JP6641132B2 - Image forming apparatus and image processing apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus and an image processing apparatus that can reduce the consumption of a developer.

  2. Description of the Related Art In an image forming apparatus, it is required to reduce consumption of toner as a developer. Patent Literature 1 discloses a configuration in which an image having a certain area is formed with reduced exposure intensity to reduce toner consumption. Further, in the image forming apparatus, a phenomenon called sweeping of the electrostatic latent image formed on the photoconductor in which the amount of toner adhering to the rear end in the rotation direction of the photoconductor increases may occur. Reference 2 discloses a configuration for suppressing the influence of sweeping. Specifically, the correction area is determined based on the data value of the pixel and the data value of the pixel located downstream of the pixel by a predetermined amount in the sub-scanning direction. Then, a configuration is disclosed in which a pixel located upstream of a pixel in the correction region by a predetermined amount in the sub-scanning direction is further set as a correction region, and the amount of exposure to the pixel in the correction region is adjusted to suppress the influence of sweeping. . By suppressing the influence of the sweeping, the toner consumption is reduced.

  Patent Document 3 discloses a configuration in which the exposure time is shortened by pulse width modulation in order to suppress image quality deterioration due to sweeping. Further, Patent Document 4 discloses a configuration in which an exposure amount is adjusted in order to suppress image quality deterioration due to an edge effect.

JP 2004-299239 A JP 2007-272153 A JP 2003-345076 A JP 2000-343748 A

  However, in the configuration of the above document, there is a possibility that the dot reproducibility may be reduced or the image quality of a thin linear image may be reduced by adjusting the exposure amount.

  2. Description of the Related Art In recent years, there has been an increasing demand for image forming apparatuses to reduce image consumption while reducing the amount of developer consumed. Further, the image forming apparatus is also required to suppress unnecessary radiation noise (radiated electromagnetic waves).

  SUMMARY An advantage of some aspects of the invention is to provide an image forming apparatus and an image processing apparatus that reduce developer consumption while suppressing a decrease in image quality.

According to one aspect of the present invention, an image forming apparatus that forms an image based on image data includes a photoconductor, an exposure unit that exposes the photoconductor to form an electrostatic latent image, and an electrostatic latent image of the photoconductor. Developing means for developing an image with a developer to form an image; specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data; and Correcting means for correcting the exposure amount by the exposure means from the exposure amount indicated by the image data; and a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data. Holding means for holding, and detecting means for detecting state information indicating the state of the image forming apparatus , wherein the specifying means is configured to detect the state information from the plurality of first information based on the state information detected by the detecting means. The supplement Selecting a first information to use for a particular target pixel, on the basis of the selected first information to identify the correction target pixel, said correction means, said correction target pixel, the image formed by the image data The exposure amount of the correction target pixel is corrected by not exposing at least a part of the area of the correction target pixel in accordance with the distance to the edge of the correction target pixel.

  ADVANTAGE OF THE INVENTION According to this invention, the consumption of a developer can be reduced, suppressing the fall of an image quality.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 3 is an explanatory diagram of a developing method according to one embodiment. FIG. 3 is an explanatory diagram of the principle of generation of the edge effect. The figure which shows the image in which the edge effect and sweeping occurred. FIG. 4 is an explanatory diagram of the principle of occurrence of sweeping. FIG. 3 is a diagram illustrating a control configuration of an exposure amount according to an embodiment. FIG. 4 is an explanatory diagram of a control method of an exposure amount according to an embodiment. FIG. 3 is a functional block diagram of a CPU for controlling an exposure amount according to one embodiment. FIG. 4 is a diagram illustrating an image according to an embodiment. FIG. 4 is a diagram illustrating pixel values of an image according to an embodiment. FIG. 4 is a diagram illustrating correction target pixels of an image according to an embodiment. FIG. 4 is an explanatory diagram of correction for an edge effect according to one embodiment. FIG. 4 is a diagram illustrating exposure adjustment parameters according to an embodiment. FIG. 4 is a diagram illustrating a pixel exposure method according to an embodiment. 9 is a flowchart of a correction process according to an embodiment. FIG. 4 is a diagram illustrating correction target pixels of an image according to an embodiment. FIG. 4 is a diagram illustrating correction target pixels of an image according to an embodiment. FIG. 4 is a diagram illustrating exposure adjustment parameters according to an embodiment. FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 4 is an explanatory diagram of a control method of an exposure amount according to an embodiment. FIG. 3 is a functional block diagram of a CPU for controlling an exposure amount according to one embodiment. FIG. 4 is a diagram illustrating parameters according to an embodiment. FIG. 2 is a diagram illustrating an image, a pixel value of the image, and a correction target pixel of the image according to the embodiment. FIG. 4 is a diagram illustrating a pixel exposure method according to an embodiment. 9 is a flowchart of a correction process according to an embodiment. FIG. 4 is a diagram illustrating correction target pixels of an image according to an embodiment. FIG. 3 is a functional block diagram of a CPU for controlling an exposure amount according to one embodiment. FIG. 4 is a diagram illustrating a pixel exposure method according to an embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The following embodiment is an exemplification, and the present invention is not limited to the content of the embodiment. In the following drawings, components not necessary for the description of the embodiment are omitted from the drawings.

<First embodiment>
FIG. 1 is a configuration diagram of the image forming apparatus 101 according to the present embodiment. The photoreceptor 1, which is an image carrier, is rotated in the direction of the arrow in FIG. The charging unit 2 charges the surface of the photoconductor 1 to a uniform potential. The exposing unit 7 forms an electrostatic latent image on the photoconductor 1 by exposing the charged surface of the photoconductor 1 with light based on image data. The exposure unit 7 is driven by a drive signal 71 output from the image calculation unit 9. The exposure control unit 19 of the image calculation unit 9 adjusts the exposure intensity by the exposure unit 7 to a target value by the voltage Va.

