JP3810271B2 - Image processing apparatus and image processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention identifies a character area, a photographic area, or a halftone dot area from an image obtained by scanning a document in an image forming apparatus such as a scanner, a digital copying machine, or a facsimile, and according to the characteristics of each area. The present invention relates to an image processing apparatus that performs optimum filter processing.
[0002]
[Prior art]
Conventionally, in a copying machine, a facsimile, and the like, areas such as a character part and a photographic part in a document are identified, and optimum image processing is performed on each area based on the identification result. Japanese Patent Laid-Open No. 6-133159 discloses a configuration of an image processing apparatus that accurately detects a halftone dot region with a simple configuration. In this configuration, first, local changes in the main scanning direction and the sub-scanning direction of the image data are respectively detected, and it is determined whether or not the detected value is a halftone dot region based on pixels having a predetermined value or more. A smoothing filter is used to prevent the generation of moire for the halftone area, while a sharp image is obtained for the non-halftone area using an MTF correction filter (edge enhancement filter). It has gained.
[0003]
However, when performing region separation for identifying regions such as a character portion and a photo portion in a document, there are the following problems depending on the position where the region separation is performed. In other words, when performing area separation after performing density conversion by exposure adjustment on input data, it is necessary to have an area separation setting table and a filter setting table for each exposure curve. It becomes quantity. In addition, the actual setting requires a lot of labor and time.
[0004]
On the other hand, if region separation is performed before density conversion by exposure adjustment is performed on input data, the input data will be smaller if the document is thin, and character edge detection will not be performed sufficiently and character emphasis will not be performed. It may become a blurred character. In order to prevent this, if the edge detection is set to be performed even on a thin document, there is a problem that the edge detection is performed to a place other than the character, and an image is enhanced.
[0005]
[Problems to be solved by the invention]
Accordingly, the present invention can address these problems, minimize the amount of area separation setting table and filter setting table provided in the image processing apparatus, and perform optimum area separation even for a thin document. It is an object to provide an image processing apparatus.
[0006]
That is, a first object of the present invention is to perform region separation with the minimum necessary setting table without having a region separation setting table and a filter setting table for each density conversion table in region separation.
[0007]
A second object of the present invention is to perform optimum region separation according to the density of a document.
[0008]
A third object of the present invention is to correctly perform region separation even on a thin document and to perform optimum filter processing on characters.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an image processing apparatus of an image forming apparatus, a document reading unit that reads a document and generates input data, and a character area, a photographic area, or a dot area of the document using the input data. A region separation unit for identifying the input data, a density conversion unit for performing density conversion based on a density conversion table set in advance for input data, and a filter set in advance for each region separated by the region separation unit A filter unit that performs filter processing based on the setting table, and the processing order of the density conversion unit and the region separation unit can be switched.
[0010]
In the image processing apparatus, the image processing apparatus further includes density selection means for selecting a density conversion table of the density conversion unit based on the density of the document, and the density conversion unit and the region separation based on the selection signal. The processing order of the parts was changed.
[0011]
Furthermore, according to the present invention, in the image processing apparatus, the processing order in the region separation unit and the density conversion unit is basically processed in the order of the region separation unit and the density adjustment unit, and the density selection unit performs dark processing. Only when the eye is set, the processing is performed in the order of the density conversion unit and the region separation unit.
[0012]
According to the present invention, in the image processing apparatus, the conversion density selection of the density selection means is set to dark when the document density is low, and light when the document density is high.
