JP6084877B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus capable of reducing the amount of data to be transferred to a printing apparatus.

Conventionally, the following processing is performed in a printing apparatus such as an ink jet printer. That is, in the host computer or scanner, the number of gradations of the generated image data is converted into the number of gradations that can be printed by the printing apparatus, and then transferred as image data to be printed from the host computer or the like to the printing apparatus.

  However, in recent years, the amount of data to be transferred tends to increase as the printing accuracy in the printing apparatus becomes higher. For this reason, the time for transferring the print target image data from the host computer or the like to the printing apparatus is increased, leading to a decrease in print throughput (an increase in time from a print start instruction to completion of printing).

  For this reason, conventionally, as a technique for reducing the transfer time of image data to be printed, for example, a predetermined thinning process is performed on the pixel value of each pixel constituting the image data, and the data amount is reduced and transferred. Things have been done. However, in this method, if the data amount of the print target image data is reduced and transferred by the thinning process, the image quality of the print image formed by the printing apparatus is deteriorated.

  Thus, for example, in the technique described in Patent Document 1, the amount of transfer data is reduced by reducing the number of gradations of image data to be printed in accordance with each color component.

Japanese Patent Laid-Open No. 9-238262

However, the above-described conventional technology has the following problems. For example, in the case of printing using ink, the number of ink ejections corresponding to each print density required for print image formation may be one due to the degree of ink bleed onto printing paper, or two in proximity. There may be more. Here, the number of ink ejections generally corresponds to the gradation value.

For this reason, if the number of gradations is reduced without considering the degree of ink bleed on the printing paper, one gradation value corresponding to each print density may be deleted. Therefore, it can be said that if the transfer data amount is reduced without considering the print density actually printed, the image quality may be deteriorated.

The present invention has been made in view of the problems as described above, and reduces the transfer data amount of image data to be printed and prevents image quality deterioration in consideration of the print density actually printed. An object of the present invention is to provide an image processing apparatus capable of performing the above.

The image processing apparatus according to the present invention quantizes the first image data having a predetermined number of gradations, converts the first image data to second image data having a number of gradations lower than the predetermined number of gradations and the number of gradations, and then prints Print density data for storing in advance print density data indicating print density that can be obtained when quantized with a predetermined quantization number, as an image processing apparatus that transfers image data to a printing apparatus via a predetermined communication path With reference to the storage means and the print density data, at least one of the print densities that are close to each other is deleted based on a print density distribution that can be obtained when quantized with the predetermined quantization number. Quantization number determination means for determining a quantization number smaller than the predetermined quantization number, and quantization control for quantizing the first image data with the quantization number determined by the quantization number determination means With means It is an butterfly.

  In the above invention, the print density data is a table showing a relationship between a code value that can be taken after quantization with a predetermined quantization number and a print density corresponding to the code value, and the quantization number determining means includes: Referring to the table, it is possible to determine the small number of quantization by repeatedly reducing one of the two corresponding code values sequentially from the case where the difference in print density is the smallest. .

  In the above invention, the image processing apparatus further comprises a designation unit that designates a high-speed transfer mode for transferring the image data to be printed to a printing apparatus at a high speed. You may make it perform the process which determines few quantization numbers.

  Further, in the above invention, the quantization number determining means may store the print target image data quantized with the predetermined quantization number to the printing apparatus per unit time when the high-speed transfer mode is designated. The data transfer amount to be transferred may be compared with the data communication amount that can be transferred per unit time through the predetermined communication path, and the process of determining the small quantization number may be performed based on the comparison result. .

  In the above invention, the number of quantizations determined by the quantization determining means may be indicated by a power of 2.

  According to the first aspect of the present invention, the print density that is close to the density based on the distribution of print density that can be obtained when quantized with a predetermined quantization number with reference to the print density data stored in advance. A quantization number smaller than a predetermined quantization number is determined so as to delete any one of the above.

