JP4192838B2 - Image forming apparatus, method of generating reference image used in image forming apparatus, and image forming apparatus control program - Google Patents

Description

  The present invention relates to an image forming apparatus, a method for generating a reference image used for gradation adjustment thereof, and an image forming apparatus control program, and more particularly to gradation adjustment of an image forming apparatus.

  An image forming apparatus (such as a copying machine or a printer) that forms an image based on image data controls the amount of toner, the amount of ink, and the like based on the image data. Tones are generated. For example, in an electrophotographic image forming apparatus, the amount of toner adhering to a latent image is controlled by controlling the intensity of laser light that forms a charged latent image on a photoreceptor, thereby generating gradation on the medium. Is done. In order to perform this control, the image forming apparatus defines a correspondence relationship (reference gradation characteristic) between image data (input value) and a target density (output value) that is a target value of density formed on the medium. Has a conversion table. For example, in an image forming apparatus that forms an image using toners of four colors of cyan (C), magenta (M), yellow (Y), and black (K), a reference gradation characteristic is set for each CMYK component. Is done. Then, using the reference gradation characteristics for each color component, each color component value of the image data is converted to a target density for each color component, and based on control conditions such as laser light intensity determined according to the target density. Thus, the amount of toner fixed on the medium is controlled as described above.

  However, even if an attempt is made to control each part of the image forming apparatus under a predetermined condition, the density of the image actually formed on the medium is not necessarily constant due to the influence of the usage environment and changes in the components over time. The target concentration is not always achieved. For this reason, the image forming apparatus conventionally holds a gradation correction table, adjusts the density of the image on the medium based on the table, and performs a calibration process to bring it closer to the target density. In order to obtain the corrected data to be stored in the gradation correction table, a reference image is formed on the medium by the image forming apparatus based on the reference image data in which a predetermined gradation pattern is expressed, and is displayed in the reference image. For example, a gradation pattern image such as a patch chart is converted again into image data by an image reading device such as a scanner. Then, based on the output image data, correction data that cancels the difference in the output image data with respect to the input reference image data is obtained, and stored in the gradation correction table.

The calibration process is one of the menus of the print service software or is provided by a single application software. Conventionally, for example, when the system administrator determines that it is necessary, patches are made using the software. The chart is printed and calibration is performed.
Japanese Patent Laid-Open No. 11-164140 JP 2001-239731 A

  It is not easy for a general user to determine whether or not the image forming apparatus is in a state that requires calibration. Further, general users are not accustomed to the work of forming a patch chart and measuring the density of the gradation pattern represented on the patch chart. Therefore, there is a problem that the image forming apparatus can be used for a long time in a state where calibration is required. In addition, when the color image forming apparatus is placed in such a state, even if a defect is recognized in the color reproduction on the image medium, the general user is caused by the image forming apparatus itself, There is also an inconvenience that it is difficult to determine whether it is caused by image processing for generating image data input to the image forming apparatus.

  The present invention has been made in order to solve the above-described problems. By determining whether calibration processing is necessary or making the processing itself relatively easy and increasing the number of persons who can perform the image processing, It is easy to keep the state of the forming apparatus good.

  The image forming apparatus according to the present invention includes an image forming unit that forms a reference image including a predetermined gradation pattern in a peripheral margin of an image medium on which the target image is formed when the target image is formed. The forming unit generates the reference image by switching a plurality of types of gradation patterns according to a predetermined order. According to the present invention, the reference image is formed in the marginal margin of the continuous or jumping image medium. A plurality of gradation patterns constituting the reference image are prepared, and the reference image formed on one image medium and the reference image formed on another image medium are formed with different gradation patterns.

  In another image forming apparatus according to the present invention, each of the gradation patterns includes a plurality of image element regions having different image formation densities. Here, each gradation pattern may have the same combination of image element regions and different layouts, or may have a different combination of image element regions.

  In another image forming apparatus according to the present invention, one set of the image element regions having different densities is divided into a plurality of subsets, and one subset is assigned to each of the gradation patterns. In the present invention, the combination of image element regions constituting each gradation pattern itself changes sequentially, and one set of image element regions having different densities is divided into a plurality of subsets S1, S2,... The reference image to be formed includes a gradation pattern composed of the subset S1, and then the reference image formed on another image medium includes the gradation pattern composed of the subset S2. A pattern is formed.

  In another image forming apparatus according to the present invention, the density distribution range of the image element area included in each subset has an overlapping portion between the plurality of subsets. According to the present invention, image element regions from a relatively low density to a relatively high density are mixed in each reference image.

