JPH0698171A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent assembly variation and adjustment variation by storing the normal gradation data of each gradation, and preparing the gradation data image on a medium on which a picture is prepared according to the read grada tion data, at the time of preparing the picture data read by a picture reading means on the medium. CONSTITUTION:The picture data read by an original scanning part 3 and processed by a first picture processing part 52 are supplied through a gate 53d in a gamma correcting part 53 to a gamma RAM 53c, and the correction data are transmitted through a second picture processing part 54 to a picture preparing part 4, and the corresponding picture is prepared. At that time, a printing characteristic, that is, output characteristic is affected by environmental conditions such as temperature and humidity in the processing part 54, and the gamma correction data stored in the gamma RAM 53c are corrected according to the data corresponding to the conditions detected by the environment sensor 38. Thus, the gradation chart including the variance of the gamma characteristic is outputted, compared with the normal gradation data, the correction data are calculated, temporarily stored in the gamma correcting part, and then the picture data are corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine for reading an image on a document and forming an image on a sheet according to the read signal.

[0002]

2. Description of the Related Art Recently, as a copying machine, a copying machine using a thermal transfer type ink ribbon has been developed and put into practical use by utilizing digital technology. That is, an image from a document is read by a CCD type line sensor, and a signal from this line sensor is quantized and processed.

In such an apparatus, as a method of improving gradation reproducibility, the relationship between the input signal from the scanner and the output image from the printer is measured in advance to grasp the γ characteristic (scanning characteristic of the scanner and output characteristic of the printer). do it,
By calculating a correction parameter having a desired γ characteristic and storing it in the ROM, the input signal from the scanner is corrected in the LUT (lookup table) format.

Such a conventional method is based on the precondition that the γ characteristic is the same for all mass-produced machines. However, in mass production, there are variations in the γ characteristics of individual machines due to variations in assembly and adjustment. Therefore, the use of the ROM in which the same correction parameters are stored causes a disadvantage that the machine cannot be corrected. In addition, there is a disadvantage that the accuracy of the γ correction becomes low due to the use of the correction parameter in consideration of the variation, which causes a machine body.

Therefore, in order to avoid the above-mentioned drawbacks, several kinds of correction parameters are prepared in the ROM, and a picture, that is, an output image is output by each correction parameter, and among the set several kinds of correction parameters. Therefore, there is a drawback in that the laborious adjustment work of selecting the optimum correction parameter must be performed. Therefore,
There is a drawback that variations in individual γ characteristics due to variations in assembly and adjustment cannot be easily corrected.

[0006]

SUMMARY OF THE INVENTION As described above, according to the present invention, the individual .gamma.
This eliminates the drawback that the characteristic variation cannot be easily corrected.Each γ characteristic variation due to assembly variation and adjustment variation can be easily corrected, and the optimum parameter for each device is An object of the present invention is to provide an image forming apparatus capable of setting correction data.

[0007]

An image forming apparatus according to the present invention is an image reading apparatus that optically scans a document placed on a document table using optical means, and reads image data by this optical scanning. In the image forming device, the image forming device forms an image corresponding to the image data read by the image reading device on an image forming medium, and stores regular gradation data for each gradation. Storage means,
Instructing means for instructing the output of a gradation data image composed of a plurality of gradations, and in response to the instruction of the instructing means, the normal gradation data for each gradation stored in the first storage means is read out, First processing means for forming a gradation data image of a plurality of gradations on the image forming medium by the image forming means in accordance with the read gradation data, and the gradation data image is formed by the first processing means. Second processing means for reading the image forming medium by the image reading means, gradation data for each gradation read by the second processing means, and for each gradation stored in the first storage means. Calculation means for calculating correction data by comparing with normal gradation data, second storage means for storing correction data for each gradation calculated by this calculation means, image data read by the image reading means The above Correction means for correcting the correction data stored in the second storage means, and a third image forming means for forming an image corresponding to the image data corrected by the correction means on the image forming medium using the image forming means. The processing means of