  As a result, the quantization number is determined so as to delete any one of the print densities that are close to each other, so even if the number of gradations is reduced, it corresponds to each print density necessary for print image formation. The gradation value is not deleted. Then, image data to be printed is transferred with the number of gradations reduced from the predetermined number of quantizations as the number of gradations. Accordingly, it is possible to reduce the transfer data amount of the print target image data in consideration of the print density that is actually printed, and to prevent image quality deterioration.

  According to the second aspect of the present invention, the quantization number determining means repeatedly reduces one of the two corresponding code values sequentially from the case where the difference in the print density is the smallest, thereby obtaining a predetermined quantum. Since the quantization number smaller than the quantization number is determined, it is possible to further reduce the transfer data amount of the print target image data while preventing the image quality deterioration.

According to the third aspect of the present invention, when the high-speed transfer mode for transferring the print target image data to the printing apparatus at a high speed is designated, the process for determining the small quantization number is performed. For this reason, when the user gives priority to the speed of data transfer, it is possible to perform the determination processing of the small number of quantizations, and when the user gives priority to the prevention of image quality deterioration over the speed of data transfer, It is possible to prevent the determination process of a small number of quantizations.

  According to the fourth aspect of the present invention, when the high-speed transfer mode is designated, the amount of data transferred to the printing device per unit time is compared with the amount of data communication that can be transferred per unit time. Based on the comparison result, the small quantization number is determined.

For this reason, in consideration of the communication status of a predetermined communication path, when the data transfer amount is larger than the data communication amount, the quantization number is not reduced, and when the data transfer amount is smaller than the data communication amount, The number of quantization can be reduced. As a result, the quantization number reduction process is performed when necessary in accordance with the communication status of the predetermined communication path. In addition to the effect of the third aspect, the image quality deterioration prevention can be further achieved.

  According to the fifth aspect of the present invention, the number of quantizations determined by the quantization determination means is represented by a power of 2. The unit of data transmitted and received in normal data communication is a bit unit. Further, since the print target image data having the quantization number as the gradation number is transferred, the amount of the data is determined depending on the quantization number. For this reason, by reducing the number of quantization in bit units, it is possible to reliably reduce the amount of image data to be printed while preventing image quality deterioration.

1 is a block diagram illustrating a configuration of a printing system according to a first embodiment. In the printing system of a 1st embodiment, it is a figure showing explanation of quantization number reduction processing by a quantization control part. It is a flowchart figure which shows the printing method of 1st Embodiment. It is a flowchart figure which shows the production | generation process of the printing object data of 1st Embodiment. It is a flowchart figure which shows the production | generation process of the printing object data of 2nd Embodiment. FIG. 10 is a block diagram illustrating a configuration of a printing system according to a first modification.

Hereinafter, the printing system of the present embodiment will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of a printing system 1 according to the present embodiment.
[Configuration of printing system]

  As shown in FIG. 1, the printing system 1 includes an operation system for performing basic operations such as a user interface and the like, a terminal device 100 capable of executing various software, an inkjet printing device 200, and the like. Are connected via a network such as a wired LAN.

(Terminal device)
The terminal device 100 includes an application unit 11, a printer driver unit 12, a print data generation unit 13, an input / output unit 14, and a terminal side communication unit 15. The application unit 11 and the printer driver unit 12 are configured by a program installed in the terminal device 100 being subjected to processing such as decoding by a CPU or the like.

  The application unit 11 includes a program for generating document data such as documents and images. The document data generated by the application unit 11 is output to the printer driver unit 12.

  The printer driver unit 12 causes the output function of the input / output unit 14 to display a print operation screen, a print setting screen, and the like, receives print settings from the user via the input function of the input / output unit 14, and sets information regarding printing And the printing status are notified to the user via the output function of the input / output unit 14. The printer driver unit 12 generates print job data (for example, PDL data) based on information set by the user and document data.