  In another image forming apparatus according to the present invention, each of the gradation patterns includes a plurality of image element regions having different image formation densities for each color component of image formation.

  In another image forming apparatus according to the present invention, a set of the image element regions having different densities from each other for each color component is divided into a plurality of subsets, and one gradation component is provided for each color component. The subset is assigned.

  In another image forming apparatus according to the present invention, the densities of the plurality of image element regions included in each of the gradation patterns are different from each other regardless of the type of the color component.

  In another image forming apparatus according to the present invention, the gradation patterns are different in arrangement of a plurality of types of the image element regions on the image medium.

  A preferred aspect of the present invention is an image forming apparatus that reduces the target image or changes the size of the image medium in accordance with the size of the target image with respect to the image medium. If the marginal margin is narrow enough to form the reference image, the target image is reduced or the image medium size is increased so that the marginal margin is wide enough to form the reference image.

  In the reference image generation method according to the present invention, when a target image is formed on an image medium according to input target image data, a predetermined floor is formed in a marginal margin of the image medium on which the target image is formed. An image forming step of forming a reference image including a tone pattern, and the image forming step generates the reference image by switching a plurality of types of gradation patterns in a predetermined order.

  The image forming apparatus control program according to the present invention forms a target image when the target image is formed on a computer that controls the image forming apparatus that forms the target image on an image medium according to the input target image data. An image forming procedure for forming a reference image including a predetermined gradation pattern in a marginal margin of the image medium is executed, and the image forming procedure switches the plurality of types of gradation patterns according to a predetermined order and performs the reference An image is generated.

  According to the present invention, the target image required by the user is formed on the image medium, and the reference image is formed on the peripheral margin of the image medium. That is, no special user work is required to form the reference image. Calibration is performed by setting the image medium on which the image is formed in this manner to the scanner and reading the gradation pattern from the reference image. Further, according to the present invention, the reference image is formed on the image medium by switching the gradation pattern. Thereby, based on a plurality of reference images, information on density fluctuation in the plane of the image medium or between image media can be obtained without the user being particularly conscious, and suitable calibration reflecting the information can be performed. . As described above, according to the present invention, it is possible to improve the frequency and maintain the quality of the calibration process by simplifying the user work and reducing the dependence on the user skill, and keep the state of the image forming apparatus in a good state. Is possible.

[Embodiment 1]
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. Here, a mode of adjusting the gradation of each component color realized by printing with a color printer is shown, but the adjustment target device may be another image forming device that forms an image on a medium such as a multifunction peripheral. it can. FIG. 1 is a block diagram showing a schematic configuration of an image forming system according to the present invention. The system includes a printer 2, a print server 4, a scanner 6, a client computer 8, and a communication network 10 such as a local area network (LAN) that enables data transmission therebetween.

  Here, the printer 2 is a device that performs printing using toners of four colors of CMYK. The client computer 8 issues a print instruction to the print server 4 based on a user operation. The print server 4 accumulates image data (target image data) requested to be printed by, for example, the client computer 8 via the communication network 10 or the like, and sets a schedule to send the image data to the printer 2 for printing. In particular, in this system, the print server 4 has a function of combining reference image data including a predetermined gradation pattern with target image data and inputting it to the printer 2. The print server 4 also has a function of performing arithmetic processing related to gradation adjustment, generating gradation correction data for realizing the reference gradation characteristics in the printer 2, and setting the gradation correction data in the printer 2 gradation correction table. The scanner 6 is a color scanner provided for measuring the density of the image represented by the gradation pattern printed on the medium by the printer 2 based on the reference image data, and reads the gradation pattern into image data. Convert. Here, the image data corresponds to the density measurement result of the printed image. For example, the gradation pattern is configured by a patch chart for each color of CMYK. Each patch chart is composed of patches which are a plurality of image element regions having different image formation densities. For example, each patch has a rectangular print pattern.

  As described above, when printing the target image, the printer 2 prints an image obtained by combining the target image and the reference image based on the image data generated by the print server 4. Many documents have margins at the periphery of the paper. A reference image is printed in the peripheral margin. That is, the print server 4 generates image data in which the reference image is printed in the marginal margin of the paper on which the target image is printed, and outputs the image data to the printer 2. On the other hand, when the print server 4 detects that the target image has no margin at the peripheral edge of the paper or that the reference image has only a narrow margin for printing, the print server 4 reduces the target image or specifies the paper designated for the print job. The size is changed to a larger one and a marginal margin sufficient to print the reference image is provided. Whether to select reduction or paper size change can be configured so that, for example, an administrator can specify in advance. If the margin is wide, the print server 4 may enlarge the size of the patch printed as the reference image or increase the number of patches, thereby improving the calibration accuracy. .

