JP2008079339A - Distribution curve generating apparatus and distribution curve generating program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distribution curve generating apparatus capable of maintaining the linearity of the density with respect to an input level and preventing occurrence of pseudo-contours. <P>SOLUTION: The distribution curve generating apparatus inputs a color signal of an image, processes the inputted color signal based on a first distribution curve for distributing the color signal between a color signal corresponding to normal ink and a color signal corresponding to light ink whose color is lighter than that of the normal ink, detects density information of the image outputted by an image forming device, and generates a second distribution curve based on the detected density information and the inputted color signal, wherein the length in which the variation quantity of the detected density information is almost zero is calculated as a horizontal quantity, and a distribution curve in which the calculated horizontal quantity is minimum is selected as the second distribution curve to be generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is used in an image forming apparatus, and generates a distribution curve for generating a distribution curve for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink having a lighter color than the normal ink. The present invention relates to an apparatus and a distribution curve generation program.

  In recent years, color printers (so-called ink jet printers) of a type that ejects several colors of ink from a head have become widespread as output devices for computers, and output images processed by computers and the like in multiple colors and multiple gradations. Widely used in This color printer, when outputting an image in multi-color and multi-tone, has four colors of black (BK), cyan (C), magenta (M), yellow (Y) or black (BK), cyan (C ), Magenta (M), yellow (Y), light cyan (Lc), and light magenta (Lm) inks are generally mixed and output in accordance with the image signal. Light cyan (light ink) is often created by distributing from cyan (normal ink), and light magenta (light ink) is often created by distributing from magenta (normal ink). In this case, the distribution ratio of each color ink is referred to as a distribution curve. Based on the input level and distribution curve of the input image that is input, the distribution ratio between normal ink and light ink output from the color printer. Was decided. FIG. 11 is a diagram showing an example of a conventional distribution curve.

  However, when output from a color printer using a distribution curve as shown in FIG. 11, the linearity of the density information is not maintained with respect to the input level, and an inflection point of the density information occurs with respect to the input level. There was a problem.

  Further, when the distribution curve is a curve that changes sharply with respect to the input level, there is a problem that a pseudo contour is likely to occur.

  The present invention has been made to solve the above problems, and provides a distribution curve generation device and a distribution curve generation program that maintain the linearity of density information with respect to an input level and prevent pseudo contours. It is another object of the present invention to provide a distribution curve and a distribution curve generation program according to usage conditions of the image forming apparatus.

  In order to achieve this object, a distribution curve generating apparatus according to claim 1 of the present invention includes a color signal input means for inputting a color signal of an image, a color signal corresponding to normal ink, and the normal ink. First distribution curve storage means for storing a first distribution curve for distributing color signals corresponding to light ink of a light color, and the color signal input by the color signal input means as the first distribution curve. Processing based on the first distribution curve stored in the storage means and detecting density information of the image output by the image forming apparatus; density information detected by the density information detecting means; and In particular, the first distribution includes a second distribution curve generating unit that generates a second distribution curve based on the color signal input by the color signal input unit. The probe storage means stores a plurality of first distribution curves, and the second distribution curve generation means outputs density information detected by the density information detection means and color signals input by the color signal input means. Based on this, a second distribution curve is generated.

  In the distribution curve generation device according to claim 1 of the present invention, the first distribution curve storage means stores a plurality of first distribution curves, and the second distribution curve generation means is detected by the density information detection means. Since the second distribution curve is generated based on the density information and the color signal input by the color signal input means, it is possible to generate a distribution curve according to the use conditions of the image forming apparatus.

  In the distribution curve generation device according to claim 2, the first distribution curve storage unit monotonically increases the total ink amount of the normal ink and the light ink as the value of the input color signal increases. The first distribution curve indicating the tendency is stored.

  3. The distribution curve generation device according to claim 2, wherein the first distribution curve storage means shows a tendency that the total ink amount of normal ink and light ink increases monotonously as the value of the input color signal increases. Since the first distribution curve is stored, when the second distribution curve is generated based on the first distribution curve, the characteristic of the total ink amount with respect to the input color signal value is obtained. It is possible to generate a second distribution curve that has no inflection point, excellent gradation characteristics, and prevents pseudo contours.

  The distribution curve generation device according to claim 3, wherein the first distribution curve storage means has a maximum density information expressed by mixing the normal ink and the light ink. A first distribution curve with a distribution ratio of 0 is stored.

  4. The distribution curve generation device according to claim 3, wherein the first distribution curve storage means sets the light ink distribution ratio to 0 when density information expressed by mixing normal ink and light ink is maximum. Therefore, when the second distribution curve is generated based on the first distribution curve, the total ink amount at the time of maximum density information can be reduced. And a second distribution curve that prevents ink bleeding can be generated.

