JP3976494B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an image reading apparatus used in a scanner, a digital copying machine, a digital color copying machine, a facsimile, a color facsimile, etc.And image forming apparatusIn particular, the present invention relates to a background removal technique.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 7-264421 discloses an image processing having a color correction processing device that reads an original with an R, G, B digital signal by an image reading device and obtains K, C, M, Y recording signals in a frame sequential manner. In the device, a recording signal of any of K, C, M, and Y is obtained at the time of the first scan, and at the same time, a threshold value used for background detection after the second scan is automatically set, and the background detection after the second scan is performed by the first scan. A technique using a threshold value that is sometimes set is disclosed.
[0003]
Japanese Patent Application Laid-Open No. 7-264408 discloses a technique for identifying the document holding plate and the background of the document and detecting the density level of the document background area excluding the document holding plate area with high accuracy.
[0004]
Further, the present applicant has applied for a technique for adjusting the background removal level of the background removal means to adjust the offset of the reference voltage of the A / D conversion means with respect to the peak value of the document image.
[0005]
[Problems to be solved by the invention]
However, in a conventional image reading apparatus that performs background removal, when the original to be read is an arbitrary cut of a newspaper or a special original such as a newspaper that is cut into a blank sheet, When the background is removed, the back platen surface and the cut mount are whiter than the newspaper manuscript part that you want to remove, so the white part will be taken as a higher area of the background, so the newspaper manuscript surface cannot be skipped. There was a problem.
[0006]
Other special manuscripts include manuscripts that include totally reflected light due to floating of the binding portion of this manuscript and materials that totally reflect light such as printed circuit boards. Since it is bright, there is a problem that it is not possible to remove the background as expected by removing this part from the background.
[0007]
Also, if you place an arbitrarily cut newspaper on the contact glass and close the pressure plate that holds the document, the newspaper may be misaligned. For this reason, it is necessary to reposition and read the document many times. There was a problem that there was.
In addition, if the process is performed again and again, there is a problem in that in the case of a digital copying machine, miscopying occurs, and consumables such as paper and toner are wasted.
[0008]
  Therefore, the present inventionmainThe object is to be able to set the density to be skipped on the background of the document, and to remove the background better for special documents.
[0009]
  Also,Secondary to the present inventionThe purpose is to display the density level for which the background is to be removed by pre-scanning so that it can be accurately set in the display editor.
  It is another object of the present invention to specify the background removal density region for the read image so that the above-described document repositioning and reading need not be repeated again and again.
  It is another object of the present invention to prevent consumables such as paper and toner in the case of a digital copying machine.
[0010]
  Also,Secondary to the present inventionThe purpose is not to use the above-mentioned special manuscript, there is no problem in performing the full peak value background removal mode without pre-scan which is the normal background removal. It is to be able to respond to user needs by having a mode for preventing the above-mentioned problems.
[0011]
  Also,Secondary to the present inventionThe purpose is to show the contrast and brightness of the display during pre-scanning when selecting the background removal mode so that the area can be set by grasping the density of the background even if the display editor has no gradation.WhenIs to make it easier for the user to adjust the background removal density region.
[0013]
[Means for Solving the Problems]
  To achieve the above object, the present inventionAccording to the first aspect of the present invention, there is provided a first background removal mode for removing the background based on the background density of the entire surface of the original image, and a second mode for removing the background based on the background density of a specific area of the original image. An image reading apparatus having a background removal mode,Photoelectric conversion means for optically reading a document image and converting it into an image signal; A / D conversion means for converting an image signal read by the photoelectric conversion means into digital image data;Based on image display means for displaying image data obtained by converting the read original image, change means for changing the contrast and / or brightness of the display means, and image data displayed on the display meansOn the original imageSpecific areaCoordinate designating means for designating,The selection means for selecting the first background removal mode and the second background removal mode, and when the first background removal mode is selected by the selection means, the background removal is performed based on the background of the entire original image, When the background removal mode 2 is selected, the prescan is performed and the image data of the document image displayed on the image display means is used.A background removal means for performing background removal processing of a document image read on the basis of the background density of a specific area of the document image designated by the coordinate designation means;, And the change means lowers the contrast and / or brightness of the display means when the second background removal mode is selected and the pre-scan is performed to display the image data of the original image on the display means.It is characterized by that.