According to the image forming method of the present invention, the document placed on the document table is optically scanned using the optical means, and the image data is read by the optical scanning, and the image reading means. A step of instructing the output of a gradation data image consisting of a plurality of gradations, and an image forming means for forming the image data read by the means on an image forming medium. A step of reading out the normal gradation data for each gradation stored in the first storage means for storing the normal gradation data, and a plurality of image forming means are provided in accordance with the read gradation data. Forming a gradation data image of gradation on the image forming medium; reading the image forming medium having the gradation data image formed thereon by the image reading means;
A step of calculating correction data by comparing the read gradation data for each gradation with the regular gradation data for each gradation stored in the first storage means, each calculated gradation Storing the correction data for each of the above in the second storage means, the step of correcting the image data of the original read by the image reading means by the correction data stored in the second storage means, and this correction The image forming means comprises the step of forming an image corresponding to the image data on the image forming medium.

[0009]

According to the present invention, in the above-mentioned structure, there is provided the image reading means for optically scanning the original placed on the original table by using the optical means and reading the image data by the optical scanning. In the case where the image data read by the image reading unit is formed on the image forming medium, the normal gradation data for each gradation is stored in the first storage unit, and the gradation consisting of a plurality of gradations is stored. The output of the data image is instructed by the instructing means, the normal gradation data for each gradation stored in the first storage means is read out in response to the instruction, and the image is read out in accordance with the read out gradation data. A gradation data image of a plurality of gradations is formed on the image forming medium by the forming means, the image forming medium on which the gradation data image is formed is read by the image reading means, and the floor for each read gradation is read. Key data and above The correction data is calculated by comparing with the regular gradation data for each gradation stored in the storage means, and the calculated correction data for each gradation is stored in the second storage means. The image data read by the image reading unit is corrected by the correction data stored in the second storage unit, and the image corresponding to the corrected image data is formed on the image forming medium by the image forming unit. Is formed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a thermal transfer type color copying machine as an example of the image forming apparatus of the present invention. That is, reference numeral 1 is a main body of a copying machine, and an automatic document feeder 40 for automatically conveying an original O is mounted on the upper portion of the main body 1. A document table (transparent glass) 2 on which the document O fed by the automatic document feeder 40 is placed is provided on the upper surface of the copying machine body 1.

In the main body 1 of the copying machine, there is an original scanning section 3 for scanning and reading an original O set on an original table 2, and an image forming section 4 at the lower part. In addition, the document table 2
Is fixed to the main body 1.

The document scanning unit 3 is constructed as shown in FIG. 3, for example. That is, the first carriage 7 on which the exposure lamp 6 as a light source is installed, the second carriage 8 that bends the optical path by a mirror, the zoom lens 16, and the reflected light from the original O are guided to the photoelectric conversion unit 11, and the optical path length is changed during zooming. , A photoelectric conversion unit 11 that receives reflected light from the original O, a drive system (not shown) that changes the position of each unit, and the output of the photoelectric conversion unit 11, that is, image data is converted into analog data. Is composed of an A / D conversion unit 37 for converting the data into digital data.

The first carriage 7 has an exposure lamp 6 for irradiating the original O with light, a reflector 12 as a reflecting mirror for collecting the light from the exposure lamp 6 on the surface of the original, and a light reflected from the original O. A mirror 13 for guiding the second carriage 8 is mounted.

On the second carriage 8, a mirror 8a for guiding the light guided by the mirror 13 to the zoom lens 16,
8b is installed. The first and second carriages 7,
8 are connected to each other by a timing belt (not shown), and the second carriage 8 is 1/2 of the first carriage 7.
It is designed to move in the same direction at the speed of. As a result, scanning can be performed so that the optical path length to the zoom lens 16 is constant. The zoom lens 16
Has a fixed focal length and is moved in the optical axis direction during zooming.

