JP2009232229A - Image processing system, image processing program and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily correct processing contents of color material amount limitation processing. <P>SOLUTION: A personal computer 1 transmits image data generated by representing an image to be printed by an RGB color system to a multifunction device 2 to instruct it to print. The multifunction device 2 once receiving the print instruction from the personal computer 1 performs total ink amount limitation processing for converting the image data (RGB data) into image data (RGB data) such that the total amount of ink used for the printing is limited. Then the image data of the RGB color system after the conversion are converted into image data of a CMYK color system corresponding to colors of ink, and the image is printed based upon the image data (CMYK data) after the conversion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing system, an image processing program, and an image processing method for limiting the amount of color material used for printing.

  2. Description of the Related Art Conventionally, printing apparatuses that print color images using a plurality of color materials (ink, toner, etc.) such as cyan (C), magenta (M), yellow (Y), and black (K) are known.

  In such a printing apparatus, image data representing an image to be printed (for example, RGB color system image data) is converted into a color system (for example, CMYK color system) corresponding to the color of the color material, and the converted image data Print an image based on Here, since the color of the image is expressed by overlapping each color material, depending on the color of the image, the total amount of the color material used to express the color becomes excessive, and a good printing result cannot be obtained. Sometimes.

In view of this, there has been proposed a method of printing an image after converting image data so that the total amount of color materials used for printing is limited. For example, a copying machine described in Patent Document 1 inputs RGB color system image data from an image input unit, converts the image data into CMYK color system image data corresponding to the color of the color material, and then converts the color data. The image data is further converted so that the total amount of the material is less than a preset regulation value, and then the image is printed.
JP 2003-125225 A

  By the way, the limit amount of the color material for obtaining a good printing result varies depending on the printing conditions such as the type of the color material and the type of the printing medium. It is preferable to correct the processing content of the color material amount restriction processing.

  However, as described above, the color material amount restriction process is generally executed by a program that is preliminarily incorporated in the printing apparatus, and the image data of the color system corresponding to the color of the color material is used. Since the processing is performed after the conversion to, the processing contents cannot be easily changed later.

  The present invention has been made in view of these problems, and an object thereof is to provide an image processing system, an image processing program, and an image processing method capable of easily correcting the processing content of the color material amount restriction processing. Yes.

  The image processing system according to claim 1 of the present invention, which has been made to achieve the above object, includes a creating means for creating a look-up table, and image data representing an image to be printed. Using a lookup table, conversion means for converting image data for printing expressed by values, and image data before being converted by the conversion means into image data in which the amount of color material used for printing is limited Limiting means for performing processing for limiting the amount of color material to be converted.

  According to such an image processing system, since color material amount restriction processing is performed before converting image data into image data for printing, it is possible to rewrite a program incorporated in the printing apparatus without rewriting. The processing content of the color material amount restriction process can be easily corrected (change of the color material restriction amount, addition of a lookup table, etc.). Note that the image processing system of the present invention can be configured as a single device (for example, a printing device) or a plurality of devices.

  Further, by using a look-up table, for example, when cyan toner is used, it is possible to easily perform complicated restrictions according to combinations of color materials to be used, such as limiting yellow toner. The calculation load for the amount limiting process can be suppressed.

  In addition, the look-up table can store information corresponding to printing conditions such as the type of color material used for printing and the type of print medium, but the color material and print medium are assumed in advance. There is a possibility that a different type from that used (a corresponding lookup table is not stored) is used. Even in such a case, an appropriate color material amount restriction process can be performed using a look-up table created according to printing conditions such as the type of color material and the type of print medium.

  Here, the creation of the lookup table can be performed as described in claim 2, for example. That is, in the image processing system according to claim 2, the creating unit converts the color value of the color patch with poor print result to the color value of the color patch with good print result based on the print result of the color patch. Create an uptable.

  According to such an image processing system, it is possible to easily create a look-up table for obtaining a good print result by preventing a decrease in print quality due to an excessive amount of color material used for printing. .

  In the image processing system according to claim 3, the image data for printing is expressed in an N-dimensional color space corresponding to the number of colors of the color material, and the image data to be converted by the conversion unit is M-dimensional. It is expressed in a color space of (M <N).

  According to such an image processing system, since the color material amount restriction process is performed on the image data for printing compared to the case where the color material amount restriction process is performed, the color material amount restriction process is simplified. It is possible to reduce the amount of memory used and improve the processing speed.

  In particular, in the image processing system according to claim 4, the limiting unit converts the image data expressed in a three-dimensional color space into image data expressed in a three-dimensional color space as a color material amount limiting process. Perform the process.

