JP6700707B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus and an image processing method for performing image processing on image data using a look-up table.

  2. Description of the Related Art A conventional inkjet printer (hereinafter referred to as a printer) is configured to apply a parameter held in the printer when performing image processing on image data to be printed received from a host computer. This is because parameters suitable for printer engine characteristics such as the type of printing paper, ink characteristics, and print head characteristics are required.

  On the other hand, when the received image data is subjected to image processing and converted into image data suitable for print output, the tint at the time of printing may deviate from the tint intended by the user. To solve this problem, contrary to the conventional technique, a technique has been proposed in which a host computer generates an image processing lookup table for realizing the intended tint and transfers the lookup table to a printer. (Patent Document 1).

JP, 2011-088300, A

  However, while there is a demand for the user to adjust the parameters so that the tint desired by the user can be obtained as in the technique of Patent Document 1, it is desired to perform printing using the parameters prepared in advance in the printer. In some cases.

An image forming apparatus according to the present invention converts an image based on data included in a print job into data of a color space of a color material used for image formation, and calculates the number of color materials based on the converted data. Image processing means for generating corresponding print data, storage means for storing parameters used in the conversion, and image forming means for forming an image on the recording medium using the color material according to the print data. When the print job includes a predetermined parameter used in the conversion, the image processing unit uses the predetermined parameter and is based on the data included in the print job. The image of the first color space using the value of is converted into data of the color space of the color material , and when the predetermined parameter is not included in the print job, it is stored in advance in the storage unit. The image in the second color space using RGB values based on the data included in the print job is converted into the data in the color space of the color material using the parameter .

  According to the present invention, it is possible to provide an image forming apparatus capable of flexibly coping with a partial user who wants to individually specify a tint while providing a regular image processing function to a general user as usual.

FIG. 3 is a functional block diagram showing a configuration of a printer. It is a figure which shows the concept of two types of print jobs, (a) is a conventional print job which does not contain a lookup table, (b) is a print job which contains a lookup table. 3 is a graph showing an example of an LUT and its characteristics. It is a block diagram which shows the internal structure of a multivalued image processing part. It is a figure explaining two types of image processing systems. It is a figure which shows 1DLUT used for converting directly from CMYK to an ink color. It is a figure which shows the hardware constitutions of a printer. 6 is a flowchart showing the overall flow of printing processing in the printer.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

(Example 1)
FIG. 1 is a functional block diagram showing the configuration of an inkjet recording type printer as an example of the image forming apparatus according to the present embodiment.

  The printer 100 includes a print control unit 101 including a CPU and the like, and the print control unit 101 centrally controls the following processing units. Specifically, the communication I/F 102, the reception buffer 103, the job analysis unit 104, the drawing processing unit 105, the multi-valued image buffer 106, the multi-valued image processing unit 107, the binary image buffer 108, the binary image processing unit 109, A print output buffer 110 and a print engine 111.

  The printer 100 is connected to a host computer (not shown) via the communication I/F 102 and performs communication using a communication means such as USB or a network. A print job received from the host computer via the communication I/F 102 is stored in the reception buffer 103. Then, the job analysis unit 104 analyzes the print job. A print job that can be used in the image forming apparatus according to the present embodiment includes print settings (print paper type, print quality, etc.) and image data types, and parameters applied to image processing (this embodiment. In the example, there are two types, which further include a lookup table for color conversion processing. 2A and 2B are diagrams showing the concept of these two types of print jobs. FIG. 2A shows a conventional print job that does not include a lookup table, and FIG. 2B shows a print job that includes a lookup table. ing. Here, the look-up table (hereinafter, LUT) is an array in which an input value (pixel value) and an output value (pixel value) are associated with each other. For example, an input value is a one-dimensional LUT (1DLUT), There are multidimensional LUTs (3DLUT, 4DLUT, etc.) whose input values are three-dimensional and four-dimensional. FIG. 3 shows an example of the LUT and a graph showing its characteristics. FIG. 3A is an example of a 1D LUT in which an input value (In) of 0 to 255 and an output value (Out) of 0 to 250 are associated with each other. By thus providing the output values with respect to the input values as an array, it is possible to realize a high-speed operation even with a nonlinear input/output relationship as shown in the graph of FIG. Further, FIG. 3C shows three input values (In[0], In[1], In[2]) each having a value of 0 to 255 and an output value (Out) of 0 to 250. It is an example of a 3D LUT in which

  The job analysis unit 104 analyzes a command described in a printer language called PDL (Page Description Language) in the print job, acquires image data in the print job, and transfers the image data to the drawing processing unit 105. The drawing processing unit 105 performs rendering processing on the received image data to generate multivalued bitmap data. The generated multivalued bitmap data is stored in the multivalued image buffer 106. Here, the multi-valued bitmap image is, for example, an image in which each CMYK color of the CMYK color space is represented by 8 bits. Further, the job analysis unit 104 analyzes the PDL command, acquires print settings from the print job, and notifies the print control unit 101 of the print settings. After that, the print control unit 101 notifies each processing unit of the print settings.

