JP2000188687A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in an image by eliminating noise in an image being input that might cause large deterioration for the image quality through an MTF filter processing applied to the image data prior to the MTF filter processing. SOLUTION: This image forming device, where an image processing section 102 applies image processing to image data received from a scanner section 201 and a printer section 207 outputs the image data after the processing as a manifest image, is provided with a noise detection section 203 that detects an image noise from the difference between a processed pixel in the input picture data and pixels to the left and right of the processed pixel and with a noise elimination section 204, that removes the image noise on the basis of the result of detection by the noise detection section 203.

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 for outputting a visualized image based on input image data, and more particularly to a copying apparatus capable of forming an image by removing noise in input image data. And an image forming apparatus such as a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art As a device having a means for removing noise in a document image, a technology disclosed in, for example, JP-A-6-35976 and JP-A-7-152908 is known. Both are configured to remove noise pixels from the image data after the MTF filter processing.

[0003]

The MTF filter processing is necessary as an emphasis processing for clearly displaying characters and the like of image data read by a scanner.
In principle, image noise will also be amplified. In particular, when the input image data is image data that is significantly different from other pixels by one pixel due to noise, the image is greatly deteriorated by the MTF filter processing.

[0004] The present invention has been made in view of such a situation of the prior art, and removes noise in an input image such that image data before MTF filtering is greatly degraded by MTF filtering. Another object of the present invention is to provide an image forming apparatus capable of performing image output while suppressing image deterioration.

[0005]

In order to achieve the above object, a first means performs image processing on image data input from an image input unit in an image processing unit, and converts the processed image data into an image. In an image forming apparatus for outputting a visual image from an output unit, an image noise detection unit for detecting image noise from a difference between a processing pixel in input image data input from the image input unit and pixels on the left and right of the processing pixel And image noise removing means for removing the image noise based on the detection result detected by the means for detecting the image noise.

[0006] With this configuration, an image noise pattern in input image data whose image quality is greatly deteriorated by the MTF filter processing is detected, and image deterioration hardly occurs even when the MTF filter processing is performed.

The second means is an image forming apparatus based on the same premise as the first means, wherein a difference between a processing pixel in input image data input from the image input section and pixels on the left and right of the processing pixel is provided. Image noise detecting means for detecting image noise from the image data, and image noise for removing image noise based on a processing pixel in the input image data, an average value of left and right pixels of the processing pixel, and a detection result of the image noise detecting means. And a removing means.

With this configuration, the image noise pattern in the input image data whose image quality is greatly deteriorated by the MTF filter processing is converted into an image data pattern which is hardly deteriorated even when the MTF filter processing is performed, thereby preventing the image deterioration.

A third means is an image forming apparatus based on the same premise as the first means, wherein the difference between the processing pixel in the input image data input from the image input unit and the left and right pixels of the processing pixel is provided. And image noise detection means for detecting image noise from the difference between the upper and lower pixels, an average value of the processing pixel in the input image data and its left and right pixels, an average value of the upper and lower pixels, and the image Image noise removing means for removing image noise based on the detection result of the noise detecting means.

With this configuration, image degradation is prevented by converting an image noise pattern in input image data whose image quality is greatly degraded by the MTF filter processing into a vertical pattern and a horizontal pattern.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same components are denoted by the same reference numerals, and redundant description will be omitted.

<First Embodiment> FIG. 1 is a block diagram schematically showing an electrical configuration of a digital copying machine according to a first embodiment, FIG. 2 is a block diagram showing details of the configuration of FIG. 1, and FIG.
FIG. 4 is a block diagram illustrating a configuration of a noise detection unit according to the first embodiment, FIG. 4 is a block diagram illustrating a configuration of a noise removal unit according to the first embodiment, and FIG. 7 is an explanatory diagram illustrating a configuration of a filter. 8 is a diagram showing a display example of the operation unit of the digital copying machine according to the first embodiment, FIG. 9 is a diagram showing a display example of the operation unit of FIG. 8 when the noise removal function is turned on, and FIG. FIG. 11 is a diagram showing a display example of an operation unit of the digital copying machine when a removal level is selected, and FIG. 11 is a schematic configuration diagram showing a mechanical configuration of the digital copying machine according to the first embodiment.