  According to such an image processing system, compared to the case where the color material amount restriction process is performed on the image data for printing, the gradation obtained by converting the image data after the color material amount restriction process into a three-dimensional monitor signal. Therefore, monitor simulation can be performed with high accuracy. This is because the image data after the color material amount restriction processing is expressed in a three-dimensional color space, and color matching can be performed on a three-dimensional monitor signal without reducing the number of dimensions. As a result, the output image after the color material amount restriction process can be simulated with higher accuracy than when the number of dimensions is reduced from N dimensions (N> 3) to 3 dimensions.

  Next, an image processing program according to claim 5 is an image for printing in which creation means for creating a look-up table and image data representing an image to be printed are expressed by color values of color materials used for printing. Conversion means for converting data, and color material amount restriction processing for converting image data before conversion by the conversion means into image data in which the amount of color material used for printing is restricted using a lookup table The computer system is caused to function as a limiting means.

  According to such an image processing program, it is possible to cause the computer system to function as the image processing system according to the first aspect, thereby obtaining the above-described effects.

  Next, an image processing method according to claim 6 creates a look-up table and converts image data representing an image to be printed into image data for printing represented by color values of color materials used for printing. Before the image data is subjected to color material amount restriction processing for converting image data in which the amount of color material used for printing is restricted using a lookup table.

  According to such an image processing method, an effect similar to that of the image processing system according to claim 1 can be obtained.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[1. overall structure]
FIG. 1 is a block diagram illustrating a schematic configuration of a communication system according to an embodiment.

  As shown in the figure, this communication system is configured such that a personal computer (PC) 1 and a multifunction device 2 can perform data communication via a network (LAN: Local Area Network in this embodiment).

The personal computer 1 is a general-purpose information processing apparatus, and includes a control unit 11, a storage unit 12, a communication unit 13, an operation unit 14, and a display unit 15.
The control unit 11 includes a CPU 111, a ROM 112, a RAM 113, and the like, and comprehensively controls each unit constituting the personal computer 1.

  The storage unit 12 is for storing various information, and a hard disk device is used. The storage unit 12 is preinstalled with an operating system (OS) 121, an application program 122 such as image browsing software, a printer driver 123 for the multifunction machine 2, and the like. Further, the storage unit 12 stores a total ink amount limiting lookup table (hereinafter referred to as “a total ink amount limitation lookup table”) for converting image data representing an image to be printed into image data in which the total amount of ink used for printing is limited in the RGB color system. "Total Ink Limit LUT") 124 is stored. The storage unit 12 also stores a program for causing the CPU 111 to execute a process (FIG. 3) described later.

The communication unit 13 is an interface for communicating with the multifunction device 2 via a network.
The operation unit 14 is for inputting a command by an external operation from the user, and includes a keyboard and a pointing device (such as a mouse).

The display unit 15 is for displaying various information as an image that can be visually recognized by the user, and a liquid crystal display is used.
On the other hand, the multifunction device 2 is a multi-function device having a scanner function, a printer function, and the like, and includes a control unit 21, a storage unit 22, a communication unit 23, an operation unit 24, a display unit 25, a reading unit 26, and the like. And a printing unit 27.

The control unit 21 includes a CPU 211, a ROM 212, a RAM 213, and the like, and comprehensively controls each unit constituting the multifunction machine 2.
The storage unit 22 is for storing various types of information, and a flash memory is used. The storage unit 22 also stores a program for causing the CPU 211 to execute a process (FIG. 6) described later.

The communication unit 23 is an interface for communicating with the personal computer 1 via a network.
The operation unit 24 is for inputting a command by an external operation from the user, and includes various operation buttons.

The display unit 25 is for displaying information such as a message as an image that can be visually recognized by the user, and a small liquid crystal display is used.
A reading unit (scanner) 26 reads an image of a document set at a predetermined document reading position, and generates image data representing the image (specifically, image data expressed in an RGB color system).

  The printing unit (printer) 27 is of an ink jet type, and discharges each color ink of cyan (C), magenta (M), yellow (Y), and black (K) onto a sheet as a printing medium to generate a color image. Print.

[2. Overview of processing executed in communication system]
Next, an outline of processing executed in the communication system of the present embodiment will be described.
As shown in FIG. 2, the personal computer 1 issues a print instruction by transmitting image data representing an image to be printed in the RGB color system to the multifunction device 2. When the MFP 2 receives a print instruction from the personal computer 1, the MFP 2 performs a total ink amount limiting process for converting the image data (RGB data) into image data (RGB data) in which the total amount of ink used for printing is limited. Do. Then, the converted RGB color system image data is converted into CMYK color system image data corresponding to the ink color, and an image is printed based on the converted image data (CMYK data).