The input / output unit 14 has an input function and an output function. The input function is composed of a keyboard or the like, and the output function is composed of a liquid crystal display monitor or the like. The input / output unit 14 allows a user to input various data, and outputs the input data to the printer driver unit 12 or the application unit 11. The input / output unit 14 notifies the user of the output result from the printer driver unit 12 or the application unit 11.

The print data generation unit 13 generates print target data for causing the inkjet printing apparatus 200 to print. Specifically, the print data generation unit 13 includes an RIP processing unit 131, an RGB-CMYK conversion unit 132, a multi-value halftone processing unit 133, a print density data storage unit 134, and a quantization control unit 135.

Based on the print job data output from the printer driver unit 12, the RIP processing unit 131 has a predetermined resolution bit of red (hereinafter, R) component, green (hereinafter, G) component, and blue (hereinafter, B) component. Expanded print job data (hereinafter referred to as expanded print job data), which is raster data that has been expanded on the map, is generated. Here, in the developed print job data, for each pixel developed at a predetermined resolution (corresponding to each coordinate position in the developed print job data), an R component value (for example, 0 to 255), G component Value (for example, 0 to 255) and B component value (for example, 0 to 255) are associated with each other.

The RGB-CMYK conversion unit 132 converts the R, G, and B component developed print job data generated by the RIP processing unit 131 into a cyan (hereinafter referred to as C) component, a magenta (hereinafter referred to as M) component, and a yellow (hereinafter referred to as “yellow”). , Y) component and black (hereinafter referred to as K) component. Here, in the developed print job data, for each coordinate position developed at a predetermined resolution, a C component value (for example, 0 to 255), an M component value (for example, 0 to 255), a Y component value, and the like. Values (for example, 0 to 255) and K component values (for example, 0 to 255) are associated with each other.

The multi-value halftone processing unit 133 reduces the number of gradations according to the quantization number set by the quantization control unit 135 for the developed print job data converted by the RGB-CMYK conversion unit 132. Tone processing is performed to generate print target data having the number of quantizations as the number of gradations.

A specific description will be given with reference to FIG. In the developed print job data, the multi-value halftone processing unit 133 performs, for example, the quantum (C to K component) values (0 to 255) for each coordinate position (FIG. 2A), for example, quantum When the quantification number 10 is set, 28, 56, 85,... 226, 255 are set as the determination values for quantization (FIG. 2B). Then, a code value (gradation value) 0 which is a quantized value with respect to a color component value 0, a code value 1 with respect to a color component value 1 to 28, and a color component value 29 to 56 The code value 2..., The quantization value for the quantization number 10 is applied by associating the code value 9 with the color component values 227 to 256, and the quantized print job data of 256 gradations is quantized. A sign value that is a digitized value is generated. As a result, for the color component values (0 to 255) that can be taken by the developed print job data, the code values that can be taken after quantization are 0 to 9, and the number of gradations is 10. The above-described quantization process is performed for each of the C, M, Y, and K color components.

Here, the quantization control unit 135 is connected to a print density table storage unit 135 that stores a print density table indicating a print density that can be obtained when quantization is performed with a predetermined quantization number. As an example of the print density table, for example, a relationship between a code value that can be obtained after quantization with a predetermined quantization number and a print density when the inkjet printing apparatus 200 prints with a discharge amount corresponding to the code value is shown. There is a table.

An example of the print density table is shown below. Here, code values (0 to 9) that can be obtained when quantization is performed with a quantization number of 10 correspond to ink ejection amounts (0 drop number to 9 drop number).

Then, the print density (for example, OD value) when the ink discharge amount is changed from 1 drop number to 9 drop number is experimentally acquired for each ink color and each type of printing paper. Then, when the user inputs the print density or the like to the input / output unit 14, the ink discharge amount (1 to 9 drops), the print density (OD values X1 to X9), and the type of printing paper (plain paper) , Mat paper,...) Is stored in the print density table storage unit 134 for each ink color (C, M, Y, K).