  According to a fourth aspect of the present invention, in the distribution curve generating device, the length of the change amount of the density information detected by the density information detection unit with respect to the color signal input by the color signal input unit is substantially zero. A horizontal amount calculating means for calculating is provided, wherein the second distribution curve generating means selects and generates a second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculating means.

  5. The distribution curve generating device according to claim 4, wherein the horizontal amount calculating means horizontally sets a length in which the amount of change in density information detected by the density information detecting means for the color signal input by the color signal input means is substantially zero. Since the second distribution curve generation unit selects and generates the second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation unit, the second distribution curve is generated using the second distribution curve. When an image is output by the color printer 2, the gradation of the image is improved and pseudo contour can be prevented.

  According to a fifth aspect of the present invention, there is provided a distribution curve generation device that corresponds to a color signal input means for inputting a color signal of an image, a color signal corresponding to normal ink, and light ink having a lighter color than the normal ink. First distribution curve storage means for storing a plurality of first distribution curves for distributing color signals, and a first distribution curve storage means for storing color signals input by the color signal input means. Density information detecting means for detecting density information of an image output by the image forming apparatus and density information detected by the density information detecting means and the color signal input means. Second distribution curve generating means for generating a second distribution curve based on the color signal; and the second distribution curve for the color signal input by the color signal input means. A maximum change amount calculating means for calculating the maximum change amount of the second distribution curve generated by the generating means, and a second distribution curve for which the maximum change amount calculated by the maximum change amount calculating means is minimized. And third distribution curve generation means for generating the distribution curve.

  6. The distribution curve generating device according to claim 5, wherein a second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculating means is selected and generated, and therefore the second distribution curve is used. When the color printer 2 outputs an image, the gradation of the image is improved and pseudo contour can be prevented.

  According to a sixth aspect of the present invention, there is provided a distribution curve generation device that corresponds to a color signal input means for inputting a color signal of an image, a color signal corresponding to normal ink, and light ink having a lighter color than the normal ink. First distribution curve storage means for storing a first distribution curve for distributing color signals, and a first distribution curve storage means for storing color signals input by the color signal input means. Density information detecting means for detecting density information of the image processed based on the distribution curve and output by the image forming apparatus, density information detected by the density information detecting means, and color input by the color signal input means In particular, the first distribution curve storage means includes a second distribution curve generation means for generating a second distribution curve based on the signal. A plurality of first distribution curves are stored corresponding to the large adhesion amount, and the second distribution curve generation means selects the first distribution curve from the first distribution curve storage means according to the maximum adhesion amount of the medium. The second distribution curve is generated based on the selected first distribution curve.

  7. The distribution curve generation device according to claim 6, wherein the second distribution curve generation means selects the first distribution curve from the first distribution curve storage means according to the maximum amount of adhesion of the medium, and the selected first Since the second distribution curve is generated based on the distribution curve, it is possible to generate an appropriate second distribution curve depending on the media.

  According to a seventh aspect of the present invention, there is provided a distribution curve generation device that corresponds to a color signal input means for inputting a color signal of an image, a color signal corresponding to normal ink, and light ink having a lighter color than the normal ink. First distribution curve storage means for storing a first distribution curve for distributing color signals, and a first distribution curve storage means for storing color signals input by the color signal input means. Density information detecting means for detecting density information of the image processed based on the distribution curve and output by the image forming apparatus, density information detected by the density information detecting means, and color input by the color signal input means In particular, the first distribution curve storage means includes a medium, a second distribution curve generation means for generating a second distribution curve based on a signal, A plurality of first distribution curves are stored in correspondence with printing conditions such as a link, a resolution, or a printing method, and the second distribution curve generating unit is configured to store a first distribution curve from the first distribution curve storage unit according to the printing conditions. The distribution curve is selected and a second distribution curve is generated based on the selected first distribution curve.

  8. The distribution curve generation device according to claim 7, wherein the second distribution curve generation unit selects a first distribution curve from the first distribution curve storage unit according to a printing condition, and the selected first distribution curve. Since the second distribution curve is generated based on the curve, an appropriate second distribution curve can be generated depending on the printing conditions.

  The distribution curve generation program according to claim 8 is a computer for generating a distribution curve, a color signal input means for inputting a color signal of an image, and a color signal input by the color signal input means. Processing is performed based on a first distribution curve for distributing the color signal corresponding to the normal ink and the color signal corresponding to the light ink having a lighter color than the normal ink, and the density of the image output by the image forming apparatus Density information detection means for detecting information, second distribution curve generation means for generating a second distribution curve based on density information detected by the density information detection means and the color signal input by the color signal input means; The change amount of the density information detected by the density information detection unit with respect to the color signal input by the color signal input unit is horizontally set to a length of substantially zero. Horizontal amount calculating means for calculating as is characterized by the horizontal amount calculated by the horizontal amount calculating means to function as means for selecting the second distribution curve becomes minimum.