  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the background removal means performs the background removal processing by changing the reference level of the A / D conversion means based on the background density. .
  According to a third aspect of the present invention, there is provided an image forming apparatus including the image reading apparatus according to the first or second aspect.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 8 shows an embodiment of an image forming apparatus in which an image reading apparatus according to an embodiment of the present invention is used.
In FIG. 8, the image reading unit 202 scans the original while irradiating the original with a light source, reads reflected light from the original with a three-line CCD sensor, and sends the image data to the image processing unit 203. The image processing unit 203 performs image processing such as scanner γ correction, color conversion, main scanning scaling, image separation, processing, area processing, and gradation correction processing, and sends the processed image data to the image writing unit 204.
[0015]
The image writing unit 204 modulates the driving of an LD (laser diode) according to the image data. In the drum unit 208, a latent image is written on the uniformly charged rotating photosensitive drum by the laser beam from the LD, and toner is attached by the developing unit 210 to be visualized. The image formed on the photosensitive drum is retransferred onto the transfer belt of the intermediate transfer unit 209. In the case of full-color copying, four colors (Bk, C, M, Y) of toner are sequentially stacked on the intermediate transfer belt.
[0016]
In the case of full-color copying, when the four-color image forming / transfer process of Bk, C, M, and Y is completed, the transfer paper is fed from the paper feeding unit 211 in synchronization with the intermediate transfer belt, and the paper transfer The toner is transferred from the intermediate transfer belt to the transfer paper at the same time on the transfer paper. The transfer paper onto which the toner has been transferred is sent to the fixing unit 212 through the conveying unit, and is thermally fixed by the fixing roller and the pressure roller and then discharged.
[0017]
Also, what the user sets such as the copy mode is input by the operation unit unit 205. The operation mode such as the set copy mode is sent to the system control unit 201, and the system control unit 201 performs a control process for executing the set copy mode. At this time, the system control unit 201 issues a control instruction to each unit such as the image reading unit 202, the image processing unit 203, the image writing unit 204, and the image display unit 207.
[0018]
The image data output from the image processing unit 203 is stored in the DRAM 222 for image data storage by the DMA controller built in the CPU 223 via the FIFO 221 in the functional block diagram of the image display unit 207 shown in FIG. Since the image data control signal is also sent to the image display unit 207 together with the image data, it is possible to capture only the effective image area.
[0019]
Valid image data stored in the DRAM 222 is DMA-transferred to the VRAM 224 by the CPU 223. At this time, the CPU 223 can transfer an arbitrary part of the image data in the DRAM 222, and can perform processing such as enlargement / reduction and thinning. The image data transferred to the VRAM 224 is displayed on the LCD panel 226 under the control of an LCDC (LCD controller) 255.
[0020]
Next, an image reading apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 10 is a configuration diagram of the image display unit 207.
The image display unit 207 may also serve as a display editor for displaying an image on an LCD (liquid crystal panel) display 71 and performing area specification / mode setting for editing / processing within the screen. Each setting key 72 to 86 in FIG. 10 corresponds to the keyboard 231 in the functional block diagram of FIG.
[0021]
In FIG. 10, the LCD display 71, the selected key 72, the reading key 73, the contrast adjustment knob 74, the brightness adjustment knob 75, the whole key 76, the enlargement key 77, the scale display section 78, the display reference 79, and the cursor 80. A clear key 81, an all clear key 82, a close key 83, a point designation key 84, a cursor key 85, and a screen movement key 86 are provided.
[0022]
FIG. 11 shows the configuration of the operation unit unit 205 of FIG.
Numeric keypad 41, mode clear / preheat key 42, interrupt key 43, image quality adjustment key 44, program key 45, print start key 46, clear / stop key 47, area processing key 48, brightness adjustment knob 49, arranged on LCD display 71 Touch panel keys 50, initial setting keys 51, and the like are provided.
[0023]
The numeric keypad 41 is used when inputting numerical values such as the number of copies. The mode clear / preheat key 42 is used to cancel the set mode and return to the initial setting, or to set the preheat state when the button is continuously pressed for a predetermined time or longer. The interrupt key 43 is used when interrupting during copying and copying another document. The image quality adjustment key 44 is used when adjusting the image quality. The program key 45 is used to register or call a frequently used mode. The print start key 46 is a key for starting copying.
