JP2001092209A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide color copying machine which shortens processing time of automatic gradation correcting function, by the color copying machine provided with the automatic gradation correcting function. SOLUTION: This image-forming device, makes an adding machine 302 to add the density value of a pattern being present in the specific pattern position 305 on the color pattern, and the density value of a pattern position 305, which is preserved by a read-out density RAM 304. The correction property 503, computed from the mean value by meaning the added value, is determined by averaging the added values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a digital color multifunction peripheral, and more particularly to an image processing apparatus for correcting the gradation of a color image.

[0002]

2. Description of the Related Art In recent years, an automatic gradation correction function using an image scanner unit as a measuring device has been used as a mechanism for correcting the effects of environmental and temporal changes in a printing unit in a color copying machine.

[0003] The above technique is performed by the following procedure.
Prior to outputting the actual document, the printing unit forms a reference color pattern on the transfer paper. The formed color pattern is read by the scanner unit. The color copier realizes the above automatic gradation correction function by adjusting image forming conditions in the color copier based on the read color pattern.

However, a color copying machine has to read a plurality of color patterns for gradation correction, and has to scan the scanner unit a plurality of times. Therefore, it has been pointed out that it takes time until the processing of the automatic gradation correction function is completed.

As a prior art relating to a color copying machine having an automatic gradation correction function using an image scanner unit as a measuring device, there is one disclosed in Japanese Patent Application Laid-Open No. 10-20603.

The color copier according to the prior art has means for setting whether or not to apply the automatically corrected gradation characteristics at the time of image formation, and refers to the setting conditions at the time of image formation. If it is set to apply the automatically corrected tone characteristics, such a color copying machine performs tone correction based on the automatically corrected tone characteristics at the time of image formation. When it is set not to apply the automatically corrected tone characteristics, the color copier performs tone correction based on the initial tone characteristics at the time of image formation.

Thus, even if a satisfactory result is not obtained by gradation correction, the user can easily return the image forming conditions to the original state.

[0008]

However, according to the above-mentioned prior art, there is no measure against the problem that it takes time to complete the processing of the automatic gradation correction function.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a color copying machine that shortens the time required for completing the processing of the automatic gradation correction function.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a color pattern forming means for forming a color pattern on a transfer paper, and a color pattern forming means for forming a color pattern on the transfer paper. Pattern reading means for reading the density value of each pattern from the formed color pattern; density value holding means for holding the density value of each pattern read by the pattern reading means; and each of the color values held by the density value holding means. And a tone correction unit for averaging the density values of the patterns and correcting the tone characteristics based on the averaged density values of the color patterns.

According to a second aspect of the present invention, in the apparatus of the first aspect, the reference position mark adding means for adding a reference position mark to the color pattern formed by the color pattern forming means and the reference position mark adding means. Reading position control means for controlling the reading position of the color pattern by the reference position mark of the color pattern, wherein the reading position control means is provided to the user when the color pattern is not set at the predetermined reading position. It is characterized in that a color pattern is set at a predetermined reading position, and when the color pattern is set at the predetermined reading position, the density value holding means is activated.

The invention described in claim 3 is the first or second invention.
The color pattern reading means also reads the background level of the transfer paper on which the color pattern is formed, and the density value holding means also holds the background level of the transfer paper; The means is characterized in that the gradation characteristic is corrected using the background level of the transfer paper.

According to a fourth aspect of the present invention, in the apparatus according to any one of the first to third aspects, the gradation correction means obtains a gamma characteristic from the density value of the color pattern held by the density value holding means. It is characterized in that the gradation characteristic is corrected based on the obtained gamma characteristic.

According to a fifth aspect of the present invention, in the apparatus according to any one of the first to fourth aspects, the apparatus further comprises a correction notifying means for notifying a user whether or not to correct the gradation characteristic. I have.

According to a sixth aspect of the present invention, in the device according to the fifth aspect, the notification by the correction notifying unit is notified after a predetermined period has elapsed after the gradation characteristic has been corrected by the gradation correcting unit. It is characterized by:

The invention according to claim 7 is the invention according to claim 5 or 6.
In the apparatus, the notification by the correction notifying means is performed after the image forming is performed a predetermined number of times after the gradation characteristic is corrected by the gradation correcting means.

