information of the post-process using the gradation information processing image processed with the gradation information of the scanned image. It may be possible to include information on the type of image.

The information regarding the gradation of the image may include at least one of the ink amount and the density. For example, a scanned image gradation conversion table associated with an image having a relatively large amount of ink and a scanned image gradation conversion table associated with an image having a relatively small amount of ink may be selectable. Further, the ink amount may be divided into multiple stages, and the scanned image gradation conversion table associated with each ink amount may be selectable.

Information about the substrate may include at least one of thickness and light transmittance. The light transmittance of the base material may be obtained as the type of the base material.

The functional information of the post-process may include at least one of bending amount detection of the nozzle of the inkjet head on which the image is printed, unevenness correction, and inspection of the printed matter. Nozzle bending amount detection is to detect the difference between the landing position of the ink ejected from each nozzle and the ideal landing position. The unevenness correction is to eliminate the variation in the ejection amount for each nozzle and correct the density unevenness of the image by adjusting the amount of ink ejected from each nozzle. The inspection of the printed matter is to detect the image defect generated in the printed matter in order to judge the quality of the printed matter.

The functional information of the post-process may be acquired as the mode of the printing apparatus. The image type information may include at least one of an NCP chart and an ACP chart (density chart).

<Second embodiment>
FIG. 8 is a flowchart showing an example of the image inspection method according to the second embodiment. Further, FIG. 9 is a process diagram showing the processing of the image inspection device 10 in the image inspection method. In the second embodiment, an example of performing gradation conversion processing on the scanned image according to the scanning conditions when the image printed with white ink is scanned will be described.

In step S11, the user inputs lighting information as an example of reading conditions using the input device 14. The illumination information is information about the illumination used in the reading system 16, and here includes information on either the reflection illumination 20 or the transmission illumination 22. The host system 12 determines the illumination to be used according to the input from the input device 14 to be either the reflection illumination 20 or the transmission illumination 22. Here, it is assumed that the determined illumination is the transmitted illumination 22.

In step S12, the host system 12 transmits the determined illumination information to the scanned image gradation information control unit 30. Here, the host system 12 transmits to the scanned image gradation information control unit 30 that the illumination is the transmission illumination 22.

In step S13 (an example of a print information reading condition acquisition process, an example of a table selection process), the scanned image gradation information control unit 30 acquires lighting information from the host system 12. Further, the scanned image gradation information control unit 30 has a scanned image gradation associated with the illumination information acquired from the plurality of scanned image gradation conversion tables stored in the scanned image gradation conversion table storage unit 32. Select a conversion table. Here, the scanned image gradation information control unit 30 selects the scanned image gradation conversion table A associated with the transmission illumination 22.

In step S14, the host system 12 instructs the reading system 16 to read the image. Here, the host system 12 instructs to read the image using the transmitted illumination 22 determined in step S11. This image is an image printed on a substrate with white ink.

In step S15 (an example of the scanned image acquisition step), the scanning system 16 acquires the scanned image. That is, the reading system 16 irradiates the base material with illumination light by the transmitted illumination 22, and reads the image printed on the base material by the in-line sensor 18. _{I 11} shown in FIG. 9 is an example of a scanned image acquired by the scanning system 16.

In step S16, the reading system 16 _{transmits the acquired read image I 11} to the image processing unit 24.

In step S17 (an example of the gradation information processing step), the scanned image gradation information control unit 30 of the image processing unit 24 has the scanned image gradation selected in step S13 with respect _{to the scanned image I 11 acquired in step S16.} The gradation conversion process is performed using the conversion table A. _{I 12} shown in FIG. 9 is an example of an image after the gradation conversion process.

Finally, in step S18, the correction detection processing unit 34 performs image processing on the _{image I 12.} Here, the correction detection processing unit 34 performs a process of calculating the density correction value for each nozzle based on _{the image I 12.}

With the above, the image inspection method is completed. Similar to the first embodiment, steps S12 to S17 of the image inspection method constitute an image processing method.