  The reference image can be formed in the margin of each side of the paper, but can also be formed only in a part of the four sides. For example, when the target image is a horizontally written document, if the reference image is formed in the margin located on the right side and the margin located on the lower end of the document, the user cares about the presence of the reference image when reading the document. It can be mitigated. From the same viewpoint, if the target image is a vertically written document, the reference image can be formed in the margin located on the left side and the margin located on the lower end of the document.

  FIG. 2 is a schematic diagram illustrating an example of a layout of a target image and a reference image on a sheet. For example, the size (original size) specified for the target image is A4 size, and the print server 4 combines the target image and the reference image to generate image data and a job to be printed on B4 size paper. To the printer 2. In this example, the target image 20 is arranged in an A4 size area with the upper left corner as a reference, and the reference image 22 is printed in the right and lower margin areas of the paper outside the area. In order to make it easy for the user to cut out the reference image 22 as necessary, for example, a broken line 24 is printed at the boundary of the A4 size area where the target image 20 is arranged.

  For example, as the reference image 22, two color charts 26-1 and 26-2 of CMYK are arranged in the right margin of the sheet, and the remaining two color patch charts 26-3 and 26-4 are arranged in the lower margin. . The plurality of patches constituting the patch chart 26 for each color are arranged at a predetermined interval in a direction along the side of the paper, for example. Here, the target image is printed using a gradation correction table that is currently set in the printer 2, and for example, the patch chart 26 is controlled so as not to perform the correction process. The print result reflects the state of the printer as it is.

  Further, additional information (not shown) such as printing date and time of the image, document mode, screen type, and identification information of calibration data at the time of printing is also included in the reference image 22 and printed, for example, in the lower margin of the sheet. . The additional information is described in one or both of an expression format (for example, text) that can be read by the user and an expression format (for example, one-dimensional / two-dimensional barcode) suitable for computer processing. In addition, positioning marks are printed on the reference image at several positions so that the position of the image on the sheet can be easily specified. For example, in the example shown in FIG. 2, black squares 28 are arranged as positioning marks in the upper right, lower left, and lower right corners of the paper.

  Now, according to the present invention, a plurality of types of gradation patterns to be printed on the reference image are prepared, and the gradation patterns are switched in a predetermined order every time the reference image is formed on the paper. In the example shown in FIG. 2, a plurality of images having different correspondence relationships between colors and the patch charts 26-1 to 26-4 are prepared as gradation patterns, which are sequentially switched. That is, for example, in the reference image 22 of a certain sheet, the first gradation pattern in which the colors C, M, Y, and K are respectively associated with the patch charts 26-1 to 26-4 is printed, and the next sheet The second gradation pattern in which the colors M, Y, K, and C are associated with the patch charts 26-1 to 26-4, respectively, and the color Y is displayed on the patch charts 26-1 to 26-4 on the next sheet. , K, C, and M are associated with a third gradation pattern, and on the next sheet, patch charts 26-1 to 26-4 are associated with colors K, C, M, and Y, respectively. The gradation pattern is printed, and the next sheet returns to the first gradation pattern again. Thereafter, the gradation pattern switching is repeated in this order. These gradation pattern types are indicated in the additional information.

  The calibration is performed using the output result of the print job of the target image. The user places the printed paper on the auto document feeder of the scanner 6 and instructs reading. Then, the scanner 6 sequentially reads the set paper and transmits the obtained image data to the print server 4. The print server 4 detects the positioning mark represented in the read image of each sheet, identifies the reference image 22 from the target image 20 based on the positional relationship, and obtains gradation information from the patch chart 26. Acquire and read additional information. The print server 4 analyzes the gradation information, grasps the current color reproduction state of the printer, and updates the contents of the gradation correction table when there is a problem. For example, if there is a problem in color reproduction in the printed target image at this time, by comparing the content of the gradation correction table used for correcting the target image with the gradation information obtained from the reference image, The cause can be determined.

  The image data obtained from the scanner 6 may be stored with an appropriate name so that it can be used later. Although the reference image 22 is formed on each sheet here, the reference image 22 may be formed by switching the gradation correction table in order to a skip sheet among a series of sheets on which the target image is formed.

[Embodiment 2]
The schematic configuration of an image forming system according to the second embodiment of the present invention is basically the same as that shown in FIG. 1, and this figure is used in the following description. Further, the same components as those in the first embodiment are denoted by the same reference numerals, and the description is simplified.

