JP2002084423A - Image data processor, image reader and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor that can automatically eliminate a high background level over a wide range where a background level is fluctuated even on one line, process characters and a line drawing of a blue print clipped and pasted on white paper so as to be sharply copied, and select optimum background elimination processing corresponding to a large variety of the background of an original image. SOLUTION: Applying weight summation to target image data IDn and a background level JODn-1 employed for preceding image data calculates a background level JODn to be applied to the target image data and also calculates background elimination data AODn=IDn-M.JODn. A 1st or 2nd ratio that is expressed by a fraction whose numerator is a maximum value HD taken by data and whose denominator includes the background level M.JODn is multiplied with the background elimination data AODn (Equation (3) or (4)) to correct the contrast. An operation section OPB can designate which of the Equation (3), (4) and either of them automatically selected. In the case of automatically selecting either of them, the Equation (3) is used when the background level JOD is high and the Equation (4) is used when the background level JOD is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing digital image information, that is, image data so as to clearly express an image, and an image reading apparatus and an image forming apparatus using the same. The present invention relates to a digital copying machine suitable for processing image data of a low-contrast character document, such as a blue-printed document, whose background density fluctuates greatly, into image data that clearly reproduces a character image.

[0002]

2. Description of the Related Art In recent years, digitization of documents has been advanced, and there has been an increasing demand for reading and digitizing paper documents with a scanner or the like. Especially in the design and architectural fields, there is a demand for digitizing and storing blueprints. In a blueprint, a density is present in a background portion which is originally unnecessary information, and the background may not be completely removed by a normal scanner or copy. In some cases, a blueprint is cut and pasted on a white sheet of paper. In this case, only the blueprint is darkened, and the readability of an image in a copy area corresponding to the blueprint is extremely reduced. For example, since the read image data Idn fluctuates as shown in FIG. 17 and the fluctuation range of the background level is large, when the image data Idn is binarized with the fixed threshold value THp, the binary image data, that is, the image signal As shown in (1), in an area where the background is dark, the image signal is continuously at a high level 1 (black), and a high-density image cannot be expressed. In an area where the background is thin, the image signal continuously becomes low level 0 (white), and the thin image disappears.

Japanese Patent Application Laid-Open No. 6-31359 discloses a method in which a low density peak is detected on each line of an image scan, and a value obtained by adding an offset value to an average value of the low density peaks of each line is set as a threshold. Background Art A background removal apparatus that removes an image density as a background is disclosed.

[0004] Japanese Patent Application Laid-Open No. Hei 9-186872 discloses a background removing apparatus which detects a white peak value in a certain area and sets it as a basic background level.

[0005]

However, Japanese Patent Application Laid-Open No.
The background removing device described in Japanese Patent No. -311359 removes the same background data for each line of image scanning.
It cannot cope with the case where the background density varies on one line.
In the device disclosed in Japanese Patent Application Laid-Open No. 9-186872, a white peak value in a certain area is used as a basic background level, and the background density cannot be calculated or removed following a fluctuating background.

SUMMARY OF THE INVENTION It is a first object of the present invention to effectively remove a background of image data representing an image having a relatively wide range of background level fluctuation, for example, a background level fluctuation even on one line. . Specifically, even when the density of the background changes drastically, for example, when a blueprint is cut and pasted on a white paper, the background can be effectively removed without requiring special inspection of the entire image by pre-scanning etc. Is a second purpose. A third object is to convert image data of an image in which high-density and low-density backgrounds are mixed into image data that clearly expresses a binary image such as a character or a line drawing. A fourth object is to make it possible to select image data conversion characteristics corresponding to various originals, and a fifth object is to automatically select image data conversion characteristics in correspondence with background characteristics. It is desirable to convert character, line drawing, etc. of a document having thin portions into image data which can be quantized satisfactorily, in particular, without missing an image in a high density background portion and / or a thin image in a low density portion. 6. Objective A seventh object is to make it possible to select contrast correction and to select, for example, character emphasis on a portion with a high background density or character emphasis on a low portion.

[0007]

Means for Solving the Problems (1) At least the target image data (IDn) and the background level (JODn-1) defined by the image data preceding the target image data are weighted and added to the target image data. Ground level (J
ODn) (IPP; 2 in FIG. 10); and the difference (AODn) between the target image data (IDn) and the background level (JODn) directed thereto is defined by the background level (JODn). Coefficient (HD / (HD-PM)
Calculation means (IPP; multiplying by JODn) or HD / M · JODn)
An image data processing apparatus (IPP; BDP in FIG. 10) including: (5/9/11/12 in FIG. 10).

