JP2019028296A - Image formation apparatus - Google Patents

Abstract

To provide an image formation apparatus which suppresses formation of an unnecessary measurement image.SOLUTION: An image formation apparatus includes control means which controls image formation means to form a measurement image, controls measurement means to measure the measurement image and generates a conversion condition on the basis of the measurement result of the measurement means. The measurement image contains a prescribed measurement image. The control means generates the conversion condition corresponding to a prescribed type of half-tone processing on the basis of the measurement result of the prescribed measurement image by the measurement means. The control means controls whether or not to form the prescribed measurement image every time the image formation means forms a prescribed number of images transferred to a sheet by transfer means on the basis of the type of the half-tone processing executed by image processing means with respect to the image data corresponding to the plurality of images when the image formation means continuously forms the plurality of images.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus.

  In an image forming apparatus, the density of an image to be formed varies from a target density due to various factors. In addition, in an image forming apparatus that performs a plurality of halftone processes (dither processing), it is necessary to create gradation correction conditions for each halftone process so that the image density approaches the target density. Patent Document 1 forms a (measurement image) pattern image for correcting gradation correction conditions for one halftone process, detects its density, and feeds back to the gradation correction conditions for another halftone process The structure to perform is disclosed. Patent Document 2 discloses a configuration in which pattern images for correcting gradation correction conditions for different halftone processes are formed at regular intervals, the density thereof is detected, and fed back to the gradation correction conditions. .

JP 2013-031162 A JP-A-2015-198364

  In order to obtain stable image quality in an image forming apparatus that performs a plurality of halftone processes, the density of the pattern image formed by performing the halftone process to be corrected is detected and fed back to the gradation correction conditions of the halftone process There is a need to. Here, halftone processing used in actual image formation differs depending on the content of the image to be formed. For example, there are cases where images that use halftone processing with a low number of lines are continuously formed, and images that use halftone processing with a high number of lines are formed continuously. When images that use low-tone halftone processing are continuously formed, high-tone halftone processing is performed to form a pattern image, and tone correction conditions for high-line-number halftone processing Even if the correction is made, the toner is wasted.

  The present invention provides an image forming apparatus that suppresses the formation of unnecessary measurement images.

  According to an aspect of the present invention, the image forming apparatus converts the image data based on the conversion condition corresponding to the type of halftone processing, and performs halftone processing on the image data converted by the conversion unit. An image processing means for executing, an image forming means for forming an image based on the image data on which the halftone processing has been executed, an intermediate transfer body onto which the image formed by the image forming means is transferred, and A transfer unit that transfers the image transferred to the intermediate transfer member to a sheet, a measurement unit that measures the measurement image transferred to the intermediate transfer member, and the image forming unit to form the measurement image Control means for controlling the measurement means to measure the measurement image and generating the conversion condition based on the measurement result of the measurement means, and the measurement image is a predetermined measurement image. The control means generates a conversion condition corresponding to a predetermined type of halftone processing based on a measurement result of the predetermined measurement image by the measurement means, and the control means includes the image forming means If the image forming unit forms a predetermined number of images each time the image forming unit forms a predetermined number of images transferred to the sheet by the transfer unit, the plurality of images are determined. Control is performed based on the type of halftone processing executed by the image processing means on the image data corresponding to the image.

  According to the present invention, formation of unnecessary measurement images can be suppressed.

1 is a configuration diagram of an image forming apparatus. FIG. 3 is a control configuration diagram of the image forming apparatus. 10 is a flowchart showing tone correction condition update processing. 10 is a flowchart of processing for determining halftone processing for correcting gradation correction conditions. Explanatory drawing of the process which determines the halftone process which correct | amends gradation correction conditions. 10 is a flowchart of processing for determining halftone processing for correcting gradation correction conditions. Explanatory drawing of the process which determines the halftone process which correct | amends gradation correction conditions.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In addition, the following embodiment is an illustration and does not limit this invention to the content of embodiment. In the following drawings, components that are not necessary for the description of the embodiments are omitted from the drawings.