The quantization control unit 135 refers to the print density table and deletes at least one of the print densities that are close in density based on the print density distribution that can be obtained when quantization is performed with a predetermined quantization number. In addition, a quantization number smaller than a predetermined quantization number is determined.

Specifically, the quantization control unit 135 refers to the print density table and repeatedly reduces one of the corresponding two code values sequentially from the case where the difference in print density is the smallest. Decide a small number of quantizations. At this time, the quantization number determination process is performed independently for each color component. However, when the data transfer amount is sufficiently reduced, the quantization number determination process may be performed on not more than four color components but on three or less color components. The same applies to a second embodiment described later.

A detailed description of the processing of the quantization control unit 135 will be given below. The quantization control unit 135 refers to the print density table, and acquires the print density corresponding to each of the code values 0 to 9 corresponding to the quantization number 10. The quantization control unit 135 repeatedly reduces one of the two corresponding code values sequentially from the print density distribution corresponding to each of the code values 0 to 9 in the case where the difference in print density is the smallest. Thus, the quantization number is determined to be equal to or less than the determined quantization number.

For example, as shown in FIG. 2, a case where the predetermined quantization number is 10 and the print density corresponding to the code values 0 to 9 is 0 to 80 (OD value) will be described as an example. The quantization controller 135 determines the print density between the code values (between 1, 2 and 8, 9) based on the print density distribution for each code value in the print density table (FIG. 2B). A combination of code values whose difference is within a predetermined value is searched. Here, the predetermined value is, for example, when printing is performed with the number of ejection drops corresponding to each code value in the printing conditions (printing paper, ink, ejection driving conditions (drive waveform voltage, etc.)) of the inkjet printing apparatus 200, Although there is a difference in the print density value, it is determined by experimentally obtaining a range of code values that can be visually equivalent.

As a result of the above search, the quantization control unit 135 extracts a combination of code values in which the difference in print density between code values (between 1, 2 and 8, 9) is within a predetermined value. At this time, the quantization control unit 135 sequentially determines whether the combination of code values within a predetermined value from the case where the difference in print density is the smallest, and reduces one of the two corresponding code values. repeat. For example, in the case of FIG. 2B, when the predetermined value is 5 (OD value), the quantization control unit 135 has a combination of code values with the smallest print density difference (code values 1, 2 and code values 8, 9) is searched, and since the difference 2 (OD value) is within the predetermined value 5 (OD value), it is determined that the code values 2 and 8 are deleted. At this time, the quantization control unit 135 determines to delete the code value that makes the difference between the adjacent print density values more uniform among the two adjacent code values to be deleted. Then, the quantization control unit 135 searches for a combination of code values having the next smallest print density difference (code values 1, 3 and the like), and the difference 10 (OD value) is larger than the predetermined value 5 (OD value). It is determined that the code value is not deleted any more.

Then, the quantization control unit 135 quantizes the expanded print job data with the determined quantization number (for example, 8), and generates print target data. As a result, in the print target data, the C component value (for example, 0 to 7), the M component value (for example, 0 to 7), and the Y component value for each coordinate position developed at a predetermined resolution. (For example, 0 to 7) and K component values (for example, 0 to 7) are associated with each other, and the color component value for each coordinate position is reduced from 4 bits to 3 bits. At this time, the print target data includes information from which the code values 2 and 8 are deleted.

The terminal side communication unit 15 transfers the print target data processed by the multi-value halftone processing unit 133 to the inkjet printing apparatus 200 via the communication path 300.

(Inkjet printer)
The ink jet printing apparatus 200 includes a printing side communication unit 21 and an ink jet printing unit 22. The print-side communication unit 21 receives the print target data transferred via the communication path 300.

The ink jet printing unit 22 converts the value of each color component in the print target data into an ink ejection amount. A specific description of this process is shown below.