According to an eighth aspect of the present invention, in the apparatus according to any one of the fifth to seventh aspects, the notification by the correction notifying means is performed after the gradation characteristic is corrected by the gradation correcting means. It is characterized by being notified when it is replenished.

According to a ninth aspect of the present invention, in the apparatus according to any one of the sixth to eighth aspects, a period setting means for setting a predetermined period is further provided.

The invention according to claim 10 is the invention according to claims 7 to 9
The apparatus according to any one of the above, further comprising a number setting means for setting a predetermined number.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an image processing section in a digital color copying machine according to an embodiment of the present invention. According to FIG. 1, the image processing unit of the present invention includes a scanner unit 10
1, shading correction unit 102, scanner gamma correction unit 103, filter unit 104, color conversion unit 105, scaling circuit 106, image processing circuit 107, gamma correction circuit 10
8, gradation processing circuit 109, printer unit 110, CPU1
11, an operation unit 112, and a display unit 113.

A scanner unit 101 scans a document image,
Convert to GB image data. Shading correction unit 10
2 performs shading correction on the RGB image data.
The shading correction unit 102 corrects unevenness of RGB image data, unevenness of illumination of a light source, and the like caused by characteristics of the image sensor. The scanner gamma correction unit 103 performs gamma correction of each component of the RGB signal. The filter unit 104 includes an RG
A smoothing process and an emphasis process of the B image data are performed.

Although not shown, the position correction unit uses C
Position correction between the CD line sensors is performed. Separation processing for performing local determination from image data by a separation circuit is also performed. The separation circuit determines a character portion and a photograph portion. The separation circuit also determines a chromatic color or an achromatic color.

The color conversion unit 105 converts the RGB image data into C
Convert to MYK image data. The scaling circuit 106 is a CM
A scaling process is performed on the YK image data. Image processing circuit 107
Performs a CMYK image repeat process, an italic process, and a shadowing process.

The gamma correction circuit 108 performs gamma correction according to the gamma characteristics of the printer. Gamma correction circuit 1
08 corrects the image signal according to the image quality mode such as text and photograph. The gradation processing circuit 109 performs gradation processing such as dither processing and error diffusion processing.

The printer section 110 prints CMYK image data on recording paper. The CPU 111 includes the scanner unit 10
1. Shoeing correction unit 102, scanner gamma correction unit 103, filter unit 104, color conversion unit 105, scaling circuit 106, image processing circuit 107, gamma correction circuit 10
8, gradation processing circuit 109, printer unit 110, operation unit 1
12 and the display unit 113 are controlled. CPU11
1 generates an image desired by the user in cooperation with the control unit of the main system.

The operation unit 112 receives information for determining the operation mode of the system from the user. The display unit 113
Displays the status of the system to the user. Display unit 11
3 displays a message prompting the user to perform processing. Although not shown, the backup memory stores initial system conditions, user setting conditions, and the like.

FIG. 4 is an output example of a color test pattern output to transfer paper by a digital color copying machine according to the embodiment of the present invention. As shown in FIG. 4, the color test pattern of the present invention includes a reference position mark 409, a reference position mark 410, and C (cyan), M (magenta), Y (yellow), and K (black) color components. Are a plurality of patterns represented by a plurality of density values output on transfer paper.

CMYK of the color test pattern of the present invention
Each color component is subjected to gradation processing for a plurality of density values. Each of the CMYK color components of the color test pattern of the present invention has been subjected to gradation processing according to the character mode and the photograph mode, respectively.

The reference position mark 409 and the reference position mark 410 regulate the sampling timing at which the gamma correction circuit 108 reads a color pattern. The gamma correction circuit 108 has a reference position mark 409 and
Based on the reference position mark 410, it is determined whether or not the color pattern has been read by the scanner unit 101 at a predetermined reading position. Thereby, the detection accuracy of each color pattern is improved.

The horizontal video signal 411 of the reference position mark and the vertical video signal 412 of the reference position mark shown in FIG. 4 are obtained when the gamma correction circuit 108 reads the reference position mark 409 and the reference position mark 410. This shows the sampling value of the video signal.