<First embodiment>
FIG. 1 is a schematic configuration diagram of the image forming apparatus 100. The image forming apparatus 100 is, for example, a laser beam printer that forms a full color image on a sheet 110. The image forming apparatus 100 includes a printer unit 101 and an operation panel 180. The operation panel 180 provides an input / output interface for displaying the state of the image forming apparatus 100 to the user and for performing input for the user to operate the image forming apparatus 100.

  The printer unit 101 includes four image forming units 120 to 123 that form an image for each color component. The image forming unit 120 forms a yellow image, the image forming unit 121 forms a magenta image, the image forming unit 122 forms a cyan image, and the image forming unit 123 forms a black image. Since the configurations of the image forming units 120 to 123 are the same, the configuration of the image forming unit 120 that forms a yellow image will be described below. The charger 111 charges the surface of the photoconductor 105 to a uniform potential. The laser scanner 108 emits a laser beam controlled based on the image data to the photoconductor 105, and scans the photoconductor 105 with this laser beam. As a result, the laser scanner 108 forms an electrostatic latent image on the photoconductor 105. The developing device 112 includes a developer containing toner and a magnetic carrier. The developing device 112 develops the electrostatic latent image on the photoconductor 105 using a developer. As a result, the developing device 112 forms a toner image on the photosensitive member 105. The toner image on the photoreceptor 105 is transferred to the intermediate transfer member 106. The image forming units 120 to 123 transfer the toner images of the respective colors on the intermediate transfer member 106 so that a full-color toner image is formed on the intermediate transfer member 106.

  The toner image formed on the intermediate transfer member 106 is conveyed to a position facing the transfer roller 114 by the rotation of the intermediate transfer member 106. On the other hand, a sheet 110 is accommodated in the cassette 113. The sheets fed one by one from the cassette 113 by the sheet feeding mechanism are conveyed to a position facing the transfer roller 114 along the conveyance path. A transfer voltage is applied to the transfer roller 114. With this transfer voltage, the transfer roller 114 transfers the toner image (print image) of the intermediate transfer body 106 to the sheet 110.

  The sheet 110 on which the toner image has been transferred is conveyed to the fixing devices 150 and 160. The fixing devices 150 and 160 heat and press the toner image transferred to the sheet 110 to fix the toner image on the sheet 110. The fixing device 150 includes a fixing roller 151, a pressure belt 152 that presses the sheet 110 against the fixing roller 151, and a first post-fixing sensor 153 that detects completion of fixing. The fixing device 160 is disposed downstream of the fixing device 150 in the conveyance direction of the sheet 110. The fixing device 160 gives gloss to the toner image on the sheet 110 that has passed through the fixing device 150. The fixing device 160 includes a fixing roller 161, a pressure roller 162 that presses the sheet 110 against the fixing roller 161, and a second post-fixing sensor 163 that detects completion of fixing.

  When the image is fixed on the sheet 110 in the mode for imparting the gloss or when the image is fixed on the sheet 110 having a large amount of heat necessary for the fixing process, the sheet 110 that has passed through the fixing device 150 is conveyed to the fixing device 160. Is done. On the other hand, when fixing an image on thin paper, the sheet 110 that has passed through the fixing device 150 is conveyed along a conveyance path 130 that bypasses the fixing device 160. Note that the angle of the flapper 131 is controlled in order to control whether the sheet 110 is conveyed to the fixing device 160 or whether the sheet 110 is conveyed around the fixing device 160.

  The flapper 132 is a guide member that switches whether to guide the sheet 110 to the transport path 135 or to the transport path 139 to the outside. The sheet 110 conveyed along the conveyance path 135 is conveyed to the reversing unit 136. When a reverse sensor (not shown) provided in the transport path 135 detects the trailing edge of the sheet 110, the transport direction of the sheet 110 is reversed. The flapper 133 is a guide member that switches whether the sheet 110 is guided to the conveyance path 138 for double-sided image formation or to the conveyance path 135. When the face-down paper discharge mode is executed, the sheet 110 is conveyed again to the conveyance path 135 and is discharged from the image forming apparatus 100.