[0024]
The clear / stop key 47 is used to clear an input numerical value or to interrupt copying during copying. The area processing key 48 is used when a mode such as area processing / editing is used on the image display unit (display editor). The brightness adjustment knob 49 adjusts the brightness of the LCD panel screen. The touch panel key 50 sets a key area in the same range as the range of various keys displayed on the LCD display, and when the touch panel detects a press within the set range, processing of the set key is performed. I do. The initial setting key 51 is pressed when the user can select each initial setting.
[0025]
FIG. 12 shows an example of a liquid crystal display screen of the LCD display 71. As shown in FIG. 12, there is a mode selection display such as a color mode, automatic density, manual density, image quality mode, automatic paper selection, paper tray, automatic paper scaling, equal magnification, sorting, stack, etc. on the LCD screen. In addition, there are sub-screen selection displays such as create, color processing, double-sided, and variable magnification. A key having the same size as each display is set on the touch panel.
[0026]
FIG. 13 shows an example of screen expansion by pressing the scaling key 71a in FIG.
When the scaling key 71a is pressed, the scaling setting screen is scrolled up from the bottom of the screen. On the scaling setting screen, a key for fixed scaling (a scaling mode in which a scaling ratio is set in advance) is set. For example, when a 71% touch panel key is pressed, a scaling factor of 71% is selected. In this screen, a zoom key, a size scaling key, and an independent scaling / enlarged continuous shooting key are set on the left side of the screen in order to select a scaling mode other than the standard scaling.
[0027]
FIG. 14 shows a configuration example of the touch panel detection circuit, and FIG. 15 shows a setting state of X1, X2, Y1, and Y2 in FIG.
The controller 90 in FIG. 14 sets the detection terminal to the high state, and sets X1, X2, Y1, and Y2 as shown in FIG. Since the Y1 and Y2 circuits are pulled up by resistors, Y1 becomes + 5v when the touch panel is OFF, and 0V when it is ON. Therefore, the ON / OFF state is confirmed from the output of the A / D converter 91. When the controller 90 detects the touch panel ON state, the controller 90 switches to the measurement mode. In the X direction, X1 is + 5v, X2 is 0v, and the potential at the input position is connected to the A / D converter 91 through Y1 to calculate coordinates. The coordinates in the Y direction are also calculated in the same way by switching circuits. With such a touch panel detection circuit, the pressed position of the touch panel is detected.
[0028]
FIG. 16 is a block diagram of the operation unit unit 205.
In FIG. 16, the address signal from the CPU 100 is taken into the address latch 101 and is controlled here by the signal from the CPU 100. A part of the address signal output from the address latch 101 enters the address decoder 102, where a chip select signal for each IC is generated and used to create a memory map. The address enters the memories 103, 104, 105 such as ROM and RAM and the LCD controller 106, and is used for address designation.
[0029]
On the other hand, a data bus from the CPU 100 is connected to the memories 103 to 105 and the LCD controller 106 to perform bidirectional data communication. In addition to the address bus and data bus from the CPU 100, the LCD controller 106 is connected to an LED driver 107, a keyboard 108, an analog touch panel 109, an LCD module 110, a display data ROM 104, a RAM 105, and the like. The LCD controller 106 creates display data from ROM and RAM data in accordance with a signal from the keyboard 108 and a signal from the touch panel 109, and controls display on the LCD. Further, an optical transceiver 111 is connected to the CPU 100 via an optical fiber connector, and performs communication with the outside.
[0030]
FIG. 1 is an overall block diagram of an image reading apparatus according to an embodiment of the present invention.
In FIG. 1, a CPU 1 on a scanner IPU control unit executes a program stored in a ROM 2 and reads and writes data and the like on a RAM 3 to control the entire scanner / IPU unit. Further, it is connected to the system control unit 4 by serial communication, and performs an operation instructed by transmission / reception of commands and data. Furthermore, the system control unit 4 is connected to the operation display unit 5 by serial communication, and can set an instruction such as an operation mode by a key input instruction from the user.
[0031]
The CPU 1 is connected to a document detection sensor, an HP sensor, a pressure plate opening / closing sensor, a cooling fan, and the like, which are I / O 6, and performs detection and ON / OFF control. The scanner motor driver 7 is driven by the PWM output from the CPU 1, generates an excitation pulse sequence, and drives a pulse motor 8 for document scanning drive.