  The developing unit 3 includes a container 13 for storing a toner as a developer, and a developing roller 14. The toner may be a non-magnetic one-component toner, a two-component toner, or a magnetic toner. The regulating blade 15 is provided to regulate the layer thickness of the toner supplied to the developing roller 14 to a predetermined value. The regulating blade 15 can also be configured to apply a charge to the toner. By the developing roller 14, the toner is transported to the developing area 16. The developing region 16 is a region where the developing roller 14 and the photoconductor 1 are close to or in contact with each other, and a region where toner is adhered to the electrostatic latent image. The developing unit 3 applies toner to the electrostatic latent image formed on the photoconductor 1 and visualizes the electrostatic latent image as a toner image. The transfer unit 4 transfers the toner image formed on the photoconductor 1 to the recording material P. The fixing unit 6 applies heat and pressure to the recording material P to fix the toner image transferred to the recording material P to the recording material P.

  The CPU 10 of the image calculation unit 9 is a control unit that controls the entire image forming apparatus 101 as a whole. Note that not only a configuration in which all of the control described below is executed by the CPU 10 but also a configuration in which a part of the control is executed by the ASIC 18 can be adopted. Further, a configuration in which the ASIC 18 executes all of the control described below may be employed. The memory 11 is a holding unit that stores the image data and holds the LUT 112. The LUT 112 is a look-up table, and includes a correction width parameter and an exposure amount adjustment parameter described later. The image calculation unit 9 receives the image data transmitted from the host computer 8 and suppresses the effects of the edge effect and sweeping-out based on the correction width parameter and the exposure adjustment parameter held by the LUT 112, thereby reducing the toner consumption. The image data is corrected as described above.

  Next, a developing method in the developing unit 3 will be described with reference to FIG. FIG. 2A shows a configuration using a jumping development method. In the jumping development method, a gap 17 having a predetermined distance is provided without making the developing roller 14 and the photoconductor 1 contact. Then, as a developing bias output from the developing roller 14, an AC bias on which a DC bias is superimposed is used. FIG. 2B shows a configuration in a contact development system. In the contact method, the developing roller 14 and the photoconductor 1 are brought into contact. Then, a DC bias is used as a developing bias output from the developing roller 14. In the contact development method, for example, the rotation directions of the photoconductor 1 and the development roller 14 are opposite to each other as shown in FIG. 2B, that is, in the development region 16, the respective surfaces move in the same direction. It can be configured as follows.

  Next, an edge effect in which the amount of toner adhering to the electrostatic latent image increases in an edge portion and a principle of occurrence of sweeping will be described. The edge effect means that an electric field is concentrated on an electrostatic latent image formed on the photoreceptor 1, that is, a boundary between an exposed area and a non-exposed area, so that toner is applied to each edge of the electrostatic latent image. This is a phenomenon of excessive adhesion. For example, it is assumed that an image to be formed has a uniform density. As shown in FIG. 3, the lines of electric force from the non-exposure areas 301 and 302 around the exposure area 300 wrap around the edge of the exposure area 300, and the electric field intensity at the edge is stronger than the other areas of the exposure area 300. Become. Therefore, more toner adheres to the edge of the exposure area 300 than in other areas.

  FIG. 4A shows a toner image 400 in which an edge effect has occurred. The arrow A in FIG. 4A indicates the direction in which the toner image is conveyed, that is, the direction in which the photoconductor 1 rotates. The image data on which the toner image 400 is based has the same value for all pixels, that is, the toner image 400 is an image having a uniform density. When the edge effect occurs, the toner concentrates and adheres to all edge regions 402a of the toner image 400. As a result, the density of the edge region 402a becomes higher than the density of the non-edge region 401a. The edge effect mainly occurs in a jumping developing method in which there is a gap between the photoconductor 1 and the developing roller 14.

  On the other hand, sweeping is a phenomenon in which toner concentrates on the rear end of the toner image in the rotation direction of the photoconductor 1. In the contact developing method, the peripheral speed of the developing roller 14 is set higher than the peripheral speed of the photoconductor 1 in order to set the toner thickness of the photoconductor 1 to a predetermined value. As shown in FIGS. 5A to 5C, in the developing area 16, the electrostatic latent image is developed by the toner conveyed by the developing roller 14. In FIG. 5, the toner is indicated by a circle. Since the developing roller 14 is rotating at a speed higher than that of the photoconductor 1, the positional relationship between the two on the surfaces is constantly shifted. As shown in FIG. 5A, at the time when the rear end of the electrostatic latent image 600 has entered the developing area 16, the toner on the developing roller 14 is located behind the start position of the developing area 16 in the rotation direction. Located in. However, since the rotation speed of the developing roller 14 is faster than the rotation speed of the photoconductor 1, as shown in FIG. The toner passes the rear end of the electrostatic latent image 600. Then, as shown in FIG. 5C, since the toner of the developing roller 14 is supplied to the rear end of the electrostatic latent image 600, the amount of toner adhering to the rear end of the electrostatic latent image increases. This is the mechanism of occurrence of sweeping.

  FIG. 4B shows a toner image 410 in which sweeping has occurred. The arrow A in FIG. 4B indicates the direction in which the toner image is transported, that is, the direction in which the photoconductor 1 rotates. The image data on which the toner image 410 is based has the same value for all pixels, that is, the toner image 410 is an image having a uniform density. When sweeping occurs, the toner concentrates and adheres to the rear end region 402b of the toner image 410. As a result, the density of the rear end region 402b becomes higher than the density of the other region 401b.

  FIG. 6 shows a control configuration of the exposure unit 7. The exposure control unit 19 includes an IC 2003 including an 8-bit DA converter (DAC) 2021 and a regulator (REG) 2022. The IC 2003 adjusts the voltage VrefH output by the regulator 2022 based on the intensity adjustment signal 73 set by the CPU 10. The voltage VrefH becomes a reference voltage of the DA converter 2021. When the IC 2003 sets the input data 2020 of the DA converter 2021, the DA converter 2021 outputs the voltage Va to the exposure unit 7. The VI conversion circuit 2306 of the exposure unit 7 converts the voltage Va into a current value Id and outputs the current value Id to the driver IC 2009. The driver IC 2009 controls the exposure intensity of the exposure unit 7 based on the current value Id. That is, the exposure control unit 19 can control the exposure intensity of the exposure unit 7 by the voltage Va. Further, the driver IC 2009 switches the switch (SW) of the driver IC 2009 in accordance with the drive signal 71 output from the image calculation unit 9. The SW controls ON / OFF of the light emission of the LD by switching between flowing the current IL to the laser diode (LD) of the exposure unit 7 and flowing the current IL to the dummy resistor R1.

