JP5736423B2 - Image processing apparatus and image processing method - Google Patents

Description

  Embodiments described herein relate generally to an image processing apparatus and an image processing method that correct image output characteristics in accordance with characteristics of a printing sheet.

  Conventionally, an MFP (Multifunction Peripheral) having a scanner function is equipped with an automatic gradation correction function for maintaining gradation characteristics appropriately. In this automatic gradation correction, first, execution of automatic gradation correction is selected from the menu on the control panel of the device, and a test pattern is printed on the printing paper. Next, the test pattern printed out is read by the scanner. A gradation correction table for correcting the target gradation characteristics from the read test pattern data is calculated, and image correction is performed based on the calculated gradation correction table at the time of printing.

  However, when using special printing paper such as a postcard, it may not be suitable for the automatic gradation correction function. For example, (1) the test pattern for automatic gradation correction does not fit in the printing range of the paper, (2) the color density of the background color of the paper is high, (3) the paper itself is expensive, and the paper is used in the gradation correction test. This is the case when you do not want to waste.

  In such a case, automatic gradation correction is performed using a printing paper that is different from the original paper. However, because the paper characteristics such as paper color and thickness are different, the intended gradation reproduction is obtained. There is a problem that it is not possible.

  In addition, when printing a design image on a postcard with a background color with a high color density, if the paper color and design color interfere with each other in a similar color, a false color slightly different from the design color may be caused by faithful color correction. Sometimes it is better to correct and print as a color.

JP 2003-54078 A

  The problem to be solved by the present invention is to provide an image processing apparatus and an image processing method capable of solving the above-described problem and obtaining an intended gradation expression even on a printing paper having different paper characteristics.

In order to achieve the above object, an image processing apparatus according to an embodiment includes a standard table storage unit storing a standard table for gradation correction for a standard paper, and a color and density of a printing target paper different from the standard paper. and difference feature quantity representing at least one of the thickness, and the feature quantity setting unit that sets in accordance with an operation of the user, the feature quantity table storage unit feature quantity table is store for tone correction for difference feature quantity If, before Symbol feature quantity setting unit for the feature quantity table storage unit or al selection of the feature quantity table corresponding to the difference feature amount set in the feature quantity table selection unit, a standard table for the standard paper, and a combined correction table generation unit for generating a composite correction table to fit only multiplying the feature quantity table selected by the feature quantity table selection unit, by using the combined correction table Having an image correction unit that performs image correction for serial printing target paper.

In the image processing method of the embodiment, the standard paper and different color of printed paper, the difference feature quantity representing at least one of density and thickness, the feature quantity setting step of setting in accordance with user operation, the the feature quantity table for tone correction corresponding to the difference feature amount set in the feature quantity setting step, and the feature quantity table selection step of selecting from the feature quantity table storage unit, before Kishirube gradation correction for quasi paper and the standard table, and combined correction table generation step of generating a combined correction table the feature quantity table selection combined only multiplying the selected feature quantity table, in step for, with respect to the printed sheet by using the combined correction table And an image correction step for performing image correction .

1 is an overall block diagram of an image processing apparatus according to a first embodiment. 2 is an example of a test pattern in the embodiment. Explanatory drawing of the standard table calculation with respect to the standard paper in the same embodiment. The block block diagram of the feature-value setting part in the embodiment. FIG. 5 is a flowchart of standard table calculation for standard paper in the embodiment. FIG. 3 is a flowchart of tone correction of a printing target paper in the embodiment. A setting screen for paper color information in the embodiment. The process color selection table for the color classification of the embodiment. The example of the feature-value table in the embodiment. The process color selection table for the intermediate color classification in the embodiment. FIG. 10 is a flowchart of gradation correction of a printing target paper in the second embodiment. FIG. 10 is a setting screen diagram for setting paper thickness information in the third embodiment. The process color selection table of the feature-value table with respect to the paper thickness in the embodiment. The example of the feature-value table in the embodiment. The flowchart figure of the gradation correction process in the embodiment.

  The image processing apparatus of the present invention can perform various processes such as a color printer having a scanning function, a function of copying a base paper, a function of communicating with an external device, a function of transmitting / receiving and printing as a facsimile apparatus, and the like. It includes composite devices (MFPs) that can be used. Hereinafter, embodiments will be described in detail with reference to FIGS. 1 to 15.

