JP2017154293A - Image formation device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image formation device that can detect a failure of a device even when an image formed with gray level correction has no problem, and to obtain a program.SOLUTION: The image formation device 10 includes an image formation part 42 for forming a first image in which an image to be a formation target has been subjected to gray level correction and a second image the image has not been subjected to the gray level correction, on a recording medium. The image formation device conducts a predetermined process when density of the first image formed by the image formation part 42 is within an acceptable range and density of the second image is outside the acceptable range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus and a program.

  Patent Document 1 discloses a calibration device for matching or approximating an input / output characteristic indicating a relationship between a density setting value and an output density value in image processing to a preset ideal input / output characteristic. The calibration apparatus includes a characteristic acquisition unit that acquires input / output characteristics of a predetermined color related to an output image for each color. The calibration apparatus selects an input / output characteristic related to one color from the input / output characteristics based on a predetermined condition, and sets a reference characteristic correlated based on the input / output characteristic for each color. Characteristic setting means; and correction table generation means for generating a correction table corresponding to the reference characteristic for each color. The calibration apparatus further includes a calibration unit that calibrates the input / output characteristics for each color related to the output image to the reference characteristics set for the color by correcting the output density value based on the correction table. It has more.

JP 2010-130470 A

  An object of the present invention is to provide an image forming apparatus and a program capable of detecting an abnormality of the apparatus even when there is no problem in an image formed by gradation correction.

  In order to achieve the above object, the image forming apparatus according to claim 1 includes a first image in which gradation correction is performed on an image to be formed, and a second image in which gradation correction is not performed on the image. A predetermined process is performed when the density of the forming unit formed on the recording medium and the density of the first image formed by the forming unit are within an allowable range and the density of the second image is outside the allowable range. Processing means to perform.

  According to a second aspect of the present invention, in the invention according to the first aspect, the processing means is such that the density of the first image formed by the forming means is within an allowable range, and the second image When the density is outside the allowable range, a process for notifying that the density of the second image is outside the allowable range is performed as the predetermined process.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the processing means has a density of the first image formed by the forming means within an allowable range, and When the density of the second image is outside the allowable range, as the predetermined process, a process of adjusting the density of the image formed by the forming unit is performed on the forming unit.

  According to a fourth aspect of the present invention, in the invention according to the third aspect, the processing means is such that the density of the first image formed by the forming means is within an allowable range, and the second image When the density is out of the allowable range, as the predetermined process, the density of the image formed by the forming unit is adjusted with respect to the forming unit, and the second image formed by the forming unit is adjusted. The process is repeated until the density falls within the allowable range.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the forming means is formed by the forming means even if the processing for adjusting the density is repeatedly performed a predetermined number of times or more. If the density of the second image is out of the allowable range, the process of adjusting the density is stopped and a process of notifying that the density of the second image is out of the allowable range is performed.

  On the other hand, in order to achieve the above object, a program according to a sixth aspect causes a computer to function as processing means of the image forming apparatus according to any one of the first to fifth aspects. .

  According to the first and sixth aspects of the present invention, it is possible to detect an abnormality of the apparatus even when there is no problem in an image formed by gradation correction.

  According to the second aspect of the present invention, the user can grasp the abnormality of the apparatus.

  According to the third aspect of the present invention, it is possible to suppress an abnormality in the density of an image caused by an abnormality in the apparatus.

  According to the fourth aspect of the present invention, it is possible to more reliably suppress an abnormality in the density of an image caused by an abnormality in the apparatus as compared with a case where the forming unit is adjusted only once.

  According to the fifth aspect of the present invention, the user can grasp that the abnormality of the apparatus does not recover even if the forming means is adjusted a plurality of times.

1 is a block diagram illustrating a configuration of an image forming apparatus according to an embodiment. 6 is a graph for explaining density of an image formed without performing gradation correction in the image forming apparatus according to the embodiment. 6 is a graph for explaining density of an image formed by performing gradation correction in the image forming apparatus according to the embodiment. It is a top view which shows an example of the test chart which concerns on embodiment. It is a flowchart which shows the flow of a process of the density | concentration inspection process program which concerns on embodiment. It is a graph with which it uses for description of the process which determines whether the density | concentration of the 2nd image which concerns on embodiment is in tolerance level. It is the schematic which shows an example of the error notification screen which concerns on embodiment.