  Subsequently, a method of controlling the exposure amount of the pixel will be described. FIG. 7A shows a state in which all regions of one pixel are exposed at an intensity of 100% with respect to a predetermined target intensity. FIGS. 7B and 7C show pixels having approximately half the density of the pixels in FIG. 7A. The pixel in FIG. 7B is formed by exposing the entire area of one pixel at 50% of the target intensity. Note that the exposure intensity is controlled by the voltage Va output from the exposure control unit 19 to the exposure unit 7 as described with reference to FIG. In FIG. 7C, one pixel is divided into N (N is a natural number of 2 or more) subpixels, and the subpixels are formed by exposing every other subpixel at an intensity of 100% of the target intensity. Things. This is realized by setting the voltage Va so that the exposure intensity becomes the target intensity and turning ON / OFF the SW by the drive signal 71 in the control configuration of FIG. In this case, the drive signal 71 is a PWM (pulse width modulation) signal.

  FIG. 8 shows functional blocks of the CPU 10 for suppressing the edge effect. In the present embodiment, the CPU 10 performs the processing for suppressing the edge effect. However, as described above, the CPU 10 may perform the processing together with the ASIC 18 or may perform the processing using only the ASIC 18. The parameter setting unit 902 notifies and sets the correction width parameter of the LUT 112 to the image analysis unit 901. Further, the parameter setting unit 902 notifies and sets the exposure adjustment parameter of the LUT 112 to the exposure adjustment unit 903. The image data 904 transmitted from the host computer 8 is stored in the memory 11 shown in FIG. Based on the correction width parameter, the image analysis unit 901 specifies a pixel where an edge effect can occur from the pixels of the image formed by the image data 904, and notifies the specified pixel to the exposure adjustment unit 903. That is, the image analysis unit 901 functions as a specification unit of a correction target pixel. The exposure adjustment unit 903 corrects the pixel value of the pixel specified by the image analysis unit 901 based on the exposure adjustment parameter, and generates corrected image data. That is, the exposure adjustment unit 903 functions as an exposure correction unit. The exposure unit 7 is controlled by the corrected image data. Note that the correction width parameter is information indicating a range of pixels in which an edge effect can occur by a distance from the edge, in this example, the number of pixels from the edge. For example, if the correction width parameter is “5”, it is determined that an edge effect occurs in five pixels on the edge side. The correction width parameter is a width required for correcting the generated edge effect, and may be any value that is the same as or close to the generation width of the edge effect. In the present embodiment, when the number of pixels having a width in a certain direction is smaller than the value of the correction width parameter, the pixel to be corrected is not specified in the direction. Further, the correction width parameter and the exposure amount adjustment parameter are obtained in advance by experiments and simulations. As described with reference to FIGS. 7B and 7C, the method of adjusting the exposure amount of the pixel is different from the method of adjusting the exposure intensity, and the method of adjusting the exposure intensity by using the PWM signal without changing the exposure intensity. There is a method of changing the number of pixels. After changing the exposure intensity, the number of sub-pixels to be exposed by the PWM signal may be changed.

  Next, processing in the image analysis unit 901 will be described. Note that the correction width parameter is “5”. FIG. 9A shows an image formed by the image data 904. The image has three image areas 1801, 1802, 1803 where toner is used. FIGS. 10A and 10B show the pixel values of the image areas 1801 and 1802. Note that FIG. 10C illustrates a central portion of the image area 1803 in a direction orthogonal to the toner image transport direction (arrow A in the figure). Note that the pixel value “255” is black. FIGS. 11A to 11C each show a pixel in which an edge effect occurs, that is, a pixel specified as a correction target pixel of the exposure amount, by the image analysis unit 901. Note that a value “0” in FIGS. 11A to 11C indicates a pixel that is not a correction target, and a pixel having a value other than “0” indicates a correction target pixel. The value of the correction target pixel indicates the distance from the edge. In the present embodiment, the correction amount of the exposure amount is changed according to the distance from the edge.

  As shown in FIGS. 10B and 11B, the width of the image area 1802 in the rotation direction (sub-scanning direction) of the photoconductor 1 is 3 pixels, which is smaller than the correction width parameter. In this case, in the image area 1802, it is not determined whether or not pixels along the rotation direction from the edge in the rotation direction are to be corrected. However, since the width of the image area 1802 in the direction (main scanning direction) orthogonal to the rotation direction of the photoconductor 1 is 16 pixels, it is determined whether or not the orthogonal direction is a correction target. Therefore, as for the image area 1802, as shown in FIG. 11B, five pixels from each edge in the direction orthogonal to the rotation direction are pixels to be corrected. As shown in FIGS. 10A and 11A, for a pixel having a plurality of edges within the correction width parameter, correction is performed based on the distance from the closest edge. Although the direction orthogonal to the rotation direction of the photoconductor 1 has been described as a correction target here, when the width in the rotation direction is smaller than the correction width parameter, the direction orthogonal to the rotation direction may be excluded from the correction target. The same applies to the case where the number of pixels in the rotation direction and the number of pixels in the direction orthogonal to the rotation direction are opposite to those in FIG.