The mirror unit 10 includes two mirrors 10a,
10b, the positions of the mirrors 10a and 10b are changed according to the change of the optical path length corresponding to the selected magnification, and the light from the zoom lens 16 is moved to the two mirrors 10a, By bending the optical path at 10b, the light is guided to the photoelectric conversion unit 11.

The photoelectric conversion unit 11 photoelectrically converts the reflected light from the original O, and is mainly composed of, for example, a CCD type line image sensor. In this case, one pixel of the document O corresponds to one element of the CCD sensor. The output of the photoelectric conversion unit 11 is output to the A / D conversion unit 37. The movements of the first and second carriages 7 and 8 and the mirrors 10a and 10b are performed by a stepping motor 18, respectively.

The first and second carriages 7 and 8 have a drive pulley (not shown) and an idle pulley (not shown) connected to the rotation shaft of the stepping motor 18.
It is adapted to be moved according to the operation of a timing belt (not shown) which is suspended between them.

In the zoom lens 16, a spiral shaft (not shown) is rotated by a corresponding stepping motor (not shown), and the movement of the spiral moves the zoom lens 16 in the optical axis direction.

The image forming section 4 is constructed, for example, as shown in FIG. That is, the platen drum 22 is arranged at a substantially central portion of the image forming unit 4. The periphery of the platen drum 22 is made of an elastic body such as rubber and has a function as a platen roller of the thermal head 24.

The platen drum 22 winds the paper P around itself by rotating it clockwise so that the paper P does not shift during overlay printing. Around the platen drum 22, pressure rollers 25, ... Are provided at predetermined intervals to prevent the paper P from floating above the platen drum 22. Platen drum 2
The circumference of 2 is slightly longer than the length of the maximum paper size in the longitudinal direction.

A thermal head 24 is disposed on the lower left portion of the platen drum 22. The thermal head 24 is attached to a radiator integrally formed on the rear end surface of the holder. Further, an ink ribbon 26 as an image forming medium is interposed between the platen drum 22 and the thermal head 24.

Cores 30, 31 of the ink ribbon 26
Is connected to a drive shaft of a motor (not shown) through a drive force transmission mechanism (not shown), and is rotationally driven as necessary.

At the lower part of the main body 1, a paper feed roller 3 is provided.
2 is provided so that the paper P as the image forming medium stored in the paper feed cassette 20 is taken out one by one.

The paper P taken out by the paper feed roller 32 is sent by the carrying roller 33 to the registration roller 21 disposed diagonally above and left of the carrying roller 33 to align the leading edge of the paper P, and then the registration is performed. Guide 3 by roller 21
The sheet is transported to the platen drum 22 via 4 and is wound around the platen drum 22 by the gripper 23, the pressing roller 25, ... Here, the paper feed cassette 20 is detachable from the side surface of the main body 1.

Reference numeral 36 in FIG. 2 is a manual paper feeding device for manually feeding the paper P and the like. The paper P supplied from the manual paper feeding device 36 is also wound around the platen drum 22 in the same manner as described above.

The paper P, the front end of which is fixed by the gripper 23, is rotated clockwise to cause the platen drum 2 to rotate.
After wrapping around 2, and the leading edge passing through the printing area, the thermal head 24 is pressed against the platen drum 22 and printing is performed.

When printing is completed and the paper is discharged, the platen drum 22 is rotated clockwise until the trailing edge of the paper P reaches the paper discharge guide 27, and when it reaches, the platen drum 22 is reached. Is rotated counterclockwise, and the rear end of the paper P is separated from the platen drum 22 by a separation claw (not shown) and guided to the paper discharge guide 27. Finally, the front end of the paper P is released from the gripper 23, and the paper P that has been copied by the paper ejection guide 27 is ejected onto the paper ejection tray 28.