<First Embodiment>
FIG. 1 shows an overall block diagram of the image processing apparatus according to the present embodiment. In the present embodiment, it is assumed that the image processing apparatus 1 is an MFP, and a scan operation and a print operation can be executed. Although the description will be made assuming that paper is used as the print medium, it is defined as print paper including print media other than paper. In the image processing apparatus 1, a PC (Personal Computer) 2 that controls the image processing apparatus 1 and a wireless portable terminal 3 such as a smartphone are connected via a network 4.

  As shown in FIG. 1, the image processing apparatus 1 includes a control panel unit 11 where a user inputs various instructions, a pattern generation unit 12 that generates a test pattern for gradation correction for a standard sheet, and a gradation correction table for a standard sheet. A standard table calculation unit 13 for calculating, a scanner unit 14 for reading an image, a standard table storage unit 15 for storing a standard table as a database, a feature amount setting unit 16 for setting a difference feature amount between a print target sheet and a standard sheet, and a difference feature amount A feature amount table storage unit 17 that stores a gradation correction table based on the feature amount table storage unit 17; a feature amount table selection unit 18 that determines which process color to select from the gradation correction table based on the difference feature amount; a standard table; Combining feature quantity tables and generating final tone correction table (referred to as composite correction table) A composite correction table generation unit 19, an image correction unit 20 that corrects an output image using the composite correction table, a printer unit 21 that prints the corrected output image, and a CPU unit 22 that controls the image processing apparatus in an integrated manner. doing.

  Here, since automatic gradation correction is performed on a paper different from the printing target paper, and this is used as a gradation reference, a paper different from the printing target paper is defined as a standard paper. Further, a paper feature such as paper color information and thickness information is defined as a feature amount, and a difference between feature amounts of the print target paper and the standard paper is defined as a difference feature amount. In this embodiment, the color of the standard paper is described as white. However, the standard paper is not necessarily white, and the user can freely define an arbitrary paper for the standard paper, but the paper characteristics are similar to the print target paper. It is preferable to select what is.

  The control panel unit 11 includes a liquid crystal screen and a selection switch for a user to give a control command to the image processing apparatus 1.

  The pattern generation unit 12 generates a test pattern for performing gradation correction on a standard sheet serving as a gradation reference. An example of this test pattern is shown in FIG. Test patterns 23 printed on a part of standard paper are shown for each process color (23C, 23M, 23Y, and 23K) (C is cyan, M is magenta, Y is yellow, and K is black). . In FIG. 2, a plurality of density patch patterns are shown only for the K color, but the same applies to each process color.

  The standard table calculation unit 13 calculates a gradation correction table (hereinafter referred to as a standard table) for standard paper based on the test pattern read result executed by the scanner unit 14.

  FIG. 3 shows a calculation example of the standard table. The horizontal axis indicates the pixel value of the density patch of the test pattern 23, and the vertical axis indicates the output pixel value. Originally, it is preferable that the gradation characteristic is linear with a one-to-one input / output relationship as indicated by a line segment 30. However, the read value fluctuates like a curve 31 depending on engine characteristics, process temperature, printing environment, printing paper, and the like. A correction value for correcting the input / output relationship to be linear is a curve 32. In general, this correction is called gamma correction. In this embodiment, the gamma correction value is tabulated for each process color, and this is used as a standard table. Therefore, this standard table can be corrected including not only the gradation correction of the standard paper itself but also the engine characteristics caused by the image processing apparatus 1.

  The standard table storage unit 15 stores the standard table calculated by the standard table calculation unit 13 as a database for each process color.

  The feature amount setting unit 16 is configured to set the difference between the print target paper and the standard paper, that is, the difference feature amount from the control panel unit 11, the network-connected PC 2, or the wireless portable terminal 3 such as a smartphone. FIG. 4 is a block diagram of the feature amount setting unit 16. The feature amount setting unit 16 includes a paper color information setting unit 161 and a thickness information setting unit 162. In addition, various paper characteristic information such as glossiness and hygroscopicity may be set as necessary. First, in the present embodiment, the paper color information setting unit 161 will be described, and the information setting unit 162 will be described in the third embodiment.

  In the feature quantity table storage unit 17, an image correction table (hereinafter referred to as a feature quantity table) for the difference feature quantity divided into a plurality of sections is created for each process color that can be used by the printer unit 21 of the image processing apparatus 1. Stored as a database. A necessary feature quantity table can be searched according to the difference feature quantity.

  The feature quantity table selection unit 18 selects which process color feature quantity table is to be applied or not among the searched feature quantity tables. This process color selection is usually performed automatically, but may be made manually selectable by the user.