  According to an eighth aspect of the present invention, there is provided a distribution curve generation program, comprising: a color signal input means for inputting a color signal of an image; a color signal input by the color signal input means; a color signal corresponding to normal ink; Density information detection means for processing density information of the image output by the image forming apparatus, processing based on the first distribution curve for distributing the color signal corresponding to light ink of a lighter color than normal ink; Second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means, input by the color signal input means A horizontal amount calculating means for calculating a length in which a change amount of the density information detected by the density information detecting means for the color signal is substantially zero as a horizontal amount; When the image is output by the color printer 2 using the second distribution curve, it is made to function as a means for selecting the second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation means. As a result, the gradation of the image is improved and pseudo contour can be prevented.

  Further, the distribution curve generation program according to claim 9 is a computer for generating a distribution curve, a color signal input means for inputting a color signal of an image, and a color signal input by the color signal input means. Processing is performed based on a first distribution curve for distributing the color signal corresponding to the normal ink and the color signal corresponding to the light ink having a lighter color than the normal ink, and the density of the image output by the image forming apparatus Density information detection means for detecting information, second distribution curve generation means for generating a second distribution curve based on density information detected by the density information detection means and the color signal input by the color signal input means; Maximum change of the second distribution curve generated by the second distribution curve generation unit with respect to the color signal input by the color signal input unit And a third distribution curve generation unit that selects and generates the second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculation unit. Yes.

  According to a ninth aspect of the present invention, there is provided a distribution curve generation program, comprising: a color signal input means for inputting a color signal of an image; a color signal input by the color signal input means; a color signal corresponding to normal ink; Density information detection means for processing density information of the image output by the image forming apparatus, processing based on the first distribution curve for distributing the color signal corresponding to light ink of a lighter color than normal ink; Second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means, input by the color signal input means Maximum change amount calculating means for calculating the maximum change amount of the second distribution curve generated by the second distribution curve generating means for the color signal; The second distribution curve generated by the third distribution curve generation unit is made to function as the third distribution curve generation unit that selects and generates the second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculation unit. When the image is output by the color printer 2 using this distribution curve, the gradation of the image is improved and the pseudo contour can be prevented.

  As is apparent from the above description, according to the distribution curve generating device of the first aspect of the present invention, the first distribution curve storage means stores a plurality of first distribution curves, and the second distribution curve. Since the curve generation unit generates the second distribution curve based on the density information detected by the density information detection unit and the color signal input by the color signal input unit, the distribution curve according to the use conditions of the image forming apparatus Can be generated.

  According to the distribution curve generating device of the second aspect, the total ink amount of the normal ink and the light ink monotonously increases in the first distribution curve storage means as the value of the input color signal increases. Since the first distribution curve indicating the tendency of the first distribution curve is stored, when the second distribution curve is generated based on the first distribution curve, the total ink for the value of the input color signal is stored. It is possible to generate a second distribution curve that has no inflection point in quantity characteristics, excellent gradation characteristics, and prevents pseudo contours.

  According to the distribution curve generating device of the third aspect, when the density information expressed by mixing the normal ink and the light ink is maximum, the first distribution curve storage unit stores the light ink. Since the first distribution curve with the distribution ratio set to 0 is stored, when the second distribution curve is generated based on the first distribution curve, the total ink amount at the maximum density information is calculated. The second distribution curve can be generated, which can be reduced and prevents ink bleeding.

  According to the distribution curve generating device of the fourth aspect, the horizontal amount calculating means is such that the change amount of the density information detected by the density information detecting means with respect to the color signal input by the color signal input means is substantially zero. The length is calculated as a horizontal amount, and the second distribution curve generation unit selects and generates the second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation unit, so that gradation is improved. A second distribution curve in which pseudo contour is prevented can be generated.

  According to the distribution curve generating device of the fifth aspect, since the second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculating means is selected and generated, the gradation is improved. A second distribution curve can be generated that is improved and prevents false contours.

  Further, according to the distribution curve generation device of claim 6, the second distribution curve generation means selects the first distribution curve from the first distribution curve storage means according to the maximum adhesion amount of the medium, and the selection Since the second distribution curve is generated based on the set first distribution curve, an appropriate second distribution curve can be generated depending on the media.

  Further, according to the distribution curve generation device according to claim 7, the second distribution curve generation means selects the first distribution curve from the first distribution curve storage means according to the printing condition, and the selected Since the second distribution curve is generated based on the first distribution curve, an appropriate second distribution curve can be generated according to the difference in printing conditions.