A digital copying machine as an image forming apparatus according to the first embodiment of the present invention comprises an image input unit 101, an image processing unit 102, an image output unit 103, a control unit 104, and an operation unit 105. . The image input unit 101
It corresponds to a scanner of a digital copying machine or a digital facsimile, reads a document in accordance with an instruction from the control unit 104, and sends it to the image processing unit 102 as input image data. The image processing unit 102 performs various image processing such as noise removal, filter processing, γ conversion processing, and gradation processing on the input image data, and sends the processing result to the image output unit 103. The image output unit 103 corresponds to a printer of a digital copier,
The bitmap image data after the processing is printed out on paper. The control unit 104 controls the entire apparatus when performing a copying operation. That is, the operation of the scanner is controlled with respect to the image input unit 101, and the setting of the level of noise removal, γ conversion processing, filter processing, gradation processing, and other various image processing are performed with respect to the image processing unit 102. The parameters used for the processing are set, and the operation of the printer is controlled for the image output unit 103. In addition, the operation unit 105 performs input control of display control of various information, operation mode, or level change. The operation unit 105 allows the user to set an operation mode and input an instruction to start a copy operation,
It is used for setting on / off of noise removal and setting of a noise removal level.

FIG. 2 is a block diagram showing the configuration of FIG. 1 in more detail. In this figure, the image processing unit 102
Matrix generation unit 202, noise detection unit 203, noise removal unit 204, MTF filter unit 205, γ conversion processing
The control unit 104 is composed of a CPU 209, a ROM 210, and a RAM 211, and these units are connected to an internal system bus 208.
Connected through. In FIG. 2, the image input unit 1
01 is replaced by a scanner unit 201, and the image output unit 103 is replaced by a printer unit 207.

In the above configuration, the matrix generation unit 202 performs filtering and noise detection, and the noise detection unit 20
In 3, the image noise is detected based on the difference value of the pixel data. The noise removing unit 204 removes image noise based on the image noise detected by the noise detecting unit 203. The printer unit 207 outputs the image information as a copy image. The CPU 209 controls the entire apparatus, and
In 0, static information such as a control program of the CPU 209 is stored. RAM 211 is CPU 209
, Which is used temporarily by the control program and stores dynamic information used for data processing. The system bus 208 exchanges data between the control blocks, gives an instruction such as operation mode selection, start, stop, and the like from the operation unit 212, and also shows a mode and setting state executed on the display of the operation unit 212. Is displayed.

FIG. 11 is a schematic explanatory view showing a mechanical configuration of the scanner unit 201 and the printer unit 207. The scanner unit 201 includes a contact glass 1 on which a document is placed, a pressure plate 39 for pressing the document placed on the contact glass 1,
Illumination light sources (lamp) 2a and 2b for irradiating the original from the lower surface of the contact glass 1; first to fifth mirrors 3 for guiding reflected light from the original to the CCD image sensor 9;
4, 5, 6, 7 and the imaging lens 8 and the first traveling body 1
0 and the second traveling body 11.

The scanner unit 201 having these components illuminates a document placed on the contact glass 1 and reflects light reflected from the read document on the first to fifth mirrors 3 to 7 and the imaging lens. An image is formed on the light-receiving surface of the CCD image sensor 9 via the reference numeral 8. The light sources 2a, 2b and the first mirror 3 are mounted on a first traveling body 10, the second and third mirrors 4, 5 are mounted on a second traveling body 11, and the second traveling body 1
Reference numeral 1 moves in the sub-scanning direction at half the speed of the first traveling body in conjunction with the first traveling body 10. The scanning in the main scanning direction is
This is performed by the individual scanning of the CCD image sensor 9, and the original image is read by the CCD image sensor 9. As a result, the entire document is scanned and read.

The printer unit 207 has a laser writing system,
It is composed of an image reproducing system and a paper feeding system. The laser writing system includes a laser output unit 21, an imaging lens 2
2 and a mirror 23. Laser output unit 2
1 includes a laser diode as a laser light source and a polygon mirror (polygon mirror) rotated at high speed by a motor, and a laser beam emitted from the laser diode energized based on image data is applied to the photosensitive drum 2.
4 Irradiates the surface. Around the photosensitive drum 24, a charger 25, an eraser 26, a developing unit 27,
Transfer charger 28, separation charger 29, separation claw 3
0, a cleaning unit 31 and the like are arranged.
A beam sensor (not shown) for generating a main scanning synchronization signal is provided at a position near one end of the photosensitive drum 24 where the laser beam is irradiated.