[0013]
In order to solve the above-described problems, the present invention provides a document reading unit that reads a document and generates input data, a region separation unit that identifies a character region, a photographic region, or a halftone region of the document using the input data, and an input A density conversion unit that performs density conversion on data based on a preset density conversion table, and a filter process based on a filter setting table set in advance for each region separated by the region separation unit An image processing method in an image processing apparatus having a filter unit, in which input data read by a document reading unit is processed in the order of density conversion processing and area separation processing when the density setting value of the density setting means is set high. When the density setting value is set thin, the area separation process and the density conversion process are performed in this order, and then the filter process is performed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments shown in the drawings, but the present invention is not limited thereto. FIG. 1 is a schematic front sectional view showing a configuration of a digital color copying machine 1 which is an image forming apparatus to which an image processing apparatus according to an embodiment of the present invention is applied. A document table 111 and an operation panel are provided on the upper surface of the copying machine main body 1, and an image reading unit 110 and an image forming unit 210 are provided inside the copying machine main body 1. A double-sided automatic document feeder (RADF) 112 is mounted on the upper surface of the document table 111 so as to be openable and closable with respect to the document table 111 and having a predetermined positional relationship with respect to the surface of the document table 111. Has been.
[0015]
Further, the double-sided automatic document feeder 112 first transports the document so that one side of the document faces the image reading unit 110 at a predetermined position on the document table 111, and after the image reading on the one side is completed. The document is reversed and conveyed toward the document table 111 so that the other side faces the image reading unit 110 at a predetermined position on the document table 111. The double-sided automatic document feeder 112 discharges the original after one-sided image reading for one original is completed, and executes a double-sided conveyance operation for the next original. The operations of document conveyance and front / back reversal described above are controlled in relation to the operation of the entire copying machine.
[0016]
The image reading unit 110 is disposed below the document table 111 in order to read an image of the document conveyed on the document table 111 by the double-sided automatic document feeder 112. The image reading unit 110 includes document scanning bodies 113 and 114 that reciprocate in parallel along the lower surface of the document table 111, an optical lens 115, and a CCD line sensor 116 that is a photoelectric conversion element.
[0017]
The document scanning bodies 113 and 114 are composed of a first scanning unit 113 and a second scanning unit 114. The first scanning unit 114 includes an exposure lamp that exposes the surface of the document image and a first mirror that deflects the reflected light image from the document in a predetermined direction, and is constant with respect to the lower surface of the document table 111. While reciprocally moving in parallel at a predetermined scanning speed. The second scanning unit 114 includes a second mirror and a third mirror that further deflect the reflected light image from the original deflected by the first mirror of the first scanning unit 113 in a predetermined direction. The first scanning unit 113 reciprocates in parallel while maintaining a constant speed relationship.
[0018]
The optical lens 115 reduces the reflected light image from the original deflected by the third mirror of the second scanning unit, and forms the reduced light image at a predetermined position on the CCD line sensor 116.
[0019]
The CCD line sensor 116 sequentially photoelectrically converts the formed light image and outputs it as an electrical signal. The CCD line sensor 116 is a three-line color CCD that can read a black-and-white image or a color image and output line data separated into R (red), G (green), and B (blue) color components. . The document image information converted into an electrical signal by the CCD line sensor 116 is further transferred to an image processing unit (not shown) and subjected to predetermined image data processing.
[0020]
Next, the configuration of the image forming unit 210 and the configuration of each unit related to the image forming unit 210 will be described. Below the image forming unit 210, a paper feed mechanism 211 that separates sheets (recording media) P stacked and accommodated in a paper tray one by one and supplies them to the image forming unit 210 is provided. The sheets P separated and supplied one by one are transported to the image forming unit 210 with timing controlled by a pair of registration rollers 212 arranged in front of the image forming unit 210. Further, the paper P on which an image is formed on one side is re-supplied and conveyed to the image forming unit 210 in synchronization with the image formation of the image forming unit 210.
[0021]
A transfer conveyance belt mechanism 213 is arranged below the image forming unit 210. The transfer conveyance belt mechanism 213 is configured to convey the paper P by electrostatically adsorbing the transfer conveyance belt 216 stretched between the driving roller 214 and the driven roller 215 so as to extend substantially in parallel.