  According to the distribution curve generation program according to claim 8, the computer corresponds to the color signal input means for inputting the color signal of the image, and the color signal input by the color signal input means corresponds to the normal ink. A density for detecting density information of an image output by the image forming apparatus by processing based on a first distribution curve for distributing a color signal and a color signal corresponding to light ink having a lighter color than the normal ink. Information detection means, second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means, the color signal input means The horizontal amount is calculated by calculating the length of the amount of change in the density information detected by the density information detecting means with respect to the color signal input by the above as a horizontal amount. Since the calculation means and the means for selecting the second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation means function, the color printer 2 outputs an image using the second distribution curve. In this case, the gradation of the image is improved and pseudo contour can be prevented.

  Further, according to the distribution curve generation program according to claim 9, the computer corresponds to the color signal input means for inputting the color signal of the image, and the color signal input by the color signal input means corresponds to the normal ink. A density for detecting density information of an image output by the image forming apparatus by processing based on a first distribution curve for distributing a color signal and a color signal corresponding to light ink having a lighter color than the normal ink. Information detection means, second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means, the color signal input means The maximum change for calculating the maximum change amount of the second distribution curve generated by the second distribution curve generation means for the color signal input by Since the calculation means and the third distribution curve generation means for selecting and generating the second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculation means, the calculation means is generated by the third distribution curve generation means. When the image is output by the color printer 2 using the second distribution curve, the gradation of the image is improved and the pseudo contour can be prevented.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a distribution curve generating device of the present invention. In FIG. 1, the distribution curve generating device is composed of a personal computer (hereinafter referred to as PC) 1 and a colorimeter 3, and a color printer 2 (image forming device) is connected to the outside. The PC 1, the colorimeter 3, and the color printer 2 are connected to each other via dedicated interface cables 4 and 5 so that data communication is possible.

  The PC 1 functions as a CPU 11 (functions as a color signal input means, density information detection means, second distribution curve generation means, horizontal amount calculation means, maximum change amount calculation means, and third distribution curve generation means of the present invention), ROM 12 ( A first distribution curve storage means), a RAM 13, a hard disk device (HD) 14, a printer interface (I / F) 15, a colorimeter interface (I / F) 16, and a display device (CRT) 17. These are connected via a bus 18 so that data communication is possible.

  The CPU 11 executes various calculations and control on the controlled object according to various programs stored in the ROM 12 which is a read-only storage element or various programs read from the HD 14 and stored in the RAM 13.

  The ROM 12 stores a distribution curve (hereinafter referred to as a first distribution curve) for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink lighter than the normal ink, and various programs described above. In addition, data and the like that do not need to be rewritten are stored. In particular, for the first distribution curve, a plurality of types of first distribution curves as shown in FIGS. 2A and 2B are stored. Yes. 2A and 2B, the solid line represents the output level with respect to the input level of the color signal corresponding to light ink (light cyan or light magenta), and the wavy line represents the color corresponding to normal ink (cyan or magenta). It represents the output level relative to the input level of the signal. The first distribution curve shown in FIG. 2A is a first distribution curve in which the light ink distribution ratio is 0 when density information expressed by mixing normal ink and light ink is maximum. An example of a curve is shown. A second distribution curve, which will be described later, is generated based on the first distribution curve, the color signal of the input image is processed based on the second distribution curve, and the image formed by the processing is processed by the color printer. In the case of output by 2, even when the maximum density information is expressed, the total amount of ink to be used can be reduced, and ink bleeding can be prevented.

  Further, the first distribution curve shown in FIG. 2B is a first distribution curve in which the total ink amount of normal ink and light ink tends to increase monotonically as the value of the input color signal increases. An example of a curve is shown. A second distribution curve, which will be described later, is generated based on the first distribution curve, the color signal of the input image is processed based on the second distribution curve, and the image formed by the processing is processed by the color printer. 2, since there is no inflection point in the characteristic of the total ink amount with respect to the input color signal value, an image having excellent gradation characteristics can be output, and an image without pseudo contour can be output. Can be output.

  The RAM 13 is a storage element that can be arbitrarily read and written, and can store data obtained by various operations of the CPU 11 in addition to the various programs read from the HD 14.

  The HD 14 is an auxiliary storage device that stores data such as programs and image data that are not constantly stored in the main storage device such as the ROM 12 and the RAM 13 as files, and is used for performing a profile creation method. Various profiles are stored, such as a profile creation program, an upper profile for color correction created by the profile creation program, and a lower profile for calibration that corrects individual differences and changes with time of the printer itself.

  The printer interface 15 and the colorimeter interface 16 are two-way data between the color printer 2 and the colorimeter 3 according to a specific communication protocol negotiated between the color printer 2 and the colorimeter 3. Communication is performed, and the CRT 17 displays the data in a form that allows the user of the system to visually recognize various data.