FIG. 3 is a circuit diagram showing a circuit for storing the density value of each color pattern in a memory according to the embodiment of the present invention. As shown in FIG. 3, the circuit for storing the density value of each color pattern in the memory according to the embodiment of the present invention includes an adder 302, an accumulated value register 303, and a read density RAM 304.

The CPU 111 reads data corresponding to the pattern position 305 shown in FIG.
To the accumulated value register 303. The pattern position 305 is determined by the gamma correction circuit 108 by the reference position mark 409 and the reference position mark 41 shown in FIG.
It is calculated from 0.

The reference position mark 409 and the reference position mark 410 regulate the sampling timing at which the gamma correction circuit 108 extracts an appropriate pattern position.
The horizontal video signal 41 of the reference position mark shown in FIG.
1, and the vertical video signal 41 of the reference position mark
2 indicates that the gamma correction circuit 108 has the reference position mark 409,
And the sampling value of the video signal when the reference position mark 410 is read.

The adder 302 adds the density value of the pattern read from the color pattern shown in FIG. 4 and the data registered in the cumulative value register 303 corresponding to this pattern. The added data is stored in the cumulative value register 3
03 is returned.

The above circuit is used for reading the density values of all the patterns shown in FIG. 4 and for reading the background of the transfer paper. The contents of the reading density RAM 304 are initialized before tone correction.

Each time the tone correction is performed, the density value of each color pattern is stored in the reading density RAM 304. The gradation correction is performed based on the density value stored in the reading density RAM 304. Thus, the scanner unit 101 does not need to scan a plurality of times to read a plurality of color patterns. Therefore, once the color pattern is scanned by the scanner unit 101 at the time of executing the gradation correction, appropriate correction data can be created by using the data of each color pattern stored in the reading density RAM 304.

FIG. 5 is a diagram illustrating a gamma characteristic of the printer unit 110, a target characteristic of the printer, and a correction characteristic of the printer according to the embodiment of the present invention. As shown in FIG. 5, this figure shows the gamma characteristic 50 of the printer.
1, a target characteristic 502 and a correction characteristic 503 are shown. In this table, the horizontal axis indicates the input density value of the image data read from the scanner unit 101, and the vertical axis indicates the printer unit 11
Indicates the output density value of the data output from 0.

The gamma characteristic 501 of the printer is obtained based on a representative point of the density value. Between the representative points of the density values, the gamma characteristic 501 of the gap is filled by interpolation using a spline function or the like. The correction characteristics 503 are calculated from the obtained gamma characteristics and target characteristics.

The correction characteristic 503 is calculated as follows. An output value 511 having the same input value as the input value 510 of the color pattern is obtained from the target characteristic 502. An input value 512 having the same output value as the output value 511 on the target characteristic 502 is obtained from the gamma characteristic 501. From the obtained input value 512 on the gamma characteristic 501, the input value 513 on the target characteristic 502 having the same output value is obtained. The output value of the input value 513 is an output value 514 for the input value 510.

The output value 514 is a correction value for the input value 510. This operation is performed for all input values, and the correction characteristic 503 is calculated.

The gradation correction performed by the color copying machine of the present invention is as follows.
This will be described with reference to FIGS. 1, 2, 3, 4, and 5. FIG. When the user instructs the printer device to start gradation correction using the operation unit 112, the gradation processing unit 109
The color pattern shown in FIG. Such a color pattern is output on transfer paper by the printer unit 110 (step S201).

The display unit 113 instructs the user to cause the scanner unit 101 to read the color pattern output on the transfer paper into the color copier. Scanner unit 10
1 is based on an instruction from a user on the operation unit 112,
The color pattern is scanned and converted into RGB image data (step S202).

The CPU 111 checks the overlap of the video signals of the reference position mark 409 and the reference position mark 410 detected by the gamma correction circuit 108. When the video signals of the reference position mark 409 and the reference position mark 410 do not overlap sufficiently, the CPU 111
The scanner unit 101 determines that the color pattern has been scanned while being tilted, and the display unit 113 instructs the user to replace the color pattern.

When the video signals of the reference position mark 409 and the reference position mark 410 overlap sufficiently, the background level of the transfer paper is read. The background level is read from a background level reading position 401 on the color pattern shown in FIG. For the read background level, the circuit shown in FIG. 3 calculates the cumulative value of the background level. The calculated result is stored in the reading density RAM 304.

