JP2000272212A - Image-forming apparatus, image-forming system, method for processing image and computer readable recording medium with image-processing program recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming apparatus which can thin an output gradation to a density range matching a human gradation distinction ability without generating deterioration in image quality. SOLUTION: There are provided a printing part 17 for outputting image data, a CPU 13 which carries out a process of making the printing part 17 form a test chart by developing an output gradation into a pattern for every fundamental color, thinning the output gradation based on the test chart to a visually distinguishable minimum density range and forming a calibration table, an NVRAM 12 for storing the calibration table, and a CPU 13 which carries out a process of thinning gradations of image data input from a data input interface 11 on the basis of the calibration table stored in the NVRAM 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus. More specifically, the present invention is an image forming apparatus capable of thinning out output gradations to a density range that matches human gradation discrimination ability without deteriorating image quality.

[0002]

2. Description of the Related Art In recent years, the image quality of image forming apparatuses such as printers, copiers and display monitors has been improved, and the number of image forming apparatuses capable of processing multi-gradation and high-resolution images has increased. For example, in the case of a color image, the highest gradation that can be handled by the image forming apparatus is generally 256 gradations (8-bit processing). In this case, each of R (red), G (green), and B (blue) is used. Since there are 256 gradations for each basic color, a total of 167
Expression in 77,216 colors is possible, which is called full color for convenience.

In such a full-color image forming apparatus, when image data is processed at the highest gradation of the apparatus,
As a result, an excessively high quality image far exceeding the human gradation discrimination ability may be output. In such a case, an enormous amount of data that is not originally needed is processed, which requires unnecessary processing time and wastes hardware resources such as disks and buffers. In addition, when such an image forming apparatus is used in a network, the traffic amount increases, which causes unnecessary load on the network.

[0004] For this purpose, for example, it is conceivable to lower the output gradation uniformly by lowering the processing capability, or to perform uniform thinning processing of data using a specific conversion table or the like. It is difficult for the means to match the human tone discrimination range, and there is a high possibility that the image quality is still excessive or deteriorates. Furthermore, there is an individual difference in the gradation identification range of an image. For example, when an image forming apparatus shared on a network is used by different users, it is necessary to perform image processing at a gradation necessary and sufficient for all users. Was difficult.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to enable an output gradation to be distinguished by a human without deteriorating image quality. It is an object of the present invention to provide an image forming apparatus, an image forming system, an image processing method, and a computer-readable recording medium on which an image processing program is recorded, capable of thinning out to a minimum density range.

Another object of the present invention is to provide an image forming apparatus, an image forming system, an image processing method, and an image processing program capable of thinning out to a minimum density range identifiable for each user even when used by different users. To provide a computer-readable recording medium on which is recorded.

[0007]

The above object of the present invention is achieved by the following means (1) to (4).

(1) Image output means for outputting image data, test chart creation means for causing the image output means to create a test chart in which output gradation is developed for each basic color, and the test chart creation means Calibration table creating means for creating a calibration table by thinning the output gradation to a minimum density range that can be visually identified based on the created test chart,
Storage means for storing the calibration table created by the calibration table creation means; and image processing means for thinning out the tone of the input image data based on the calibration table stored by the storage means. An image forming apparatus comprising:

(2) An image output device for outputting image data, a means for causing the output means to create a test chart in which output gradations are developed for each basic color, and an output gradation based on the test chart Means for creating a calibration table by thinning out the minimum density range that can be visually identified, means for storing the calibration table, and gradation of image data input based on the stored calibration table. And an image processing apparatus having means for thinning out images.

(3) A step of outputting a test chart in which the output gradation of the image output means is developed in a pattern for each basic color in advance, and then, based on the test chart, the smallest output gradation that can be visually identified. An image processing method comprising: a step of creating and storing a calibration table by thinning out a density range; and a step of thinning out tone of input image data based on the calibration table.