  The multi-valued image processing unit 107 performs multi-valued image processing such as color conversion processing, gamma correction processing, and halftone processing on the multi-valued bitmap data stored in the multi-valued image buffer 106 to obtain binary bitmap data. To generate. In the color conversion processing, the pixel values of the color space (for example, C, M, Y, K) of the input signal are converted into the color space (for example, B, G, LG, LC) corresponding to the color material (ink color) used for image formation. , M, LM, Y, LY). Here, B is black, G is gray, LG is light gray, C is cyan, LC is light cyan, M is magenta, LM is light magenta, Y is yellow, and LY is light yellow. The gamma correction process is a process for correcting the pixel value (gradation value) subjected to the color conversion processing according to the gradation characteristic of the printer engine 111. The halftone process is a process for converting the number of gradations of image data into the number of gradations (binary here) that can be expressed by the printer engine 111. The specific method and contents of these multi-valued image processing differ depending on the type of input image data and print settings. Through the halftone processing, the input image data is converted into binary bitmap data (1 bit data) corresponding to the number of output ink colors (here, 9 colors) in the print engine 111. The binary bitmap data generated by the multivalued image processing is stored in the binary image buffer 108.

  The binary image processing unit 109 rearranges the image data in the nozzle direction of the print head for the binary bitmap data stored in the binary image buffer 108 (HV conversion), corrects the image in the scan boundary area, and the like. Binary image processing is performed. Image data for print output subjected to the binary image processing (hereinafter, print data) is stored in the print output buffer 110.

  The print engine 111 reads the print data from the print output buffer 110, ejects ink from the print head in accordance with the print data while repeating paper feeding and scanning of the carriage on which the print head is mounted on the print paper. Print.

  In this embodiment, an inkjet recording type printer will be described as an example, but other recording types such as an electrophotographic type may be used.

  Next, the multi-valued image processing unit 107, which is a feature of the present invention, will be described in detail. FIG. 4 is a block diagram showing the internal configuration of the multi-valued image processing unit 107. The multi-valued image processing unit 107 includes an image processing unit 201, an image processing method determination unit 202, a default parameter storage unit 203, an in-job LUT analysis unit 204, and an in-job LUT temporary storage unit 205.

  The image processing unit 201 performs the above-described image processing (color conversion processing, gamma correction processing, halftone processing). The image processing method determination unit 202 determines a method to be actually applied from a plurality of image processing methods based on the print settings included in the print job and the analysis result of the in-job LUT analysis unit 204. In this embodiment, it is possible to perform image processing by any one of two types of image processing methods. FIG. 5 is a diagram illustrating two types of image processing methods according to this embodiment. Here, it is assumed that the input multi-valued image data is CMYK 8-bit data.

  FIG. 5A shows a specified image processing method of the printer 100, and FIG. 5B shows an image processing method applied when the color conversion processing LUT created by the user is included in the print job. ing. In the image processing method of FIG. 5A (hereinafter, default method), CMYK is converted into RGB, and then RGB is converted into ink colors (all nine colors in this embodiment). At this time, a 4D LUT prepared in advance is used for color conversion from CMYK to RGB, and a 3D LUT prepared in advance is also used for color conversion from RGB to ink colors. In particular, the 3D LUT is related to the characteristics of the print engine 111 (characteristics depending on the type of printing paper or ink, characteristics of the print head, etc.), and requires a high degree of knowledge for the user to generate it independently. After the color conversion processing, gamma correction processing and halftone processing are performed, and 1-bit data for the number of ink colors is output. In the case of the default method, prescribed parameters such as an LUT stored in advance in the default parameter storage unit 203 are used in all of the color conversion processing, gamma correction processing, and halftone processing.