  FIG. 3 is a schematic diagram illustrating an example of a layout of a target image and a reference image on a sheet. In the present embodiment, for example, both the size (document size) designated for the target image and the paper size are A4 sizes. In this case, for example, if the target image is printed as it is, the marginal margin portion becomes narrow and it is likely that the reference image cannot be formed. In such a case, the print server 4 reduces the target image (for example, 95 of the original document size). Image data to be passed to the printer 2 by synthesizing the reference image with the resulting margin. In this example, the target image 40 is arranged close to the top of the A4 size area, and the reference image 42 is arranged in a blank area generated at the bottom of the sheet.

  For example, the reference image 42 includes two patch charts 46-1 and 46-2 that are associated with different colors. The colors associated with these patch charts 46 are sequentially switched for each sheet output from the printer 2. For example, the patch charts 46-1 and 46-2 are associated with C and M for odd-numbered output sheets and Y and K for even-numbered output sheets. Also, which one of the two patch charts 46 of the odd-numbered paper is associated with C and M, and which of the two patch charts 46 of the even-numbered paper is associated with Y, K is alternated according to the output order of the paper. You may switch to. Here, as in the first embodiment, it is possible to perform control so that correction processing is performed for printing the target image, and correction processing is not performed for printing the patch chart 46. Further, additional information (not shown) and positioning marks 48 similar to those in the first embodiment are arranged on the reference image 42.

  The calibration is performed using the output result of the print job of the target image. Here, a case where the scanner 6 does not include an auto document feeder will be described. For example, the user selects calibration from the software menu of the print server 4 and designates the number of reading sheets. Then, after the first output sheet is set in the scanner 6, the scanner 6 performs reading. When the scanner 6 completes the reading of the first sheet, the print server 4 informs the user to set the next output sheet, and accordingly, the user sets the next sheet and starts the reading process. By repeating this operation, a specified number of output sheets are read, and the obtained image data is transmitted to the print server 4. The print server 4 detects the positioning marks represented in the read image of each sheet, identifies the reference image 42 from the target image 40 based on the positional relationship, and obtains gradation information from the patch chart 46. Acquire and read additional information. The print server 4 analyzes the gradation information, grasps the current color reproduction state of the printer, and updates the contents of the gradation correction table when there is a problem.

[Embodiment 3]
The schematic configuration of an image forming system according to the third embodiment of the present invention is basically the same as that shown in FIG. 1, and this figure is used in the following description. Further, the same components as those in the first embodiment are denoted by the same reference numerals, and the description is simplified.

  In the present embodiment, for example, both the size (document size) designated for the target image and the paper size are A4 sizes. The print server 4 reduces the target image (for example, reduces it to 85% of the original document size), and arranges the target image and the reference image in the same layout as in FIG. 2 shown for the first embodiment.

  In the present embodiment, the color associated with the patch charts 26-1 to 26-4 is changed for each sheet, and the correspondence between the patch chart 26 and the color is one for four sheets as in the first embodiment. It switches in turn as a cycle. One point that this embodiment differs from the first embodiment is that the type of density of the patches constituting each patch chart 26 is also switched for each sheet. That is, one set of patches having different densities is divided into, for example, four subsets, and one subset is assigned to each patch chart 26. As a result, four types of gradation patterns in which the correspondence relationship between the patch chart 26 and the colors and the subset of patches constituting the patch chart 26 are different are sequentially formed in the reference image.

  For example, assuming that the maximum density is 100%, a set of patch density types [3, 6, 9, 12, 15, 18, 22, 26, 30, 34, 38, 42, 46, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100%], and these 24 kinds of concentrations are divided into the following four subsets S1 to S4.

Subset S1: [3, 15, 30, 46, 65, 85]
Subset S2: [6, 18, 34, 50, 70, 90]
Subset S3: [9, 22, 38, 55, 75, 95]
Subset S4: [12, 26, 42, 60, 80, 100]

  Here, the distribution range of density values constituting each subset is determined so as to have overlapping portions. In each sheet, the types of subsets associated with the colors CMYK of the patch chart 26 are determined to be different from each other. For example, in the first sheet, S1 is associated with C, S2 with M, S3 with Y, and S4 with K. Hereinafter, each patch is represented by a combination of a color symbol and a density value. For example, a patch having a color C and a density of 3% is expressed as “C03”. Using this notation, examples of four types of gradation patterns formed in the reference image will be specifically shown.