  The colorimeter 3 includes a reading device 31 and a PC interface 32, and the reading device 31 performs data communication with the PC 1 via the PC interface 32 and the colorimeter interface 16. It has become.

  The reading device 31 measures the intensity of reflected or transmitted light from the measurement object, and outputs the density information level for each color when the color of the measurement object is divided into three primary colors as a color measurement database. Is.

  The upper profile for color correction is a data file used when correcting input image data so that it looks like an appropriate color in consideration of the mutual relationship between colors, and includes cyan (C), magenta ( Output color data is provided for each of six combinations of input color data such as M), yellow (Y), black (K), light cyan (Lc), and light magenta (Lm). Note that this upper profile does not have output color data for all 256 gradations (0 to 255) for each input color, but output color data is prepared at a constant gradation value interval. Yes. Therefore, for gradation values for which output color data is not prepared, a correction value (approximate value) is calculated by interpolation from surrounding data and used.

  The color printer 2 includes an ink jet printing device 21 and a PC interface 22, and the printing device 21 performs data communication with the PC 1 via the PC interface 22 and the printer interface 15. It has become.

  The printing device 21 has six types such as cyan (C), magenta (M), yellow (Y), black (K), light cyan (Lc), and light magenta (Lm) based on input image data given from the PC 1. An image is formed on a recording medium by ejecting the ink, and is configured so that a multi-tone color image having 256 gray levels can be recorded.

  Next, a method for generating a distribution curve (second distribution curve of the present invention) will be described.

  FIG. 3 is a flowchart showing a process of generating the second distribution curve. In S1, the color signal of the image data stored in the HD 14 is input. This step corresponds to the color signal input means. As shown in FIG. 12, this image data is image patch data formed with an input level of 0 to 255 in increments of 5. Next, in S3, the first distribution curve stored in the ROM 12 is input. In S5, the color signal input in the process of S1 is based on the first distribution curve input in the process of S3. Execute color signal processing and distribute to light ink and normal ink.

  In S7, an instruction is issued to cause the color printer 2 to print the image formed in the color signal processing in S5 via the printer interface (I / F) 15.

  When an image is output by the color printer instructed to print, the colorimeter 3 measures the density information of each of the output image patches, and the density information is input in S9. This step corresponds to the density information detecting means. The density information input at this time is shown in the graph of FIG.

  In step S11, a second distribution curve is generated based on the detected density information, the input color signal (the level of each patch specified by the image patch), and the first distribution curve. This step corresponds to the second distribution curve generating means.

  The second distribution curve generating means in S11 is a so-called density linear correction portion. This correction portion will be described in more detail with reference to FIG.

FIG. 15 is a flowchart showing a flow of processing for correcting density information linearly by interpolating density information in order to create a second distribution curve. First, the density information is interpolated in S81. Since the image patch data is in increments of 0 to 255, the density information at the input level where density information does not exist is obtained in advance by interpolation based on the density information acquired in S9. In S83, density information for one gradation is obtained. The minimum density information of this patch is 0.1 and the maximum density information is 2.2. If the density information is equally divided into 256 gradations of 0-255, one gradation is 0.0082. . In S84, if a desired gradation level for obtaining density information corresponding to each gradation of all 256 gradations is i (0 ≦ i ≦ 255), and density information corresponding to this gradation level i is Di, Calculated according to the formula. Di = (density information for one gradation) * gradation level + minimum density information = 0.008 * i + 0.1
In S85, an input level for each tone level density information Di is obtained based on the correspondence relationship obtained in S81. Referring to the graph of FIG. 6, for example, when the density information is 0.5, the input level is 50, and when the density information is 1, the input level for the density information is obtained as 185.

  In S87, the input level corresponding to each gradation obtained in S85 is distributed to the color signals of normal ink and light ink based on the first distribution curve to obtain the second distribution curve in FIG. Referring to FIG. 13, if the input level is 50, the light ink output level is 100 and the normal ink output level is 0. If the input level is 145, the light ink output level is 225 and the normal ink output level is 35.

  Table 2 shows a correspondence table of each gradation, the input level corresponding to it, and the distributed normal ink / light ink.

  On the other hand, as shown in FIG. 4, the color printer 2 inputs the color signal of the image data stored in the HD 14 (S21), and the first distribution curve stored in the ROM 12 or the generated second distribution curve. (S23), the color signal input in the process of S21 is executed based on the first distribution curve or the second distribution curve input in S23 (S25), and the color signal processing is performed. The image formed by is printed.

  FIG. 4 is a flowchart showing the flow of color signal processing in the color printer 2 (image forming apparatus).