The printer section 20 constructed as described above
When image formation is performed in step 7, the image formation is performed as follows. That is, when the peripheral surface of the photosensitive drum 24 is uniformly charged to a high potential by the charging charger 25 and the peripheral surface of the photosensitive drum 24 is irradiated with the laser beam, the potential of the irradiated portion decreases. Since the laser light is on / off controlled in accordance with recording / reproducing black / white, irradiation of the laser light causes a potential distribution corresponding to the recorded image on the peripheral surface of the photosensitive drum 24,
In other words, an electrostatic latent image is formed. When the portion where the electrostatic latent image is formed passes through the developing unit 27, toner adheres according to the level of the potential, and the electrostatic latent image becomes a visualized toner image. The recording sheet 32 is fed from the cassette 33 to the portion where the toner image is formed at a predetermined timing, and overlaps the toner image. This toner image is transferred to the recording sheet 32 by the transfer charger 28, and is further separated from the photosensitive drum 24 by the separation charger 29 and the separation claw 30. The separated recording sheet 32 is transported by the transport belt 3
4, the fixing roller 35 having a built-in heater
The sheet is discharged onto the sheet discharge tray 36 after being fixed by heating.

In this embodiment, the printer unit 8 has two paper feeding systems, one of which is the upper paper feeding cassette 3.
3a and a manual feed tray 33c, both of which are fed by a feed roller 37a. The other system includes a lower paper cassette 33b, which is fed by a paper feed roller 37b. The recording sheet 32 fed from one of the paper feed rollers 37a and 37b (in the figure, denoted by reference numeral 32a in the upper paper feed cassette 33a and denoted by reference numeral 32b in the lower paper feed cassette 33b) is sent to the registration roller 38. The sheet is temporarily stopped in the contact state, and is fed to the photosensitive drum 24 at a timing synchronized with the progress of the recording process.

The details of the function of each section shown in FIG. 2 are as follows.

The image data input from the scanner unit 201 is formed into a matrix of 5 pixels × 5 lines by a matrix generation unit 202 of the image processing unit 102. The matrixed data is used by the noise detection unit 203, the noise removal unit 204, and the MTF filter processing unit 205. The noise detection unit 203 detects image noise to be removed, and sends a detection signal to the noise removal unit 204. The noise removing unit 204 removes noise of the processing pixel based on the signal from the noise detecting unit 203 and sends the processed pixel to the MTF correction filter processing unit 205. The image data from which noise has been removed is MTF
Filter processing unit 205, γ conversion processing / gradation processing unit 206
, And output as a copy in the printer unit 207.

The matrix creating section 202 creates line-delayed image data using a FIFO memory or the like in the sub-scanning direction (line direction) and flip-flop (F) in the main scanning direction (pixel direction). / F) to create a matrix by creating pixel-delayed image data. Since the matrix creation performed here is a known technique that has been conventionally performed, a detailed description thereof will be omitted.

FIG. 7A and FIG. 7B show image data that is formed into a matrix of 5 × 5. These two figures correspond to the same image data. However, when the MTF filter processing is described, it is represented as shown in FIG. 7A, and when the noise detection is described, FIG. It expresses like. Image data located at F23 in FIG.
The image data located at A in FIG. 7B is the same. Similarly, F33 and X, F43 and B, F32 and C, F
34 and D correspond respectively. Since these image data correspond to the pixels at that location, in the following description, the meaning of specifying a pixel is used both when referring to a pixel and when referring to pixel data (pixel signal) of the pixel. And the above code is used in common.

FIG. 7A shows the MTF filter processing unit 205.
A product-sum operation is performed using each of the pixels F11 to F55 in the matrix shown in FIG.
Since this process itself is a known process that has been performed conventionally, a detailed description thereof will be omitted. However, the processing of the pixel data of F33 is performed using the pixel data F33 ′ after noise removal created by the noise removing unit 204.