[0032]
The original image is imaged on a three-line CCD 11 by passing light signals through a plurality of mirrors and lenses by the light output of the halogen lamp 10 driven by the lamp regulator 9. The 3-line CCD 11 is supplied with respective drive clocks by the timing circuit 12 under scanner IPU control, and outputs the RGB odd and even analog image signals to the emitter followers 13 to 15. The signals input from the emitter followers 13 to 15 to the analog processing circuits 16 to 18 are subjected to subtraction CDS in the analog processing circuit, line clamped in the optical black portion of the CCD, and corrected for the output difference between odd and even. Adjust each amplifier gain.
[0033]
After the gain adjustment, the signals are synthesized by a multiplexer, finally input to the A / D converters 19 to 21 after the DC level offset adjustment, digitized, and input to the shading circuit 22. The shading circuit 22 has a function of correcting unevenness in the amount of light in the illumination system and variations in CCD pixel output. The shading-corrected image data is input to the inter-line correction memories 23 and 24, and the image data of the number of lines B and G, B and R of the 3-line CCD 11 is delayed by one or more lines in the read image of BGR. Are output to the dot correction unit 25.
[0034]
In the dot correction unit 25, the image data output from the inter-line correction memories 23 and 24 corrects the deviation of dots within one line of RGB data. The scanner γ correction unit 26 corrects the reflectance linear data using a lookup table method. The corrected image data includes the first route input to the RGB filter, the color conversion process, the scaling process, and the create 30 via the automatic document color determination circuit 28, the automatic image separation circuit 29, and the delay memory 27, and the image. The data memory 33 (R), 34 (G), and 35 (B) are divided into second routes.
[0035]
The image data memory is composed of a DRAM that can store the image data of the scanner's maximum reading area separately for each RGB, and it is possible to capture RGB image data in one scan. This can be handled by outputting from the image memory and returning to the first route.
[0036]
The automatic document color determination circuit 28 inputs ACS (chromatic / achromatic determination) processing to automatic image separation circuit 29 (character / halftone dot) processing. In the ACS processing, black and gray are determined. In image area separation processing, edge determination (determined by the continuity of white and black pixels), halftone dot determination (determined by the repetitive pattern of peak / valley peak pixels in the image), photo determination (image data outside character / halftone dots) And determine the character, print (halftone) area, and photographic area, and send them to the CPU 1. The RGB filter 30, color conversion printer gamma correction unit 31, YMCK filter, and gradation processing parameters Used for switching of coefficients.
[0037]
The image data is input to the RGB filter 30. In the RGB filter 30, filter coefficients such as RGB MTF correction, smoothing, edge enhancement, and through are switched and set by the previous determination area. In the color conversion process, YMCK conversion, UCR, and UCA processes are executed from RGB data. Enlargement / reduction processing is executed on the image data input to the scaling processing and subjected to main scanning. The branch of the image display unit 32 is performed after this processing, and is connected to the image display unit 32 via the I / F.
[0038]
In create, create editing and color processing. In create editing, italics, mirroring, shadowing, hollowing processing, etc. are executed. In color processing, color conversion, specified color erasure, undercolor, etc. are executed. The printer γ correction unit 31 and the YMCK filter set the printer γ conversion and the filter coefficient based on the previous determination area. Dither processing is executed in gradation processing, writing timing setting, image area and white area setting, test pattern generation such as gray scale and color patch can be performed in video control, and final image data is written in LD by writing processing. It is processed so that it can be output to (laser diode) and output to LD.
[0039]
Each function process is connected to the CPU 1, and the setting and operation of each process is executed according to an instruction from the system control unit 4 by a program stored in the ROM 2.
[0040]
Next, the operation of the present embodiment will be described with reference to FIG. 2 differs from FIG. 1 in that analog signals output from the analog processing circuits 16, 17, 18 are input to the A / D converters 19, 20, 21 and input to the background removal circuits 33, 34, 35. In the background removal circuit, the background is removed in real time by using the voltage corresponding to the background of the document as the upper limit reference voltage of the A / D converters 19, 20, and 21.
[0041]
FIG. 3 shows a detailed view of the G background removal circuit 34. The circuits for R and B have the same configuration.