  Next, the correction of the exposure amount will be described. FIG. 12A shows the height of the toner on a cross section of the image area 1801 where the edge effect has occurred. In addition, the height of the toner of the pixel where the edge effect does not occur is normalized as 1. As shown in FIG. 12A, the height of the toner of the pixel at the end is smaller than 1. FIG. 12B shows a reduction ratio of the toner height when the height of the toner of all the pixels is set to one. On the other hand, FIG. 12C shows the reduction ratio when the correction of the toner height is not performed for the pixels at the end portions. In FIG. 12C, the exposure amount of the correction target pixel is set to be the same or reduced. FIG. 13A shows exposure amount adjustment parameters corresponding to FIGS. 12B and 12C. As shown in FIG. 13A, the exposure amount adjustment parameter is information indicating a correction amount of the exposure amount, that is, a correction amount of the pixel value, for adjusting the height of the toner. Note that the exposure intensity in FIG. 13A corresponds to the method of adjusting the exposure amount according to the exposure intensity as described in FIG. 7B, and the PWM is as described in FIG. 7C. This corresponds to a method of adjusting the exposure amount by PWM. FIG. 14A shows the sub-pixels to be exposed of the pixel having the pixel value “255” for each distance from the edge when adjusting the exposure amount by PWM. In FIG. 14A, the sub-pixel to be exposed at each distance is turned on and off, but the off period may be continuous.

  FIG. 12D shows the toner height at a cross section of the image area 1803 where the edge effect has occurred. Note that as shown in FIG. 11C, in the image area 1803, an edge effect occurs in all pixels. Further, the height of the toner of the pixel at the end is smaller than 1. FIG. 12E shows a reduction ratio of the height when the height of the toner of all the pixels is set to one. FIG. 12F shows the reduction ratio when the height of the toner of the pixel at the end is not corrected. FIG. 13B shows exposure amount adjustment parameters corresponding to FIGS. 12E and 12F.

  The exposure adjustment unit 903 corrects the pixel value (exposure) for each correction target pixel according to the exposure adjustment parameters shown in FIGS. Then, the image calculation unit 9 controls the exposure unit 7 based on the corrected pixel value.

  FIG. 15 is a flowchart of the exposure correction processing executed by the CPU 10. In S10, the CPU 10 acquires the correction width parameter and the exposure adjustment parameter indicated by the LUT 112. In S11, the CPU 10 specifies a correction target pixel in the image data based on the correction width parameter. In S12, the CPU 10 corrects the pixel value of the correction target pixel based on the exposure adjustment parameter. In this specification, the term “correction” includes a case where no correction is made as a result.

  Next, a method for suppressing the influence of sweeping will be described. The suppression of sweeping is the same as the edge effect except that the pixels in which sweeping occurs are the number of pixels indicated by the correction width parameter from the rear end of the toner image. FIGS. 16A to 16C show correction target pixels in the image areas 1801, 1802, and 1803 in FIG. 9A, respectively. In this example, the correction width parameter is set to "5". As shown in FIG. 16B, since the number of pixels in the rotation direction of the photoconductor 1 in the image area 1802 is smaller than the correction width parameter, all the pixels in the image area 1802 are not to be corrected. Further, when the number of pixels in a direction orthogonal to the rotation direction of the photoconductor 1 is shorter than a certain width, even if the number of pixels in the rotation direction is longer than the correction width parameter, the pixel may be excluded from the correction target.

  As described above, based on the correction width parameter, the pixel in which the effect of the edge effect or the sweeping effect is specified is specified as the correction target pixel. Then, for the correction target pixel, the exposure amount is corrected according to the distance from the edge. Note that the correction of the exposure amount includes a case where the correction is not performed as a result. With this configuration, it is possible to adjust the exposure amount of the pixel to which the toner excessively adheres due to the edge effect or sweeping. Further, since the exposure amount is not unnecessarily reduced, it is possible to suppress a decrease in dot reproducibility and a decrease in image quality of a thin linear image. In particular, when the width of the image is smaller than the correction width parameter, the determination of the correction target pixel is not performed in the width direction. In this way, it is determined whether or not the exposure amount is to be corrected according to the width of the image in the main scanning direction or the sub-scanning direction. As a result, it is possible to further suppress a decrease in dot reproducibility and a decrease in image quality of a thin linear image. Further, by preventing the toner from excessively adhering, the amount of toner consumption can be suppressed. In the present embodiment, if the width of an image in a certain direction is smaller than the value indicated by the correction width parameter, it is not determined whether or not the image is a correction target pixel in that direction. However, a predetermined value is set separately from the correction width parameter, and if the width in a certain direction of the image is smaller than the predetermined value, it is not determined whether or not the image is a correction target pixel in that direction. You can also.

<Second embodiment>
In the first embodiment, when the width in a certain direction is smaller than the correction width parameter, the correction target pixel determination process is not performed in the direction. In the present embodiment, the pixel to be corrected is determined even in such a case. Hereinafter, the present embodiment will be described focusing on differences from the first embodiment.

  FIG. 9B shows an image formed by the image data 904. The image has three image areas 1601, 1602, and 1603 where toner is used. Note that the pixel values of all the pixels in each image area are “255”. Further, the correction width parameter is set to “5”. FIGS. 17A to 17C each show a pixel in which an edge effect can occur, that is, a pixel specified as a correction target pixel of the exposure amount, by the image analysis unit 901. FIGS. 17A to 17C respectively show the extracted portions of the regions 1601a, 1601b, and 1601c in FIG. 9B. In the region 1601a, the width of the photoconductor 1 in the rotation direction is one pixel, and therefore, the distance from the edge is 1 in all cases. In the region 1601b, the width of the photoconductor 1 in the rotation direction is 3 pixels, and therefore, the distance from the edge of the pixel at the end in the rotation direction is 1 and the distance from the edge of the pixel at the center in the rotation direction is 2. . In the area 1601c, the distance from each edge in the rotation direction is set.

  FIG. 18 shows the exposure adjustment parameters according to the present embodiment. Unlike the first embodiment, in the present embodiment, no correction is performed for pixels whose distance from the edge is equal to or less than a predetermined value. In this example, the predetermined value is 2. In the present embodiment, the correction target pixels are set within 5 pixels from the edge, and the exposure amount is not adjusted for the distances 1 and 2 from the edge in the exposure amount adjustment parameter. However, a configuration may be adopted in which “3” and “5” are set in the correction width parameter, and pixels whose distance from the edge is 3 pixels or more and 5 pixels or less are set as correction target pixels. In such a configuration, the correction target pixel is a pixel for which the exposure amount is adjusted. When PWM is used, the correction target pixel is a pixel that reduces the exposure amount. FIG. 14B shows the sub-pixels to be exposed of the pixel having the pixel value “255” for each distance from the edge when the exposure amount is adjusted by PWM. In FIG. 14B, the sub-pixel to be exposed at each distance is turned on and off, but the off period may be continuous.