To facilitate understanding, symbols of corresponding elements or corresponding items in the embodiments shown in the drawings and described later are added for reference in parentheses. The same applies to the following.

According to this, the image data of interest (IDn)
A background level (JODn) is determined, and the background level (JODn) indicates a uniform or smoothed change in the image data when viewed in the sequential switching flow of the image data of interest. A dark level (high level) is a light level (low level) in an area where the background is light. By adjusting the value of the weight K given to the image data of interest (IDn), a background level (JODn) that follows only a background density change having a long fluctuation cycle other than a level fluctuation in each pixel or several pixel groups corresponding to an image. Is obtained. This background level (JODn), primary background level (JODn)
n) is closely related to the image level, so in the preferred embodiment of the present invention, 0 <M <to the primary background level (JODn) to provide an offset from the image level.
Multiplied by an adjustment value M of 1 (M · JOD)
n).

The background level addressed to the target image data (IDn) is thus generated by smoothing or smoothing the preceding image data including the target image data (IDn), and following the image data in pixel units. Since the background level is updated, the reliability of representing the background of image data representing an image in which the background level variation is relatively wide such that there is a background level variation even on one line is high.

Then, the calculation means (IPP; 5/9 in FIG. 10)
/ 11/12) is the difference (A) between the target image data (IDn) and the secondary background level (M · JODn) addressed to it.
ODn = Idn−M · JODn) and the background level (J
ODn) (HD / (HD-PM-JODn) or
HD / M / JODn). As a result, the reduction in the level of the processed image data due to the subtraction of the secondary background level (M · JODn) is corrected, and the contrast is enhanced. For example, even when the background density changes drastically, such as when a blueprint is cut and pasted on a white sheet of paper, the background can be effectively removed without requiring special inspection of the front surface of the image by pre-scanning or the like. It is possible to convert image data of an image in which high-density and low-density backgrounds are mixed into image data that clearly expresses a binary image such as a character or a line drawing.

[0012]

(2) The image data processing apparatus according to (1), further comprising means for adjusting the weight K of the weighting. By increasing the value of the weight K given to the target image data (IDn) and decreasing the weight 1-K given to the background level (JODn-1) defined by the preceding image data, the background level (JODn) can be reduced. Data (IDn)
, The response speed is fast, and conversely, the response speed is slowed by decreasing the weight K. By adjusting the weight K, it is possible to set a background level calculation characteristic that responds sensitively to background density fluctuation and is insensitive to image density fluctuation.

(3) The coefficient (HD / (HD−P−M · JODn) or HD / M · JODn) includes a product (M · JODn) obtained by multiplying the background level by an adjustment value M in a denominator. It is a ratio that can be expressed as a fraction.

According to this, for example, when the numerator is set to the maximum value (HD) that can be represented by the number of bits determined in the processed image data (CODn), the processed image data (CODn) becomes the maximum. The value is amplified in proportion to the value (HD), that is, in proportion to the number of bits of the processed image data, and is amplified according to the background level (JODn) (HD / (HD−
P−M · JODn): Equation) or attenuation (HD / M · JODn: Equation). The mode of amplification (expression) emphasizes the image data of the dark background density portion and suppresses the image data of the light background density portion, so that there is an effect that the image of the dark background density portion is preferentially extracted. The mode of attenuation (expression) suppresses image data of a dark background density portion and enhances image data of a light background density portion, and thus has an effect of preferentially extracting an image of a light background density portion.

(4) A first ratio (HD / (HD-P) which can be expressed as a fraction including a value obtained by subtracting a product obtained by multiplying the background level by the adjustment value M from the set value, to the denominator. −M ・ JOD
n): Expression) and a second ratio (HD / M · JODn: Expression) in which the denominator is the product of the background level multiplied by the adjustment value M, and the calculating means determines that the background level (JODn) is the set value. The first ratio is set when the difference is equal to or more than TH1, and the second ratio is set when the difference is smaller than the set value TH1.
Is multiplied by the difference between the density represented by the image data and the background level.