The voltage of the analog signal input from the analog processing circuit 17 for G to the background removal circuit 34 is divided by R1 and R2, accumulated in C1 via the buffer OP1, and peak detection is performed. The time constant for charging is determined by R3 and C1. At the same time, discharge is performed by R4. The discharge time constant is determined by R4 and C1.
[0042]
OP2 amplifies the accumulated voltage with R7 and R8, and inputs the reference voltage Vref of the A / D converter 341, whereby the background can be removed by changing Vref in real time according to the document density. The background removal level can be determined by the amplification factor fixed at R7 and R8 and the offset voltage arbitrarily output by CH1 of the D / A converter 342.
[0043]
The set value of the D / A converter 342 is set by the control program of the CPU 1. The gate signal in the main scanning direction for peak detection is controlled by the PWIND signal from the timing circuit 343. The start of peak detection in the sub-scanning direction is started when TR1 is turned OFF by the AEMODE signal of the timing circuit 343.
[0044]
In the normal mode (a mode in which no background removal is performed), a predetermined voltage is applied from CH2 of the D / A converter 342. In the background removal mode, the background removal can be performed corresponding to the document image by lowering the voltage of CH2 to the effective area of the background removal voltage. Fine adjustment of the background removal level is determined by connecting the set voltage of CH1 of the D / A converter 342 to the CPU1 and setting the set value by the control program by the address and data bus.
[0045]
This can be dealt with by adjusting the background level with respect to the reference document at the time of factory adjustment and inputting the set value of CH1. In addition, if the set value is registered in the SP mode, it can be adjusted even when the illuminance distribution changes and the background removal level changes when the serviceman changes lamps or other optical components. It is.
[0046]
  Fig. 4 shows the entire background removal mode without pre-scan.(First skin removal mode)It is a timing chart of time.
  The PWIND width is a fixed value, and the AEMODE performs the background removal corresponding to the document image in real time while charging and discharging the background voltage with the selection SW turned ON over the same reading area as the FGATE.
  Fig. 5 shows the density area specified background removal mode with prescan.(Second skin removal mode)It is a timing chart which shows operation at the time.
[0047]
A flowchart for selecting the background removal mode is shown in FIG.
In FIG. 6, when the background removal mode selection key is pressed, the entire background removal mode and the entire density designated background removal mode described above are divided, and the respective set values are set.
[0048]
FIG. 7 shows a flowchart when the entire-surface density designated background removal mode is selected.
In FIG. 7, when the whole-surface density designated background removal mode is selected, the standby state is kept until the pre-scan key is pressed. When the pre-scan key is pressed, a normal scan pre-scan is executed and displayed on the display. When the scanned image data is displayed on the display, lower the contrast adjustment or brightness adjustment so that the background density is easy to recognize, so that you do not want to remove the background even if the gradation of the display editor is not high. Adjust so that you can distinguish.
[0049]
Next, when the area selection key is pressed, coordinates are input from the touch panel on the display editor. When the coordinates are input, the count values of the main scanning start X1 and end X2 and the sub-scanning start Y1 and end Y1 + Y2 are calculated from the input coordinates. The main scan coincides with the start and end of PWIND. The start of sub-scanning is equal to AEMODE, but the end is controlled by the number of times the PWIND signal is generated Y2.
[0050]
Next, the mode selection SW (analog SW) is turned OFF, the discharge circuit is opened, and a pre-scan for sampling the background density level of the designated area is executed. The PWIND signal is generated a specified number of times in the specified area, and the AEMODE signal operates in the ON state to hold the background density voltage. As a result, the Vref of the AD converter is fixed to the specified density level.
[0051]
By executing the main scan in this state, the entire background can be removed at a specified density. Further, fine adjustment of the background removal can change the offset voltage of CH1 of the D / A converter by software setting from the CPU. For example, it is possible to adjust by inputting a set value from the operation unit or changing the set value from the SP mode.
[0052]
【The invention's effect】
  As explained aboveBookAccording to the present invention, even when the original to be read is an original obtained by arbitrarily cutting a newspaper, an original obtained by cutting a newspaper or the like on a white paper, or a special original that cannot be removed such as an original having total reflection light, Since the density at which the background is desired to be set can be set, there is an effect that the background can be satisfactorily removed even for special documents.
[0053]
  Also,BookAccording to the invention, there is an effect that it is possible to set accurately by the display editor by displaying the density level desired to remove the background by pre-scanning.