An environmental sensor 38 for detecting environmental data corresponding to environmental conditions such as temperature and humidity is provided in the main body 1 of the copying machine. For example, the environmental sensor 38
Is composed of a temperature detector and a humidity detector.

An operation panel section 40 is provided on the front surface of the main body 1 as shown in FIG. The operation panel section 40 has a copy key 41 for instructing the start of copying.
A display unit 42 for displaying various guides, a numeric keypad 43 for setting the number of copies, a copy magnification setting unit 44 for setting a copy magnification, and a copy density setting unit 45 for setting, for example, seven types of copy density. And a mode selection key 46 input when selecting a mode, an execution key 47 for instructing execution of the mode displayed on the display unit 42 by the mode selection key 46, and the like.

For example, when the mode selection key 46 is pressed, the test mode and the γ correction data setting mode are displayed.
By pressing the enter key 47 when
The test mode or γ correction data setting mode is selected.
With the above test mode selected, press the numeric keypad 4
By inputting the number for instructing the output of the gradation chart using 3, the output of the gradation chart is instructed. Figure 1
Shows a general control system.

That is, a control section 51 for controlling the entire image forming apparatus is provided. The control unit 51 stores a control CPU 51a and a control program, and also stores a density data value for each gradation of 16 gradations used when outputting a gradation chart.
b, a working RAM 51c, and various IO interface circuits (not shown). The gradation number of the gradation chart may be 32 gradations or 64 gradations. The gradation chart is divided by the number of gradations perpendicular to the conveyance direction of the paper P, and images of different gradations are printed.

Further, the control section 51 includes an original scanning section 3, an image forming section 4, an environment sensor 38, an operation panel 40, a first image processing section 52, a γ correction section 53, and a second image processing section 54. Are connected.

The first image processing section 52 comprises a shading correction section 52a and an image memory 52b.
The shading correction unit 52a performs shading correction on the image data (digital signal) supplied from the A / D conversion unit 37 in the document scanning unit 3, that is, the variation correction of the photoelectric conversion unit 11 (white reference signal and black reference signal. Is used for normalization) and its output is supplied to the image memory 52b.

The image memory 52b stores one line or a plurality of lines of image data after the shading correction by the shading correction section 52a. The output of the image memory 52b is the γ correction unit 53 or the control unit 5
1 is supplied to the CPU 51a.

The second image processing section 54 is composed of a filtering processing section 54a and an image memory 54b. The filtering processing unit 54a performs a filtering process (modulation transfer function correction process) on the image data supplied from the γ correction unit 53 using a linear digital filter having a parameter of 3 × 3 pixels. Thus, the edge enhancement processing and the smoothing processing are performed, and the output thereof is supplied to the image memory 54b.

The image memory 54b is the image data after the filtering process or the CPU 51a in the control unit 51.
The image data for each gradation for the gradation chart, which is supplied from, is stored for one line or for a plurality of lines. The output of the image memory 54b is supplied to the image forming unit 4 or the CPU 51a in the control unit 51.

The γ correction unit 53 corrects the γ characteristic so that the output image density is equal to the input image density, and the γ characteristic is corrected as shown in FIG. IO port) 53a, 53b, γRAM
53c and the gate 53d.

Correction data is stored in the γRAM 53c for each address, and the CP in the control unit 51 is used.
The correction data supplied from the U 51a via the registers 53a and 53b is stored.

When the instruction to output the gradation chart is supplied from the operation panel 40, the CPU 51a in the control section 51 reads out the density data value for each gradation of 16 gradations from the ROM 51b, and reads out each floor. Image data for each line corresponding to the density data value for each key is sequentially output to the image memory 54b in the second image processing unit 54.

When the γ correction data setting mode is instructed from the operation panel 40, the CPU 51a in the control unit 51 reads from the gradation chart by the manuscript operation unit 3 and reads the first chart.
The correction data is calculated from the density data value as the image data stored in the image memory 52b of the image processing unit 52 and the density data value read from the ROM 51b corresponding to the reading position (scanning position) of the gradation chart. Then, the calculated correction data is stored in the γRAM 53c in the γ correction unit 53. The density data value of the gradation chart is determined by the average value of the image data of one line or the average value of the image data of a plurality of lines.