According to this, the amplification using the first ratio (
Applying the aspect of (Expression) to the dark background density portion and applying the aspect of the attenuation (Expression) using the second ratio to the thin background density portion is based on the comparison result between the background level (JODn) and the set value TH1. Selected automatically. Therefore, the image data of the dark background density portion is emphasized, and the image data of the light background density portion is also emphasized, so that the image data (CODn) that clearly shows both the image of the dark background density portion and the image of the light background density portion is clear. can get.

(5) The image data processing apparatus according to the above (1), (2), (3) or (4); and an image data processing device which reads an original surface, converts the original surface into digitally converted image data, Means for providing to the device (200);

According to this, for example, an original having a high density and a low density background mixed together, such as a blue print original, is read, and image data which clearly expresses a binary image such as a character or a line drawing on the original can be obtained. .

(6) The image reading device according to the above (5);
And a printer (400) for forming an image represented by the image data output by the image data processing device on a sheet.

According to this, it is possible to obtain a clear copy of a binary image such as a character or a line drawing on an original such as a blue-printed original or the like in which a high density and a low density background are mixed.

(7) The coefficient includes a maximum value (HD) that can be represented by the number of bits defined in the processed image data in the numerator, and a fraction (HD / DOD) that includes the background level (JODn) in the denominator.
(HD-PM-JODn): The image data processing apparatus according to the above (1), wherein the ratio is a ratio that can be represented by the following expression, and the denominator includes the background level (JODn) and the addition / subtraction value P. According to this, the denominator value increases and decreases according to the increase and decrease of the addition / subtraction value P, and the value of the ratio changes. That is, the image data (COD
The amplification factor of n) changes. The increase / decrease of the addition / subtraction value P adjusts the amplification factor regardless of the background level being high or low. By adjusting the addition / subtraction value P, the saturation density of the image data (CODn) from which the background has been removed can be adjusted. In addition, image data (CODn) from which background has been removed corresponding to various originals
Can be adjusted.

(8) The coefficient is calculated by adding the maximum value (HD) to the numerator.
And the denominator is subtracted from the maximum value (HD) by the product of the background level multiplied by the adjustment value M (M · JODn) (HD-M · JODn).
The image data processing device according to the above (1), wherein the ratio (expression) can be expressed by a fraction including According to this, the processed image data (CODn) is amplified in proportion to the maximum value (HD), that is, amplified in proportion to the number of bits of the processed image data, and the background level (JODn) (HD / (HD-PM-JODn): Formula). As a result, the image data of the dark background density portion is emphasized, and the image data of the light background density portion is suppressed, so that there is an effect that the image of the dark background density portion is preferentially extracted.

(9) The image data processing apparatus according to the above (8), wherein the denominator further includes an addition / subtraction value P. According to this, the saturation density of the image data (CODn) from which the background is removed can be adjusted by adjusting the addition / subtraction value P. In addition, image data (CODn) from which background has been removed corresponding to various originals
Can be adjusted.

(10) In the coefficient, the numerator is the maximum value (H
D), wherein the denominator is a ratio (HD / M · JODn: expression) that is a product (M · JODn) of the background level multiplied by the adjustment value M (HD). According to this, the processed image data (CODn) is amplified in proportion to the maximum value (HD), that is, amplified in proportion to the number of bits of the processed image data, and the background level (JODn) Is attenuated according to Therefore, the image data of the dark background density portion is suppressed and the image data of the light background density portion is emphasized, so that there is an effect that the image of the light background density portion is preferentially extracted.

(11) The coefficient includes the maximum value in the numerator.
(HD), a first ratio (formula) that can be expressed as a fraction including a value obtained by subtracting a product obtained by multiplying the background level by the adjustment value M from the maximum value in the denominator, and the numerator being the maximum value; The second ratio (formula) that is the product of the denominator and the background level multiplied by the adjustment value M
And the apparatus further determines one of the first and second ratios as a difference (AOD) of the density represented by the image data with respect to the background level.
n) means for setting the ratio to be multiplied by (OPB 80i, 80j),
The image data processing apparatus according to the above (1), comprising:

When the first ratio (formula) is set, the processed image data (CODn) is amplified (HD / (HD-PM-JODn): formula) according to the background level (JODn). Since the image data of the dark background density portion is emphasized and the image data of the light background density portion is suppressed, the priority extraction of the image of the dark background density portion is realized. When the second ratio (expression) is set, the processed image data (COD
n) is the attenuation (HD / M · JOD) according to the ground level (JODn)
n: expression), the image data of the dark background density portion is suppressed, and the image data of the light background density portion is emphasized, so that the preferential extraction of the image of the light background density portion is realized. Such conversion characteristics can be selectively set by setting means (OPB 80i, 80j) in accordance with the image quality of the document.