  DETAILED DESCRIPTION Hereinafter, exemplary embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  With reference to FIG. 1, a configuration of an image forming apparatus 10 according to the present exemplary embodiment will be described. In the following, when yellow is represented by Y, magenta color is represented by M, cyan color is represented by C, and black is represented by K, each component and toner image need to be distinguished for each color. In the following description, reference numerals (Y, M, C, K) of colors corresponding to are attached. Further, in the following, when the component parts and the toner image are collectively referred to without being distinguished for each color, the description of the color at the end of the code is omitted.

  As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment includes a control unit 12, a paper supply unit 40, an image forming unit 42, an image reading unit 44, a paper discharge unit 46, a communication line I / F (InterFace ) 48 and an operation display unit 50.

  The control unit 12 according to the present embodiment includes a CPU (Central Processing Unit) 20 that controls the overall operation of the image forming apparatus 10 and a ROM (Read Only Memory) 22 in which various programs, various parameters, and the like are stored in advance. I have. The control unit 12 also includes a RAM (Random Access Memory) 24 used as a work area when the CPU 20 executes various programs, a non-volatile storage unit 26 such as a flash memory, and an input / output I / F 28. .

  The CPU 20, the ROM 22, the RAM 24, the storage unit 26, and the input / output I / F 28 are connected to each other via a bus 30 such as an address bus, a data bus, and a control bus. Further, a paper supply unit 40, an image forming unit 42, an image reading unit 44, a paper discharge unit 46, a communication line I / F 48, and an operation display unit 50 are connected to the input / output I / F 28.

  The sheet supply unit 40 according to the present embodiment includes a sheet storage unit on which a plurality of sheets P (see also FIG. 4) as an example of a recording medium are stacked, and a sheet P stacked on the sheet storage unit one by one. A supply mechanism and the like are provided that are taken out and supplied to an image forming unit 42 described later.

  The image forming unit 42 according to the present embodiment includes Y, M, C, and K image forming units. Each color image forming unit includes an image carrier, a charger that charges the surface of the image carrier, and an exposure device that irradiates exposure light that forms an electrostatic latent image on the surface of the charged image carrier. Each color image forming unit includes a developing unit that develops an electrostatic latent image formed on the surface of the image holding member by irradiation of exposure light from an exposure device with a developer and visualizes the image as a toner image.

  Further, the image forming unit 42 includes an endless intermediate transfer belt, and a primary transfer roll disposed on the opposite side of each color image holding body with the intermediate transfer belt interposed therebetween. With the above configuration, the toner images of each color Y, M, C, and K, which are sequentially formed on the image carrier of each color image forming unit, are transferred onto the intermediate transfer belt in a multiple manner by the primary transfer roll of each color. The

  The image forming unit 42 is provided on the opposite side of the auxiliary roll and the intermediate transfer belt, and transfers the toner image transferred on the intermediate transfer belt onto the conveyed paper P. It has a roll. The secondary transfer roll is grounded, and the auxiliary roll forms a counter electrode of the secondary transfer roll. By applying a secondary transfer bias to the auxiliary roll, the toner image is transferred from the intermediate transfer belt to the paper P. Transcribed.

  Further, the image forming unit 42 includes a fixing device that fixes the toner image transferred onto the paper P by pressurizing and heating.

  The image reading unit 44 according to the present embodiment includes an image reading sensor such as a CCD (Charge Coupled Device) line sensor. The image reading unit 44 reads the image formed on the paper P by the image forming unit 42 and outputs the image data obtained by reading to the CPU 20 via the input / output I / F 28.

  The paper discharge unit 46 according to the present embodiment has a discharge unit from which the paper P is discharged and the paper P on which the image is formed by the image forming unit 42 and the image read by the image reading unit 44 on the discharge unit. A discharge mechanism for discharging is provided.

  The communication line I / F 48 according to the present embodiment transmits / receives communication data to / from an external device. The operation display unit 50 according to the present embodiment accepts an instruction from the user to the image forming apparatus 10, while displaying various information related to the operation status of the image forming apparatus 10 to the user. The operation display unit 50 includes, for example, a display button that realizes reception of an operation instruction by executing a program, a display provided with a touch panel on a display surface on which various information is displayed, and hardware keys such as a numeric keypad and a start button. including.