(4) A procedure for outputting a test chart in which the output gradation of the image output means is developed in a pattern for each basic color in advance, and the minimum which can visually identify the output gradation based on the test chart. A computer-readable recording program for causing a computer to execute a procedure of creating and storing a calibration table by thinning out the density range and a procedure of thinning out the gradation of input image data based on the stored calibration table. Possible recording medium.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the image forming apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram for explaining a configuration of a control unit of a printer to which the present invention is applied.

This printer has the same control unit as shown in the figure and the mechanical structure (not shown) similar to those of a general electrophotographic color printer. Therefore, referring to FIG. The configuration will be briefly described together with the general operation.

First, image data from an external personal computer or scanner is input to a data input interface (I / F) 11. Then, the CPU 13 sets R
By executing a predetermined program stored in the OM 15, necessary processing for input image data can be performed.
For example, rasterization or the like is executed, and the data is developed as bitmap data in the RAM 14. The developed bitmap data is sent to the printing unit 1 through the image output I / F 16.
7, the image is formed (printed) by the electrophotographic method in the printing unit 17, and is output as a printed matter. The NVRAM 12 is a memory for storing initial settings, various parameters, and the like. The data bus 18 is a path for transmitting various control signals in addition to image data to each unit. The RAM 14 is used as a memory for expanding image data as bitmap data, and has a function of storing received image data as it is. Further, in addition to the RAM 14, as means for storing image data, a large-capacity storage means such as a hard disk drive (HDD) may be provided.

In such a printer to which the present invention is applied, what differs from a conventional printer is image processing performed by the CPU 13 executing a program created in accordance with a procedure described later. Therefore, the basic operation relating to image formation, for example, the process of forming a color image by the electrophotographic method itself is not different from a conventional printer at all, and for a color image, C (cyan), M (magenta), Y (Yellow) and K (black) toner images are sequentially formed and transferred to paper for printing.

FIG. 2 is a flowchart showing a sequence of processing from output of a test chart to registration of a calibration table in the printer according to the present embodiment.

First, a test chart for each basic color is output by the printer having the above configuration (S11). The test chart is obtained by developing the output gradation of the printer in a single color pattern for each basic color. As shown in FIG. 3, for example, if the highest gradation of the print engine of the printing unit 17 of the printer is 256 gradations, 25
Test charts on which six patterns are printed are separately created for the three primary colors of CMY. If necessary, a test chart is created for K as well.

Next, using the output test chart, the user visually discriminates the gradation of the gradation pattern shown in the chart, and determines the gradation of the printer so as to match the minimum identifiable density range. Separate values (S1
2). In other words, a multi-gradation printer having an output of 256 gradations for each color as in the present embodiment, especially for a high-resolution printer, the output gradation number of the printer is greater than the gradation number that can be identified by humans. It is usually much wider. In such a case, the density parameter of the printer printed by the printer, that is, the gradation value, and the user-specific density parameter corresponding to the minimum density range that can be visually identified by the user are intended to be corresponded. By thinning out the data of the density parameter of the printer according to, the image quality can be reduced to the minimum necessary image data while preventing substantial deterioration of the image quality.

FIG. 4 is a flowchart showing a data input procedure of the sorting process by the user. The user
Each of the gradation patterns developed on the test chart output from the printer is compared and observed (S201). First, gradation value 0 which is the first gradation pattern of the test chart is obtained.
The range of the gradation value recognized as the same is divided and the maximum value among them is input to the printer as n (S202). Next, a range of gradation values recognized as the same as n + 1 is divided, and the maximum value among them is input to the printer as n (S
203). This sort processing is continued until the last gradation pattern of the test chart, that is, until n becomes the maximum gradation value of the printer output gradation (S204), and the processing for the test chart ends. Since the test chart is created for each basic color, this operation is repeated for each basic color (S205).

In this process, the numerical value obtained as a result of the user classification is operated by operating an "UP" key, a "DOWN" key, an "ENTER" key or the like via an operation panel of a printer as shown in FIG. Input directly to the printer. Further, as shown in FIG. 6, the processing may be performed via a personal computer or the like. In this case, as shown, the user can specify and input a range using a mouse or a keyboard on the display of the personal computer.