(12) The coefficient includes the maximum value in the numerator.
(HD), a first ratio (formula) that can be expressed as a fraction including a value obtained by subtracting a product obtained by multiplying the background level by the adjustment value M from the maximum value in the denominator, and the numerator being the maximum value; The second ratio (formula) that is the product of the denominator and the background level multiplied by the adjustment value M
The apparatus further includes means for specifying a first ratio, a second ratio, and the use of either of the two, wherein the computing means is configured to output the first ratio when the use of the first ratio is specified. Is multiplied by the difference between the density represented by the image data and the background level, and when the use of the second ratio is specified, the second
Is multiplied by the difference of the density represented by the image data with respect to the background level. When the use of both is designated, the first ratio is set when the background level is equal to or higher than the set value TH1, and Is an image data processing apparatus according to the above (1), wherein the second ratio is multiplied by a difference in density represented by the image data with respect to the background level.

This is a combination of the above-mentioned mode (11) and the above-mentioned mode (4) so that the above-mentioned mode (4) can be selectively carried out. Therefore, the functions and effects described in the above-mentioned modes (4) and (11) can be obtained. .

(13) An apparatus (200) for reading a document surface and converting it into a digitally converted image signal, means (IPP; 2, 3 in FIG. 10) for calculating a background level (JODn), and background removal (IPP; 3 in FIG. 10), and the background level (JODn) is calculated in pixel units, and the calculation result can be adjusted with one or more parameters (K, M). Image processing device. According to this, accurate background removal can be realized by adjusting the parameters (K, M).

(14) Means for correcting the image data (AODn) from which the background level has been removed (IPP: 5 in FIG. 10)
/ 9/11/12), wherein the correction means includes one or more parameters (HD, P, T) for adjusting the correction characteristics.
(1) The image processing apparatus as described in (13) above, wherein According to this, the correction of the image data (AODn) can be applied to various originals.

(15) The correction by the correction means is performed by adding the coefficient (HD / HD) to the image data (AODn) from which the background level has been removed.
(14) The image processing apparatus according to the above (14), wherein the contrast is multiplied by (HD-PM JODn) or HD / M JODn. According to this, the image density after the background removal can be improved to a desired density by manipulating the coefficient.

(16) The image processing apparatus according to the above (15), wherein the coefficient can be changed by one or more operation parameters (HD, P) when correcting the contrast. According to this, it is possible to set the optimum contrast correction for the document. Since the saturation density can be adjusted by the parameters (HD, P), it is possible to thicken a thin original as a whole with a simple calculation.

(17) An apparatus (200) for reading a document surface and converting it into a digitally converted image signal, means (IPP; 2, 3 in FIG. 10) for calculating a background level (JODn), and background removal Means (IPP; 3, FIG. 10) and means (IPP;
The background level calculation means calculates the background level (JODn) for each pixel, and adjusts the calculation result using one or more parameters (K, M). The image processing apparatus, wherein the density correction unit enhances the contrast of an image having a low background level. According to this, the background removal can be realized with high accuracy, it is possible to deal with a document having various density distributions, and it is possible to prevent image data loss in a portion having a low background density.

(18) The density correction means can selectively perform two or more types of correction calculations (expressions, expressions).
7) The image processing apparatus according to the above. According to this, the output image can be adjusted according to the request.

(19) Calculated background level (JODn)
Accordingly, the density correction unit switches the image correction calculation formula. According to this, there is no missing image, the background density is suppressed and its influence is small,
A balanced image data enhancement effect is obtained.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0037]

FIG. 1 shows an outline of a mechanism according to an embodiment of the present invention. This embodiment is a digital full-color copying machine.
Color image reading device (hereinafter, referred to as scanner) 20
0 denotes an image of the original 180 on the contact glass 202, the illumination lamp 205, the mirror group 204A, 204B, 20
4C and the like, and the color sensor 2 via the lens 206.
07, the color image information of the original is converted into, for example, blue (hereinafter, referred to as B), green (hereinafter, referred to as G).
And red (hereinafter, referred to as R) color-separated light, and converted into an electrical image signal. Color sensor 207
Is composed of a three-line CCD sensor in this example, and reads B, G, and R images for each color. Scanner 20
Based on the B, G, and R color separation image signal intensity levels obtained at 0, color conversion processing is performed by an image processing unit (not shown), and black (hereinafter, referred to as Bk) and cyan (hereinafter, referred to as C) ), Magenta (hereinafter M) and yellow (hereinafter Y) recording color information.