  On the other hand, when the duplex printing mode is executed, the sheet 110 is conveyed again to the position facing the transfer roller 114 along the conveyance path 138. When the duplex printing mode is executed, after the image is fixed on the first surface of the sheet 110, the sheet 110 is switched back in the reversing unit 136, conveyed along the conveyance path 138, Images are formed on two sides.

  The flapper 134 is a guide member that guides the sheet 110 to a conveyance path for discharging the sheet 110 from the image forming apparatus 100. When the sheet 110 is discharged face-down, the flapper 134 guides the sheet switched back in the reversing unit 136 to the discharge conveyance path 139. The sheet 110 transported along the paper transport path 139 is discharged to the outside of the image forming apparatus 100.

  The density sensor 115 is an optical sensor that measures reflected light from a pattern image (measurement image) formed on the intermediate transfer member 106. Four density sensors 115 are arranged at different positions in the direction orthogonal to the moving direction of the surface of the intermediate transfer member 106, and each of them measures the density of the pattern image based on the reflected light from the pattern image.

  FIG. 2 shows a control configuration of the image forming apparatus according to the present embodiment. The printer control unit 900 generally controls the image forming apparatus 100. Specifically, the CPU 901 of the printer control unit 900 controls the image forming apparatus 100 by executing a program stored in the ROM 902. At that time, the CPU 901 uses the RAM 903 as a temporary data storage area. At the time of image formation, the printer control unit 900 receives a digital image signal from an external computer and outputs it to the image signal control unit 907. The color processing unit 911 of the image signal control unit 907 performs color conversion of the RGB bitmap image indicated by the input digital image signal to generate image data indicating the YMCK bitmap image.

  The gradation correction unit 912 converts the input value (image signal value) of the input image data based on a gradation correction table corresponding to the type of halftone processing. The density of the image formed by the printer unit 101 is not a desired density. Therefore, the gradation correction unit 912 converts the input value (image signal value) of the image data so that the density of the image formed by the printer unit 101 is corrected to a desired density. The gradation correction table functions as a conversion condition stored in a memory (not shown). Note that the gradation correction table is stored for each screen, which will be described later, and is stored for each color. In the following description, the gradation correction table is described as a gradation correction condition. Note that the gradation correction unit 912 may be realized by an integrated circuit such as an ASIC, or may be realized by the CPU 901 converting image data based on a program stored in advance.

  The halftone processing unit 913 performs screening (image processing) suitable for the type of image on the image data converted by the gradation correction unit 912. The halftone processing unit 913 converts image data based on, for example, a 190 dot screen (number of low lines) so that a photographic image or a graphic image becomes an image having excellent gradation. The halftone processing unit 913 converts the image data based on, for example, a 230 dot screen (high line number) so that the character image is clearly printed. The halftone processing unit 913 converts the image data based on, for example, an error diffusion method so that the high-resolution image becomes an image in which moire is suppressed. When printing an image other than a character image of a document read by a reading device (not shown), the halftone processing unit 913 converts image data transferred from the reading device based on a copier screen (copy). The printer unit 101 forms an image based on the image data on which the halftone processing is executed by the halftone processing unit 913. Here, the 190 Dot screen, the 230 Dot screen, and the copier screen have different types of halftone processing. Note that the number of halftone processes that can be executed by the halftone processing unit 913 is not limited to four.