  Incidentally, the image forming apparatus 10 according to the present embodiment is equipped with a gradation correction function for performing gradation correction for correcting gradation characteristics of image data indicating an image to be formed. Further, the image forming apparatus 10 can select whether or not to execute the gradation correction function.

  Further, in the image forming apparatus 10 according to the present embodiment, the density of the image formed on the paper P may be outside the allowable range due to a change in the state of component parts over time. With reference to FIGS. 2 and 3, an abnormality in the density of an image formed on the paper P by the image forming apparatus 10 will be described.

  2 and 3, the horizontal axis (Cin) indicates the density of an image (hereinafter referred to as “input image”) indicated by the input image data, and the vertical axis (Dout) indicates the image. The density of an image (hereinafter referred to as “output image”) formed on the paper P by the forming apparatus 10 is shown. 2 and 3, each solid line represents the relationship between the density Cin of the input image and the density Dout of the output image at a plurality of different time points, and the range surrounded by two broken lines is the density of the input image. The allowable range R of the output image density Dout with respect to Cin is shown. FIG. 2 shows the relationship between the density Cin of the input image and the density Dout of the output image (hereinafter referred to as “gradation characteristics”) when an image is formed without gradation correction, and FIG. The relationship between the density Cin of the input image and the density Dout of the output image when an image is formed by performing tone correction is shown. Further, the gradation characteristic corresponding to the gradation characteristic of the line L1 in FIG. 2 is the line L2 in FIG.

  As an example, as shown by a line L1 in FIG. 2, when an image is formed without performing gradation correction due to an abnormality in a component related to image formation of the image forming apparatus 10, the output image density Dout is allowable. There is a case where it falls outside the range R. However, in the image forming apparatus 10, when an image input from the outside by an instruction from a user or the like is formed, the image is often formed by performing gradation correction. As a result, as shown by the line L2 in FIG. 3 as an example, the density of the image formed on the paper P after gradation correction is often within the allowable range R. Therefore, in this case, even if a user, maintenance personnel, or the like confirms the image formed on the paper P by visual observation or the like, there are many cases where no abnormality of the image forming apparatus 10 is detected.

  Therefore, the image forming apparatus 10 according to the present embodiment uses a test chart including a first image in which gradation correction has been performed on an image to be formed and a second image in which gradation correction has not been performed on the image. An abnormality of the image forming apparatus 10 is detected.

  With reference to FIG. 4, an example of the test chart TC according to the present embodiment will be described. As shown in FIG. 4, the test chart TC according to the present embodiment is composed of a first image G1 and a second image G2. The formation positions of the first image G1 and the second image G2 on the paper P are not limited to the example shown in FIG. 4, and the first image G1 and the second image G2 are formed in different regions on the paper P. Just do it.

  The first image G1 and the second image G2 according to the present embodiment are images in which striped images of each color of Y, M, C, and K are adjacent, and the striped image of each color has a density within the image. The images are different. Specifically, in the present embodiment, the band-shaped image of each color is an image whose density gradually increases along the transport direction of the paper P. Note that the belt-like images of the first image G1 and the second image G2 may be multi-color images in which two or more of Y, M, C, and K are superimposed.

  Further, the image data of the portions corresponding to the formation positions of the first image G1 and the second image G2 in the image data indicating the test chart TC according to the present embodiment are the same data. The image forming apparatus 10 according to the present embodiment forms a first image G1 on the paper P by performing gradation correction on the image data corresponding to the first image G1. On the other hand, the image forming apparatus 10 forms the second image G2 on the paper P without performing gradation correction on the image data corresponding to the second image G2.

  In the image forming apparatus 10 according to the present embodiment, image data indicating the test chart TC is stored in the storage unit 26 in advance. In the image forming apparatus 10 according to the present embodiment, correction data used for gradation correction is stored in the storage unit 26 in advance. Hereinafter, the image data indicating the test chart TC is referred to as “test image data”. In the following, the image data of the portion corresponding to the first image G1 of the test image data is referred to as “first image data”, and the image data of the portion corresponding to the second image G2 is referred to as “second image data”.