Using this color image data, a color image recording device (hereinafter referred to as a color printer) 4 described below
00, the images of Bk, C, M, and Y are superimposed on the intermediate transfer belt and transferred to a transfer sheet. The scanner 200 receives the scanner start signal at the same timing as the operation of the color printer 400, and
Illumination / mirror optical system including mirror group 05, mirror group 204A, 204B, 204C, etc.
Image data of one color is obtained for each scan. Then, each time, while visualizing the images sequentially with the color printer 400, these are superimposed on the intermediate transfer belt to form four full-color images.

A writing optical unit 401 as an exposure unit of the color printer 400 converts color image data from the scanner 200 into an optical signal, performs optical writing corresponding to a document image, and applies an electrostatic charge to the photosensitive drum 414. Form a latent image. The optical writing optical unit 401 includes a laser light emitter 441, a light emission drive control unit (not shown) for driving the light emission, a polygon mirror 443, a rotation motor 444 for rotating the same, a fθ lens 442, a reflection mirror 446, and the like. Have been. Photoconductor drum 414
Rotates in the counterclockwise direction as indicated by the arrow, around which is a photoconductor cleaning unit 421, a neutralization lamp 414M, a charger 419, a potential sensor 414D for detecting a latent image potential on the photoconductor drum, A selected developing device of the revolver developing device 420, a development density pattern detector 414P, an intermediate transfer belt 415, and the like are arranged.

The revolver developing device 420 includes a BK developing device 420K, a C developing device 420C, an M developing device 420M, and a Y developing device 420Y, and a revolver rotating drive for rotating each developing device in a counterclockwise direction as indicated by an arrow. (Not shown). In order to visualize the electrostatic latent image, each of these developing devices rotates developing sleeves 420 KS and 420 which rotate by contacting the ears of the developer with the surface of the photosensitive drum 414.
Assemble the developer with CS, 420MS, 420YS
It is composed of a developing paddle that rotates for stirring. In a standby state, the revolver developing device 420 is set at a position where development is performed by the BK developing device 420, and when a copying operation is started, reading of BK image data is started by the scanner 200 at a predetermined timing, and this image is read. On the basis of the data, optical writing / latent image formation by laser light starts. Hereinafter, the electrostatic latent image based on the Bk image data is referred to as a Bk latent image. The same applies to each of the C, M, and Y image data. In order to enable development from the tip of this Bk latent image,
Before the leading end of the latent image reaches the developing position of the Bk developing device 420K, the rotation of the developing sleeve 420KS is started to develop the Bk latent image with Bk toner. Thereafter, the developing operation of the Bk latent image area is continued. When the rear end of the latent image passes the Bk latent image position, the developing operation of the next color developing unit is immediately performed from the developing position of the Bk developing unit 420K. The revolver developing device 420 is driven and rotated to the position. This rotation operation is completed at least before the leading end of the latent image based on the next image data arrives.