As described above, the image inspection device 10 acquires the reading conditions from the host system 12, selects and selects the scanned image gradation conversion table suitable for the acquired reading conditions from the plurality of scanned image gradation conversion tables. Since the scanned image gradation conversion table is used to perform gradation conversion of the scanned image obtained by scanning the image under the scanning conditions, the optimum gradation conversion processing can be performed on the scanned image. Post-processes such as high-quality detection and correction can be performed using the image after the key conversion process.

According to the present embodiment, by using the information regarding the lighting used in the reading system 16 as the reading condition, the original gradation conversion process can be performed regardless of whether the reflective lighting 20 or the transmitted lighting 22 is used. It can be applied, and the image processing algorithm of the post-process can be shared with other color inks.

The host system 12 may acquire the reading conditions from the reading system 16. The image processing unit 24 may acquire the reading conditions directly from the reading system 16. The illumination information may be information on the illuminance of the illumination light.

<Third embodiment>
FIG. 10 is a flowchart showing an example of the image inspection method according to the third embodiment. Further, FIG. 11 is a process diagram showing the processing of the image inspection device 10 in the image inspection method. A third embodiment describes an example in which a plurality of scanned image gradation conversion tables are used for one scanned image, and a plurality of images subjected to gradation conversion processing are held.

In step S21, the host system 12 instructs the reading system 16 to read the image. Here, the host system 12 instructs the reading of the image using the reflective illumination 20.

In step S22 (an example of the scanned image acquisition step), the scanning system 16 acquires the scanned image. That is, the reading system 16 irradiates the base material with the illumination light by the reflected illumination 20, and reads the image printed on the base material by the in-line sensor 18. _{I 21} shown in FIG. 11 is an example of a scanned image acquired by the scanning system 16.

In step S23, the reading system 16 _{transmits the acquired read image I 21} to the image processing unit 24.

In step S24 (an example of a table selection process and an example of a gradation information processing process), the scanned image gradation information control unit 30 of the image processing unit 24 refers to the scanned image level with respect _{to the scanned image I 21 acquired in step S22.} Gradation conversion processing is performed using a plurality of scanned image gradation conversion tables stored in the tone conversion table storage unit 32. _{I 22} shown in FIG. 11 is an example of an image after gradation conversion performed by using the scanned image gradation conversion table C, and I ₂₃ uses the scanned image gradation conversion table D. This is an example of an image after gradation conversion that has been subjected to gradation conversion processing.

In step S25, the image processing unit 24 saves the plurality of gradation-converted images converted in the gradation in step S24 in the memory 28.

In step S26, the image processing unit 24 acquires the function of the post-process using the image after the gradation conversion. The image processing unit 24 acquires the function of the post-process from, for example, the host system 12. Further, the image processing unit 24 selects the image after gradation conversion suitable for the function of the post-process from the plurality of images after gradation conversion saved in step S25. For example, the contrast of the entire image is calculated for each of a plurality of images after gradation conversion, and the image after gradation conversion having a large contrast is selected. The image processing unit 24 may include an image selection unit (not shown) that performs this processing. Further, the process of selecting an image may be performed by the correction detection processing unit 34, or the correction detection processing unit 34 may include an image selection unit.

Finally, in step S27, the correction detection processing unit 34 performs image processing on the image after gradation conversion selected in step S26. Here, the correction detection processing unit 34 calculates the density correction value for each nozzle based on the image after gradation conversion selected in step S26.

With the above, the image inspection method is completed. Steps S21 to S26 of the image inspection method constitute an image processing method.

As described above, the scanned image is subjected to gradation conversion processing using a plurality of scanned image gradation conversion tables, and the subsequent process is performed from among the plurality of images after gradation conversion that have undergone gradation conversion processing. Since the image after gradation conversion suitable for the above is selected, it is possible to appropriately perform post-processes such as correction and detection.