The first purpose of gradation correction using the background level is to correct the whiteness of transfer paper on which a color pattern is printed. This is because, even when an image is formed on the same machine at the same time, the value read by the scanner unit 101 differs depending on the whiteness of the transfer paper used.

Further, the second method of gradation correction using the background level
Is to correct the whiteness based on the thickness of the transfer paper on which the color pattern is printed. This is because the thickness of the transfer paper on which the color pattern is printed is read by the scanner through the color of the pressure plate or the like that presses the transfer paper.

The density value of each color pattern is read in the same manner as the background level, and the read density R
Stored in the AM 304. When the densities of all the color patterns are stored in the read density RAM 304, the CPU 111 reads the stored density values from FIG.
The correction characteristic 503 shown in FIG. The calculated correction characteristic 5
03 is stored in the backup memory.

The reading density RAM 304 stores each pattern density value of the color pattern read before. By calculating the average value of the stored density value and the read density value, it is not necessary to scan the color pattern a plurality of times, and it is possible to create an appropriate correction characteristic 503 by a single scan.

The CPU 111 checks with the user whether or not to rewrite the correction characteristic 503. (Step S20
4). Such confirmation is performed using the display unit 113.
The user determines whether or not to rewrite the correction characteristic by operating the operation unit 112.
Respond using.

The user inputs the correction characteristic 50 from the operation unit 112.
3 is rewritten (step S204 / Y)
ES), the CPU 111 rewrites the correction characteristics 503 stored in the backup memory (step S20)
5). When the user responds from the operation unit 112 that the correction characteristic 503 is not rewritten (step S204 / N
O), the CPU 111 performs gradation correction using the correction characteristics 503 stored in the backup memory.

If there is no response from the user within a predetermined time after the display unit 113 notifies the user, the correction characteristic 503 stored in the backup memory may be rewritten. . Further, when there is no response from the user within a predetermined time after the display unit 113 notifies the user, the correction characteristic 503 stored in the backup memory may not be rewritten.

Prior to the confirmation, the correction characteristic 503 stored in the backup memory may be rewritten, and a color pattern may be output based on the rewritten correction characteristic 503. In this case, the correction characteristic 503 before rewriting is stored in a backup memory, and after the above output, the user can select from the operation unit 112 to use the correction characteristic 503 before rewriting. To If the user selects to use the correction characteristic 503 before being rewritten, the correction characteristic 503 becomes
The correction characteristics 503 before being rewritten are corrected.

Thus, the user can compare the correction characteristic 503 stored in the backup memory with the output result of the rewritten correction characteristic 503, and determine whether or not to rewrite the correction characteristic 503. Will be possible.

The CPU 111 asks the user via the display unit 113 whether or not to execute the confirmation gradation correction (step S206). The user responds using the operation unit 112 whether or not to execute the confirmation gradation correction. When the user responds that the confirmation gradation correction is performed (step S206 / YE
S), the gradation processing circuit 109 generates a color pattern using the correction characteristics 503 stored in the backup memory. The generated color pattern is output on transfer paper by the printer unit 110 (step S207). Thus, the user can confirm the result of the correction by looking at the color patterns before and after the correction.

When the correction characteristic 503 is rewritten, the correction characteristic 503 before rewriting may be stored in a backup memory separately from the new correction characteristic 503. Then, after executing the above-described confirmation gradation correction, the correction characteristic 503 after being rewritten by the user using the display unit 113 is used, or the correction characteristic 5 before being rewritten is used.
Ask if you use 03. When the user responds from the operation unit 112 that the correction characteristic 503 before rewriting is used, the correction characteristic 503 before rewriting may be used.

According to this, the color pattern based on the correction characteristic 503 after rewriting is compared with the color pattern based on the correction characteristic 503 before rewriting, and as a result of comparison, the correction characteristic 503 before rewriting is selected. Becomes possible.

When the correction characteristic 503 in the backup memory is rewritten, the CPU 111 stores the environment information of the color copying machine in the backup memory.

If the user responds that the confirmation gradation correction is not to be performed (step S207 / NO), the CPU 111
Saves the environment information of the color copier in the backup memory. The environment information includes the date and time when the gradation correction was performed, the background information of the transfer paper that output the color pattern, and the like.