  In the present embodiment, as shown in FIG. 18, pixels whose distance from the edge is equal to or less than a predetermined value are excluded from correction. With this configuration, it is possible to suppress a decrease in dot reproducibility and a decrease in image quality of a thin linear image.

  The above embodiments have been described using the image forming apparatus 101. However, the present invention can also be realized as an image processing apparatus that supplies corrected image data to the image forming apparatus. The image processing apparatus has the image calculation unit 9 shown in FIG. 1, and adjusts the exposure amount as described above to generate corrected image data. The image calculation unit 9 of the image processing device functions as an output unit that outputs the generated image data to the image forming apparatus instead of the exposure unit 7. Then, the exposure unit 7 of the image forming apparatus exposes the photoconductor 1 with the corrected exposure amount based on the corrected image data.

<Third embodiment>
Subsequently, a third embodiment will be described. FIG. 19 is a configuration diagram of the image forming apparatus 101 according to the present embodiment. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The detection unit 12 detects state information indicating the state of the image forming apparatus 101 and notifies the CPU 10 of the state information. The status information includes, for example, environment information or usage status information, or both of them. The environment information is information indicating an environment of the image forming apparatus, such as an environmental temperature and an environmental humidity. The use state information is information indicating the degree of deterioration due to the use of the image forming apparatus 101, such as the number of images formed, the cumulative operating time of the image forming apparatus 101, the surface resistance value of the photoconductor 1, and the like.

  Subsequently, a method of adjusting the exposure amount of one pixel in the present embodiment will be described. First, in the present embodiment, the exposure intensity is fixed at a predetermined value, and one pixel is divided into N sub-pixels, and then the number of sub-pixels to be exposed at the predetermined value and the number of non-exposed sub-pixels are changed. Adjust the exposure amount of one pixel. FIG. 20 shows pixels in which the exposure amount is 75%. Note that the exposure amount of 100% is the exposure amount when all the sub-pixels of one pixel are exposed at a predetermined exposure intensity. In FIG. 20D, N = 4, and in other cases, N = 8. When exposing the sub-pixel, the SW in FIG. 6 is turned on, and when not exposing, the SW in FIG. 6 is turned off. That is, in the present embodiment, the drive signal 71 output from the image calculation unit 9 to the exposure unit 7 is a PWM signal.

  FIG. 21 shows functional blocks of the CPU 10 for suppressing the edge effect. In the present embodiment, the CPU 10 performs the processing for suppressing the edge effect. However, as described above, the CPU 10 may perform the processing together with the ASIC 18 or may perform the processing using only the ASIC 18.

  The state detection unit 610 receives the state information detected by the detection unit 12 and outputs the state information to the parameter setting unit 602. The parameter setting unit 602 notifies and sets the correction width parameter corresponding to the received state information to the image analysis unit 601 among the correction width parameters of the LUT 112 based on the state information. Also, the parameter setting unit 602 notifies and sets the exposure adjustment parameter corresponding to the received state information to the exposure adjustment unit 603 among the exposure adjustment parameters of the LUT 112. The image data 604 transmitted from the host computer 8 is stored in the memory 11. The image analysis unit 601 specifies a pixel where an edge effect can occur from the pixels of the image formed by the image data 604 based on the correction width parameter, and notifies the specified pixel to the exposure adjustment unit 603. Here, the image means an area where toner adheres, and the image analysis unit 601 specifies a pixel where an edge effect can occur in the area from the edge of the area where toner adheres. The exposure adjustment unit 603 corrects the pixel value of the pixel specified by the image analysis unit 601 based on the exposure adjustment parameter, and drives the exposure unit 7 using the corrected image data. The correction width parameter indicates a range of pixels in which an edge effect can occur by the number of pixels from an edge pixel. For example, if the correction width parameter is “5”, it is determined that the edge effect is generated in the five pixels on the edge side of the area to which the toner adheres. The exposure adjustment parameter indicates a correction amount of the exposure of the correction target pixel. For example, in the present embodiment, the reduction ratio of the exposure amount is indicated, but any other value can be used.

  FIGS. 22A to 22C show an example of the LUT 112. In this example, FIG. 22B shows an LUT 112 used when both the temperature and the humidity included in the state information are higher than the reference range. FIG. 22C shows an LUT 112 used when both the temperature and the humidity included in the state information are lower than the reference range. FIG. 22A shows an LUT 112 used in other cases. In the present embodiment, it is assumed that there is an LUT 112 corresponding to any combination of temperature and humidity. However, if there is a combination of temperature and humidity that does not need to be corrected, the LUT 112 corresponding to those combinations is used. It is not necessary to provide.

  The conditions 1 to 4 in FIGS. 22A to 22C are obtained by evaluating the use state of the image forming apparatus 101 in four steps. In this example, it is assumed that the degree of deterioration of the image forming apparatus 101 is advanced in the order of conditions 1 to 4. For example, it is assumed that the cumulative number of formed images is used as the use state information. If the cumulative number of image formation is from 0 to 1000, condition 1 is used, and if the cumulative image formation is from 1001 to 2000, condition 2 is used. Further, if the cumulative number of image formations is from 2001 to 3000, condition 3 is used, and if the cumulative number of image formations is 3001 or more, condition 4 is used. For example, if the state information notified by the detection unit 12 is higher than the reference range in both temperature and humidity and the cumulative number of image formation is 2500 sheets, the parameter setting unit 602 sets the condition 3 of the LUT 112 in FIG. Is determined to be used. In this case, the parameter setting unit 602 sets three pixels in the image analysis unit 601 as a correction width parameter, and sets a 30% reduction in the exposure amount adjustment unit 603 as an exposure amount adjustment parameter. Note that "-" in condition 4 in FIG. 22B indicates that the exposure amount is not corrected.