The noise detecting section 203 detects image noise to be removed as described above, and outputs a detection signal to the noise removing section 2.
Send to 04. Image noise is detected as image noise when the difference value between the target processing pixel and the left pixel and the difference value between the right pixel are both larger than a preset threshold. This is because if the value of the processed pixel is greatly different from that of its neighboring pixels, it is highly likely that the processed pixel is image noise, and if the MTF filter processing is performed in that state, a data pattern that causes a large image deterioration will result. is there.

FIG. 3 is a block diagram showing a detailed configuration of the noise detection unit 203. The noise detection unit 203 includes first and second difference detection units 301 and 302, first and second comparators 303 and 304, and an AND circuit 305, and is held by the matrix generation unit 202 in FIG.
The processing pixel X (FIG. 7) is selected from the matrix shown in FIG.
(A) corresponds to F33) and the pixel A on the left of the processing pixel
Noise detection is performed using (corresponding to F23) and the pixel B (corresponding to F43) on the right of the processing pixel, and whether or not the processing pixel is image noise is output to the noise removing unit 204 as a noise detection signal.

The image signal from the processing pixel X and the pixel A on the left side thereof are input to the first difference detection unit 301, and the difference value of the signal level is calculated. Here, the absolute value of the difference between the pixel X and the pixel A is obtained regardless of the magnitude of the signal level. The difference value is input to the first comparator 303 and is compared with a preset threshold value. As a result of the comparison, if the difference value is larger, “1” is output from the comparator 303.

Similarly, the image signals from the processing pixel X and the pixel B on the right thereof are input to the second difference detection unit 302, and the difference value is calculated. Also here, the absolute value of the difference between the pixel X and the pixel B is obtained regardless of the magnitude of the signal level. The difference value is input to the second comparator 304 and compared with the threshold. As a result of the comparison, if the difference value is larger, the comparator 304 outputs “1”.

The AND gate 305 outputs "1" when the comparison results from the two comparators 303 and 304 are both "1". The output of the AND gate 305 is sent to the noise removing unit 204 as a noise detection signal. The noise detection signal is "1" indicating that image noise has been detected.

The detection level of the image noise is set from the system bus 208. Again, if the level threshold is small, it is easy to recognize as image noise, and as a result, the noise removal effect becomes large.

FIG. 4 is a block diagram showing a detailed configuration of the noise removing unit 204. The noise removing unit 204 in this embodiment includes first and second adders 401 and 402,
It comprises a divider 403 and a selector 404. The first adder 401 adds the pixel signals of the pixels A and B input from the matrix generation unit 202, and the second adder 402 compares the addition result of the first adder 401 with the signal of the processing pixel X. Is added. The divider 403 divides the addition result of the second adder 402 by 3, and outputs average value data of the pixels X, A, and B. The selector 404 removes noise based on the noise detection signal 405.

When the noise removal signal is "0", no noise is detected, and the signal of the pixel X is selected and output from the selector 404. In this case, of course, noise removal is not performed. When the noise removal signal is “1”,
When noise is detected, a signal from the divider 403 is selected and output from the selector 404. Selector 4
04 is the processed pixel signal (F3
3 ′) is sent to the MTF filter processing unit 205.

The gamma correction processing and gradation processing unit 206 converts the signal input from the MTF filter processing unit 205 into the printer unit 2.
At 07, the image is converted into a signal suitable for outputting an image. The γ correction process is a conversion process for determining the density of an output image. The density characteristics are set by the CPU 2 from the density characteristics prepared in advance.
09 is selected by the system bus 20.
8 is set to the γ conversion processing of the γ conversion processing / gradation processing unit 206. In the gradation processing, the image density is divided into predetermined gradations and processed. Since the configuration and operation of the γ correction processing / gradation processing unit 206 are known, detailed description thereof will be omitted.

The operation when the image processing apparatus having the above configuration is actually used is as follows.

FIG. 8 is a diagram showing an example of a display on the operation unit. The operation unit 801 includes a liquid crystal display and a touch panel, and display and input can be performed from the operation unit 801. The image processing apparatus according to this embodiment is mounted on a copying machine as a noise removing function. The initial screen of the operation unit 801 is as shown in FIG. 8, and no function is selected. Therefore, when it is desired to remove noise, FIG.
The "noise removal" 802 function is selected from the operation screen.
In other words, the display part of “noise removal” 802 is pressed.
As a result, the display changes to a display indicating that the “noise removal” 802 function is selected as shown in FIG. "Noise removal"
When 802 is off, the noise removal control set by the system bus 208 in FIGS. 3 and 5 is “0”.
Therefore, the noise detection signal does not become “1”, and the noise removal unit 204 does not remove the noise. It should be noted that not only the “noise removal” 802 function but also “edit” 803,
Selection of “magnification” 804 and other functions is also performed by pressing a display portion of each function from the operation unit 801.