In the first gradation pattern,
Patch chart 26-1: C03, C15, C30, C46, C65, C85
Patch chart 26-2: M06, M18, M34, M50, M70, M90
Patch chart 26-3: Y09, Y22, Y38, Y55, Y75, Y95
Patch chart 26-4: K12, K26, K42, K60, K80, K100,
In the second gradation pattern,
Patch chart 26-1: M22, M38, M55, M75, M95, M09
Patch chart 26-2: C26, C42, C60, C80, C10, C12
Patch chart 26-3: K15, K30, K46, K65, K85, K03
Patch chart 26-4: Y18, Y34, Y50, Y70, Y90, Y06,
In the third gradation pattern,
Patch chart 26-1: Y42, Y60, Y80, Y100, Y12, Y26
Patch chart 26-2: K38, K55, K75, K95, K09, K22
Patch chart 26-3: C34, C50, C70, C90, C06, C18
Patch chart 26-4: M30, M46, M65, M85, M03, M15,
In the fourth gradation pattern,
Patch chart 26-1: K70, K90, K06, K18, K34, K50
Patch chart 26-2: Y65, Y85, Y03, Y15, Y30, Y46
Patch chart 26-3: M80, M100, M12, M26, M42, M60
Patch chart 26-4: C75, C95, C09, C22, C38, C55,
It is. Here, patches are arranged on each patch chart 26 so as to be arranged in one direction in the order of the symbols shown above. That is, in the above example, the four patches arranged at the same position in the first to fourth gradation patterns have different colors and densities. By arranging patches of various colors and densities in the vertical and horizontal directions of the paper in this way, for example, even if information on any of these four types of gradation patterns is lost, the effect is lost. And the influence of density unevenness in the paper can be suppressed.

  The above-described embodiments correspond to color printing consisting of four colors of CMYK. However, the present invention can also be applied to color printing consisting of other color components, and can also be applied to single color printing. it can. For example, in the case of a single color, subsets whose density ranges overlap each other can be defined, and the subset associated with the patch chart can be switched for each sheet.

1 is a block diagram showing a schematic configuration of an image forming system according to the present invention. FIG. 3 is a schematic diagram illustrating an example of a layout of a target image and a reference image on a sheet. FIG. 3 is a schematic diagram illustrating an example of a layout of a target image and a reference image on a sheet.

Explanation of symbols

  2 Printer, 4 Print server, 6 Scanner, 8 Client computer, 10 Communication network.

Claims (4)

In an image forming apparatus that adjusts gradation based on a gradation correction table and forms a target image on an image medium according to input target image data.
Upon formation of the target image, the image forming the reference image data by combining said target image data, to form the criteria image to the periphery margin of the image medium in which the object image is formed comprising a predetermined gradation pattern Means ,
Image reading means for reading the reference image formed by the image forming means and generating output image data;
Calibration means for updating the gradation correction table so that a difference in the output image data with respect to the reference image data is canceled for the gradation pattern;
Have
As the gradation pattern, a plurality of types including a subset of a plurality of image element regions, one for each color component of image formation, are set in advance,
The image forming unit generates a reference image by switching a plurality of types of gradation patterns according to a predetermined order every time the target image is formed .
The subset is set for each of the color components by dividing each set of the plurality of image element regions having different image formation densities set for each of the color components.
The density distribution range of the image element region included in the subset has an overlapping portion between the plurality of subsets of the color components;
The image element regions in the same position of the gradation patterns are different from each other in the color component and the density;
An image forming apparatus. The image forming apparatus according to claim 1 .
In each of the gradation patterns, an arrangement of a plurality of types of image element regions on the image medium is different. The image forming apparatus according to claim 1 , wherein:
An image forming apparatus, wherein the target image is reduced or the image medium is resized according to a size of the target image with respect to the image medium. A computer that controls the image forming apparatus that adjusts the gradation based on the gradation correction table and forms the target image on the image medium according to the input target image data.
In forming the target image, reference image data including a predetermined gradation pattern is combined with the target image data to form a reference image in a marginal margin of the image medium on which the target image is formed When,
An image reading procedure for reading the reference image formed by the image forming procedure and generating output image data;
A calibration procedure for updating the gradation correction table so that a difference in the output image data with respect to the reference image data is canceled for the gradation pattern;
And execute
As the gradation pattern, a plurality of types including a subset of a plurality of image element regions, one for each color component of image formation, are set in advance,
The image forming procedure generates a reference image by switching a plurality of types of gradation patterns according to a predetermined order every time the target image is formed.
The subset is set for each of the color components by dividing each set of the plurality of image element regions having different image formation densities set for each of the color components.
The density distribution range of the image element region included in the subset has an overlapping portion between the plurality of subsets of the color components;
The image element regions in the same position of the gradation patterns are different from each other in the color component and the density;
An image forming apparatus control program.

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