  Hereinafter, the update control of the gradation correction condition in the present embodiment will be described with reference to the flowchart of FIG. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the 190 dot screen (number of low lines) based on the measurement results of the three pattern images Pa having different gradations. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the 230 dot screen (high line number) based on the measurement results of the three pattern images Pb having different gradations. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the copier screen (copy) based on the measurement results of the two pattern images Pc having different gradations. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the error diffusion method based on the measurement results of two pattern images Pd having different gradations. Since a method for updating the tone correction condition based on the density of a small number of pattern images is known, detailed description thereof is omitted. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the 190 dot screen (the number of low lines) when the measurement results of the pattern image Pa of all three gradations are acquired. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the 230 dot screen (high line number) when the measurement results of the pattern image Pb of all three gradations are acquired. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the copier screen (copy) when the measurement results of the pattern image Pc of all two gradations are acquired. The image forming apparatus 100 according to the present embodiment updates the gradation correction condition corresponding to the copier screen (copy) when the measurement results of the pattern image Pd of all two gradations are acquired.

  When instructed to start printing, the CPU 901 acquires job information relating to the instructed image formation in S10. The job information includes information indicating the number of sheets to be printed in the job and the type of halftone processing applied to an image formed on each sheet to be printed. In the following description, the number of sheets to be printed is N (N is an integer of 1 or more). In step S11, the CPU 901 initializes an index P indicating the page number to be printed to 1, and determines in step S12 whether or not to update the gradation correction condition. Details of the processing in S12 will be described later. In the process of S12, when the gradation correction condition corresponding to the target halftone process is updated, the CPU 901 sets the execution flag to 1 and does not update the gradation correction condition corresponding to the target halftone process. In this case, the value 0 is set in the execution flag.

  In S13, the CPU 901 determines whether or not the execution flag is 1. If the execution flag is 1 in S13, the CPU 901 executes a correction (update) process of the gradation correction condition in S14. Specifically, the CPU 901 forms a pattern image corresponding to the halftone process to be corrected on the intermediate transfer body 106 and controls the density sensor 115 to detect the density of the pattern image. Here, in order to form a pattern image corresponding to the correction target halftone process, the halftone processing unit 913 performs the correction target halftone process on the pattern image data for forming the pattern image. The printer unit 101 forms a pattern image based on the measurement image data transferred from the halftone processing unit 913. The CPU 901 generates a gradation correction condition corresponding to the halftone process based on the density of the pattern image detected by the density sensor 115. Here, when all the pattern images having a predetermined gradation are measured, the CPU 901 updates the gradation correction condition based on the measurement result of the pattern image having the predetermined gradation. For example, the CPU 901 does not update the gradation correction condition corresponding to the 190 dot screen (the number of low lines) unless the measurement result of the three gradation pattern image Pa is acquired. That is, if only the measurement result of the pattern image of one gradation can be acquired, the CPU 901 proceeds to S15 without updating the gradation correction condition. After forming the pattern image corresponding to the halftone process to be corrected, the CPU 901 forms a print image in S15. The print image is transferred to the sheet by the transfer roller 114. On the other hand, if the execution flag is not 1 in S13, the CPU 901 forms a print image in S15 without executing the correction of the gradation correction condition. When the formation of the print image to be transferred to one sheet is completed, the CPU 901 determines in step S16 whether all images based on the job information have been formed. In S16, the CPU 901 determines whether or not the value of P is equal to the number N of sheets to be printed. If the value of P is less than N, the CPU 901 increases P by 1 in S17, and the process proceeds to S12. On the other hand, if the value of P is equal to the number N in S16, the CPU 901 ends the process.