The correction data is stored in the γRAM 53c as follows.
ΓRAM 53 from the CPU 51a via the register 53a
The write address is output to the address terminal of c, and the CPU
The correction data is output from the 51a via the register 53b to the data terminal of the γRAM 53c, and the CPU 51a outputs the γ
The write data is output to the read / write terminal of the RAM 53c, so that the correction data is corrected to the γRAM 53c.
Is stored at the write address.

As a result, the γRAM 53c outputs the correction data to the second image processing unit 54 from the address corresponding to the image data supplied from the first image processing unit 52 via the gate 53d. Next, γ of this invention
The correction method will be described. The γ characteristic is the relationship between the output image density and the input image density. That is, the γ characteristic is represented by a graph in which the horizontal axis represents the input image density and the vertical axis represents the output image density. Γ in any image processing system
The characteristic exists. What γ characteristic is desirable depends on the purpose of use of each image processing system.

In the following description, assuming that the γ characteristic that the input image density and the output image density are equal to each other is required, an image processing system for copying a photograph having an intermediate density is assumed when the γ correction is performed. There is. FIG. 6 shows a γ characteristic diagram of a copying machine (image forming apparatus) as an output device of this image processing system. When the input signal of the copying machine is 0.2, the output image density is 0.4.

That is, in order to obtain the output image density of 0.4, the input signal 0.2 may be input to the copying machine. on the other hand,
Since this image processing system is required to have a γ characteristic in which the input image density and the output image density are equal, the input image density is 0.4 when the output image density is 0.4.

That is, the γ correction unit 5 as a correction circuit for obtaining the input signal 0.2 to the copying machine from the input image density 0.4.
3 is required. The correction of the input signal of the copying machine for all the input image densities is equivalent to obtaining the input signal to the copying machine which can obtain the same output image density as the input image density. Equivalent to the interchange of the relationship between the machine input signal and the output image density.

Therefore, the correction parameter is set by multiplying the input signal and output image density of the copying machine by an appropriate coefficient, for example 255, and regarding the integer part as an address value, an appropriate coefficient of the input signal is applied to the corresponding address of the RAM. Double, for example, 25
This is performed by multiplying by 5 and storing the integer part as a correction value (correction data).

In the γ correction section 53, the CPU 51a designates the address of the γRAM 53c via the register 53a, the CPU 51a designates the correction value to the data terminal of the γRAM 53c via the register 53a, and the read / write signal from the CPU 51a to the γRAM 53c. By controlling the writing by, the correction value is set in the γRAM 53c.

As a result, the image data read by the document scanning section 3 and processed by the first image processing section 52 is transferred to the gate 5
When input to the address terminal of the γRAM 53c via 3d, the correction data is output from the data terminal of the γRAM 53c and sent to the image forming unit 4 via the second image processing unit 54 to form a corresponding image. . Next, in such a configuration, the operation will be described with reference to the flowchart shown in FIG.

First, the person in charge of the adjustment is the operation panel 40.
The test mode is selected by pressing the mode selection key 46 and the execution key 47, and the ten key 43 is used to instruct the output of the gradation chart.

Then, the CPU 51a in the control unit 51
The density data value for each gradation of 16 gradations is read from the ROM 51b, and the image data in line units corresponding to the read density data value for each gradation is sequentially stored in the image memory 54b in the second image processing unit 54. It is output to the image forming unit 4 via the.

As a result, the image forming section 4 prints the density corresponding to the image data supplied from the image memory 54b by using the thermal head 24, and as shown in FIG. The image is divided into 16 areas perpendicularly to, an image with different density is printed in each area, and a gradation chart is printed out. This gradation chart includes variations in the γ characteristic of the image forming unit 4.