As described above, when the "noise removal" display portion is pressed to turn on the function, a noise removal level display 1001 is displayed. FIG. 10 is a display example of the noise removal selection level. Here, when the user presses “strong removal level” 1002, the level threshold value set by the system bus 208 in FIGS. 3 and 5 becomes smaller, and noise removal becomes easier. In contrast, the “removal level is low” 100
Pressing 3 increases the level threshold, making it difficult to remove noise. The removal level can be visually confirmed by a step display 1004 provided between “strong removal level” 1002 and “weak removal level” 1003.

<Second Embodiment> FIG. 5 is a block diagram showing a detailed configuration of a noise detection unit 203 according to a second embodiment.

The noise removing section 203 includes first to fourth difference detecting sections 501 to 504, first to fourth comparators 505 to 508, and an AND gate 509. In this example, the noise detection is performed by the matrix generation unit 2
02. Noise detection is performed using the processing pixel (corresponding to F33), the left pixel of the processing pixel (corresponding to F23), and the right pixel B of the processing pixel (corresponding to F34) from the matrix shown in FIG. Whether the pixel is image noise is output to the noise removing unit 204 as a noise detection signal 510.

The difference value between the processing pixel X and the pixel A on the left side is calculated by the first difference detection unit 501. Here, the absolute value of the difference between the signal levels of the pixel signal X and the pixel signal A is obtained regardless of the magnitude of the signal level. The difference value calculated by the first difference detection unit 501 is compared with a noise level threshold 511 set in advance by a first comparator 505, and when the difference value is larger, the first comparator 505 outputs “ "1" is output, otherwise "0" is output. This calculation is performed by each difference detection unit 502
To 504, the differences between the processing pixel X and the pixels B, C, and D are calculated, and the comparators 506 to
Similarly at 508, the second to fourth difference detectors 502 to 502
The output from 504 is compared with the noise elimination level threshold 511, and "1" or "0" is similarly output according to the comparison result.

The AND gate 509 is connected to the first through fourth gates.
If the outputs of the comparators 505 to 508 are both "1", "1" is output; otherwise, "0" is output. The output from the AND gate 509 is sent to the noise removing unit 204 as a noise detection signal 510. The noise detection signal is "1" indicating that image noise has been detected.

The detection level of the image noise is determined by the CPU 209.
, A level threshold is set via the system bus 208. If the level threshold is small, it is easy to recognize as image noise, and the noise removal effect increases. If the level threshold is large, it is difficult to recognize the noise as image noise, and the noise removal effect is reduced.

The noise elimination unit 204 includes the noise detection unit 20
Nozzle removal is performed based on the noise detection signal from No.3. Noise removal is performed on the processing pixel, that is, F33 in FIG. 7A and X in FIG. 7B. When the noise detection signal is “0”, no image noise is detected, so that the processed pixel is output to the MTF filter processing unit 205 without performing noise removal. When the noise removal signal is “1”, since image noise has been detected, noise removal is performed, and the processed pixels after noise removal are output to the MTF filter processing unit 205.

FIG. 6 is a block diagram showing a detailed configuration of the noise removing unit 204 according to the second embodiment. The noise removing unit 204 in this embodiment includes first to fourth adders 601, 602, 603, and 604, and a divider 60.
5 and a selector 606. First adder 604
Adds the pixel signals A and B from the matrix generation unit 202. Similarly, the second adder 602 adds the pixel signals C and D. The third adder 603 further adds the addition result of the first adder 601 and the second adder 602, and the fourth adder 604 adds the processing pixel signal X to the addition result of the third adder 603. Is added. The divider 605 divides the addition result of the adder 604 by 5, and outputs averaged data of the pixels X, A, B, C, and D. The selector 606 outputs the noise detection signal 6
07, the noise is actually removed. When the noise removal signal is “0”, no noise is detected, and the signal of the pixel X is selected and output from the selector 606. In this case, no noise removal is performed. When the noise removal signal is “1”, if the noise is detected, the signal from the divider 605 is selected and the selector 606 is selected.
Output. The output of the selector 606 is sent to the MTF filter processing unit 305 as a processed pixel signal (F33 ′) after the noise removal processing.