The predetermined quantization number (for example, 10) is transmitted from the terminal device 100 to the inkjet printing unit 22 in advance. When the inkjet printing unit 22 receives the print target data, the color component values (code values) 0, 1, 2, 3,..., 7, 8, corresponding to a predetermined quantization number (for example, 10). Based on the fact that the code values 2 and 8 are deleted with respect to 9, the values 0 to 7 of the respective color components for each coordinate position developed at a predetermined resolution are set to the number of drops 0, 1, and 2 corresponding to the ink ejection amount. It has a discharge amount conversion function for converting into 3, 4, 5, 6, 7, and 9 (see FIG. 2C).

The inkjet printing unit 22 includes an ejection head corresponding to the C component value, the M component value, the Y component value, and the K component value. The ink jet printing unit 22 includes a paper supply / discharge unit that feeds the print paper and discharges the printed paper after the discharge operation is performed by the discharge head. The inkjet printing unit 22 applies the printing paper fed from the paper feeding unit based on the number of drops of each color component for each coordinate position (hereinafter referred to as ejection drop data) output by the ejection amount conversion function. Thus, ink ejection control of each ejection head is performed so as to form an image at a predetermined position.

(Printing method)
Next, a printing method using the above-described printing system will be described with reference to the flowchart shown in FIG.

  In the terminal device 100, after the application unit 11 generates document data, the printer driver unit 12 generates print job data based on the information set by the user and the document data (S1).

  The print data generation unit 13 quantizes the image data of a predetermined gradation number of each pixel based on the print job data, and converts it into image data having a gradation number (quantization number) lower than the predetermined gradation number. Then, print target data is generated (S2). The detailed process of S2 will be described later.

  The print data generation unit 13 transmits the generated print target data to the inkjet printing apparatus 200 via the terminal side communication unit 15 and the communication path 300 (S3).

In the inkjet printing apparatus 200, when the printing-side communication unit 21 receives print target data, the inkjet print unit 22 generates ejection drop data from the print target data. Based on the ejection drop data, the inkjet printing unit 22 performs ink ejection control of each ejection head so that an image is formed at a predetermined position on the printing paper fed from the paper feeding unit (S4).

  Next, detailed description of print target data generation processing in the terminal apparatus 100 will be described with reference to the flowchart shown in FIG. In each process, the items already described will be described in a simplified manner.

Based on the print job data output from the printer driver unit 12, the RIP processing unit 131 generates RGB component developed print job data (execution of RIP processing) (S21). The RGB-CMYK conversion unit 132 converts the RGB component developed print job data generated by the RIP processing unit 131 into CMYK component developed print job data (S22).

When the multilevel halftone processing unit 133 acquires the expanded print job data of the CMYK component converted by the RGB-CMYK conversion unit 132, the multilevel halftone processing unit 133 sends the developed print job data to the quantization control unit 135. The quantization control unit 135 acquires the currently set quantization number for the expanded print job data.

The quantization control unit 135 refers to the print density table to determine whether or not to delete at least one of the print densities having similar densities (S23). In the process of S23, the quantization control unit 135 refers to the print density table for the C component, the M component, the Y component, and the K component, and determines whether or not to delete at least one of the print densities that are close in density. to decide.

If it is not determined that reduction is possible, the quantization control unit 135 performs quantization processing with the set number of quantizations and sends the print target data to the terminal-side communication unit 15 (S24). If it is determined that reduction is possible, the quantization control unit 135 performs a quantization number reduction process, performs the quantization process with the determined quantization number, and sends the print target data to the terminal-side communication unit 15 (S25). ).

“Second Embodiment”

In the present embodiment, the function of the input / output unit 14 of the terminal device 100 is different from the function of the quantization control unit 135. In the present embodiment, functions and processes different from those in the first embodiment will be mainly described, and descriptions of functions and processes that are the same as or similar to those in the first embodiment will be omitted or simplified.