[0022]
Further, a fixing device 217 for fixing the toner image transferred and formed on the paper P onto the paper P is disposed on the downstream side of the transfer and transport belt mechanism 213 in the paper transport path. The sheet P that has passed through the nip portion between the pair of fixing rollers of the fixing device 217 passes through the conveyance direction switching gate 218 and is discharged onto the discharge tray 220 attached to the outer wall of the copier body 1 by the discharge roller 219. Is done.
[0023]
The conveyance direction switching gate 218 selectively selects a conveyance path for the fixed sheet P between a path for discharging the sheet P to the copier body 1 and a path for resupplying the sheet P toward the image forming unit 210. To switch to. The paper P whose transport direction has been switched again toward the image forming unit 210 by the transport direction switching gate 218 is turned upside down via the switchback transport path 221 and then supplied again to the image forming unit 210.
[0024]
Further, above the transfer conveyance belt 216 in the image forming unit 210, in close proximity to the transfer conveyance belt 216, the first image forming station Pa, the second image forming station Pb, the third image forming station Pc, and The fourth image forming stations Pd are arranged in order from the upstream side of the sheet conveyance path. The transfer conveyance belt 216 is frictionally driven by the driving roller 214 in the direction indicated by the arrow Z in FIG. 1, holds the paper P fed through the paper feed mechanism 211 as described above, and holds the paper P at the image forming stations Pa˜. Convey sequentially to Pd.
[0025]
Each of the image forming stations Pa to Pd has substantially the same configuration. Each of the image forming stations Pa, Pb, Pc, Pd is rotated by photosensitive drums 222a, 222b, 222c. And 222d, respectively.
[0026]
Around each of the photosensitive drums 222a to 222d, there are chargers 223a, 223b, 223c and 223d for uniformly charging the photosensitive drums 222a to 222d, and electrostatic latent images formed on the photosensitive drums 222a to 222d. Developing devices 224a, 224b, 224c, and 224d for developing the images, transfer discharge devices 225a, 225b, 225c, and 225d for transferring the developed toner images on the photosensitive drums 222a to 222d to the paper P, and the photosensitive member Cleaning devices 226a, 226b, 226c, and 226d that remove toner remaining on the drums 222a to 222d are sequentially arranged along the rotation direction of the photosensitive drums 222a to 222d.
[0027]
Laser beam scanner units 227a, 227b, 227c, and 227d are provided above the respective photosensitive drums 222a to 222d.
[0028]
The laser beam scanner units 227a to 227d are semiconductor laser elements (not shown) that emit dot light modulated in accordance with image data, and polygon mirrors (deflection devices) for deflecting the laser beams from the semiconductor laser elements in the main scanning direction. ) 240 and an fθ lens 241 and mirrors 242 and 243 for forming an image of the laser beam deflected by the polygon mirror 240 on the surface of the photosensitive drums 222a to 222d.
[0029]
The laser beam scanner 227a has a pixel signal corresponding to the black component image of the color original image, the laser beam scanner 227b has a pixel signal corresponding to the cyan component image of the color original image, and the laser beam scanner 227c has a color original image. The pixel signal corresponding to the magenta color component image is input to the laser beam scanner 227d, and the pixel signal corresponding to the yellow color component image of the color original image is input to the laser beam scanner 227d.
[0030]
As a result, electrostatic latent images corresponding to the color-converted document image information are formed on the respective photosensitive drums 222a to 222d. The developing device 224a contains black toner, the developing device 224b contains cyan toner, the developing device 224c contains magenta toner, and the developing device 224d contains yellow toner. The electrostatic latent images on the photosensitive drums 222a to 222d are developed with the toners of these colors. Thus, the document image information color-converted by the image forming unit 210 is reproduced as a toner image of each color.