Next, the staff member places the gradation chart on the original table 2, selects the γ correction data setting mode by pressing the mode selection key 46 and the execution key 47 of the operation panel 40, and the copy key 41 is pressed. throw into. As a result, the control unit 5
1 starts reading the gradation chart.

That is, the reflected light of the light emitted from the exposure lamp 6 to the original O is imaged on the photoelectric conversion unit 11.
The photoelectric conversion unit 11 converts the light into an analog electric signal and sends it to the A / D conversion unit 37. The A / D conversion unit 37 converts this analog image data into digital image data, and the shading correction unit 5 in the first image processing unit 52.
2a is output.

The shading correction section 52a performs shading correction on the image data supplied from the A / D conversion section 37, that is, the variation correction of the photoelectric conversion section 11, and sends the result to the image memory 52b. The image data for one line or a plurality of lines stored in the image memory 52b is output to the CPU 51a in the control unit 51.

The CPU 51a determines the density data value of the gradation chart corresponding to the area currently being scanned based on the image data supplied from the image memory 52b, and sets the density data value and the reading position of the gradation chart. Corresponding RO
Correction data is calculated from the density data value read from M51b, and the calculated correction data is stored in the γ correction unit 53 by γ.
It is stored in the RAM 53c.

That is, the correction data is stored in the γRAM 53c from the CPU 51a via the register 53a by γ.
The write address is output to the address terminal of the RAM 53c, and the γRAM is output from the CPU 51a via the register 53b.
The correction data is output to the data terminal 53c, and the CPU 5
By outputting write data from 1a to the read / write terminal of the γRAM 53c, the correction data is corrected to γRAM.
It is stored in the write address of 53c. The above processing is performed for each area having different gradations in the gradation chart.

As a result, γ correction data corresponding to 16 gradations is set in the γRAM 53c. Therefore, the image data read by the document scanning unit 3 and processed by the first image processing unit 52 is transferred to the γ correction unit 53 via the gate 53 d in the γ correction unit 53.
When supplied to the RAM 53c, the correction data is output from the γRAM 53c and sent to the image forming unit 4 via the second image processing unit 54 to form a corresponding image.

Further, in the image processing section 54, the printing characteristics (output characteristics) are influenced by the environmental conditions such as temperature and humidity. Therefore, according to the environmental data corresponding to the environmental conditions detected by the environmental sensor 38, The γ correction data stored in the γRAM 53c may be corrected.

As described above, first, a gradation chart including variations in γ characteristics is output, the gradation chart is read, and the gradation data read from this gradation chart and the normal gradation data are read. And the correction data is calculated, the calculated correction data is stored in the γ correction unit, and the read image data for the document is corrected using the stored correction data.

As a result, it is possible to easily correct individual γ characteristic variations due to assembly variations and adjustment variations, and to set correction data as optimum parameters for each device. Further, it is possible to mass-produce a copying machine in which the γ characteristic is uniformly adjusted.

In the above embodiment, the LUT (look
Although the γ correction is performed in the up table format, the γ correction is not limited to this, and the γ correction may be performed in a format in which the γ correction characteristic is expressed by a function and the function value is obtained. Further, although the case where the thermal transfer printer is used as the image forming unit has been described, the invention can be applied to other printing type printers such as a laser printer. .

[0062]

As described above in detail, according to the present invention,
It is possible to provide an image forming apparatus capable of easily correcting individual γ characteristic variations due to assembly variations and adjustment variations and setting correction data as optimum parameters for each device.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an overall control system of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the overall configuration of the image forming apparatus shown in FIG.

FIG. 3 is a cross-sectional view schematically showing a configuration of a document scanning unit in FIG.

FIG. 4 is a diagram for explaining the configuration of the operation panel of FIG.

5 is a block diagram schematically showing a configuration of a γ correction unit in FIG.