[3. Processing procedure executed in personal computer and multifunction machine]
Next, specific processing procedures executed in each of the personal computer 1 and the multifunction device 2 will be described.

  FIG. 3 is a flowchart of LUT creation processing executed by the control unit 11 (specifically, the CPU 111) of the personal computer 1. This LUT creation process is started when the user performs an operation on the personal computer 1 to newly create the total ink amount restriction LUT 124.

  When the control unit 11 starts the LUT creation process, first, in step S101, the control unit 11 transmits image data representing an ink amount confirmation chart to the multifunction device 2. Here, the ink amount confirmation chart is for confirming the amount of ink printed on the paper. Specifically, as shown in FIG. 4, the RGB value is composed of 729 patches in which 9 values are changed from (0, 0, 0) to (255, 255, 255). The patches are arranged at intervals in order to detect the degree of bleeding during printing. By the process of S101, the multifunction peripheral 2 prints the ink amount confirmation chart on the paper.

  Subsequently, in S102, the user visually observes both sides (printed surface and back surface) of the printed matter of the ink amount confirmation chart printed by the multifunction device 2, and the degree of bleeding seen from the printed surface and the show-through seen from the back surface for each patch. Let the degree be judged. Specifically, an image similar to the ink amount confirmation chart to be printed is displayed on the display unit 15, and the user selects a patch with blurring or show-through (displays a message prompting a selection operation).

  Subsequently, in S103, a good patch list composed of patches not selected in S102 (patches without blur and show-through) and a defective patch list composed of selected patches (patches with blur or show-through) are created. To do. At this time, a color value (YCrCb value in the present embodiment) expressed by lightness, saturation, and hue is calculated from the RGB value of each patch, and is associated with each RGB value.

Subsequently, in S104, one patch to be processed is selected from the defective patch list, and a patch having a YCrCb value with the smallest color difference from the YCrCb value of the patch is searched from the good patch list. Color difference ΔE of YCrCb values bug patch (Y _b Cr _b Cb _b) and YCrCb value good patch (Y _g Cr _g Cb _g) is calculated by equation (1). In Expression (1), a, b, and c are weighting factors. By adjusting the weighting factor, for example, a search with a weight on brightness (a value is increased) or a search with a weight on saturation. (Reducing the value of a) can be performed. Note that the processing in S104 to S106 is repeated until the processing for all patches in the defective patch list is completed, and in S104, a patch that has not yet been processed is selected.

続いて、Ｓ１０５では、不具合パッチリストのＲＧＢ値を、検索された良好パッチリストのＲＧＢ値に置き換える。

Subsequently, in S105, the RGB values of the defective patch list are replaced with the RGB values of the retrieved good patch list.

Subsequently, in S106, it is determined whether or not value replacement processing has been performed for all patches in the defective patch list (whether processing for all patches has been completed).
If it is determined in S106 that value replacement processing has not been performed for all patches (unprocessed patches remain), the process returns to S104.

  On the other hand, if it is determined in S106 that value replacement processing has been performed for all patches, the process proceeds to S107, where a color conversion table for converting input RGB values to output RGB values is created and stored as the total ink amount limitation LUT124. Register with the unit 12. Specifically, the RGB values of each patch in the ink amount confirmation chart are set as input RGB values, and the RGB values classified in the good patch list are set as output RGB values. In other words, the input RGB values classified into the good patch list are kept as they are, and only the input RGB values classified into the defective patch list are stored in the good patch list based on the replacement processing in S105. A color conversion table having contents to be converted into values (those having the smallest color difference from the YCrCb value) is created.

  Subsequently, in S108, image data (RGB data) representing a sample image stored in advance is converted using the ink total amount restriction LUT 124 newly created in S107 (see FIG. 5A).

  Subsequently, in S109, a sample image represented by the image data (RGB data) converted in S108 is displayed on the display unit 15 (see FIG. 5A), and whether or not there is no problem with the displayed conversion processing result. Displays a message to let the user answer.

  Subsequently, in S110, it is determined whether or not an answer indicating that there is no problem with the displayed conversion processing result is obtained from the user for the sample image and message displayed on the display unit 15 in S109.

  If it is determined in S110 that there is no answer indicating that there is no problem in the displayed conversion processing result, the process proceeds to S111, and the total ink amount restriction LUT 124 created in S107 and registered in the storage unit 12 is displayed. On the other hand, a smoothing process for relaxing irregularities of the output RGB values is performed. Thereafter, the process returns to S108, and the above-described processing is performed using the total ink amount limiting LUT 124 after the smoothing processing.