  FIG. 23A shows an image formed by the image data 604, and FIG. 23B shows image data 604 forming the image of FIG. 23A. For example, assuming that the correction width parameter is “2”, the image analysis unit 601 sets a pixel whose distance from the edge of the image is within 2 pixels as a correction target pixel. FIG. 23C shows a pixel to be corrected when the correction width parameter is “2” in the image data of FIG. 23B, and a pixel that is not a correction target by 0.

  The exposure adjustment unit 603 corrects the pixel value of the correction target pixel using the exposure adjustment parameter, and thereby adjusts the exposure. FIG. 24A shows an example of the exposure state when all the exposure amounts of four consecutive correction target pixels are 75%. In FIG. 24A, only the pattern of FIG. 20A is used. When exposure is performed as shown in FIG. 24A, a non-exposed sub-pixel becomes a repetitive pattern generated every three pixels and every five pixels. If the exposure pattern as shown in FIG. 24A, more specifically, the exposure pattern of a plurality of correction target pixels has periodicity, the possibility of occurrence of unnecessary radiation noise increases. In other words, unnecessary radiation noise may be generated when pixels with the same exposure amount continue by adjusting the exposure amount. Therefore, in the present embodiment, as shown in FIG. 24B, the exposure pattern does not have periodicity. In FIG. 24B, the exposure patterns shown in FIGS. 20A, 20B, 20C, and 20D are used, respectively. If the number of consecutive correction target pixels having the same exposure amount is smaller than a predetermined number, the influence of unnecessary radiation noise is limited. A configuration in which the exposure pattern of the pixel is changed may be employed. Although the description of FIGS. 24A and 24B is for the main scanning direction, the same applies to the sub-scanning direction.

  FIG. 25 is a flowchart of the exposure adjustment processing according to the present embodiment. The CPU 10 receives the state information detected by the detection unit 12 in S20. In S21, the CPU 10 determines whether or not the exposure amount needs to be adjusted based on the state information. If the adjustment of the exposure amount is not necessary, the process proceeds to S27, where an image is formed based on the image data. On the other hand, if the exposure amount needs to be adjusted, the CPU 10 determines the one to be used from the correction width parameter and the exposure amount adjustment parameter indicated in the LUT 112 in S22. Thereafter, the CPU 10 determines the correction target pixel based on the correction width parameter in S23, and adjusts the exposure of the correction target pixel based on the exposure adjustment parameter in S24. Thereafter, in S25, the CPU 10 determines whether or not the exposure pattern needs to be adjusted. This is determined based on whether or not the exposure pattern of the correction target pixel exposed with the PWM signal has periodicity. In addition, for the correction target pixel, the determination can be made based on whether or not pixels having the same exposure amount after correction are continuous. If there is no need for adjustment, the CPU 10 forms an image in S27. On the other hand, when the exposure pattern needs to be adjusted, the exposure pattern of the pixel to be corrected is determined in S26, and an image is formed in S27. For example, when the pixels having the same exposure amount after correction are consecutive for the correction target pixel, the CPU 10 sets the exposure pattern of at least one correction target pixel to be different from the exposure pattern of the other correction target pixels. Determine the exposure pattern. Further, regardless of the exposure amount of the correction target pixel, the CPU 10 can determine the exposure pattern so that the exposure pattern at the corrected exposure amount of the correction target pixel does not have periodicity. The correction amount of the exposure in the exposure pattern determined so that the periodicity does not occur is the same as the correction amount of the exposure in the exposure pattern in which the periodicity occurs. That is, even if the exposure pattern is changed, the amount of toner reduction is the same. After forming an image in S27, the CPU 10 determines whether or not printing has been completed in S28, and if not completed, repeats the processing from S20.

  Note that, unlike the edge effect, the sweeping occurs only on the rear end side of the image in the rotation direction of the photoconductor 1, and therefore, when correcting the sweeping, correction is performed based on the distance from the rear end edge in the rotation direction. The target pixel will be determined. FIG. 26 shows correction target pixels in the case of correcting sweeping of the image data of FIG. The correction width parameter is set to two pixels.

  According to the present embodiment, when adjusting or decreasing the exposure amount of a pixel which may cause an edge effect or sweeping out of a plurality of pixels constituting the image data, the exposure amount is set so that the exposure pattern becomes non-periodic. Is corrected. This reduces the edge effect or sweeping of the developer while suppressing noise. Therefore, excessive consumption of toner is suppressed. In addition, since the exposure pattern is adjusted so as not to have periodicity, deterioration in image quality is also suppressed.

  Note that if the period during which control is performed so that periodicity does not occur, that is, the period during which periodicity is determined is made longer, the effect of suppressing unnecessary radiation noise increases. However, for that purpose, it is necessary to increase the types of exposure patterns for each exposure amount of one pixel, and to extend the period for storing the exposure patterns of the used pixels. This leads to an increase in the required amount of memory. Therefore, in consideration of the amount of unwanted radiation noise to be suppressed, the periodicity can be controlled from a period of about several pixels to a period of about several seconds.

  For example, as an example, a configuration in which two exposure patterns are alternately switched can be adopted. In addition, the influence of the unnecessary radiation noise is limited within a predetermined period, so that the same exposure pattern can be used within the predetermined period. For example, the predetermined period is set to 100 milliseconds. In this case, the exposure adjustment unit 603 uses the same exposure pattern for 100 milliseconds even if pixels with the same exposure continue. If the exposure time exceeds 100 milliseconds, an exposure pattern of a pixel different from the previous exposure pattern can be used in the next 100 milliseconds even if pixels having the same exposure amount continue. In addition, a counter is provided to count the number of times the same exposure pattern as that of the adjacent pixel is used, and the exposure pattern is changed if pixels of the same exposure amount continue to be formed even when the count value of the counter reaches a threshold value. You can also. For example, the effect of suppressing unnecessary radiation noise can be increased by setting the threshold value to a small value such as 2 and increasing the counting period to 1 second. Further, the period for determining the periodicity is not limited to the period of the image data corresponding to the recording material for each sheet. In other words, it is also possible to adopt a configuration in which it is determined whether or not the periodicity has occurred across the image data corresponding to the plurality of recording materials. For example, in an image forming apparatus capable of printing 60 or more sheets per minute, if the counting period is set to 1 second or longer in a configuration using a counter, the periodicity is determined in a period over two continuous recording materials. Done.