  Here, since the ROM 12 stores a plurality of first distribution curves, an appropriate second distribution curve is generated according to the use conditions of the color printer 2. For example, when the density information expressed by mixing normal ink and light ink shown in FIG. 2A is maximum, the first distribution curve with the light ink distribution ratio set to 0 is used. Thus, when the second distribution curve is generated, even when the maximum density information is expressed, the total amount of ink used can be reduced and ink bleeding can be prevented. It is effective for relatively few media. In addition, the first distribution curve shown in FIG. 2B is used by using the first distribution curve in which the total ink amount of the normal ink and the light ink monotonously increases as the value of the input color signal increases. When the distribution curve of 2 is generated, there is no inflection point in the characteristic of the total ink amount with respect to the input color signal value, so that an image with excellent gradation characteristics can be output, and the pseudo contour It is effective for glossy paper because it can output a non-image. When the density information expressed by mixing the normal ink and the light ink is maximum, the first distribution curve with the light ink distribution ratio set to 0 is the distribution curve 1, and the value of the input color signal is Table 1 shows a summary of the conditions under which each first distribution curve is used, with the first distribution curve showing the tendency of the monotonous increase in the total ink amount of normal ink and light ink as distribution increases as distribution curve 2. It is.

  That is, when the adhesion amount of ink is less than 200%, when using media of matte paper type and plain paper type, when using ink with low quick drying property, when the resolution of the output image is 600 dpi or less, and when printing In the case of bidirectional printing, the image quality is better when using the distribution curve 1, when the ink adhesion amount is 200% or more, when using glossy media, ink with high quick-drying properties is used. When used, when the resolution of the output image exceeds 600 dpi and when the printing is unidirectional printing, it is confirmed that the image quality is better when the distribution curve 2 is used.

  Next, a second embodiment of the present invention will be described.

  FIG. 5 is a flowchart showing a flow of second distribution curve generation processing in the second embodiment. In FIG. 5, it is first determined whether or not the processing (S33 to S41) to be described later has been completed for all the first distribution curves stored in the ROM 12 (S31), and if not completed (S31: No) ), The color signal of the image data stored in the HD 14 is input (S33: color signal input means), the first distribution curve stored in the ROM 12 is input (S35), and the color signal input in the processing of S33 The color signal processing is executed based on the first distribution curve input in the processing of S35 (S37), and the image formed by the color signal processing is transferred to the color printer via the printer interface (I / F) 15. 2 is instructed to print (S39). When an image is output by the color printer 2 instructed to print, the density information of the output image is detected by the colorimeter 3, and the detected density information is input (S41: density information detecting means). . Then, a second distribution curve is generated based on the detected density information and the input color signal (second distribution curve generation means). On the other hand, when the processing of S33 to S41 has been completed for all the first distribution curves stored in the ROM 12 (S31: Yes), it has been detected in the processing of S41 for the color signal input in the processing of S33. A length with substantially zero change in density information is calculated as a horizontal amount (horizontal amount calculating means), a second distribution curve that minimizes the calculated horizontal amount is selected (S43), and the selected first A distribution curve of 2 is generated (S45). Here, the relationship between the color signal (input level: 0 to 255) input in the process of S33 calculated in S43 and the density information (0 to 2.5) detected in the process of S41 is shown. FIG. The curve shown in FIG. 6 is a graph showing the relationship between the color signal (input level) input in the process of S33 and the density information detected in the process of S41. Further, the plurality of vertical lines shown in FIG. 6 are obtained by dividing the density information in units of 0.1 and obtaining the corresponding input levels. The input levels of the vertical lines are 17 from the left side of FIG. 25, 37, 50, 70, 95, 145, 165. FIG. 7 is an explanatory diagram for explaining the horizontal amount of density information. In FIG. 7, when the density information change is equal to or less than a specified value (for example, 0.1), it is determined to be horizontal, and the change amount of the density information is determined to be substantially zero.

  According to the second embodiment, since the second distribution curve that minimizes the horizontal amount is selected and generated, when the color printer 2 outputs an image using the second distribution curve, As a result, the gradation of the image is improved and the pseudo contour is prevented.

  Next, a third embodiment of the present invention will be described.