Based on the environment information stored in the backup memory, the CPU 111 prompts the user to perform the tone correction using the display unit 113 after a predetermined period has elapsed from the execution of the tone correction. Will be possible.

Further, when executing the gradation correction, the CPU 111 can determine whether or not the transfer paper is different from the transfer paper when the previous gradation correction was performed. As a result of this determination, if the transfer paper is different from the transfer paper when the tone correction was performed last time, the user is notified using the display unit 113 to that effect. This allows the user to know that there is a high possibility that tone correction must be performed.

When the tone correction is executed, the environment information is stored in the RAM, and the color copying machine ends the processing.
If tone correction has not been performed, the color copier ends the process after receiving the above response from the user.

According to the above embodiment, the reading density R
The provision of the AM 304 makes it possible to perform gradation correction only by scanning the color pattern once with a simple circuit and a small memory configuration.

According to the above embodiment, by attaching the reference position mark to the color pattern, it is possible to improve the detection accuracy of reading the color pattern.

According to the above embodiment, it is possible to perform more accurate gradation correction by reading the background information of the transfer paper that has output the color pattern. Also,
At the time of tone correction, the user can know whether or not the color pattern was output on the same transfer paper as that on which the color pattern was previously output, and determine whether or not to perform the tone correction Can be easily performed.

According to the above embodiment, it is possible for the user to know that a certain period has elapsed since the execution of the gradation correction. Therefore, the user can easily determine when to perform the gradation correction.

[0067]

As is apparent from the above description, according to the first aspect of the present invention, there is provided a color pattern forming means for forming a color pattern on a transfer paper, and a color pattern formed on the transfer paper by the color pattern forming means. From the pattern
A pattern reading unit that reads the density value of each pattern; a density value holding unit that holds the density value of each pattern read by the pattern reading unit; and a density value of each pattern held by the density value holding unit. And
By having gradation correction means for correcting gradation characteristics based on the averaged density value of each color pattern, gradation correction can be performed only once by scanning the color pattern with a simple circuit and a small memory configuration. It is possible to do.
Further, even with a small sample value, it is possible to perform appropriate gradation correction.

According to the second aspect of the present invention, in the apparatus of the first aspect, the reference position mark adding means for adding the reference position mark to the color pattern formed by the color pattern forming means, and the reference position mark adding means. Reading position control means for controlling the reading position of the color pattern by the reference position mark of the color pattern, wherein the reading position control means is used when the color pattern is not set at the predetermined reading position. To the user to place the color pattern at the predetermined reading position, and when the color pattern is placed at the predetermined reading position, the detection value can be improved by operating the density value holding means. Become.

According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the color pattern reading means reads the background level of the transfer paper on which the color pattern is formed. Is for maintaining the background level of the transfer paper, and the gradation correction means corrects the gradation characteristics also using the background level of the transfer paper. Can be corrected.

According to a fourth aspect of the present invention, in the apparatus according to any one of the first to third aspects, the gradation correcting means includes:
The gamma characteristic is obtained from the density value of the color pattern held by the density value holding means, and the gradation characteristic is corrected based on the obtained gamma characteristic, so that appropriate gradation correction can be performed from a small number of sample values. Will be possible.

According to a fifth aspect of the present invention, the apparatus according to any one of the first to fourth aspects further comprises a correction notifying means for notifying a user whether or not to correct the gradation characteristic. Person can easily know the time when the gradation correction has to be performed.

According to a sixth aspect of the present invention, in the device according to the fifth aspect, the notification by the correction notifying means is notified after a predetermined period has elapsed after the gradation characteristic has been corrected by the gradation correcting means. Thus, the user can easily know the time when the gradation correction has to be performed.

The invention described in claim 7 is directed to claim 5 or 6.
In the apparatus, the notification by the correction notifying unit is notified after the image forming is performed a predetermined number of times after the gradation characteristic is corrected by the gradation correcting unit, so that the user can perform the gradation correction. It is possible to easily know the time when the operation must be performed.

According to an eighth aspect of the present invention, in the apparatus according to any one of the fifth to seventh aspects, the notification by the correction notifying means is performed after the gradation characteristic is corrected by the gradation correcting means. By being notified at the time of replenishment, the user can easily know the time when the gradation correction has to be performed.