  Next, the operation of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of processing of the density inspection processing program executed by the CPU 20. This density inspection processing program is, for example, when an instruction to start execution is input by the user via the operation display unit 50, or whenever an image is formed on a predetermined number (for example, 1000 sheets) of paper P. To be executed. The density inspection processing program is installed in the ROM 22 in advance.

  In step 100 of FIG. 5, the CPU 20 initializes the flag F to a lowered state. Further, the CPU 20 initializes the counter A and the counter B to 0 (zero). In the next step 102, the CPU 20 reads test image data and correction data stored in the storage unit 26. Then, the CPU 20 performs gradation correction using the correction data for the first image data, and controls the image forming unit 42 without performing the gradation correction for the second image data to control the test chart. TC is formed on the paper P.

  In the next step 104, the CPU 20 controls the image reading unit 44 to read the test chart TC formed on the paper P and obtain image data obtained by reading. In the following, the portion corresponding to the first image G1 of the image data obtained by reading is referred to as “first read image data”, and the portion corresponding to the second image G2 is referred to as “second read image data”. . In the following, the first image G1 indicated by the first image data is referred to as “input first image G1”, and the first image G1 indicated by the first read image data is referred to as “output first image G1”. Further, hereinafter, the second image G2 indicated by the second image data is referred to as “input second image G2”, and the second image G2 indicated by the second read image data is referred to as “output second image G2”.

  In the next step 106, the CPU 20 determines whether or not the density of the output first image G1 indicated by the first read image data acquired in step 104 is within an allowable range. Specifically, for example, the CPU 20 determines that the density difference between the color regions formed at corresponding positions between the input first image G1 and the output first image G1 is the density of the input first image G1 in advance. It is determined whether or not it is within a predetermined ratio range (for example, within a range of ± 10%).

  In this step 106, for example, the CPU 20 derives the similarity between the input first image G1 and the output first image G1, and the derived similarity is equal to or greater than a predetermined threshold (for example, 90%). By determining whether or not the density of the output first image G1 is within an allowable range, it may be determined. When the determination at step 106 is negative, the CPU 20 proceeds to step 108, whereas when the determination is affirmative, the CPU 20 proceeds to step 122.

  In step 108, the CPU 20 determines whether or not the density of the output second image G2 indicated by the second read image data acquired in step 104 is within an allowable range. With reference to FIG. 6, the determination process in this step 108 will be described. FIG. 6 shows, as an example, a time-series transition of the density Dout of the output second image G2 for a certain density Cin of the input first image G1. In addition, the vertical axis in FIG. 6 indicates the density Dout of the output second image G2, and the horizontal axis indicates the elapsed time Time.

  As an example, as illustrated in FIG. 6, the CPU 20 derives an average value AVG of the density of the output second image G2 formed by the image forming unit 42 in the past for each color and density of the input second image G2. Note that this average value AVG is relatively stable in the state of the apparatus, for example, immediately after the image forming apparatus 10 is installed or immediately after maintenance work, and the variation amount of the density of the output second image G2 is within an allowable range ( What is necessary is just to apply the average value in the period etc. which are in the range between the broken lines shown in FIG.

  Then, for each color and each density of the input second image G2, the CPU 20 outputs the second output when the absolute value of the difference between the density of the output second image G2 and the derived average value AVG is equal to or greater than the threshold value TH1. It is determined that the density of the image G2 is outside the allowable range.

  As the threshold value TH1, a value determined in advance according to the required detection accuracy of density abnormality or the like may be applied. Further, the CPU 20 may determine whether or not the density of the output second image G2 is within an allowable range using, for example, a variance value or a standard deviation instead of the average value AVG. When the determination at step 108 is negative, the CPU 20 proceeds to step 110, whereas when the determination is affirmative, the CPU 20 proceeds to step 112.

  In step 110, after setting the flag F, the CPU 20 proceeds to step 112. In step 112, the CPU 20 matches the density of the image formed on the paper P with the target density based on the first image data stored in the storage unit 26 and the first read image data acquired in step 104. Alternatively, correction data to be approached is generated and stored (updated) in the storage unit 26.