When the image forming cycle is started, the photosensitive drum 414 rotates counterclockwise as indicated by an arrow, and the intermediate transfer belt 415 is rotated clockwise by a drive motor (not shown). Move. Intermediate transfer belt 41
5, the BK toner image formation, the C toner image formation, the M toner image formation, and the Y toner image formation are sequentially performed, and finally, on the intermediate transfer belt 415 in the order of BK, C, M, and Y. , A toner image is formed. The formation of the BK image is performed as follows. That is, the charger 41
9 uniformly charges the photosensitive drum 414 with a negative charge to about -700 V by corona discharge. Subsequently, the laser diode 441 performs raster exposure based on the Bk signal. When the raster image is exposed in this manner, in the initially exposed portion of the photosensitive drum 414 that is uniformly charged, the charge proportional to the amount of exposure light disappears, and an electrostatic latent image is formed. The toner in the revolver developing device 420 is negatively charged by stirring with the ferrite carrier, and the BK developing sleeve 420KS of the present developing device is charged.
Is biased by a power supply circuit (not shown) with respect to the metal base layer of the photosensitive drum 414 to a potential at which a negative DC potential and an AC are superimposed. As a result, no toner adheres to the portion of the photosensitive drum 414 where the charge remains, and Bk is applied to the portion having no charge, that is, the exposed portion.
The toner is attracted, and a Bk visible image similar to the latent image is formed. The intermediate transfer belt 415 includes a driving roller 415D, a transfer facing roller 415T, and a cleaning facing roller 415.
C and a group of driven rollers, and is driven to rotate by a drive motor (not shown). Now, the photosensitive drum 4
The Bk toner image formed on the belt 14 is transferred onto a surface of an intermediate transfer belt 415, which is driven at a constant speed in a state of contact with the photoconductor, by a belt transfer corona discharger (hereinafter, referred to as a belt transfer unit) 4.
16 transferred. Hereinafter, the transfer of the toner image from the photosensitive drum 414 to the intermediate transfer belt 415 is referred to as belt transfer. Some untransferred residual toner on the photoconductor drum 414 is cleaned by the photoconductor cleaning unit 421 in preparation for reuse of the photoconductor drum 414. The collected toner is stored in a waste toner tank (not shown) via a collection pipe.

On the intermediate transfer belt 415, the toner images of Bk, C, M, and Y, which are sequentially formed on the photosensitive drum 414, are sequentially aligned on the same surface, and a four-color superposed belt transfer image is formed. After that, batch transfer is performed on transfer paper by a corona discharge transfer device. By the way, the photosensitive drum 41
On the fourth side, the process proceeds to the C image forming process after the BK image forming process.
Starts reading of C image data, and a C latent image is formed by laser light writing using the image data.
The C developing device 420C moves the Bk
After the rear end portion of the latent image has passed and before the leading end of the C latent image has arrived, the rotating operation of the revolver developing device is performed to develop the C latent image with C toner. Thereafter, the development of the C latent image area is continued. When the rear end of the latent image has passed, the revolver developing device 420 is driven in the same manner as in the case of the Bk developing device described above,
C developing device 420C is sent out, and the next M developing device 420M
Is located at the developing position. This operation is also the next M
This is performed before the leading end of the latent image reaches the developing section. In the process of forming the M and Y images, the operations of reading the image data, forming the latent image, and developing are in accordance with the processes of the Bk image and the C image described above, and a description thereof will be omitted.

The belt cleaning device 415U includes an inlet seal, a rubber blade, a discharge coil, and a mechanism for contacting / separating the inlet seal and the rubber blade. 1
After the Bk image of the color is transferred to the belt, while the images of the second, third, and fourth colors are transferred to the belt, the entrance seal, the rubber blade, and the like are separated from the intermediate transfer belt surface by the blade contact / separation mechanism. .

A paper transfer corona discharger (hereinafter, referred to as a paper transfer device) 417 uses an AC corona discharge method to transfer the superposed toner image on the intermediate transfer belt 415 to transfer paper.
+ DC or a DC component is applied to the transfer paper and the intermediate transfer belt.

Transfer paper of various sizes is stored in a transfer paper cassette 482 in the paper feed bank.
The sheet is fed and conveyed in the direction of the pair of registration rollers 418R by 83. Reference numeral 412B2 indicates a paper feed tray for manually feeding OHP paper, thick paper, and the like. At the time when the image formation is started, the transfer paper is fed from any of the paper feed trays, and is waiting at the nip of the pair of registration rollers 418R. Then, when the leading end of the toner image on the intermediate transfer belt 415 approaches the paper transfer unit 417, the registration roller pair 418R is driven so that the leading end of the transfer paper coincides with the leading end of the image, and the paper and the image are transferred. Matching is performed. In this way, the transfer paper is superimposed on the color superimposed image on the intermediate transfer belt, and passes over the paper transfer unit 417 connected to the positive potential. At this time, the transfer paper is charged with a positive charge by the corona discharge current, and most of the toner image is transferred onto the transfer paper. Subsequently, when the transfer paper passes through a separation neutralizer with a neutralization brush (not shown) disposed on the left side of the paper transfer unit 417, the transfer paper is neutralized, and the intermediate transfer belt 415 is removed.
From the paper transport belt 422. The transfer paper on which the four-color superimposed toner image has been collectively transferred from the intermediate transfer belt surface is conveyed to a fixing device 423 by a paper conveyance belt 422, and the toner is conveyed to a nip portion between a fixing roller 423A and a pressure roller 423B controlled to a predetermined temperature. The image is fused and fixed
The paper is sent out of the main body by the discharge roll pair 424, and is stacked face up on a copy tray (not shown).