[0031]
Further, a paper suction (brush) charger 228 is provided between the first image forming station Pa and the paper feed mechanism 211, and the suction charger 228 charges the surface of the transfer conveyance belt 216. The paper P supplied from the paper feeding mechanism 211 is transported without deviation between the first image forming station Pa and the fourth image forming station Pd in a state where the paper P is reliably adsorbed on the transfer transport belt 216.
[0032]
On the other hand, a static eliminator 229 is provided almost directly above the drive roller 214 between the fourth image forming station Pd and the fixing device 217. An AC current for separating the sheet P electrostatically attracted to the transport belt 216 from the transfer transport belt 216 is applied to the static eliminator.
[0033]
In the digital color copying machine having the above configuration, cut sheet-like paper is used as the paper P. When the paper P is fed out from the paper feed cassette and supplied into the guide of the paper feed conveyance path of the paper feed mechanism 211, the leading end portion of the paper P is detected by a sensor (not shown), and from this sensor Based on the output detection signal, the pair of registration rollers 212 are temporarily stopped.
[0034]
Then, the paper P is sent onto the transfer conveyance belt 216 rotating in the direction of arrow Z in FIG. 1 in time with the image forming stations Pa to Pd. At this time, the transfer conveyance belt 216 is charged by the suction charger 228 as described above, so that the sheet P is stably conveyed and supplied while passing through the image forming stations Pa to Pd. The
[0035]
In each of the image forming image stations Pa to Pd, toner images of respective colors are formed and superimposed on the support surface of the paper P that is electrostatically attracted and transported by the transfer transport belt 216. When the transfer of the image by the fourth image forming station Pd is completed, the paper P is sequentially peeled from the transfer conveyance belt 216 from the leading end portion thereof by the discharger for discharging, and is guided to the fixing device 217. Finally, the paper P on which the toner image is fixed is discharged onto a paper discharge tray 220 from a paper discharge port (not shown).
[0036]
In the above description, the laser beam scanner units 227a to 227d scan and expose the laser beam to perform optical writing on the photosensitive member. However, instead of the laser beam scanner unit, a writing optical system (LED head) including a light emitting diode array and an imaging lens array may be used. The LED head is smaller than the laser beam scanner unit and has no moving parts and is silent. Therefore, it can be suitably used in an image forming apparatus such as a tandem digital color copying machine that requires a plurality of optical writing units.
[0037]
Next, the configuration and function of an image processing unit for color image information installed in a color digital copying machine will be described with reference to FIG. FIG. 2 is a block configuration diagram schematically showing the functional configuration of the image processing unit included in the color digital copying machine 1.
[0038]
The image processing unit included in the digital copying machine 1 includes an image data input unit 40, an image processing unit 41, an image memory 43 including a hard disk device or a RAM (random access memory), an image data output unit 42, A central processing unit (CPU) 44, an image editing unit 45, and external interface units 46 and 47 are included.
[0039]
The image data input unit 40 reads a black and white document or a color document image, and outputs line data that is color-separated into RGB color components. The line data of the line data read by the color CCD 40a and the color CCD 40a. A shading correction circuit 40b for correcting the level, a line matching unit 40c such as a line buffer for correcting a shift of image line data read by the three-line color CCD 40a, and line data of each color output from the three-line color CCD 40a. From a sensor color correction unit 40d for correcting color data, an MTF correction unit 40e for correcting the change in the signal of each pixel to have a sharpness, a γ correction unit 40f for correcting the lightness and darkness of the image and correcting the visibility. Become.
[0040]
The image processing unit 41 corresponds to a monochrome data generation unit 41a that generates monochrome data (monochrome data) from RGB signals that are color image signals input from the image data input unit 40, and RGB signals corresponding to the recording units of the recording apparatus. An input processing unit 41b for converting the image data into a YMC signal and density conversion, a region separating unit 41c for separating whether the input image data is a character part, a halftone photograph or a photographic paper photograph, and an input processing part 41b A black generation unit 41d that generates black by performing undercolor removal processing based on the YMC signal output from the color correction circuit 41e that adjusts each color of the color image signal based on each color conversion table, and based on the set magnification A zoom processing circuit 41f that converts the input image information to a magnification, a spatial filter 41g, and gradations such as multi-value error diffusion and multi-value dither. It consists like halftone processing unit 41h for.