FIG. 8 is a flowchart showing the flow of the second distribution curve generation process in the third embodiment. In FIG. 8, it is first determined whether or not the processing (S53 to S63) to be described later has been completed for all the first distribution curves stored in the ROM 12 (S51), and if not completed (S51: No) ), The color signal of the image data stored in the HD 14 is input (S53: color signal input means), the first distribution curve stored in the ROM 12 is input (S55), and the color signal input in the processing of S53 The color signal processing is executed based on the first distribution curve input in the processing of S55 (S57), and the image formed by the color signal processing is sent to the color printer via the printer interface (I / F) 15. 2 is instructed to print (S59). When an image is output by the color printer 2 instructed to print, density information of the output image is detected by the colorimeter 3, and the detected density information is input (S61: density information detection means). . Then, a second distribution curve is generated based on the detected density information and the input color signal (S63: second distribution curve generation means). On the other hand, when the processing of S53 to S63 is finished for all the first distribution curves stored in the ROM 12 (S51: Yes), the maximum change with respect to the color signal value of the second distribution curve generated in S63. The amount is calculated (maximum change amount calculation means), and the second distribution curve having the minimum maximum change amount is selected and generated (S65: third distribution curve generation means).
FIG. 9 is an explanatory diagram for explaining the maximum amount of change in the third embodiment. That is, in the distribution curve shown in FIG. 9, the area indicated by the arrow is calculated as the maximum change amount.

  According to the third embodiment, since the second distribution curve with the smallest maximum change amount is selected and generated, an image is output by the color printer 2 using the second distribution curve. In this case, the gradation of the image is improved and the pseudo contour is prevented.

  Next, a fourth embodiment of the present invention will be described.

FIG. 10 is a flowchart showing the flow of the second distribution curve generation process in the fourth embodiment. In FIG. 10, first, when printing conditions such as the maximum ink deposition amount, media type, ink type, output image resolution, and printing direction are input from an input device such as a keyboard (not shown) (S71). A first distribution curve corresponding to the printing conditions is selected (S73). Then, the color signal of the image data stored in the HD 14 is input (S75: color signal input means), the first distribution curve selected in the process of S73 is input (S77), and is input in the process of S71. The color signal is processed based on the first distribution curve input in the process of S77 (S79), and the image formed by the color signal process is sent via the printer interface (I / F) 15. The color printer 2 is instructed to print (S81). When an image is output by the color printer 2 instructed to print, the density information of the output image is detected by the colorimeter 3, and the detected density information is input (S83: density information detecting means). . Then, a second distribution curve is generated based on the detected density information and the input color signal (S85: second distribution curve generation means).
According to the fourth embodiment, the first distribution curve is selected according to the maximum adhesion amount of the medium, and the second distribution curve is generated based on the selected first distribution curve. Depending on the difference, an appropriate second distribution curve can be generated. In addition, the first distribution curve is selected according to the printing conditions such as the printing direction, and the second distribution curve is generated based on the selected first distribution curve. Two distribution curves can be generated.

  While various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various embodiments can be implemented without departing from the scope of the present invention. For example, in the present embodiment, image data is input from the HD 14, but may be input from the outside of the distribution curve generation device via a communication line such as the Internet.

  Further, the various processes described above are executed by the CPU 11 provided in the distribution curve generation device, but the function for executing such processes may be implemented as a distribution curve generation program. In this case, the distribution curve generation program can be implemented via a recording medium such as a CD-ROM or via the Internet.

It is a schematic block diagram of the distribution curve production | generation apparatus of this invention. It is a figure showing the example of the 1st distribution curve. It is the flowchart which showed the process which produces | generates a 2nd distribution curve. 6 is a flowchart illustrating a flow of color signal processing in the image forming apparatus. It is a flowchart which shows the flow of the 2nd distribution curve production | generation process in 2nd Embodiment. It is the figure which showed the density | concentration information graph in 2nd Embodiment. It is explanatory drawing for demonstrating the horizontal amount of density | concentration information. It is a flowchart which shows the flow of the 2nd distribution curve production | generation process in 3rd Embodiment. It is explanatory drawing for demonstrating the maximum variation | change_quantity in 3rd Embodiment. It is a flowchart which shows the flow of the 2nd distribution curve production | generation process in 4th Embodiment. It is a figure showing the conventional distribution curve. It is a figure showing the image patch data of this Embodiment. It is a figure showing the example of the 2nd distribution curve. It is a figure showing the example of the 2nd distribution curve. It is a flowchart which shows the flow of the process which interpolates density | concentration information and correct | amends in density linearity in order to produce a 2nd distribution curve.