In the third embodiment, since the gradation conversion processing is performed using each of the plurality of scanned image gradation conversion tables, the processing amount is increased as compared with the first embodiment and the second embodiment. However, when performing an inspection to determine the quality of an image printed on a substrate based on a scanned image, an unspecified number of images are inspected, so the optimum scanned image gradation conversion table for inspection differs depending on the image. come. According to the third embodiment, since a plurality of images after gradation conversion can be compared, it is possible to select an image after gradation conversion suitable for inspection. For example, if the post-process is an inspection of printed matter, an image after gradation conversion processing that facilitates detection of image defects may be selected.

<Inkjet printing device>
The inkjet printing apparatus 50 to which the image inspection apparatus 10 is applied will be described. FIG. 12 is a schematic view of the inkjet printing apparatus 50. The inkjet printing apparatus 50 is a printing apparatus that prints an image on a web-shaped film substrate 1 which is a non-penetrating medium by a single pass method.

The film substrate 1 is a transparent medium used for flexible packaging. The film substrate 1 is, for example, ONY (Oriented Nylon), OPP (Oriented Poly Propylene), PET (Polyethylene Terephthalate). Transparency means that the transmittance of visible light is 30% or more and 100% or less, preferably 70% or more and 100% or less.

The inkjet printing apparatus 50 manufactures a back-printed printed matter in which the printing target is visually recognized from the surface opposite to the printing surface with respect to the film substrate 1.

As shown in FIG. 12, the inkjet printing apparatus 50 includes a plurality of pass rollers 52, inkjet heads 54K, 54C, 54M, 54Y, and 54W, and a reading system 16.

The inkjet printing apparatus 50 conveys the film substrate 1 to positions facing the inkjet heads 54K, 54C, 54M, 54Y, and 54W by a main feed roller (not shown), and subsequently faces the in-line sensor 18 of the reading system 16. Transport to the desired position. The plurality of pass rollers 52 are arranged at predetermined intervals along the transport path of the film base material 1 and guide the back surface side of the film base material 1.

The inkjet heads 54K, 54C, 54M, 54Y, and 54W are line-type recording heads that can be printed by one scan on the film substrate 1 to be conveyed, respectively. The inkjet heads 54K, 54C, 54M, 54Y, and 54W are each configured by connecting a plurality of head modules in the width direction of the film substrate 1.

In the inkjet heads 54K, 54C, 54M, 54Y, and 54W, nozzle surfaces (not shown) are arranged facing the pass roller 52 at regular intervals along the transport path. A plurality of nozzles, which are water-based ink ejection ports, are two-dimensionally arranged on the nozzle surfaces of the inkjet heads 54K, 54C, 54M, 54Y, and 54W.

The inkjet heads 54K, 54C, 54M, 54Y, and 54W eject black (K), cyan (C), magenta (M), yellow (Y), and white (W) water-based inks, respectively. The water-based inks K, C, M, and Y are color inks. The water-based ink of W is a white ink. The water-based ink refers to an ink in which a coloring material such as a dye or a pigment is dissolved or dispersed in water and a solvent soluble in water. As the pigment of each water-based ink, an organic pigment is used. Water-based ink is supplied to the inkjet heads 54K, 54C, 54M, 54Y, and 54W from ink tanks of corresponding colors (not shown) via piping paths (not shown).

At least one of the inkjet heads 54K, 54C, 54M, 54Y, and 54W ejects droplets of water-based ink toward the printing surface of the film substrate 1 to be conveyed. The ejected droplets are applied to the printing surface of the film base material 1, and an image is printed on the film base material 1. The inkjet printing apparatus 50 can produce a back-printed printed matter by printing an image with the inkjet heads 54K, 54C, 54M, and 54Y and then printing a white background image with the inkjet head 54W.

Although the configuration using four color inks and white ink is shown here, the ink color and the number of colors are not limited to the present embodiment. Further, the arrangement order of the inkjet heads of each color is not limited.