  On the other hand, in the image processing method of FIG. 5B (hereinafter referred to as LUT providing method), color conversion is performed directly from CMYK to ink colors. For the color conversion at this time, the 1DLUT incorporated in the print job is used. FIG. 6 shows a 1D LUT used for direct conversion from CMYK to ink colors (all 9 colors). As shown in FIG. 6, the same number of 1DLUTs as the number of ink colors (three corresponding to each of B, G, and LG for K, two corresponding to C and LC for C, and M and LM for M). It is necessary for the user to create two pieces corresponding to (1) and two pieces corresponding to Y (two pieces corresponding to Y and LY). This creation also requires a certain degree of knowledge about the characteristics of the print engine 111, but in the case of the 1DLUT, it is relatively easy because the input/output relationship is simple. After the color conversion processing, gamma correction processing and halftone processing are performed as in the default method, and 1-bit data for the number of ink colors is output. Although the LUT incorporated in the print job is used for the color conversion process in the LUT providing method, the parameters held in the default parameter storage unit 203 are used in the subsequent gamma correction process and halftone process. It

  The default parameter storage unit 203 is composed of a ROM and a RAM, and stores prescribed (default) parameters used in each image processing including the LUT used in the image processing unit 201 as described above. The in-job LUT analysis unit 204 analyzes whether or not the LUT included in the received print job can be used. The in-job LUT temporary storage unit 205 is configured by a RAM and temporarily stores the LUT included in the received print job.

  Subsequently, main hardware constituting the printer 100 will be described. FIG. 7 is a diagram showing a hardware configuration of the printer 100.

  The CPU 301 is an arithmetic processing unit that controls the entire printer 100. The CPU 301 executes a predetermined control program to implement each processing unit including the job analysis unit 104 described above. The ROM 302 is a non-volatile memory, and stores control programs of various processing units including the job analysis unit 104 and various image processing parameters. The RAM 303 is used as a work area of the CPU 301 and a temporary storage place for various data. The reception buffer 103, the multi-valued image buffer 106, the binary image buffer 108, and the print output buffer 110 described above are realized by the RAM 303. The I/F 304 is an interface for connecting the printer 100 to an external device such as a host PC, and corresponds to the communication I/F 102 described above. The printer 100 receives a print job via a network or USB and notifies the external device of the status of the printer 100. The PNL 305 is an operation panel unit that has a liquid crystal display that displays the status of the printer 100 and keys that allow the user to set the printer 100. The ImgProc 306 is a processor that performs each of the above-described image processes in the image processing unit 201, and performs each image process by setting the LUT and the like by the CPU 301 and receiving an execution instruction. The engine 307 includes a CR (carriage) that moves the print head, an LF (LF roller) that feeds the paper, a head (print head) that ejects ink, and the like, and corresponds to the print engine 111 described above. Then, these respective units are mutually connected by a bus 300.

  Next, the flow of the entire printing process in the printer 100 according to this embodiment will be described. FIG. 8 is a flowchart showing the flow of the entire printing process in the printer 100. The following series of processing is realized by the CPU 301, which constitutes the print control unit, reads out a predetermined program from the ROM 302, expands it in the RAM 303, and executes it.

  In step 801, the print job sent from the host computer is received by the communication I/F 102. The received print job is stored in the reception buffer 103.

  In step 802, the job analysis unit 104 reads the print job from the reception buffer 103 and analyzes it. Specifically, first, the PDL in the print job is interpreted to acquire the image data and the print settings. In this embodiment, the input image data is assumed to be CMYK color space data. The acquired image data and print settings are sent to the drawing processing unit 105 and the print control unit 101, respectively. Further, as a result of the PDL interpretation, if there is an LUT holding command indicating that the print job includes the LUT, the LUT in the print job is acquired and sent to the drawing processing unit 105.

  In step 803, the drawing processing unit 105 performs rendering processing on the image data to generate a multi-valued bitmap image. The data of the generated bitmap image is stored in the multi-valued image buffer 106.

  Further, as a result of the analysis in step 802, if the LUT carrying command is present, the drawing processing unit 105 stores the LUT included in the print job in the intra-job LUT temporary storage unit 205 in step 804.

  Each processing from the next step 805 to step 809 is performed in the multi-valued image processing unit 107.

  In step 805, the image processing method determination unit 202 makes an inquiry to the in-job LUT temporary storage unit 205 and determines whether or not the LUT provided by the print job exists. If there is an LUT provided by the print job, the process proceeds to step 806. On the other hand, if there is no LUT provided by the print job, the process proceeds to step 808.

  In step 806, the in-job LUT analysis unit 204 analyzes the LUT stored in the in-job LUT temporary storage unit 205 and determines whether or not the LUT is actually applicable to image processing. In the present embodiment, it is determined whether or not the total of 9 colors of 1D LUT for directly performing color conversion from CMYK to ink colors. As a result of the determination, if it is available, the process proceeds to step 807. On the other hand, if it is determined that the image cannot be used due to, for example, a 3DLUT or the number of ink colors is insufficient, the process proceeds to step 808.