  FIG. 4 is a flowchart of processing for determining whether or not correction execution is necessary in S12 of FIG. The CPU 901 corrects only one gradation correction condition in one correction process. Based on the selection information stored in advance, the CPU 901 selects the halftone process X corresponding to the gradation correction condition to be corrected from the value of P that is the page number of the sheet to be printed next. In FIG. 5A, C is a remainder value obtained by dividing the page number P by a predetermined number A. In this embodiment, A = 10. As shown in FIG. 5A, the selection information is information indicating a correspondence relationship between a remainder value C obtained by dividing the page number P by a predetermined number A and halftone processing to be corrected under the gradation correction condition. . The CPU 901 obtains the value of C in S20, and determines the halftone process X corresponding to the gradation correction condition to be corrected from the value of C and the selection information shown in FIG. 5A in S21. In step S22, the CPU 901 determines halftone processing to be applied to a print image formed on a predetermined number of sheets subsequent to the page to be printed based on the job information. In the present embodiment, the predetermined number is the same as A for obtaining the value C. Therefore, in this embodiment, the CPU 901 determines a halftone process to be applied to a print image formed on a total of A sheets from a page P to be printed next to a page (P + A-1) in S22. Here, Y is a set of halftone processes applied to images formed on a total of A sheets. Note that the predetermined number may be a value different from A for obtaining the value C. The CPU 901 determines in S23 whether the halftone process X determined in S21 is included in the set Y of halftone processes determined in S22. When the halftone process X is included in the halftone process set Y, the CPU 901 sets the execution flag to 1 in S24, and when the halftone process X is not included in the halftone process set Y, the CPU 901 In step S25, the execution flag is set to 0.

  For example, it is assumed that halftone processing applied to a print image formed on a sheet having each page number is as shown in FIG. First, when P = 1, since C = 1, the CPU 901 determines in S21 that the halftone processing X is the number of low lines from FIG. Subsequently, in S22, the CPU 901 determines each halftone process of P = 1 to P = 10, and sets these sets as Y. As shown in FIG. 5B, P = 3, 4, 7, and 8 include the number of low lines, so the process in S23 of FIG. 4 is Yes, and the CPU 901 sets the execution flag value to 1 in S24. Set. Therefore, in S14 of FIG. 3, the correction of the gradation correction condition of the low tone number halftone process is executed.

  When P = 7, C = 7. Therefore, the CPU 901 determines in S21 that the halftone process X is a copy from FIG. Subsequently, in S22, the CPU 901 determines each halftone process of P = 7 to 16, and sets these sets as Y. As shown in FIG. 5B, since no copy is included in P = 7 to 16, the process in S23 of FIG. 4 is No, and the CPU 901 sets the execution flag to 0 in S25. Therefore, the determination in S13 of FIG. 3 is No, and the correction of the gradation correction condition of the halftone process is not executed.

  As described above, in this embodiment, it is determined whether or not the gradation correction condition is to be corrected before each print image is formed on the intermediate transfer member 106. Here, the halftone process to be corrected by the gradation correction condition is determined in advance in association with the order number of the sheets in the job. Whether the CPU 901 corrects the gradation correction condition corresponding to the halftone process to be corrected based on the halftone process applied to the print image formed on the predetermined number of sheets from the print image formed on the next sheet. Decide whether or not. When correction is not performed, a print image to be formed on the next sheet is formed on the intermediate transfer member 106 without forming a pattern image for correcting the gradation correction condition to be corrected. On the other hand, when correction is performed, a pattern image for correcting the gradation correction condition to be corrected is formed to correct the gradation correction condition to be corrected. Thereafter, a print image to be formed on the next sheet is formed on the intermediate transfer member 106. If the number of sheets from the next sheet on which the image is printed to the last sheet indicated by the job information is equal to or greater than a predetermined number, an intermediate is applied to the print image printed on the predetermined number of sheets from the next sheet to be printed. Based on the tone processing, it is determined whether or not to correct the gradation correction condition to be corrected. On the other hand, if the number of sheets from the next sheet on which the image is printed to the last sheet indicated by the job information is less than a predetermined number, halftone processing is applied to the print image to be printed on the last sheet from the next sheet to be printed. Based on this, it is determined whether or not to correct the gradation correction condition to be corrected. For example, it is assumed that the predetermined number A is 10 and the number of sheets to be printed indicated by the job information is 15. In this case, before the image is formed on the first sheet, whether or not the gradation correction condition is updated based on the halftone process applied to the print images formed on the first to tenth sheets in total. Determine whether. On the other hand, before forming an image on the tenth sheet, whether or not to update the tone correction condition based on halftone processing applied to the print images formed on the tenth to fifteenth sheets in total Determine.