The in-line sensor 18 and the reflective illumination 20 of the reading system 16 are arranged on the side opposite to the printing surface of the film substrate 1 so as to face the film substrate 1. The transmissive illumination 22 is located at a position facing the in-line sensor 18 and is arranged on the printing surface side of the film substrate 1. The in-line sensor 18 and the reflective illumination 20 may be arranged on the printing surface side of the film substrate 1, and the transmission illumination 22 may be arranged on the side opposite to the printing surface of the film substrate 1. The reading system 16 is communicably connected to the host system 12 (see FIG. 5) and the image processing unit 24 (see FIG. 5).

The reading system 16 reads a test pattern image such as a density chart printed on the film substrate 1 with the inkjet heads 54K, 54C, 54M, 54Y, and 54W.

<Others>
The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined between the embodiments without departing from the spirit of the present invention.

1 ... Film substrate 10 ... Image inspection device 12 ... Upper system 14 ... Input device 16 ... Reading system 18 ... Inline sensor 20 ... Reflective lighting 22 ... Transmitted lighting 24 ... Image processing unit 26 ... Processor 28 ... Memory 30 ... Read image floor Tone information control unit 32 ... Read image gradation conversion table storage unit 34 ... Correction detection processing unit 50 ... Inkjet printing device 52 ... Pass roller 54C ... Inkjet head 54K ... Inkjet head 54M ... Inkjet head 54W ... Inkjet head 54Y ... Inkjet head S1 -S8 ... Each step of the image inspection method S11-S18 ... Each step of the image inspection method S21-S27 ... Each step of the image inspection method

Claims (14)

A memory that stores instructions for the processor to execute,
A processor that executes instructions stored in memory, and
Equipped with
The processor
Acquire the scanned image of the image printed on the base material and
At least one of the print information including the ink color information when the image is printed and the reading condition including the illumination information when the image is read is acquired.
At least one scanned image gradation information processing table is selected from the plurality of scanned image gradation information processing tables based on at least one of the print information and the reading condition.
Using the selected scanned image gradation information processing table, the gradation information of the scanned image is processed.
Image processing device. The image processing apparatus according to claim 1, wherein the print information includes information regarding the gradation of the image. The image processing apparatus according to claim 2, wherein the information regarding the gradation of the image includes at least one of an ink amount and a density. The image processing apparatus according to claim 2 or 3, wherein the print information includes functional information of a post-process using a gradation information processing image in which the gradation information of the scanned image is processed. The image processing apparatus according to claim 4, wherein the functional information includes at least one of bending amount detection of a nozzle of an inkjet head printed with the image, unevenness correction, and inspection of a printed matter. The image processing apparatus according to any one of claims 2 to 5, wherein the print information includes information about the base material. The substrate is transparent and
The image processing apparatus according to claim 6, wherein the information regarding the substrate includes at least one of a thickness and a light transmittance. The image processing apparatus according to any one of claims 1 to 7, wherein the illumination information includes information on either reflection illumination or transmission illumination. The processor
The plurality of scanned image gradation information processing tables are used for the scanned images to hold a plurality of gradation information processing images processed with gradation information.
At least one gradation information processing image to be used in the subsequent process is selected from the plurality of gradation information processing images.
The image processing apparatus according to any one of claims 1 to 8. The image processing apparatus according to any one of claims 1 to 9, wherein the processing of the gradation information of the scanned image includes a processing of reducing the number of gradation bits. Illumination that irradiates the image printed on the substrate with illumination light,
An in-line sensor that reads an image irradiated with the illumination light and generates the read image,
The image processing apparatus according to any one of claims 1 to 10.
A reader equipped with. An inkjet head that applies ink to the substrate and prints the image,
The reading device according to claim 11,
A printing device equipped with. A scanned image acquisition process for acquiring a scanned image of an image printed on a substrate, and
A print information reading condition acquisition step for acquiring at least one of a print information including ink color information when the image is printed and a reading condition including illumination information when the image is read.
A table selection step of selecting at least one scanned image gradation information processing table from a plurality of scanned image gradation information processing tables based on at least one of the print information and the reading condition.
A gradation information processing step of processing the gradation information of the scanned image using the selected scanned image gradation information processing table, and
Image processing method comprising. A program for causing a computer to execute the image processing method according to claim 13.

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