Thus, the output gradation of the printer is
The data is classified based on the classification data input by the user, and is converted into a new user density parameter with each of the classified density ranges as one unit (S13).

Next, for each of the obtained user density parameters, one suitable gradation value is selected from the corresponding range of the printer output gradation and assigned (S14). The assignment of the tone values to the user density parameters is performed in consideration of the gray balance of a single color for each basic color and the final color balance obtained by superimposing the colors. For this reason, if necessary, a test print is output in a single color or color, and the adjustment of the optimal assignment of gradation values is performed.

The relationship between the tone values of the printer, the corresponding user density parameters, and the tone values assigned to them is integrated into a calibration table (S15), and the parameters are stored in the NVRAM 12 or the like inside the printer. (S16).

FIG. 7 is a conceptual diagram showing one embodiment of the calibration table. Describing the present embodiment, this example is a calibration table for C (cyan). For example, the printer gradation values 0 to 9 are identified as the same density by the user, and the density range is determined by the user density parameter. Classified as 0,
One gradation value selected from printer gradation values 0 to 9 is allocated to such a range.

Since a series of processes starting from the output of the test chart is performed for each basic color, such a calibration table is also created and registered for each basic color. When the printer is shared by a plurality of users, a calibration table is created and registered for each user.

FIG. 8 is a flowchart showing the procedure of the printing process of the printer according to the present embodiment.

In the printing process of the printer, first, image data is input (S401), and subsequently, user information is input (S402). Then, the input user information is collated, and if the calibration table of the user corresponding to the information is registered, the calibration table of the user is read from the parameter storage memory, and If no matching user calibration table is registered, the default calibration table is read instead.

Next, the gradation of the input image data is thinned out according to the calibration table (S4).
06), the processed data is stored in an image memory such as the RAM 14 (S407). The stored image data is sequentially read out (S408), developed into bitmap data, and sent to the printing unit 17 (S409). As a result, the amount of image data handled inside the printer can be significantly reduced, the printing process can be made more efficient, the processing time can be shortened, the memory capacity for storing image data and expanding to bitmap data, and the CPU Hardware resources such as capacity can be saved.

Note that the flowchart is for a case where the printer is shared by a plurality of users.
It goes without saying that step 05 can be omitted.

As other image forming apparatuses to which the present invention is applied, there are a display monitor such as a personal computer and a copying machine. When the present invention is applied to a display monitor, R
A test chart in which the output gradation of the display monitor for each of the basic colors of GB is developed into a pattern is output to the display unit of the display monitor, and the user performs the sorting process and creates and registers the calibration table. This allows the display monitor to display the image data thinned out by the calibration table with the same image quality as in full-color display. Further, when the present invention is applied to a copying machine, the copying machine has an image input means, and when the image data is input by the image input means, a thinning process is performed by a calibration table, so that the processing in the copying machine is performed. The amount of data to be copied can be greatly reduced, which can contribute to the efficiency of copy processing and the saving of hardware resources.

Next, an embodiment of the image forming system of the present invention will be described.

FIG. 9 is a block diagram for explaining a network system to which the image forming system of the present invention is applied. In this embodiment, printers 111a and 111b as image forming apparatuses and a personal computer 12 as an image processing apparatus are used.
1 are connected by a network line 141. A scanner 131 as an image input device is also connected to the network via a personal computer. further,
A display monitor 112, which is an image forming apparatus, is connected to each personal computer.

For each user, a printer 111a outputs a test chart in which the output gradation of the printer is developed into a pattern, and creates a calibration table for the printer 1 in the same procedure as described above. Register and manage by Similarly, a calibration table for the printer 2 is created, registered, and managed by the printer 111b. If necessary, a calibration table for the display is also registered. Thus, when outputting image data to each image forming apparatus, the server machine performs the thinning processing of the image data according to the calibration table, thereby improving the efficiency of the image forming processing in each image forming apparatus. it can. Further, even when different users use the image output device shared in the network, it is possible to form an image that matches the tone recognition capability of each user.