  In step 807, the image processing method determination unit 202 determines the image processing method applied to the multi-valued bitmap data generated in step 803 as the LUT providing method using the LUT provided by the print job. The information of the decided image processing method is notified to the image processing unit 201. Further, the image processing method determination unit 202 reads out the LUT stored in the in-job LUT temporary storage unit 205 and transfers it to the image processing unit 201.

  In step 808, the image processing method determination unit 202 determines the image processing method to be applied to the multi-valued bitmap data generated in step 803 to be the default method using the specified LUT. The information of the decided image processing method is notified to the image processing unit 201.

  In step 809, the image processing unit 201 reads the multi-valued bitmap data from the multi-valued image buffer, and executes the image processing according to the notified method according to the print settings. That is, in the case of the LUT providing method, color conversion processing is performed directly from CMYK to an ink color using the 1DLUT included in the print job. After that, the gamma correction process and the halftone process are executed, and various parameters used at this time are held in the default parameter storage unit 203. On the other hand, in the case of the default method, CMYK is once converted to RGB, and then color conversion is performed in two stages from RGB to ink colors, and then gamma correction processing and halftone processing are executed. In the case of the default method, the LUT or the like held in the default parameter storage unit 203 is used in any processing. The binary bit map image data generated by the multi-value image processing according to any one of the methods is output to and stored in the binary image buffer 108. At this stage, the 1D LUT contained in the print job and stored in step 804 is erased from the RAM 303 because it has finished its role.

  In step 810, the binary image processing unit 109 reads the binary bitmap data from the binary image buffer 108 and executes the above binary image processing. The print data generated by the binary image processing is output to and stored in the print output buffer 110.

  In step 811, the print engine 111 reads the print data from the print output buffer 110, forms an image according to the print data on the recording medium, and outputs the image.

  The above is the flow of the entire printing process in the printer 100.

  When it is determined in the determination processing of step 806 described above that the LUT provided by the print job cannot be used for image processing, the user may be notified of that fact. Further, in this case, in this embodiment, the default method is automatically determined, but, for example, a configuration in which the user is allowed to select a method and the LUT input is accepted when the user newly specifies the LUT providing method May be

  Further, although the present embodiment has been described assuming that the input image data is in the CMYK color space, the present invention is not limited to this, and may be data in another color space such as the RGB color space. In this case, an LUT may be prepared according to the color space of the input image data.

  Further, in the present embodiment, one of the two types of image processing methods is determined, but it may be determined from among three or more types of image processing methods.

  Further, in the present embodiment, the parameter incorporated in the print job is the LUT for color conversion processing, but it may be any parameter related to the adjustment of the tint. For example, parameters such as a density adjustment LUT used in the gamma correction process and a matrix used in the halftone process (dither process) may be incorporated in the print job.

  As described above, according to this embodiment, a general user may send a conventional print job that does not include an LUT to the printer. In this case, the default image processing of the printer is performed, and the user can obtain the print result according to the engine characteristics of the printer. Further, the user who wants to adjust the color may generate the LUT or the like by himself, incorporate it into the print job, and send it to the printer. In this case, image processing is performed using the LUT or the like provided by the user, and the user can obtain the print result of the intended tint. That is, the image forming apparatus according to the present exemplary embodiment provides a general user with a prescribed image processing function as usual, and a mechanism capable of adjusting the tint for a user who wants to individually specify the tint. Can be provided.

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by the processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 Printer 102 I/F
201 image processing unit 202 image processing method determination unit 204 in-job LUT analysis unit

Claims (13)