  The composite correction table generation unit 19 generates a composite correction table by sequentially multiplying the standard table and the feature amount table of the selected process color for each process color.

  The image correction unit 20 corrects the print image based on the composite correction table, and is printed by the printer unit 21.

  The CPU unit 22 is a configuration used for a general computer, and includes a processor, a memory, a hard disk, various interfaces, and the like, and is configured such that the above-described blocks function using hardware and software. .

  Here, a flowchart for calculating a standard table for a standard sheet will be described with reference to FIG. First, in step ST501, the user uses the control panel unit 11 to instruct execution of automatic gradation correction for a standard sheet.

  When the gradation correction instruction is performed, in step ST502, the pattern generation unit 12 generates a test pattern 23 for gradation correction, and the printer unit 21 prints the test pattern 23 on a standard sheet.

  In step ST503, the scanner unit 14 scans the test pattern 23 placed on a document table (not shown). In step ST504, a gradation correction table for correction to target gradation correction is calculated based on the read gradation characteristic obtained from the image data of the test pattern 23 scanned and read, and this is used as a standard table. With this standard table, the engine characteristics of the image processing apparatus main body can be corrected together with the gradation correction for the standard paper.

  In step ST505, the calculated standard table is stored in the standard table storage unit 15 as a database. At that time, in order to obtain a standard table for a desired standard paper later from the database, a standard paper identification code for identifying the standard paper is added. Therefore, when a standard table for standard paper is stored in the standard table storage unit 15 in advance, standard table calculation is not performed and the standard table may be called using the standard paper identification code.

  Next, gradation correction for the printing target paper will be described with reference to the flowchart of FIG. As a premise, the standard table storage unit 15 stores a standard table for a plurality of standard papers as a database, and the feature value table storage unit 17 classifies the difference feature values from the standard paper into a plurality of categories. Assume that a feature amount table for the difference feature amounts classified into the plurality of sections is stored for each process color.

  In step ST601, the user selects a standard table for standard paper. Specifically, as shown by the dotted arrow in FIG. 1, a standard table of standard paper having characteristics close to the print target paper is read from the standard table storage unit 15 using the standard paper identification code.

  Further, when the standard table of the standard paper does not exist in the standard table storage unit 15, automatic gradation correction is performed, and when gradation correction is subsequently performed on the printing target paper, the automatic correction is automatically performed immediately. The calculated standard table is selected, and the user can omit selecting the standard table explicitly.

  In step ST602, a difference feature value is input. FIG. 7 is a setting screen in which paper color information is used as a difference feature amount. This setting screen can be specified from the control panel unit 11, the PC 2, or the wireless portable terminal 3 such as a smartphone. Now, the paper color of the standard paper is white, and the paper color (background color) to be printed is medium density red. At this time, the user presses the red button of the paper color selection buttons 71 and further presses the density M button of the paper density selection buttons 72 to input the difference feature amount. As described above, the difference feature amount is classified into a plurality of color categories and density categories by a button on the setting screen. The intermediate color button 73 will be described later.

  In step ST <b> 603, the feature amount table for the input difference feature amount classification is read from the feature amount table storage unit 17. Then, which process color feature value table is to be applied is selected. FIG. 8 shows a process color selection table for difference feature amounts (color classification and density classification). A similar process color selection table is prepared according to the difference in density category. Since the red button is now pressed, the magenta and yellow feature amount tables are selected.

  FIG. 9 is an example of the feature amount table. The feature amount tables 91L, 91M, and 91H are classified according to the density division, and the correction amount of the low density region is changed. When the density classification is density M, the feature value table 91M for the selected process color is selected.

  In step ST604, a composite correction table is generated by combining the standard table and the feature amount table 91 of the selected process color sequentially.

  In step ST605, the user confirms from the message output from the image processing apparatus 1 that a composite correction table has been generated, and executes a print job.

  In step ST606, gradation correction processing of print image data is performed based on the composite correction table, and in step ST607, the print image is output from the printer unit 21 to the print target paper.

  As a result, it is possible to prevent the print image from interfering with the paper color and hiding by correcting the paper color in the low density region. This improves the color reproduction of the same color as the printed image.

  Further, when a design image is printed on a post card having a relatively dark color density, if the correction amount is increased in proportion to the color density of the paper, the color balance of the printed image becomes strange. In such a case, it may be preferable to correct and print as a false color slightly different from the design color from the viewpoint of gradation and contrast rather than performing faithful color correction. In the present embodiment, since the difference feature amount is divided into a plurality of color sections, a slight false color is allowed in the low density region, but tone reproduction of similar colors is improved.