[0041]
Each color image data subjected to halftone processing is temporarily stored in the image memory 43. The image memory 43 sequentially receives 8-bit 4-color (32-bit) image data serially output from the image processing unit 41, and converts the 32-bit data into 8-bit 4-color image data while temporarily storing it in the buffer. And four hard disks (rotating storage media) 43a, 43b, 43c, and 43d that are stored and managed as image data for each color. Further, since the positions of the image forming stations are different, each color image data is temporarily stored in the delay buffer memory (semiconductor memory) 43e of the image memory 43, and the image data is sent to each laser scanner unit by shifting each time, Match the timing to prevent color shift. Further, the image memory 43 includes an image synthesis memory 43f for synthesizing a plurality of images.
[0042]
The image data output unit 42 performs a pulse width modulation based on each color image data from the halftone processing unit 41h, and generates a pulse width modulation signal corresponding to the image signal of each color output from the laser control unit 42a. The laser scanner units (LSU) 42b, 42c, 42d, and 42e for each color that perform laser recording on the basis thereof.
[0043]
A central processing unit (CPU) 44 has an image data input unit 40, an image processing unit 41, an image memory 43, an image data output unit 42, an image editing unit 45, which will be described later, and external interface units 46 and 47 in a predetermined sequence. Control based on.
[0044]
The image editing unit 45 is for performing predetermined image editing on the image data once stored in the image memory 43 through the image data input unit 40, the image processing unit 41, or an interface described later. The image data editing operation is performed using the image composition memory 43f.
[0045]
Further, the external interface unit 46 is a communication interface means for receiving image data from an external image input processing apparatus (communication portable terminal, digital camera, digital video camera, etc.) provided separately from the digital copying machine 1. .
[0046]
Note that the image data input from the external interface unit 46 is also converted to a data level that can be handled by the image forming unit 210 of the digital copying machine 1 by once inputting the image data to the image processing unit 41 and performing color space correction. As a result, the hard disk 43b, 43c, 43d, 43e is stored and managed.
[0047]
The external interface unit 47 is a printer interface for inputting image data created by the personal computer 2, and is a monochrome or color FAX interface for receiving image data received by FAX. The image data input from the interface 47 is already a CMYK signal, and is subjected to intermediate processing 41h and stored and managed in the hard disks 43b, 43c, 43d, and 43e of the image memory 43.
[0048]
FIG. 3 is a diagram showing a state in which the operation of each part of the entire apparatus of the digital copying machine 1 is managed by the central processing unit (CPU) 44.
[0049]
The details of the image data input unit 40, the image processing unit 41, the image memory 43, the image data output unit 42, and the central processing unit (CPU) 44 are as described in FIG. Description of is omitted.
[0050]
The central processing unit 44 manages each drive mechanism unit constituting the digital copying machine 1 such as the RADF, the scanner unit, and the laser printer unit by sequence control and outputs a control signal to each unit.
[0051]
Further, an operation board unit 48 including an operation panel is connected to the central processing unit 44 in a state where communication is possible with each other, and a control signal indicating the copy mode contents set and input by the operator according to the operation of the operation panel is received. Then, the data is transferred to the central processing unit 44, and the entire digital color copying machine 1 is controlled to operate in accordance with the set mode.
[0052]
Further, control signals indicating various operation states of the digital color copying machine 1 are transferred from the central processing unit 44 to the operation board unit 48, and on the operation board unit 48 side, what kind of apparatus is currently in use by this control signal. The operation state is displayed on the display unit or the like so as to indicate to the operator whether the state is in the state.