On the other hand, if it is determined in S110 that an answer indicating that there is no problem in the displayed conversion processing result is obtained, the present LUT creation processing ends.
Next, processing executed by the multifunction machine 2 will be described.

FIG. 6 is a flowchart of an image printing process executed by the control unit 21 (specifically, the CPU 211) of the multifunction machine 2 when receiving a printing instruction from the personal computer 1.
When the image printing process is started, the control unit 21 first performs the total ink amount limiting process on the image data (RGB data) received from the personal computer 1 using the total ink amount limiting LUT 124 stored in the personal computer 1 in S201. I do. The total ink amount limiting LUT 124 may be acquired by transmitting a transmission request to the personal computer 1 or may be transmitted from the personal computer 1 together with a print instruction.

Subsequently, in S202, the image data processed in S201 is converted from RGB data to CMYK data.
In step S203, an image is printed based on the CMYK data converted in step S202. Thereafter, the image printing process is terminated.

[4. effect]
As described above, in the communication system of the present embodiment, the multi-function device 2 performs the total ink amount restriction process on the three-dimensional RGB data before conversion into the four-dimensional CMYK data corresponding to the ink color ( S201). Therefore, as compared with the case where the total ink amount restriction process is performed after conversion into CMYK data as shown in FIG. 7, the processing contents of the total ink amount restriction process can be easily corrected (addition of the total ink amount restriction LUT 124, etc.). . In addition, the size of the total ink amount restriction LUT 124 can be reduced, and the amount of used memory can be reduced and the processing speed can be improved.

  In particular, since the image data after the total ink amount limiting process is three-dimensional RGB data, the total ink amount is compared with the case where the total ink amount limiting process is performed after converting the RGB data into CMYK data as shown in FIG. Color matching can be performed on a three-dimensional monitor signal without reducing the number of dimensions of the image data after the restriction processing. As a result, monitor simulation can be performed with higher accuracy than CMYK data.

  Further, since the MFP 2 performs the total ink amount limiting process using the look-up table (total ink amount limiting LUT 124), it is possible to easily perform complicated limitation according to the combination of inks to be used. The calculation load for processing can be suppressed.

  Further, in this communication system, since the total ink amount limit LUT 124 is stored in the storage unit 12 (hard disk device) of the personal computer 1 having a larger capacity than the storage unit 22 (flash memory) of the multifunction device 2, the total ink amount Compared to the configuration in which the limited LUT 124 is stored in the multifunction device 2, the storage capacity of the total ink amount limiting LUT 124 can be increased. In addition, the processing content of the total ink amount restriction process can be easily corrected outside the multifunction device 2 (without modifying the multifunction device 2 itself).

  On the other hand, in this communication system, since the personal computer 1 performs a process of newly creating the total ink amount limiting LUT 124 (S101 to S111), an appropriate total ink amount limiting process is performed according to the printing conditions such as the ink type and the paper type. It can be performed. As a result, a good printing result can be obtained, and the ink overflowing from the sheet due to the discharge of ink exceeding the upper limit of the ink absorption amount of the sheet stains the inside of the multifunction machine 2 and Problems such as shortening the life can be made difficult to occur. That is, there is a possibility that a new type of paper or ink that was not assumed at the time of manufacturing the printing apparatus (in the present embodiment, the multifunction machine 2) may be newly developed. In addition to paper and dedicated ink, various general-purpose papers and refill inks are on the market, and there are increasing examples of general users using them. Therefore, it is very effective to be able to create the total ink amount limiting LUT 124 according to the printing conditions.

  Further, since the personal computer 1 creates the total ink amount restriction LUT 124 by replacing the value of the defective patch list with the value of the good patch list based on the print result of the color patch, an excessive amount of ink is generated. It is possible to easily create the total ink amount limiting LUT 124 for preventing a decrease in print quality due to being used for printing and obtaining a good print result.

[5. Correspondence with Claims]
In the present embodiment, a communication system configured so that the personal computer 1 and the multifunction device 2 can communicate with each other corresponds to an image processing system. In particular, in the personal computer 1, the control unit 11 that executes the processes of S101 to S111 corresponds to a creation unit. In the MFP 2, the control unit 21 that executes the process of S201 corresponds to a restricting unit, and the control unit 21 that executes the process of S202 corresponds to a converting unit.

[6. Other forms]
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.