  On the other hand, when the paper has a low color density, the generation of false colors may not be preferable. In such a case, the number of color sections may be increased. FIG. 10 shows a process color setting table for intermediate colors. 8, an intermediate color between red and yellow (R−Y), an intermediate color between yellow and green (YG), an intermediate color between green and cyan (GC), and an intermediate color between blue and magenta ( B-M) is added. When using an intermediate color, the intermediate color selection screen appears when the intermediate color button 73 in FIG. 7 is pressed, and the intermediate color can be selected.

  At this time, when, for example, an intermediate color (RY) of red and yellow is selected as a color classification, a magenta feature table with a reduced gradation correction effect and a yellow feature table are used. The same concept applies to the selection of the other process colors of the intermediate color, which is shown in FIG. Further, by appropriately adjusting the level of the gradation correction effect, gradation correction can be performed finely for intermediate colors similar to the paper color.

  As described above, according to the first embodiment, gradation correction including the engine characteristics of the image processing apparatus is performed on the standard paper, and the level corresponding to the difference feature amount between the print target paper and the standard paper. Tone correction is performed using the feature table. Therefore, (1) the test pattern for automatic gradation correction does not fit in the printing range of the paper, (2) the color density of the background color of the paper is high, (3) the paper itself is expensive, and the gradation correction test Even when gradation correction is not successful due to reasons such as not wanting to waste paper, intended gradation expression can be obtained.

<Second Embodiment>
In the present embodiment, an embodiment in which a print image can be confirmed before executing a print job will be described. FIG. 11 is a flowchart of gradation correction of a printing target paper in the present embodiment. Step ST111 for creating a preview screen is added to the gradation correction flowchart of FIG. Since the steps other than step ST111 are the same, the description is omitted.

  In step ST605, it is assumed that print image data has already been designated on the print job execution screen. Then, by pressing a “preview” button (not shown), the process proceeds to step ST111.

  In step ST111, in accordance with an instruction from the image processing apparatus 1, the user places a print target paper on the scanner unit 14 and scans the paper color. The read result is stored as pixel values separated into RGB colors or image data. When the image data is stored, the image data and the print image data that has been subjected to gradation correction based on the composite correction table are superimposed to generate a preview screen. This preview screen is displayed on the control panel 11 or the display of the PC 2.

  As another method, the user uses the wireless portable terminal 3 such as a smartphone having a camera function, and reads the RGB color of the paper color by photographing the print target paper. Based on this paper color, the same color paper of the same size as the paper to be printed is virtually created, superimposed with the print image data that has been subjected to gradation correction based on the composite correction table, and the preview screen is wirelessly displayed. It is displayed on the display of the portable terminal 3.

  If a gradation result different from the user's intention is obtained by this preview screen, the process returns to the paper color setting shown in FIG. 7, and the intermediate color button 73 is used to adjust the paper color setting again. Continue until the gradation is reached. When the intended gradation is reached, printing is executed.

  As described above, according to the second embodiment, in addition to the effects of the first embodiment, the gradation correction result such as false color can be confirmed in advance, so that the gradation intended by the user can be obtained.

<Third Embodiment>
In the present embodiment, a case where paper thickness information is used in addition to paper color information as the difference feature amount will be described. When the paper thickness is different, printing conditions such as the paper conveyance speed and process temperature of the image processing apparatus 1 are different, so that the printing is blurred or the printing is crushed. Therefore, gradation correction based on the paper thickness is performed. Since the flowchart of gradation correction for the printing target paper is the same as that in FIG. 6, the same processing steps will be described briefly.

  In step ST601, the user selects a standard table for standard paper. In step ST602, a difference feature value is input. FIG. 12 is a setting screen in which the paper thickness information is used as a difference feature amount. This setting screen can be specified from the control panel unit 11, the PC 2, or the wireless portable terminal 3 such as a smartphone. Difference feature amounts are classified according to the thickness of the paper, such as thin paper, plain paper, thick paper 1, thick paper 2, and thick paper 3. Now, the paper color of the standard paper is plain paper, and the thickness of the print target paper is thick paper 1. At this time, the user presses the thick paper 1 button among the thickness selection buttons 121 and inputs the difference feature amount.