[0053]
Hereinafter, the relationship between the region separation process and the density conversion process in the present invention will be described with reference to FIGS. First, the relationship between the function of the region separation unit and the function of the density conversion unit will be described with reference to FIG. 4 which is a flowchart schematically showing the flow of the region separation process and the density conversion process.
[0054]
In the document reading unit, RGB image data obtained by document reading processing (S1) such as shading, line alignment, etc. on the data read from the document is the density set by the density selection means. The order of the subsequent region separation processing and density conversion processing is switched by the information of the adjustment values (exp1 to exp7).
[0055]
Specifically, in the case of a thin original written with a pencil, the user sets the density adjustment value to dark eyes (exp5 to exp7) so that the document is printed darkly. In this case, after the density conversion process is performed by the input processing unit (density conversion unit) (S4), the region separation process is performed by the region separation unit (S5), and then the filter processing unit including the spatial filter performs the filter process (S6). Is done.
[0056]
On the other hand, for the other documents, the user sets the density adjustment value to a normal value (exp4) or a light value (exp1 to exp3). In that case, after the region separation processing is performed by the region separation unit (S2), the density conversion processing (S3) is performed by the density conversion unit, and then the filter processing (S6) is performed by the filter processing unit including a spatial filter.
[0057]
FIG. 5 shows an image when a thin line pair image is read by a scanner on the left side, and a cross-sectional data value on the right side. The upper side is data before exposure adjustment, and the lower side is data after exposure adjustment. From the figure, as shown in the upper part, the read data before the exposure adjustment processing in which the image (original) is captured by the scanner is thin read data as a whole, and the difference in light and shade is not easily observed. For this read data, as shown in FIG. 6, when the document density is low, exposure adjustment is performed using an exposure curve (exp5) in which the density adjustment value is set so that the output value becomes larger than the input value. As shown in the lower part, the density of the scanner read data can be increased, a difference in density appears, and the edge can be easily detected by the region separation process.
[0058]
With reference to FIG. 7, the processing result when the region separation processing is actually performed will be described. In the figure, the upper part shows an image obtained by subjecting the scanner read data to area separation processing without performing exposure adjustment, and the lower part shows an image obtained by subjecting the scanner read data to area separation after adjusting the exposure. Is shown. In the figure, the area displayed in gray is an area detected as an edge. In the upper image before exposure adjustment, edge detection such as 7.1 line pair is insufficient and detection of 8.0 line pair is poor, but by adjusting exposure, 7.1 The edge detection of the line pair is greatly improved even at 8.0.
[0059]
Based on the region separation result, the enhancement filter processing as shown in FIG. 8A is applied to the area detected as an edge, and FIG. Smoothing filter processing as shown in B) is performed.
[0060]
【The invention's effect】
As described above, according to the present invention, the density conversion processing in the density conversion unit and the region separation processing in the region separation unit are switched, and the density conversion processing is performed after the region separation processing is performed on a document having a high density. The density separation process is performed on the original document with a low density, and then the area separation process is performed on the original document with a low density. There is no need to have an area separation setting table and a filter setting table for each, and the number of area separation setting tables and filter setting tables can be reduced, and the setting effort of the tables can be reduced.
[0061]
In addition, according to the present invention, the optimum region separation according to the density of the document is performed by switching the processing order of the density conversion unit and the region separation unit based on the density conversion table selection signal of the density selection unit, and the optimum The best image quality can be obtained by applying a simple filter.
[0062]
Furthermore, according to the present invention, by performing area separation after density conversion only when the darkness is set by the density selection means, it is possible to perform reliable edge detection on a thin document and perform sharp image reproduction. be able to.
[Brief description of the drawings]
FIG. 1 is a front sectional view for explaining the structure of a digital color copying machine to which an image processing apparatus according to the present invention is applied.
FIG. 2 is a block diagram of an image processing unit included in the digital color copying machine of FIG.