FIG. 6 is a diagram for explaining a γ characteristic of the image forming apparatus in FIG.

7 is a flowchart for explaining an operation of setting γ correction data in a γRAM shown in FIG.

FIG. 8 is a diagram illustrating a print output example of a gradation chart.

[Explanation of symbols]

3 ... Original scanning unit, 4 ... Image forming unit, 11 ... Photoelectric conversion unit,
38 ... Environment sensor, 40 ... Operation panel section, 46 ... Mode selection key, 47 ... Execution key, 51 ... Control section, 51a ... C
PU, 52 ... First image processing unit, 53 ... γ correction unit, 53
a, 53b ... Register, 53c ... γRAM, 54 ... Second
Image processing part.

Claims (3)

[Claims] 1. An image reading unit that optically scans a document placed on a platen using an optical unit, and reads image data by the optical scanning; and image data read by the image reading unit. In an image forming apparatus having an image forming means for forming an image corresponding to the above on an image forming medium, a first storage means for storing regular gradation data for each gradation and a plurality of gradations are stored. Instructing means for instructing the output of the gradation data image, and in response to the instruction of the instructing means, the normal gradation data for each gradation stored in the first storage means is read and the read gradation is read. First processing means for forming a gradation data image of a plurality of gradations on the image forming medium by the image forming means according to the data, and an image formed with the gradation data image by the first processing means. Forming medium above Second processing means for reading by the image reading means, gradation data for each gradation read by the second processing means, and regular gradation data for each gradation stored in the first storage means. And a second storage unit that stores the correction data for each gradation calculated by the calculation unit, and the image data read by the image reading unit.
Correction means for correcting the correction data stored in the storage means, and an image corresponding to the image data corrected by the correction means is formed on the image forming medium by the image forming means. An image forming apparatus comprising: a processing unit. 2. An image reading unit that optically scans a document placed on a document table by using an optical unit, and reads image data by the optical scanning; and image data read by the image reading unit. A step of instructing the output of a gradation data image consisting of a plurality of gradations, and the normal gradation data for each gradation according to this instruction. A step of reading out the regular gradation data for each gradation stored in the first storage means for storing a plurality of gradation levels by the image forming means in accordance with the read gradation data. Forming a tone data image on the image forming medium, reading the image forming medium having the tone data image formed thereon by the image reading means, and the tone data for each read tone A step of calculating correction data by comparing the normal gradation data for each gradation stored in the first storage means, and the calculated correction data for each gradation, to the second storage means. The step of storing the image data of the original read by the image reading means by the correction data stored in the second storage means, and the image corresponding to the corrected image data An image forming method comprising: forming on the image forming medium using a forming unit; 3. An image reading unit that optically scans a document placed on a document table by using an optical unit, and reads image information by the optical scanning, and image information read by the image reading unit. In an image forming apparatus having an image forming unit for forming an image on an image forming medium, a first storage unit for storing regular gradation data for each gradation and gradation data composed of a plurality of gradations. Instructing means for instructing the output of the image, and the normal gradation data for each gradation stored in the first storage means is read in accordance with the instruction of the instructing means, and in accordance with the read gradation data. The first processing means for forming a gradation data image of a plurality of gradations on the image forming medium by the image forming means, and the image forming medium on which the gradation data image is formed by the first processing means are described above. By image reading means Comparing the gradation data for each gradation read by the second processing means with the regular gradation data for each gradation stored in the first storage means. Calculating means for calculating correction data by means of, detecting means for detecting environmental data corresponding to environmental conditions such as temperature and humidity, and correcting data for each gradation calculated by the calculating means is detected by the detecting means. Correction means for correcting with environment data, second storage means for storing the correction data corrected by the correction means, and image data read by the image reading means for the second
Correction means for correcting the correction data stored in the storage means, and an image corresponding to the image data corrected by the correction means is formed on the image forming medium by the image forming means. An image forming apparatus comprising: a processing unit.