  In step ST <b> 603, the feature amount table for the input difference feature amount classification is read from the feature amount table storage unit 17. Then, which process color feature value table is to be applied is selected. FIG. 13 shows a process color selection table for the difference feature amount (thickness classification). A process color selection table is prepared according to the thickness classification, but a feature amount table for all process colors is selected. FIG. 14 is an example of a feature amount table. In the feature amount tables 140, 141, 142, 143, and 144, the difference feature amounts correspond to thin paper, plain paper, thick paper 1, thick paper 2, and thick paper 3, respectively. In the case of thick paper 1, the feature amount table 142 is selected. The gradation correction for the paper thickness is performed for the high density region in order to prevent blurring and crushing.

  In step ST604, a combined correction table is generated by combining the standard table and the feature amount table 152 sequentially for each process color. In step ST605, a print job is executed. In step ST606, gradation correction processing of print image data is performed based on the composite correction table, and in step ST607, an image is output from the printer unit 21 to a print target sheet. As a result, gradation correction of the high density region is performed.

  Finally, the case where the difference feature amount of both the paper color information and the paper thickness information is selected will be described with reference to the flowchart of FIG. In step ST151, a standard table for standard paper is selected. In step ST152, a feature value table for the paper color information of the print target paper is selected, and in step ST153, a feature value table for the paper thickness information is selected. In step ST154, a composite correction table is generated in which the standard table, the feature amount table for the paper color information, and the feature amount table for the paper thickness information are sequentially multiplied for each process color. In step ST155, the gradation correction is simultaneously performed on the low density region and the high density region by using the composite correction table.

  As described above, according to the third embodiment, by setting a plurality of difference feature amounts having different features from the standard paper, a feature amount table for each difference feature amount is obtained, and a process color corresponding to the difference feature amount is obtained. The feature amount table is selected, and a final gradation correction table is generated. Therefore, the user can obtain an intended gradation expression by a simple operation on printing paper having different paper characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. For example, although four CMYK colors have been described as an example of process colors, a printer having more process colors may have a feature amount table for the process colors. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 ... Image processing device,
2 ... PC,
3 ... Wireless portable terminal,
4 ... Network,
11 ... Control panel section,
12 ... pattern generator,
13 ... Standard table calculation unit,
14 ... scanner part,
15 ... Standard table storage unit,
16 ... feature amount setting unit,
17 ... Feature value table storage unit,
18 ... Feature value table selection unit,
19: Composite correction table generation unit,
20: Image correction unit,
21 ... Printer section,
22 ... CPU section,
161: Paper color information setting section,
162: Thickness information setting unit.

Claims (6)

A standard table storage unit storing a standard table for gradation correction for standard paper;
A feature amount setting unit that sets a difference feature amount representing at least one of the color, density, and thickness of a print target paper different from the standard paper according to a user operation;
A feature quantity table storage unit feature quantity table is store for gradation correction with respect to the difference feature quantity,
A feature quantity table selection unit for the feature quantity table storage unit or al selection of the feature quantity table corresponding to the difference feature amount set in the feature quantity setting unit,
And the standard table, and combined correction table generating unit in which the characteristic amount combined only multiplying the feature quantity table selected by the table selecting unit to generate a combined correction table for the standard paper,
An image correction unit that performs image correction on the print target paper using the composite correction table;
An image processing apparatus. Before SL feature quantity setting unit, the printing target paper at least one of color and density is classified into a plurality of sections displayed on the screen, based on the selected segment from the screen according to the user's operation, the image processing apparatus configured to claim 1, wherein the difference feature quantity representing at least one of color and density of the printed paper. Prior Symbol feature quantity setting unit, the thickness of the printing target paper displayed on the screen into a plurality of division, on the basis of the selected segment from the screen according to the operation of the user, the printed paper the difference feature quantity representing the thickness was set,
The image processing apparatus according to claim 1, wherein the feature quantity table selection unit selects a feature quantity table for all process colors corresponding to a category selected by the feature quantity setting unit according to a user operation . The image correction section further image processing apparatus according to any one of claims 1-3 for generating a preview screen when the image correction is performed on the printing target paper. Standard paper color different printed paper, the difference feature quantity representing at least one of density and thickness, the feature quantity setting step of setting in accordance with a user operation,
The feature quantity table for tone correction corresponding to the difference feature amount set in the feature quantity setting step, and the feature quantity table selection step of selecting from the feature quantity table storage unit,
And the standard table, and combined correction table generation step of generating a combined correction table multiplied only combined feature value table selected by the feature quantity table selection step for gradation correction with respect to prior Kishirube quasi sheet,
An image correction step for performing image correction on the print target paper using the composite correction table;
An image processing method. The image processing method according to claim 5, further comprising the step of generating a preview screen when the image correction is performed for the previous SL printed paper.

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