Note that each part not particularly described has the same configuration as that of the first embodiment.

[0046]

As described above, according to the first aspect of the present invention, the image noise is calculated from the difference between the processing pixel in the input image data input from the image input unit and the right and left pixels of the processing pixel. Image noise detecting means for detecting image noise, and image noise removing means for removing image noise based on the detection result detected by the means for detecting image noise. It is possible to provide an image forming apparatus which is less likely to cause the problem.

According to the second aspect of the present invention, there is provided image noise detecting means for detecting image noise from a difference between a processing pixel in input image data input from the image input unit and pixels on the left and right of the processing pixel. A processing pixel in the input image data, an image noise removing unit for removing image noise based on an average value of left and right pixels of the processing pixel and a detection result of the image noise detecting unit. It is possible to provide an image forming apparatus that does not easily cause image deterioration even when the processing is performed.

According to the third aspect of the present invention, image noise is determined from the difference between the processed pixel in the input image data input from the image input unit and the left and right pixels of the processed pixel and the difference between the upper and lower pixels. Image noise detection means for detecting the processing pixel in the input image data, the average value of the left and right pixels, and the average value of the upper and lower pixels, and the image noise based on the detection result of the image noise detection means Since the image forming apparatus includes the image noise removing unit that removes the image noise, it is possible to provide an image forming apparatus that does not easily cause image degradation even when the MTF filter processing is performed.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an electrical configuration of a digital copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram showing details of the configuration of FIG. 1;

FIG. 3 is a block diagram illustrating a configuration of a noise detection unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a noise removing unit according to the first embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of a noise detection unit according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a noise removing unit according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a configuration of a filter.

FIG. 8 is a diagram showing a display example of an operation unit of the digital copying machine according to the embodiment of the present invention.

9 is a diagram illustrating a display example of the operation unit in FIG. 8 when the noise removal function is turned on.

FIG. 10 is a diagram illustrating a display example of an operation unit of the digital copying machine when a noise removal level is selected.

FIG. 11 is a diagram schematically illustrating a main part of a mechanical configuration of a digital copying machine according to an embodiment of the present invention.

[Description of Signs] 101 image input unit 102 image processing unit 103 image output unit 104 control units 105 and 212 operation unit 201 scanner unit 202 matrix generation unit 203 noise detection unit 204 noise removal unit 205 MTF filter processing unit 206 γ conversion processing / Gradation processing unit 207 Printer unit 208 System bus 209 CPU

Claims (3)

[Claims] 1. An image forming apparatus that performs image processing on image data input from an image input unit in an image processing unit and outputs the processed image data as a visualized image from an image output unit. Image noise detection means for detecting image noise from the difference between the processing pixel in the input image data input from and the left and right pixels of the processing pixel; and a detection result detected by the image noise detection means. Image noise removing means for removing image noise;
An image forming apparatus comprising: 2. An image forming apparatus for performing image processing on image data input from an image input unit in an image processing unit and outputting the processed image data as a visualized image from an image output unit. Image noise detection means for detecting image noise from the difference between the processing pixel in the input image data input from and the left and right pixels of the processing pixel, the processing pixel in the input image data, the left and right of the processing pixel An image forming apparatus comprising: an image noise removing unit configured to remove image noise based on an average value of pixels and a detection result detected by the image noise detecting unit. 3. An image forming apparatus which performs image processing on image data input from an image input unit in an image processing unit and outputs the processed image data as a visible image from an image output unit. Image noise detecting means for detecting image noise from the difference between a processing pixel in input image data input from the CPU and pixels on the left and right of the processing pixel, and the difference between the processing pixel and pixels above and below the processing pixel Based on the average value of the processing pixel in the input image data and its left and right pixels, and the average value of the processing pixel and the pixels above and below the processing pixel, and a detection result detected by the detection unit. An image forming apparatus comprising: an image noise removing unit that removes image noise.