  As described above, it is determined whether the halftone process to be corrected by the gradation correction condition is used for image formation from the current print target to a predetermined number of sheets, and the gradation correction condition is corrected only when it is used. Do. With this configuration, the formation frequency of pattern images corresponding to halftone processing that is not used most recently decreases, so that it is possible to prevent formation of useless pattern images. Thereby, useless toner consumption can be suppressed. In the present embodiment, while a plurality of print images to be printed on a sheet are continuously formed, it is determined whether or not gradation correction conditions are to be corrected before forming the print image to be printed on each sheet. It was something to do. However, a configuration may be adopted in which it is determined whether or not the correction of the gradation correction condition is executed every time a predetermined number of images to be transferred to the sheet are formed.

<Second embodiment>
Next, the second embodiment will be described focusing on the differences from the first embodiment. 3 is different from the first embodiment in that the process in S12 of FIG. 3 is the process shown in FIG. 6 instead of the process of FIG. As in the first embodiment, the CPU 901 selects a halftone process X corresponding to the value of C from a plurality of halftone processes based on the selection information in FIG. In step S32, the CPU 901 determines halftone processing to be applied to a print image formed on the A sheet from the sheet to be printed based on the job information, and sets the determined halftone processing set to Y. In step S33, the CPU 901 determines the frequency of halftone processing included in the set Y.

  For example, assuming that the halftone processing applied to the image formed on the sheet with each page number is as shown in FIG. 7A according to the job information, the relationship between the frequency of each halftone processing and the value of P is As shown in FIG. For example, from FIG. 7A, the numbers of low lines, high lines, error diffusion, and copies included in P = 2 to 11 are 6, 8, 1, and 0, respectively. Accordingly, 6, 8, 1, and 0 are set as the low line number frequency, the high line number frequency, the error diffusion frequency, and the copy frequency, respectively, in the row of P = 2 in FIG. 7B. The CPU 901 determines in S34 whether the halftone process X determined in S31 includes the set of halftone processes determined in S32 in Y. When the halftone processing X is included in the set Y of halftone processing, the CPU 901 sets the halftone processing corresponding to the gradation correction condition to be corrected to X in S35, and sets the execution flag to 1 in S38. .

  On the other hand, if the halftone process X is not included in the set Y of halftone processes, the CPU 901 determines the halftone process Z having the highest frequency among the frequencies determined in S33 in S36 in S36. In S37, the CPU 901 sets Z as the halftone process corresponding to the gradation correction condition to be corrected, and sets the execution flag to 1 in S38. That is, in the present embodiment, the gradation correction condition correction process is always executed before the print image is formed on the intermediate transfer member 106. However, if S34 is Yes, the gradation correction condition for halftone processing X is corrected, and if S34 is No, the gradation correction condition for halftone processing Z is corrected.

  For example, when P = 1, since C = 1, the CPU 901 determines in S31 that the halftone processing X is the number of low lines from FIG. 5A. Subsequently, in S32, the CPU 901 determines each halftone process of P = 1 to P = 10, and sets these sets as Y. As shown in FIG. 7A, P = 3, 4, 6, 7, and 8 include the number of low lines, so the process in S34 is Yes, and the CPU 901 performs the correction target intermediate process in S35. Set X to. Therefore, in S14 of FIG. 3, the correction of the gradation correction condition of the low tone number halftone process is executed.

  Further, since P = 7 and C = 7, from FIG. 5A, the CPU 901 determines in S31 that the halftone process X is a copy. Subsequently, in S32, the CPU 901 determines each halftone process of P = 7 to 16, and sets these sets as Y. As shown in FIG. 7A, since P = 7 to 16 does not include a copy, the process in S34 is No. In this case, the CPU 901 determines the halftone process with the highest frequency in the set Y in S36. As shown in FIG. 7B, when P = 7, the frequency of the low number of lines is 8 and the highest. Therefore, in S14 of FIG. 3, the correction of the gradation correction condition of the low tone number halftone process is executed.