The input / output unit 14 of the terminal device 100 has a function of designating a high-speed transfer mode for transferring print target data to the inkjet printing apparatus 200 at high speed. When the high-speed transfer mode is designated, the quantization control unit 135 transfers the print target data quantized with a predetermined quantization number to the inkjet printing apparatus 200 per unit time, and the communication path 300. Is compared with the amount of data communication that can be transferred per unit time, and based on the comparison result, the number of quantizations smaller than a predetermined quantization number is determined.

A specific process of the quantization control unit 135 will be described below. Here, a speed at which the print target data is transferred from the print data generation unit 13 via the terminal-side communication unit 15 is set in advance, and the print target data is transferred per unit time based on the transfer speed. A data transfer amount to be transferred to 200 is calculated.

For example, when the productivity in the terminal device 100 (the speed at which the print target data is transferred from the print data generation unit 13 via the terminal side communication unit 15) is 60 pages / minute (60 seconds), one page per second. If the data to be printed is transferred, the productivity can be maintained. The quantization control unit 135 calculates the data amount corresponding to one page as the data transfer amount per unit time. For example, the document size is A4, the predetermined resolution, the scaling factor is the same magnification, the color conversion processing is RGB-CMYK conversion, the multi-value halftone conversion is a 4-bit quantization, and the data transfer amount is about 16 In the case of .6 MB, the quantization control unit 135 calculates the data transfer amount as 16.6 MB.

Further, the quantization control unit 135 calculates a data communication amount that can be transferred per unit time through the communication path 300. Since this calculation method is well-known and will not be described in detail, for example, the terminal-side communication unit 15 periodically transmits a test file to the FTP server in the communication path 300, and the FTP of the above file. It can be calculated based on the time required for communication between the server and the terminal communication unit.

The quantization control unit 135 compares the data transfer amount per unit time with the data communication amount that can be transferred per unit time, and the data transfer amount per unit time is the data communication amount that can be transferred per unit time. If larger (or more), a process of determining a quantization number smaller than a predetermined quantization number is performed.

If the amount of data transferred per unit time is larger than the amount of data communication that can be transferred per unit time, the data transfer amount per unit time is the communication speed of the communication path if the data to be printed is transferred as it is. This is because there is a possibility that data transfer from the terminal device 100 to the inkjet printing apparatus 200 may be delayed.

For example, when the quantization control unit 135 calculates the data transfer amount per unit time as 16.6 MB and calculates the data communication amount that can be transferred per unit time as 13 MB, the quantization control unit 135 refers to the print density table. A quantization number smaller than the predetermined quantization number is determined based on a print density distribution that can be obtained when quantization is performed with a predetermined quantization number so as to delete at least one of the print densities that are close in density. Process.

Then, as described in the first embodiment, the quantization control unit 135 performs a quantization number reduction process and determines the quantization number 10 to be 8. The quantization control unit 135 calculates the data transfer amount 16.6 MB × 3/4 = 12.5 MB because the quantization number becomes 3 bits by setting the quantization number to 8. In the quantization control unit 135, the calculated data transfer amount 12.5 MB is smaller than the data communication amount 13 MB per unit time. Therefore, 12.5 MB is determined as the data transfer amount that can be communicated from the terminal device 100 to the inkjet printing apparatus 200 (communication is possible with the data communication amount that can be transferred per unit time), and the multi-value halftone processing unit 133 is determined. The number of quantizations performed in is determined to be the number of quantizations 8 that is smaller than the predetermined number of quantizations.

Here, the quantization control unit 135 refers to the print density table and repeats reducing one of the corresponding two code values sequentially from the case where the difference in print density is the smallest, per unit time. The amount of data transfer may be determined so that the terminal device 100 can communicate with the inkjet printing apparatus 200 with the amount of data communication that can be transferred to the inkjet printer 200, and a quantization number smaller than a predetermined quantization number may be determined.