According to a ninth aspect of the present invention, the apparatus according to any one of the sixth to eighth aspects further comprises a period setting means for setting a predetermined period, thereby performing setting according to the environment of the user. It becomes possible.

The invention according to claim 10 is the invention according to claims 7 to 9
In the apparatus according to any one of the above, further comprising a number setting means for setting a predetermined number makes it possible to perform setting according to the environment of the user.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of an image processing unit of a digital multifunction peripheral according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining gradation correction performed by the digital multi-function peripheral according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a circuit for storing each density value of an output pattern in a memory according to the embodiment of the present invention.

FIG. 4 is a printing example of a color pattern according to the embodiment of the present invention.

FIG. 5 is a graph showing correction characteristics according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 scanner unit 102 shading correction unit 103 scanner gamma correction unit 104 filter unit 105 color conversion unit 106 scaling circuit 107 image processing circuit 108 gamma correction circuit 109 gradation processing unit 110 printer unit 111 CPU 112 operation unit 113 display unit 301 read value 302 Adder 303 Cumulative value register 304 Reading density RAM 305 Pattern position 401 Background reading position 409, 410 Reference position mark 411 Horizontal video signal of reference position mark 412 Vertical video signal of reference position mark 501 Gamma characteristic 502 Target characteristic 503 Correction Characteristic

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 1/407 H04N 1/40 101E F-term (Reference) 2C262 AA24 AA26 AB11 AC04 BA10 BB03 BC10 EA02 EA13 FA10 FA13 FA16 FA18 GA15 GA23 2H027 DA09 DA38 DA45 DC03 DE02 DE07 EC03 EC07 EE01 EE07 GB10 HA02 HA03 HA14 HB02 HB06 ZA07 2H030 AA03 AD11 AD17 BB36 5C077 MM03 MM27 MP08 PP05 PP15 PP58 PQ17 PQ18 PQ22 RR06

Claims (10)

[Claims] 1. A color pattern forming means for forming a color pattern on transfer paper, a pattern reading means for reading a density value of each pattern from the color pattern formed on the transfer paper by the color pattern forming means, Density value holding means for holding the density value of each pattern read by the means; and density values of the respective patterns held by the density value holding means, respectively, and averaging the density values of the averaged color patterns. An image forming apparatus, comprising: a gradation correcting unit that corrects a gradation characteristic based on the image. 2. A reference position mark adding means for adding a reference position mark to a color pattern formed by the color pattern forming means, and reading a color pattern by the reference position mark of the color pattern added by the reference position mark adding means. Reading position control means for controlling a position, wherein the reading position control means provides a user with the color pattern at the predetermined reading position when the color pattern is not set at the predetermined reading position. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is notified to install the image forming apparatus, and when the color pattern is installed at the predetermined reading position, the density value holding unit is operated. 3. The color pattern reading means also reads the background level of the transfer paper on which the color pattern is formed, and the density value holding means also holds the background level of the transfer paper. The image forming apparatus according to claim 1, wherein the gradation correction unit corrects a gradation characteristic by using a background level of the transfer paper. 4. A method according to claim 1, wherein said tone correction means obtains a gamma characteristic from the density value of the color pattern held by said density value holding means, and corrects the tone characteristic based on the determined gamma characteristic. The image forming apparatus according to claim 1, wherein: 5. The image forming apparatus according to claim 1, further comprising a correction notifying unit that notifies a user whether or not to correct the gradation characteristic. 6. The image according to claim 5, wherein the notification by the correction notifying unit is notified after a predetermined period has elapsed after the gradation characteristic is corrected by the gradation correcting unit. Forming equipment. 7. The notification by the correction notifying means, after the gradation characteristic has been corrected by the gradation correcting means, after the image formation has been performed a predetermined number of times. 7. The image forming apparatus according to 5 or 6. 8. The method according to claim 5, wherein the notification by the correction notifying unit is notified when paper is replenished after the gradation characteristic is corrected by the gradation correcting unit. 8. The image forming apparatus according to claim 7. 9. The image forming apparatus according to claim 6, further comprising a period setting unit that sets the predetermined period. 10. The image forming apparatus according to claim 7, further comprising a number setting unit for setting the predetermined number.