3 is a state diagram in which operation of each part of the digital color copying machine of FIG. 1 is managed by a CPU.
FIG. 4 is a flowchart illustrating the relationship between region separation processing and density conversion processing according to the present invention.
FIG. 5 is a view for explaining image data before and after exposure adjustment.
FIG. 6 is a diagram showing an example of an exposure adjustment curve.
FIG. 7 is a diagram for explaining a region separation result before and after exposure adjustment.
FIG. 8 is a diagram illustrating an example of filter coefficients.
[Explanation of symbols]
1 Digital color copier
40 Image data input section
40a color CCD
40b Shading correction circuit
40c Line alignment part
40d Sensor color correction unit
40e MTF correction unit
40f γ correction unit
41 Image processing unit
41a Monochrome data generator
41b Input processing unit
41c region separation part
41d black generator
41e Color correction circuit
41f Zoom processing circuit
41g spatial filter
41h Halftone processing part
42 Image data output unit
42a Laser control unit
42b-e Laser scanner unit for each color
43 Image memory
43a-d hard disk (rotating storage medium)
43e Delay buffer memory (semiconductor memory)
43f Image composition memory
44 Central processing unit (CPU)
45 Image Editing Department
46, 47 External interface
48 Operation board unit
110 Image reading unit
111 Document platen
112 Automatic document feeder
113, 114 Document scanning body
115 Optical lens
116 CCD line sensor
210 Image forming unit
211 Paper feed mechanism
212 Registration Roller
213 Transfer conveyor belt mechanism
214 Driving roller
215 Followed roller
216 Transfer conveyor belt
217 Fixing device
218 Transfer direction switching gate
219 Discharging roller
220 Discharge tray
221 Switchback transport path
222a to 222d Photosensitive drum
223a to 223d charger
224a to 224d developing device
225a to 225d Discharger for transfer
226a-226d Cleaning device
227a to 227d Laser beam scanner unit (LSU)
228 Charger for paper adsorption
240 polygon mirror
241 fθ lens
242 to 243 mirror
P paper
Pa to Pd image forming station

Claims (3)

An original reading unit that reads an original and generates input data, an area separation unit that identifies a character area, a photographic area, or a halftone area of the original using the input data, and a density conversion table set in advance for the input data A density conversion unit that performs density conversion based on the filter, a filter unit that performs filtering based on a filter setting table set in advance for each region separated by the region separation unit, and the density based on the density of the document. A density selection unit that selects a density conversion table of the conversion unit; and a unit that switches a processing order of the density conversion unit and the region separation unit based on a selection signal of the density selection unit, the density conversion unit and the region The order of processing in the region separation unit and the density conversion unit switched by means for switching the processing order of the separation unit is basically a region separation unit and a density adjustment unit. Performs processing in the order, only when set to dark eye at a concentration selection means, density conversion unit performs the order in the processing of the segmentation section, and can switch the processing order of the region separating section and the density converter An image processing apparatus characterized by that. The image processing apparatus according to claim 1, wherein the conversion density selection of the density selection unit is set to dark when the document density is low, and is set to light when the document density is high . An original reading unit that reads an original and generates input data, an area separation unit that identifies a character area, a photographic area, or a halftone area of the original using the input data, and a density conversion table set in advance for the input data A density conversion unit that performs density conversion based on the filter, a filter unit that performs filtering based on a filter setting table set in advance for each region separated by the region separation unit, and the density based on the density of the document. An image processing method in an image processing apparatus, comprising: a density selection unit that selects a density conversion table of a conversion unit; and a unit that switches a processing order of the density conversion unit and the region separation unit based on a selection signal of the density selection unit. And
The input data read by the document reader is processed in the order of density conversion processing and area separation processing when the density setting value of the density setting means is set high, and region separation is performed when the density setting value is set light. An image processing method characterized by processing in the order of processing and density conversion processing, and then performing filter processing.

Images