  In addition, even if the newspaper is shifted when a document with an arbitrarily cut newspaper is placed on the contact glass and the platen is closed, the background removal density area is specified for the scanned image. The effect is that there is no need to repeat the reading over and over.
  Further, in the case of a digital copying machine, every time repositioning and reading are repeated, misprinting occurs, and consumables such as paper and toner are wasted, but the effect of preventing these can be obtained.
[0054]
  Also,BookAccording to the invention, if it is not the above-mentioned special manuscript, there is no problem even if the full-peak value background removal mode without pre-scan which is normal background removal is performed, so there is no problem, and there is no special manuscript. By having a mode for preventing the above-described problems in the case, an effect capable of meeting user needs can be obtained.
[0055]
  Also,BookAccording to the invention, even when the display editor has no gradation, the contrast and brightness of the display unit during pre-scanning when the background removal mode is selected so that the area can be set by grasping the density of the background part.WhenBy lowering the value, the user can easily adjust the background removal density region.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration during operation of the image reading apparatus according to the embodiment of the present invention.
FIG. 3 is a configuration diagram of a background removal circuit.
FIG. 4 is a timing chart showing an operation in a background removal mode.
FIG. 5 is a timing chart showing an operation in a density area designation background removal mode with pre-scan.
FIG. 6 is a flowchart showing an operation of selecting a background removal mode.
FIG. 7 is a flowchart showing an operation when the entire-surface density designated background removal mode is selected.
FIG. 8 is a block diagram showing an embodiment of an image forming apparatus for carrying out the present invention.
FIG. 9 is a block diagram illustrating a configuration of an image display unit.
FIG. 10 is a configuration diagram of an image display unit.
FIG. 11 is a configuration diagram of an operation unit.
FIG. 12 is a configuration diagram of a display surface of an LCD display.
FIG. 13 is a configuration diagram showing an example of screen development by pressing a scaling key.
FIG. 14 is a configuration diagram of a touch panel detection circuit.
FIG. 15 is a configuration diagram illustrating a setting state of a touch panel detection circuit.
FIG. 16 is a block diagram illustrating a configuration of an operation unit.
[Explanation of symbols]
1 CPU
2 ROM
3 RAM
4 System control unit
5 Operation display section
6 I / O
7 Motor driver
8 Pulse motor
9 Lamp regulator
10 Halogen lamp
11 3-line CCD
12 Timing circuit
16 Analog processing circuit (for R)
17 Analog processing circuit (for G)
18 Analog processing circuit (for B)
21 A / O converter (for B)
22 Shading circuit (RGB)
23 Line-to-line correction memory (for R)
24 Line correction memory (for G)
25 dot correction unit
26 Scanner γ correction unit (RGB)
27 Delay memory (RGB)
28 Automatic document color judgment circuit
29 Automatic image separation circuit
30 RGB filters
31 Printer gamma correction unit
32 Image display
33 Image data memory (for R)
34 Image data memory (for G)
35 Image data memory (for B)
36 I / O inverter
341 A / D Converter
342 D / A Converter
343 Timing circuit

Claims (3)

An image reading apparatus provided with a first background removal mode for removing the background based on the background density of the entire surface of the original image and a second background removal mode for removing the background based on the background density of a specific area of the original image. There,
Photoelectric conversion means for optically reading a document image and converting it into an image signal;
A / D conversion means for converting the image signal read by the photoelectric conversion means into digital image data;
Image display means for displaying image data obtained by converting the read document image;
Changing means for changing the contrast and / or brightness of the display means;
Coordinate designating means for designating a specific area on the document image based on the image data displayed on the display means ;
Selecting means for selecting the first background removal mode and the second background removal mode;
When the first background removal mode is selected by the selection unit, the background is removed based on the background of the entire original image, and when the second background removal mode is selected, a pre-scan is performed. A background removal means for performing background removal processing of the read document image based on the background density of a specific area of the document image designated by the coordinate designation means based on image data of the document image displayed on the image display means ; Prepared,
The changing means is characterized in that when the second background removal mode is selected and the pre-scan is performed and image data of the original image is displayed on the display means, the contrast and / or brightness of the display means is lowered. Image reading device. The image reading apparatus according to claim 1, wherein the background removing unit performs a background removing process by changing a reference level of the A / D conversion unit based on a background density. An image forming apparatus comprising the image reading apparatus according to claim 1.

Images