An image in which an image based on data included in a print job is converted into color space data of a color material used for image formation, and based on the converted data, print data corresponding to the number of color materials is generated. Processing means,
Storage means for storing parameters used in the conversion,
An image forming unit that forms an image on the recording medium using the color material according to the printing data;
Equipped with
The image processing means,
If the print job includes a predetermined parameter used in the conversion, the predetermined parameter is used to create a CMYK value based on the data included in the print job in the first color space. The image is converted to the color space data of the color material,
If the predetermined parameter is not included in the print job, a second value that uses RGB values based on the data included in the print job by using the parameter stored in advance in the storage unit is used. The image of the color space is converted into the color space data of the color material,
An image forming apparatus characterized by the above. Storage means for storing parameters used in predetermined image processing,
When a print job includes a predetermined parameter for use in the predetermined image processing, a determination unit that determines whether the predetermined parameter is applicable to the predetermined image processing,
An image processing unit that performs the predetermined image processing on the image based on the data included in the print job according to the determination result by the determination unit to generate print data corresponding to the number of color materials used for image formation. When,
An image forming unit that forms an image on the recording medium using the color material according to the printing data;
Equipped with
The image processing means,
When it is determined that the predetermined parameter included in the print job is applicable by the determination unit, the predetermined image processing is performed using the predetermined parameter,
If the determination unit determines that the predetermined parameter included in the print job is not applicable, the predetermined image processing is performed using the parameter stored in advance in the storage unit.
An image forming apparatus characterized by the above. Storage means for storing parameters used when converting an image into color space data of a color material used for image formation;
When the print job includes a predetermined parameter used when converting an image into the color space data of the color material, a determination unit that determines whether the predetermined parameter is applicable to the conversion,
An image based on the data included in the print job is converted into data of the color space of the color material according to the result of the determination by the determination unit, and based on the converted data, the number of the color materials corresponding to the number of printing Image processing means for generating data,
An image forming unit that forms an image on the recording medium using the color material according to the printing data;
Equipped with
The image processing means,
Includes a predetermined parameter in the print job, if the predetermined parameter is determined to be applicable by the determination means, by using the predetermined parameters, the data contained in the prior SL print job And converting the image of the first color space using the CMYK values based on the color space data of the color material,
If the predetermined parameter is not included in the print job, and if the determination unit determines that the predetermined parameter included in the print job is not applicable, the storage unit stores the predetermined parameter in the storage unit. Converting the image of the second color space using RGB values based on the data contained in the print job into the data of the color space of the color material using the parameters stored in advance;
An image forming apparatus characterized by the above.   The determination unit is based on that the predetermined parameter included in the print job is a parameter for converting an image of the first color space into data of the color space of the color material. The image forming apparatus according to claim 3, wherein the predetermined parameter is determined to be applicable.   If the predetermined parameter is not included in the print job, the image processing unit converts the image in the first color space into an image in the second color space, and after the conversion, The image forming apparatus according to claim 1, wherein the image in the second color space is converted into data in the color space of the color material.   3. The determination unit determines that the predetermined parameter is applicable based on the fact that the predetermined parameter corresponding to the number of the color materials is included in the print job. The image forming apparatus according to any one of 4 above.   7. The method according to claim 1, wherein whether or not the predetermined parameter is included in the print job is determined by the presence/absence of a command indicating carrying the parameter. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the predetermined parameter is a lookup table used for the conversion. The predetermined image processing includes gamma correction processing for correcting the gradation value of the image based on the data included in the print job according to the gradation characteristic of the image forming unit,
The image forming apparatus according to claim 2, wherein the predetermined parameter is a look-up table used in the gamma correction process. The predetermined image processing includes halftone processing for converting the number of gradations of the image based on the data included in the print job into the number of gradations that can be expressed by the image forming unit,
The image forming apparatus according to claim 2, wherein the predetermined parameter is a matrix used for the halftone processing. An image forming method in an image forming apparatus for forming an image on a recording medium based on a print job,
An image based on the data included in the print job is converted into color space data of a color material used by the image forming apparatus, and printing corresponding to the number of color materials is performed based on the converted data. Image processing step of generating data for use,
An image forming step of forming an image on the recording medium using the color material according to the printing data;
Including,
In the image processing step,
If the print job includes a predetermined parameter used in the conversion, the predetermined parameter is used to create a CMYK value based on the data included in the print job in the first color space. The image is converted to the color space data of the color material,
When the predetermined parameter is not included in the print job, the RGB value based on the data included in the print job is used by using the parameter stored in advance in the image forming apparatus. The image of the color space of is converted into the color space data of the color material,
An image forming method characterized by the above. An image forming method in an image forming apparatus for forming an image on a recording medium based on a print job,
When a predetermined parameter for use in a predetermined image processing is included in the print job, a determination step of determining whether the predetermined parameter is applicable to the predetermined image processing,
Image processing for generating print data corresponding to the number of color materials used for image formation by performing the predetermined image processing on the image based on the data included in the print job according to the determination result of the determination step. Steps,
An image forming step of forming an image on the recording medium using the color material according to the printing data;
Including,
In the image processing step,
When it is determined that the predetermined parameter included in the print job is applicable in the determination step, the predetermined image processing is performed using the predetermined parameter,
If it is determined in the determination step that the predetermined parameter included in the print job is not applicable, the predetermined image is stored using the parameter stored in advance in the storage unit of the image forming apparatus. Do the processing,
An image forming method characterized by the above.   A program for causing a computer to execute the image forming method according to claim 11.

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