Further, when the image data is input from the scanner or from the outside, the calibration table is applied by the server to perform the thinning processing of the image data, thereby reducing the amount of data handled in the network. It can contribute to reduction of traffic volume and efficiency of network.

The above-described image processing method used in the image forming apparatus or the image forming system according to the present invention is realized by an image processing program, and the program is recorded on a recording medium. Provided.

[0037]

According to the present invention, the following effects can be attained.

(1) Since the calibration table is created by thinning out the output gradation of the image output means to a minimum density range that can be visually identified, the gradation recognition ability of the user can be substantially reduced without deteriorating the image quality. A matched image can be formed with a necessary minimum data amount.

(2) Since the process of thinning out the gradation of the input image data is performed based on the registered calibration table, the efficiency of image processing and the processing time can be reduced, and the memory capacity can be reduced. Hardware resources such as CPU and CPU capacity can be saved.

(3) When the present invention is applied to a network, the thinning process is performed when image data is taken in from an image input device, so that the amount of data handled in the network can be reduced. It can contribute to efficient operation.

(4) Since the calibration table is registered for each user, even when different users use the image output apparatus shared in the network, the calibration table matches the gradation recognition ability of each user. An image can be formed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control unit of a printer according to an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a flowchart illustrating a procedure of a calibration table registration process in the printer.

FIG. 3 is a conceptual diagram showing an embodiment of a test chart used in the registration processing.

FIG. 4 is a flowchart showing a procedure for inputting classified data by a user in the registration processing.

FIG. 5 is a conceptual diagram showing an embodiment of an operation panel of the printer for performing the data input.

FIG. 6 is a conceptual diagram showing one embodiment of a display screen of a personal computer for performing the data input.

FIG. 7 is a conceptual diagram illustrating an embodiment of a calibration table registered in the registration processing.

FIG. 8 is a flowchart showing a procedure of image data printing processing in the printer.

FIG. 9 is a block diagram illustrating a configuration of a network according to an embodiment of the image forming system of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Data input interface (I / F) 12 ... NVRAM 13 ... CPU 14 ... RAM 17 ... Printing part 111a, 111b ... Printer 112 ... Display monitor 121 ... Personal computer 131 ... Scanner 141 ... Network line

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Claims (4)

[Claims] 1. An image output means for outputting image data, a test chart creating means for causing the image output means to create a test chart in which output gradations are developed for each basic color, and a test chart created by the test chart creating means A calibration table creating means for creating a calibration table by thinning out the output gradation to a minimum density range that can be visually identified based on the test chart, and a calibration table created by the calibration table creating means. An image forming apparatus, comprising: a storage unit for performing the processing; and an image processing unit for thinning out the gradation of the input image data based on the calibration table stored by the storage unit. 2. An image output apparatus for outputting image data, means for causing the output means to create a test chart in which output gradations are developed into patterns for each basic color, and means for generating the output gradations based on the test charts. Means for creating a calibration table by thinning out to a minimum density range that can be visually identified, means for storing the calibration table, and gradation of image data input based on the stored calibration table. An image forming system in which an image processing apparatus having a thinning unit is mutually connected by a network. 3. A step of outputting a test chart in which the output gradation of the image output means is developed in a pattern for each basic color in advance, and the minimum density at which the output gradation can be visually identified based on the test chart. An image processing method comprising: a step of creating and storing a calibration table by thinning out a range; and a step of thinning out gradations of image data input based on the calibration table. 4. A procedure for outputting a test chart in which the output gradation of the image output means is developed in a pattern for each basic color in advance, and a minimum density at which the output gradation can be visually identified based on the test chart. A computer-readable recording program for causing a computer to execute a procedure of creating and storing a calibration table by thinning out a range, and a procedure of thinning out the gradation of input image data based on the stored calibration table. Recording medium.