<Fourth embodiment>
Subsequently, the fourth embodiment will be described focusing on differences from the third embodiment. In the third embodiment, the exposure intensity of one pixel is adjusted by setting the exposure intensity to a predetermined intensity and changing the ratio of sub-pixels to be exposed. In this embodiment, the exposure intensity is also changed. FIG. 27 is a functional block diagram of the CPU 10 according to the present embodiment. In the present embodiment, the exposure adjustment section 603 notifies the exposure control section 19 of the exposure intensity by a signal 7a. The exposure control unit 19 sets the voltage Va to be output to the exposure unit 7 so as to have the exposure intensity notified by the signal 7a.

  FIGS. 28 (A) to 28 (C) show pixels that have been exposed so as to have an exposure amount of 75%. The predetermined exposure intensity is defined as 100%, and the case where the entire region of the pixel is exposed with 100% intensity is defined as 100% exposure. FIGS. 28 (D) to 28 (F) show exposure methods for the pixels of FIGS. 28 (A) to 28 (C), respectively. As shown in FIG. 28D, the pixels in FIG. 28A are obtained by exposing all the sub-pixels at an exposure intensity of 75%. Further, as shown in FIG. 28 (E), the pixel in FIG. 28 (B) is obtained by exposing half of the sub-pixels at an exposure intensity of 50% and exposing the other half of the sub-pixels at an exposure intensity of 100%. It is. As shown in FIG. 28 (F), the pixel of FIG. 28 (C) also exposes half of the sub-pixels with 50% exposure intensity and the other half of the sub-pixels similarly to the pixel of FIG. 28 (B). Was exposed at an exposure intensity of 100%. However, in FIGS. 28B and 28C, the exposure patterns of the pixels, that is, the sub-pixels to be exposed are different. As described above, similarly to the third embodiment, there are a plurality of exposure patterns of pixels having the same exposure amount even when the exposure intensity is changed. Can be suppressed.

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

  1: photoreceptor, 7: exposure unit, 3: development unit, 901: image analysis unit, 903: exposure amount adjustment unit

Claims (29)