  In the next step 114, the CPU 20 increments the counter A by 1 (counter A ← counter A + 1). In the next step 116, the CPU 20 determines whether or not the counter A is greater than or equal to the threshold value TH2. When this determination is a negative determination, the CPU 20 proceeds to step 118, whereas when the determination is affirmative, the CPU 20 proceeds to step 120. The threshold value TH2 is a value for preventing the processes from step 102 to step 114 from being repeated infinitely, and may be set as appropriate.

  In step 118, the CPU 20 initializes the flag F to a lowered state, and then returns to step 102. On the other hand, in step 120, the CPU 20 initializes the counter A to 0 (zero), and then proceeds to step 126. In step 120, the CPU 20 may notify that the density of the first image is outside the allowable range, as in step 136 described later.

  On the other hand, in step 122, the CPU 20 determines whether or not the density of the output second image G2 indicated by the second read image data acquired in step 104 is within an allowable range by the same processing as in step 108. To do. When this determination is a negative determination, the CPU 20 proceeds to step 124, whereas when the determination is affirmative, the CPU 20 proceeds to step 126. In step 124, the CPU 20 sets the flag F, and then proceeds to step 126.

  In step 126, the CPU 20 determines whether or not the flag F is set. If this determination is affirmative, the CPU 20 proceeds to step 128. In step 128, the CPU 20 adjusts the density of the image formed by the image forming unit 42 by adjusting the image forming unit 42. Specifically, for example, the CPU 20 determines the primary transfer bias based on the difference between the density of the input second image G2 and the density of the output second image G2 indicated by the second read image data acquired in step 104. Adjusting at least one of the secondary transfer bias and the amount of developer supplied by the developer.

  More specifically, for example, when the density of the output second image G2 is lower than the lower limit value of the allowable range R as shown by the line L1 in FIG. 2, the CPU 20 outputs the upper limit value and lower limit value of the allowable range R and the output. Based on the difference from the density of the second image G2, in the subsequent image formation, an image is formed on the paper P as shown below. That is, in this case, for example, the CPU 20 controls the image forming unit 42 in the subsequent image formation based on the difference so that the density of the formed image is within the allowable range R. An image is formed on the paper P by increasing the amount of developer supplied.

  In the next step 130, the CPU 20 increments the counter B by 1 (counter B ← counter B + 1). In the next step 132, the CPU 20 determines whether or not the counter B is greater than or equal to the threshold value TH3. When this determination is a negative determination, the CPU 20 proceeds to step 134, whereas when the determination is affirmative, the CPU 20 proceeds to step 136. The threshold value TH3 is a value for preventing the processing from step 102 to step 130 from being repeated indefinitely, and may be set as appropriate. Further, the threshold value TH2 and the threshold value TH3 may be the same value or different values.

  In step 134, the CPU 20 initializes the flag F to a lowered state, and then returns to step 102. On the other hand, in step 136, the CPU 20 notifies that there is an abnormality in the density of the image formed by the image forming unit 42, and then ends the density inspection process. Specifically, the CPU 20 displays on the display of the operation display unit 50 an error notification screen for notifying that an abnormality has occurred in the density of the image formed by the image forming unit 42.

  FIG. 7 shows an example of an error notification screen according to the present embodiment. As shown in FIG. 7, on the error notification screen according to the present embodiment, information indicating that an abnormality has occurred in the density of the image formed by the image forming unit 42 is displayed. Here, when ending the display of the error notification screen, the user designates an end button displayed at the bottom of the error notification screen.

  In step 136, the CPU 20 may notify that the abnormality has occurred by voice or the like. Further, the CPU 20 may notify the fact that the abnormality has occurred by controlling the image forming unit 42 to form information indicating that the abnormality has occurred on the paper P. Further, the CPU 20 may notify that the abnormality has occurred by transmitting information indicating that the abnormality has occurred to a maintenance staff or the like via a network. Moreover, you may combine two or more of these some alerting | reporting methods.

  On the other hand, if the determination in step 126 is negative, the CPU 20 ends the density inspection process.