Explanation of symbols

1 Personal Computer 2 Color Printer 3 Colorimeter 11 CPU
12 ROM
13 RAM

Claims (9)

Color signal input means for inputting an image color signal;
First distribution curve storage means for storing a first distribution curve for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink having a lighter color than the normal ink;
The color signal input by the color signal input means is processed based on the first distribution curve stored in the first distribution curve storage means, and the image output by the image forming apparatus based on the processed signal Concentration information detecting means for detecting the concentration information of
Based on the density information detected by the density information detection means, the color signal input by the color signal input means, and the first distribution curve stored in the first distribution curve storage means, the color signal A distribution curve comprising second distribution curve generation means for generating a second distribution curve for distributing the color signal input by the input means to the color signal corresponding to normal ink and the color signal corresponding to light ink In the generator,
The first distribution curve storage means stores a plurality of first distribution curves,
The second distribution curve generation means includes first distribution curve selection means for selecting a desired first distribution curve from a plurality of first distribution curves stored in the first distribution curve storage means, and the first distribution curve selection means. A second distribution curve is generated based on the first distribution curve selected by the curve selection unit, the density information detected by the density information detection unit, and the color signal input by the color signal input unit. A distribution curve generating device characterized by that. The first distribution curve storage means stores a first distribution curve in which the total ink amount of the normal ink and the light ink tends to monotonously increase as the value of the input color signal increases. The distribution curve generating device according to claim 1. The first distribution curve storage means stores a first distribution curve in which the distribution ratio of the light ink is 0 when density information expressed by mixing the normal ink and the light ink is maximum. The distribution curve generation device according to claim 1, wherein: A horizontal amount calculating means for calculating, as a horizontal amount, a length in which the change amount of the density information detected by the density information detecting means with respect to the color signal input by the color signal input means is substantially zero;
2. The distribution curve generation device according to claim 1, wherein the second distribution curve generation unit selects and generates a second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation unit. . Color signal input means for inputting an image color signal;
First distribution curve storage means for storing a plurality of first distribution curves for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink having a lighter color than the normal ink;
Density information for processing the color signal input by the color signal input means based on the first distribution curve stored in the first distribution curve storage means and detecting density information of the image output by the image forming apparatus Detection means;
Second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means;
Maximum change amount calculating means for calculating the maximum change amount of the second distribution curve generated by the second distribution curve generation means for the color signal input by the color signal input means;
3. A distribution curve generation device comprising: a third distribution curve generation unit that selects and generates a second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculation unit. Color signal input means for inputting an image color signal;
First distribution curve storage means for storing a first distribution curve for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink having a lighter color than the normal ink;
Density information for processing the color signal input by the color signal input means based on the first distribution curve stored in the first distribution curve storage means and detecting density information of the image output by the image forming apparatus Detection means;
In a distribution curve generation device comprising: second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means;
The first distribution curve storage means stores a plurality of first distribution curves corresponding to the maximum adhesion amount of media,
The second distribution curve generation means selects the first distribution curve from the first distribution curve storage means according to the maximum amount of adhesion of the medium, and the second distribution curve based on the selected first distribution curve. A distribution curve generation device characterized by generating a distribution curve. Color signal input means for inputting an image color signal;
First distribution curve storage means for storing a first distribution curve for distributing a color signal corresponding to normal ink and a color signal corresponding to light ink having a lighter color than the normal ink;
Density information for processing the color signal input by the color signal input means based on the first distribution curve stored in the first distribution curve storage means and detecting density information of the image output by the image forming apparatus Detection means;
In a distribution curve generation device comprising: second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means;
The first distribution curve storage means stores a plurality of first distribution curves corresponding to printing conditions such as media, ink, resolution or printing method,
The second distribution curve generation means selects a first distribution curve from the first distribution curve storage means according to the printing conditions, and generates a second distribution curve based on the selected first distribution curve. A distribution curve generation device characterized by: Computer to generate distribution curves,
Color signal input means for inputting a color signal of an image;
The color signal input by the color signal input means is processed based on the first distribution curve for distributing the color signal corresponding to the normal ink and the color signal corresponding to the light ink having a lighter color than the normal ink. Density information detecting means for detecting density information of the image output by the image forming apparatus,
Second distribution curve generating means for generating a second distribution curve based on the density information detected by the density information detecting means and the color signal input by the color signal input means; input by the color signal input means A horizontal amount calculating means for calculating, as a horizontal amount, a length in which the change amount of the density information detected by the density information detecting means for the color signal is substantially zero;
A distribution curve generation program for functioning as a means for selecting a second distribution curve that minimizes the horizontal amount calculated by the horizontal amount calculation means. Computer to generate distribution curves,
Color signal input means for inputting a color signal of an image;
The color signal input by the color signal input means is processed based on the first distribution curve for distributing the color signal corresponding to the normal ink and the color signal corresponding to the light ink having a lighter color than the normal ink. Density information detecting means for detecting density information of the image output by the image forming apparatus,
Second distribution curve generation means for generating a second distribution curve based on the density information detected by the density information detection means and the color signal input by the color signal input means;
Maximum change amount calculating means for calculating the maximum change amount of the second distribution curve generated by the second distribution curve generating means for the color signal input by the color signal input means;
A distribution curve generation program for functioning as a third distribution curve generation unit that selects and generates a second distribution curve that minimizes the maximum change amount calculated by the maximum change amount calculation unit.

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