An image forming apparatus that forms an image based on image data,
A photoreceptor,
Exposure means for exposing the photoconductor to form an electrostatic latent image,
Developing means for developing an electrostatic latent image of the photoconductor with a developer to form an image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
Correction means for correcting the exposure amount by the exposure means for the correction target pixel from the exposure amount indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
Said correction means, said correction target pixel, depending on the distance between the edges of the image formed by the image data, the exposure amount of the correction target pixel is not exposed at least part of the region of the pixel to be corrected An image forming apparatus characterized in that the correction is performed by the following. The distance from the edge of the image formed by the image data of the pixel to be corrected indicated by the first information to the edge of the image formed by the image data includes the pixel of the edge, or is set to the correction target pixel indicated by the first information. The image forming apparatus according to claim 1 , wherein a distance of a pixel from an edge of an image formed by the image data does not include a pixel of the edge. Wherein the correction means, based on the second information indicating the correction amount corresponding to the distance between the edge, the image forming apparatus according to claim 1 or 2, characterized in that for correcting the exposure amount of the correction target pixel. Wherein the correction means, the correction target pixel is divided into N subpixels, the N any one of claims 1 to 3, characterized in that it does not expose the one or more subpixels among the subpixels Item 10. The image forming apparatus according to item 1. Said specifying means, said by the distance from each of the plurality of edges of an image formed by the image data, the image formation according to any one of claims 1 to 4, wherein the identifying the correction target pixel apparatus. Said correction means, said plurality of distances from the respective edge, the image forming apparatus according to claim 5, characterized in that for correcting the exposure amount of the correction target pixel based on the closest distance. Said specifying means, the image formed by the image data, wherein the distance from the rotation direction of the rear edge of the photoreceptor, any of claims 1 to 4, wherein the identifying the correction target pixel The image forming apparatus according to claim 1. The specifying unit, when the width of the image formed by the image data is smaller than a predetermined value, according to claim 1, the direction of the width is characterized not to perform certain whether the correction target pixel 8. The image forming apparatus according to any one of claims 1 to 7 , Wherein the correction means, when the width of the image formed by the image data is smaller than a predetermined value, any one of claims 1 to 7, characterized in that no correction of the exposure amount of the pixels included in the width 2. The image forming apparatus according to claim 1. The edge image forming apparatus according to any one of claims 1 9, characterized in that the pixels and the image which the image is formed is a boundary between pixels which are not formed. The correction unit may correct the exposure pattern of at least one correction target pixel of the plurality of correction target pixels when the plurality of correction target pixels have the same exposure amount after correction. the image forming apparatus according to any one of claims 1 to 10, characterized in that the varying the exposure pattern of the target pixel. 12. The image forming apparatus according to claim 11 , wherein the exposure pattern of the pixel is a pattern of an exposure intensity for exposing a sub-pixel forming one pixel. The image forming apparatus according to claim 11 , wherein the plurality of correction target pixels are continuous pixels. An image forming apparatus comprising: a photoconductor; an exposing unit configured to expose the photoconductor to form an electrostatic latent image; and a developing unit configured to develop the electrostatic latent image on the photoconductor with a developer to form an image. An image processing apparatus for supplying image data for forming the image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
A correction unit that generates a corrected image data by correcting a pixel value of the correction target pixel from a pixel value indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
Output means for outputting the corrected image data to the image forming apparatus,
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
It said correction means, said correction target pixel, in accordance with the distance between the edge of the image formed by the image data, corrects the pixel value of the pixel to be corrected,
An image processing apparatus according to claim 1, wherein the exposure of the correction target pixel by the exposure unit does not expose at least a part of the correction target pixel. An image forming apparatus that forms an image based on image data,
A photoreceptor,
Exposure means for exposing the photoconductor to form an electrostatic latent image,
Developing means for developing an electrostatic latent image of the photoconductor with a developer to form an image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
Correction means for correcting the exposure amount by the exposure means for the correction target pixel from the exposure amount indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
The correction unit may correct the exposure pattern of at least one correction target pixel of the plurality of correction target pixels when the plurality of correction target pixels have the same exposure amount after correction. An image forming apparatus, wherein the exposure pattern is different from an exposure pattern of a target pixel. 16. The image forming apparatus according to claim 15 , wherein the exposure pattern of the pixel is a pattern of an exposure intensity for exposing a sub-pixel forming one pixel. When the number of pixels having the same amount of exposure after correction among the plurality of correction target pixels is equal to or greater than a predetermined number, the correction unit converts the exposure pattern of at least one correction target pixel into the remaining correction target pixels. the image forming apparatus according to claim 15 or 16, characterized in that to vary the exposure pattern. Wherein the state information includes environmental information, or the image forming apparatus according to any one of claims 15 to 17, characterized in that it comprises the use state information indicating the degree of deterioration by the use of the image forming apparatus. Wherein the correction means, the correction based on the second information indicating a correction amount of the target pixel, the image formation according to any one of claims 15 to 18, characterized in that for correcting the exposure amount of the correction target pixel apparatus. Wherein the plurality of correction object pixel, an image forming apparatus according to any one of claims 15 to 19, characterized in that it is a continuous pixels. An image forming apparatus that forms an image based on image data,
A photoreceptor,
Exposure means for exposing the photoconductor to form an electrostatic latent image,
Developing means for developing an electrostatic latent image of the photoconductor with a developer to form an image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
Correction means for correcting the exposure amount by the exposure means for the correction target pixel from the exposure amount indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
Wherein the correction means, the correction as periodicity does not occur in the exposure pattern at an exposure amount after the correction of the target pixel, the image forming apparatus and determines the exposure pattern of each correction target pixel. 22. The image forming apparatus according to claim 21 , wherein the exposure pattern is a pattern of exposure intensity. The correction means period determines periodicity in the exposure pattern occurs, the image forming apparatus according to claim 21 or 22, characterized in that shorter than the period of the image data corresponding to one sheet of the recording material. The correction means period determines periodicity in the exposure pattern occurs, the image forming apparatus according to claim 21 or 22, characterized in that longer than the period of the image data corresponding to one sheet of the recording material. Wherein the correction means, when the periodicity in the exposure pattern at an exposure amount after correction of the correction target pixel occurs, as periodicity does not occur, determines the exposure pattern of the correction target pixel,
A correction amount of the exposure of the correction target pixel periodicity is determined not as occur, the correction amount of the exposure of the correction target pixel when the periodicity arises from claim 21, characterized in that the same 24 The image forming apparatus according to claim 1. An image forming apparatus comprising: a photoconductor; an exposing unit configured to expose the photoconductor to form an electrostatic latent image; and a developing unit configured to develop the electrostatic latent image on the photoconductor with a developer to form an image. An image processing apparatus for supplying image data for forming the image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
A correction unit that generates a corrected image data by correcting a pixel value of the correction target pixel from a pixel value indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
Output means for outputting the corrected image data to the image forming apparatus,
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
When the exposure amounts of the plurality of correction target pixels after the correction by the exposure unit are the same, the correction unit sets the exposure pattern of at least one correction target pixel of the plurality of correction target pixels to the plurality of correction target pixels. An image processing apparatus characterized in that the exposure pattern is different from the exposure pattern of the remaining pixels to be corrected. An image forming apparatus comprising: a photoconductor; an exposing unit configured to expose the photoconductor to form an electrostatic latent image; and a developing unit configured to develop the electrostatic latent image on the photoconductor with a developer to form an image. An image processing apparatus for supplying image data for forming the image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
A correction unit that generates a corrected image data by correcting a pixel value of the correction target pixel from a pixel value indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
Output means for outputting the corrected image data to the image forming apparatus,
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
Wherein the correction means, said correction at the exposure means based on the corrected pixel value of the target pixel as periodic exposure amount of the exposure pattern does not occur, and characterized by determining the exposure pattern of each correction target pixel Image processing device. An image forming apparatus that forms an image based on image data,
A photoreceptor,
Exposure means for exposing the photoconductor to form an electrostatic latent image,
Developing means for developing an electrostatic latent image of the photoconductor with a developer to form an image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
Correction means for correcting the exposure amount by the exposure means for the correction target pixel from the exposure amount indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
The correction unit determines whether to correct the exposure amount of the correction target pixel according to the width in the main scanning direction or the width in the sub-scanning direction of the image including the correction target pixel formed by the image data. An image forming apparatus characterized by determining. An image forming apparatus comprising: a photoconductor; an exposing unit configured to expose the photoconductor to form an electrostatic latent image; and a developing unit configured to develop the electrostatic latent image on the photoconductor with a developer to form an image. An image processing apparatus for supplying image data for forming the image,
Specifying means for specifying a correction target pixel among pixels of an image formed by the image data based on the image data;
A correction unit that generates a corrected image data by correcting a pixel value of the correction target pixel from a pixel value indicated by the image data,
Holding means for holding a plurality of first information indicating a pixel to be the correction target pixel by a distance from an edge of an image formed by the image data;
Detecting means for detecting state information indicating a state of the image forming apparatus;
Output means for outputting the corrected image data to the image forming apparatus,
With
The specifying means selects first information used for specifying the correction target pixel from the plurality of pieces of first information based on the state information detected by the detection means, and selects the correction target based on the selected first information. Identify the pixel,
The correction unit determines whether to correct the exposure amount of the correction target pixel according to the width in the main scanning direction or the width in the sub-scanning direction of the image including the correction target pixel formed by the image data. An image processing device characterized by making a decision.