  In this embodiment, while a plurality of print images to be printed on a sheet are continuously formed, the correction frequency of each gradation correction condition is controlled based on the type and number of halftone processes in the print image formed according to the job. To do. Specifically, the correction frequency of the gradation correction condition is high for halftone processing that is frequently used in a print image formed according to a job. As described above, by switching the halftone process to be corrected according to the use frequency of the halftone process in the print image formed according to the job, it is possible to improve the image stability of the halftone process that is frequently used. Note that the image forming apparatus of the present embodiment updates the gradation correction condition corresponding to the halftone process X when the halftone process X is included in the set Y of halftone processes in S34. However, the tone correction conditions corresponding to the most frequently used halftone process among the halftone processes included in the halftone process set Y may be constantly updated.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  120 to 123: image forming unit, 106: intermediate transfer member, 114: transfer roller, 912: gradation correction unit, 913: halftone processing unit, 900: printer control unit

Claims (6)

Conversion means for converting image data based on conversion conditions corresponding to the type of halftone processing;
Image processing means for performing halftone processing on the image data converted by the conversion means;
Image forming means for forming an image based on the image data on which the halftone processing has been executed;
An intermediate transfer body to which the image formed by the image forming means is transferred;
Transfer means for transferring the image transferred to the intermediate transfer member to a sheet;
Measuring means for measuring the measurement image transferred to the intermediate transfer member;
Control means for controlling the image forming means to form the measurement image, controlling the measurement means to measure the measurement image, and generating the conversion condition based on a measurement result of the measurement means; Have
The measurement image includes a predetermined measurement image,
The control means generates a conversion condition corresponding to a predetermined type of halftone processing based on a measurement result of the predetermined measurement image by the measurement means,
When the image forming unit forms a plurality of images continuously, the control unit generates the predetermined measurement image every time the image forming unit forms a predetermined number of images to be transferred to the sheet by the transfer unit. An image forming apparatus that controls whether or not to form the image data corresponding to the plurality of images based on a type of halftone processing executed by the image processing unit.   The control unit omits the formation of the predetermined measurement image by the image forming unit when the image processing unit does not perform the predetermined type of halftone processing on the image data corresponding to the plurality of images. The image forming apparatus according to claim 1.   When the image processing unit does not execute the predetermined type of halftone processing on image data corresponding to an image that has not yet been formed from the plurality of images, the control unit performs the image forming unit by the image forming unit. The image forming apparatus according to claim 1, wherein formation of a predetermined measurement image is omitted. Conversion means for converting image data based on conversion conditions corresponding to the type of halftone processing;
Image processing means for performing halftone processing on the image data converted by the conversion means;
Image forming means for forming an image based on the image data on which the halftone processing has been executed;
An intermediate transfer body to which the image formed by the image forming means is transferred;
Transfer means for transferring the image transferred to the intermediate transfer member to a sheet;
Measuring means for measuring the measurement image transferred to the intermediate transfer member;
Control means for controlling the image forming means to form the measurement image, controlling the measurement means to measure the measurement image, and generating the conversion condition based on a measurement result of the measurement means; Have
The measurement image includes a predetermined measurement image,
The control means generates a conversion condition corresponding to a predetermined type of halftone processing based on a measurement result of the predetermined measurement image by the measurement means,
The control unit determines, with respect to image data corresponding to the plurality of images, the frequency with which the image forming unit forms the predetermined measurement image while the image forming unit continuously forms a plurality of images. An image forming apparatus that performs control based on a type of halftone processing executed by the image processing unit.   When the image processing unit does not execute the predetermined type of halftone processing on the image data corresponding to the plurality of images, the control unit forms the predetermined measurement image. The image forming apparatus according to claim 4, wherein the frequency is reduced.   When the image processing unit does not execute the predetermined type of halftone processing on the image data corresponding to the plurality of images, the control unit may be configured so that the image forming unit does not use the predetermined measurement image. The image forming apparatus according to claim 4, wherein an image for measurement is formed.

Images