  In the above-described embodiment, the case has been described in which affirmative determination is made when all the colors and densities satisfy the conditions in Step 106, Step 108, and Step 122. However, the present invention is not limited to this. For example, an affirmative determination may be made when at least one color and density satisfy a condition. In this embodiment, the update of the correction data in step 112 and the adjustment of the image forming unit 42 in step 128 are exemplified for the color and density determined to be outside the allowable range.

  In the above-described embodiment, the case where the test chart is read by the image reading unit 44 provided inside the image forming apparatus 10 has been described. However, the present invention is not limited to this. The test chart may be read by an image reading device external to the image forming apparatus 10. As an example of this case, the image forming apparatus 10 obtains image data obtained by reading a test chart by an external image reading apparatus from the image reading apparatus, and the above embodiment is based on the obtained image data. The form which performs a density | concentration inspection process similarly to is illustrated.

  In the above-described embodiment, the gradation correction is performed on part of the test image data (first image data) in step 102 and the gradation correction is not performed on the other part (second image data). The image processing apparatus outside the apparatus 10 may be executed. As an example of this case, an external image processing apparatus acquires correction data and test image data from the image forming apparatus 10, performs gradation correction on a part of the acquired test image data, and performs gradation correction on other parts. An example of generating image data that has not been transmitted and transmitting it to the image forming apparatus 10 is illustrated.

  In the above-described embodiment, a case has been described in which the occurrence of an abnormality in the density of an image formed by the image forming unit 42 has been described. However, the present invention is not limited to this. For example, it is good also as a form which memorize | stores in the memory | storage part 26 as log information that the said abnormality has generate | occur | produced. In the case of this embodiment, a maintenance staff or the like grasps that the abnormality has occurred by referring to the log information during maintenance work of the image forming apparatus 10 or the like.

  In the above embodiment, the case where the density inspection processing program is preinstalled in the ROM 22 has been described. However, the present invention is not limited to this. For example, the density inspection processing program may be provided by being stored in a storage medium such as a CD-ROM (Compact Disk Read Only Memory) or provided via a network.

  Further, in the above-described embodiment, the case has been described in which the density inspection process is realized by a software configuration using a computer by executing a program. However, the present invention is not limited to this. For example, the density inspection process may be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  In addition, the configuration (see FIG. 1) of the image forming apparatus 10 described in the above embodiment is merely an example, and unnecessary portions are deleted or new portions are added within the scope not departing from the gist of the present invention. Needless to say, you can also.

  Further, the flow of the density inspection processing program described in the above embodiment (see FIG. 5) is also an example, and unnecessary steps are deleted or new steps are added within the scope of the present invention. Needless to say, the processing order may be changed.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Control part 20 CPU
22 ROM
26 Storage Unit 42 Image Forming Unit 44 Image Reading Unit 50 Operation Display Unit G1 First Image G2 Second Image P Paper

Claims (6)

Forming means for forming, on a recording medium, a first image in which gradation correction is performed on an image to be formed, and a second image in which gradation correction is not performed on the image;
Processing means for performing a predetermined process when the density of the first image formed by the forming means is within an allowable range and the density of the second image is outside the allowable range;
An image forming apparatus. When the density of the first image formed by the forming unit is within an allowable range and the density of the second image is outside the allowable range, the processing unit performs the first process as the predetermined process. The image forming apparatus according to claim 1, wherein a process of notifying that the density of the two images is outside an allowable range is performed. When the density of the first image formed by the forming unit is within an allowable range and the density of the second image is outside the allowable range, the processing unit performs the formation as the predetermined process. The image forming apparatus according to claim 1, wherein a processing for adjusting a density of an image formed by the forming unit is performed on the unit. When the density of the first image formed by the forming unit is within an allowable range and the density of the second image is outside the allowable range, the processing unit performs the formation as the predetermined process. 4. The image forming apparatus according to claim 3, wherein the image forming apparatus repeats the adjustment of the density of the image formed by the forming unit until the density of the second image formed by the forming unit falls within an allowable range. . The processing means adjusts the density when the density of the second image formed by the forming means is out of an allowable range even when the density adjustment processing is repeatedly performed a predetermined number of times or more. 5. The image forming apparatus according to claim 4, wherein the image forming apparatus performs processing for canceling and notifying that the density of the second image is outside an allowable range.   A program for causing a computer to function as processing means of the image forming apparatus according to claim 1.