The quantization control unit 135 refers to the print density table and repeatedly reduces one of the two corresponding code values sequentially from the case where the difference in print density is the smallest, so that the unit per unit time. If the data transfer amount cannot be determined so that the terminal device 100 can communicate with the inkjet printing apparatus 200 with the transferable data communication amount, the fact is output to the input / output unit 14. In this case, the input / output unit 14 performs an output (display) for the user to select whether to perform the quantization process with the current quantization number or to create the document data again.

(Printing method)
Next, a printing method using the above-described printing system will be described using the flowchart shown in FIG. Here, the functions and processes already described in the flowchart shown in FIG. 4 and the configuration of the printing system described above are denoted by the same reference numerals, and the description thereof is omitted or simplified.

In this embodiment, first, in step S1, when the user inputs an instruction to designate a high-speed transfer mode using the input / output unit 14, the printer driver unit 12 receives print job data including high-speed transfer mode designation information. Generate.

Then, the following processing is performed in the generation of the print target data in step S2. In addition, the process of step S24 and S25 is not performed, but the process of step S36 is performed instead.

In step S <b> 21, the RIP processing unit 131 sends the high-speed transfer mode designation information to the quantization control unit 135 when the high-speed transfer mode designation information is included when generating the developed print job data.

After step S22, the quantization control unit 135 determines whether or not the print target data includes high-speed transfer mode designation information (S32), and does not include the high-speed transfer mode designation information. In that case, the process of step S36 is performed.

When the high-speed transfer mode designation information is included, the quantization control unit 135 determines that the data transfer amount per unit time is a data communication amount that can be transferred per unit time (hereinafter, data communication per unit time). It is determined whether or not it is greater than (amount) (S34). In this process, from step S32, the quantization control unit 135 calculates the data transfer amount per unit time when quantization is performed with the set predetermined quantization number. From step S23, the quantization control unit 135 calculates the data transfer amount per unit time when quantization is performed with a smaller number of quantizations than the predetermined number of quantizations.

If the data transfer amount per unit time is larger than the data communication amount per unit time, the process proceeds to step S23. If the data transfer amount per unit time is smaller than the data communication amount per unit time, The process proceeds to step S36.

If it is determined in step S23 that reduction is possible, the process proceeds to step S34. If it is determined that the reduction cannot be performed, the quantization control unit 135 causes the input / output unit 14 to select a display for selecting whether to perform the quantization process with the current quantization number or to recreate the document data. (S35). When it is input that the quantization process is performed with the current quantization number, the process proceeds to step S36, and when it is input that the original data is to be recreated, this process ends. In this case, the created print target data is deleted.

  In step S <b> 36, the quantization control unit 135 performs a quantization process with the set predetermined quantization number or a quantization number smaller than the predetermined quantization number, and sends the print target data to the terminal-side communication unit 15.

(Modification 1)
In the above-described embodiment, the case where the print target data is transferred from the terminal device 100 via the communication path 300 (for example, the Internet) has been described. However, the present invention is not limited to this and may be as follows.

FIG. 6 is a diagram illustrating a printing system according to the first modification. 6, functions and processes different from those in FIG. 1 are mainly described, and descriptions of the same or similar functions and processes are omitted or simplified.

The printing system includes a scanner device 500, an inkjet printing device 200, and a communication cable 310 that performs data communication between the scanner device 500 and the inkjet printing device 200. Compared with the terminal device 100 of the first embodiment, the scanner device 500 does not include the application unit 11 and the printer driver unit 12 and includes a reading unit 138 instead of the RIP processing unit 131.

The reading unit 138 optically reads a document set in the ADF unit or the flat bed unit with a CCD or the like, thereby generating the above-described R component, G component, and B component expanded print job data. The processing after the process of converting the R component, G component, and B component expanded print job data into the C component, M component, Y component, and K component expanded print job data by the RGB-CMYK conversion unit 132 is as follows. This is the same as in the first embodiment.