[6-1. LUT creation process]
In the above embodiment, the printed matter on which the ink amount confirmation chart is printed is visually confirmed by the user, and the degree of blurring and show-through of the image is determined. However, the present invention is not limited to this. For example, both sides of the printed material may be read by the reading unit 26 of the multifunction device 2, and the control unit 21 of the multifunction device 2 may automatically determine the degree of blurring and show-through for each patch based on the read image.

  In the above embodiment, the color difference ΔE is obtained by a calculation formula such as the formula (1). However, the deviation angle φ and the elevation angle θ are calculated by the formula (2) and the formula (3), and the color difference ΔE is calculated by the formula ( By obtaining as in 4), a search with a weight applied to the hue (the value of e may be increased) may be performed. The subscript g indicates a value obtained from the YCrCb value of the good patch, the subscript b indicates a value obtained from the YCrCb value of the good patch, and d and e represent weighting factors. The calculation of these color differences is not limited to the YCrCb space, and may be performed using color difference formulas in other color spaces such as Lab and CIECAM02.

［６−２．インク総量制限処理］
上記実施形態では、インク総量制限処理を複合機２で行うようにしているが、これに限定されるものではなく、例えばパーソナルコンピュータ１で行うようにしてもよい。このようにすれば、本発明の画像処理システムをパーソナルコンピュータ１のみにより構成することも可能となる。

[6-2. Ink limit processing]
In the above-described embodiment, the total ink amount limiting process is performed by the multi-function device 2, but the present invention is not limited to this. In this way, the image processing system of the present invention can be configured only by the personal computer 1.

[6-3. Color material]
In the above-described embodiment, the inkjet printing unit 27 that prints an image using four colors of CMYK has been described as an example. However, the present invention is not limited to this. For example, more colors of ink are used. It is also possible to adopt a configuration to use. Further, the color material is not limited to ink, and for example, a laser transfer method in which an image is formed using toners of a plurality of colors may be used. In this case, the defect patch may be determined based on the degree of toner fixing failure.

[6-4. image data]
In the above embodiment, the RGB data is exemplified as the image data input to the multifunction device 2, but the present invention is not limited to this, and the present invention can be applied to other formats.

It is a block diagram showing the schematic structure of the communication system of embodiment. It is explanatory drawing of the process performed with the communication system of embodiment. 6 is a flowchart of LUT creation processing executed by a personal computer. It is explanatory drawing of an ink amount confirmation chart. It is explanatory drawing of the process which displays a sample image on a display part. 6 is a flowchart of image printing processing executed by the multifunction machine. It is explanatory drawing in the case of performing an ink total amount restriction | limiting process after converting into CMYK data.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Personal computer, 2 ... Multi-function device, 11 ... Control part, 12 ... Memory | storage part, 124 ... Total ink amount limitation LUT, 13 ... Communication part, 14 ... Operation part, 15 ... Display part, 21 ... Control part, 22 ... Memory | storage , 23 ... communication unit, 24 ... operation unit, 25 ... display unit, 26 ... reading unit, 27 ... printing unit, 40 ... ink cartridge, 401 ... IC chip, 42 ... ink cartridge mounting unit, 43 ... ink detection unit, 45... Paper detecting unit, 451... Transmittance measuring sensor, 452.

Claims (6)

A creation means for creating a lookup table;
Conversion means for converting image data representing an image to be printed into image data for printing represented by color values of a color material used for printing;
Limiting means for performing color material amount restriction processing for converting image data before being converted by the conversion means into image data in which the amount of color material used for printing is restricted using the lookup table;
An image processing system comprising: The creation means creates a look-up table that converts color values of color patches with poor print results to color values of color patches with good print results based on the print results of color patches. 2. The image processing system according to 1. The image data for printing is expressed in an N-dimensional color space corresponding to the number of colors of the color material,
The image processing system according to claim 1, wherein the image data to be converted by the conversion unit is expressed in an M-dimensional (M <N) color space. The said restriction | limiting means performs the process which converts the image data expressed by the three-dimensional color space into the image data expressed by the three-dimensional color space as the said color material amount restriction | limiting process. 4. The image processing system according to 3. A creation means for creating a lookup table;
Conversion means for converting image data representing an image to be printed into image data for printing represented by color values of a color material used for printing;
A computer system as a limiting unit that performs color material amount limiting processing for converting image data before conversion by the conversion unit into image data in which the amount of color material used for printing is limited using the lookup table. An image processing program characterized by functioning. Create a look-up table and use the look-up table to print the image data representing the image to be printed before converting it to image data for printing represented by the color values of the color materials used for printing. An image processing method comprising: performing color material amount restriction processing for converting into image data in which a color material amount to be used is restricted.

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