(Modification 2)
(1) Further, in the above-described embodiment, the quantization number is reduced because the minimum unit of the data amount is bits. For example, from the fourth power of 2 (quantization number 9 to 16) to the second power of 2 You may make it reduce by the power-of-two unit like (quantization number 5-8). However, the present invention is not limited to this, and the number of quantizations may be reduced from 10 to 9, and the amount of information related to the number of quantizations may be reduced.

(2) In the above-described second embodiment, when the high-speed transfer mode is designated by the input / output unit 14, the processes in steps S21 to S25 (except S24) are performed in the flowchart shown in FIG. When the high-speed transfer mode is not designated, the processes of S21, S22, S23, and S24 may be performed.

(3) In the first embodiment, if NO is determined in S23 shown in FIG. 4, the process of step S24 is performed. However, if NO is determined in step S35, the process is performed. If YES is determined and YES is determined, the process of step S24 may be performed.

(4) The quantization control unit 135 refers to the print density table, and sequentially repeats the reduction of either one of the two corresponding code values from the case where the difference in print density is the smallest, thereby performing predetermined quantization. Although the description has been given of determining a quantization number smaller than the number, the present invention is not limited to this. For example, when the difference in print density is smaller than a predetermined value, the place where one of the two corresponding code values is reduced may not be the place where the difference in print density is the smallest.

(5) In the above-described embodiment, the inkjet printing apparatus 200 has been described. However, the present invention is not limited to this, and the printing agent is printed on printing paper, so that the print density difference is changed with respect to the change in the amount of the printing agent. If it occurs, the same applies.

DESCRIPTION OF SYMBOLS 1 Printing system 11 Application part 12 Printer driver part 13 Print data generation part 14 Input / output part 15 Terminal side communication part 21 Printing side communication part 22 Inkjet printing part 100 Terminal device 131 RIP processing part 132 RGB-CMYK conversion part 133 Multi-value half Tone processing unit 134 Print density data storage unit 135 Quantization control unit 138 Reading unit 200 Inkjet printing apparatus 300 Communication path 500 Scanner apparatus

Claims (5)

First image data having a predetermined number of gradations is quantized and converted into second image data having a quantization number lower than the predetermined number of gradations and the number of gradations as the number of gradations. An image processing apparatus for transferring to a printing apparatus via
Print density data storage means for storing in advance print density data indicating a print density that can be taken when quantized with a predetermined quantization number;
With reference to the print density data, the predetermined density is deleted so as to delete at least one of the print densities that are close to each other based on a print density distribution that can be obtained when quantized with the predetermined quantization number. A quantization number determining means for determining a quantization number smaller than the quantization number;
An image processing apparatus comprising: a quantization control unit configured to quantize the first image data with a quantization number determined by the quantization number determination unit. The print density data is a table showing a relationship between a code value that can be taken after quantization with a predetermined quantization number and a print density corresponding to the code value;
The quantization number determining means refers to the table, and repeats reducing one of the corresponding two code values sequentially from the case where the difference in print density is the smallest, thereby obtaining the small quantization number. The image processing apparatus according to claim 1, wherein the determination is performed. A designation means for designating a high-speed transfer mode for transferring the image data to be printed to a printing apparatus at a high speed;
The image processing apparatus according to claim 1, wherein the quantization number determination unit performs a process of determining the small quantization number when the high-speed transfer mode is designated.   The quantization number determining means, when the high-speed transfer mode is designated, a data transfer amount for transferring the print target image data quantized with the predetermined quantization number to the printing apparatus per unit time The data communication amount that can be transferred per unit time through the predetermined communication path is compared, and the process of determining the small quantization number is performed based on the comparison result. Image processing device.   5. The image processing apparatus according to claim 1, wherein the number of quantizations determined by the quantization determination unit is expressed by a power of two. 6.