The photosensitive drum 414 after the belt transfer
Has its surface cleaned by a photoconductor cleaning unit 421 including a brush roller, a rubber blade, and the like.
Further, the charge is uniformly removed by the charge removing lamp 414M. Further, the intermediate transfer belt 415 after transferring the toner image to the transfer paper
Again, the blade is pressed by the blade contact / separation mechanism of the cleaning unit 415U to clean the surface.
In the case of the repeat copy, the operation of the scanner and the image formation on the photoconductor are continued from the first-color image process on the first sheet, and then proceed to the first-color image process on the second sheet at a predetermined timing. In the case of the intermediate transfer belt 415, the second Bk toner image is belt-transferred to an area whose surface has been cleaned by the belt cleaning device, following the batch transfer process of the first four-color superimposed image onto transfer paper. So that Thereafter, the operation is the same as that of the first sheet.

The color copying machine shown in FIG. 1 is provided from a host such as a personal computer via a LAN or a parallel I / F.
When a print data is provided through the printer, the print data can be printed out (image output) by the color printer 400, and the image data read by the scanner 200 can be transmitted to a remote facsimile, and the received image data can be printed out. It is a color copier. This copier is connected to a public telephone network via a private branch exchange PBX,
Via a public telephone network, facsimile communication and communication with a management server of a service center can be performed.

FIG. 2 shows an electric system of the copying machine shown in FIG. Document scanner 200 for optically reading a document
In the reading unit 4, the reflected light of the lamp irradiation on the document is condensed on the light receiving element 207 by a mirror and a lens in the reading unit 4. The light receiving element (CCD in this embodiment) is provided in a sensor board unit SBU (hereinafter simply referred to as SBU), and an image signal converted into an electric signal in the CCD is a digital signal on the SBU, ie, a read image. After the data is converted to data, the SBU converts the data from the compression / decompression and data interface control unit CDIC (hereinafter simply referred to as CDIC).
).

That is, the image data output from the SBU is input to the CDIC. The transmission of image data between the functional device and the data bus is entirely controlled by the CDIC. In other words, the CDIC uses the SB
U, the parallel bus Pb, and data transfer between the image signal processing device IPP (hereinafter simply referred to as IPP), and image data transfer between the system controller 6 which controls the entire digital copying machine shown in FIG. And communication regarding other controls. The system controller 6 and the process controller 1 communicate with each other via the parallel bus Pb, the CDIC, and the serial bus Sb. The CDIC performs data format conversion for a data interface between the parallel bus Pb and the serial bus Sb inside the CDIC.

The image data read from the SBU is CDI
C, the signal is transferred to the IPP, and the IPP corrects the signal deterioration (signal deterioration of the scanner system: distortion of the read image data due to the scanner characteristics) due to the quantization into the optical system and the digital signal. Output to CDIC is
The image data is transferred to the copy function controller MFC and written in the memory MEM. Alternatively, the processing returns to the IPP processing system for printer output.

That is, the CDIC stores the read image data.
A job in which the data is stored in the memory MEM for reuse, and a job in which the data is output to the video data control VDC (hereinafter simply referred to as VDC) without being stored in the memory MEM.
There is a job that performs image formation output at 0. As an example of storing the data in the memory MEM, when a plurality of originals are copied, the reading unit 4 is operated only once to read the read image data.
Data is stored in the memory MEM, and the stored data is read a plurality of times. As an example without using the memory MEM,
When copying only one original, it is only necessary to process the read image data as it is for the printer output, and there is no need to write the data in the memory MEM.

First, if the memory MEM is not used, the IP
The image data transferred from P to CDIC is
C returns to IPP. Image quality processing (FIG. 3) for converting luminance data by CCD into area gradation in IPP
15) is performed. The image data after the image quality processing is transferred from the IPP to the VDC. For the signal changed to the area gradation,
Post-processing relating to dot arrangement and pulse control for reproducing dots are performed by VDC, and a reproduced image is formed on transfer paper in the image forming unit 5 of the laser printer 400.

When the data is stored in the memory MEM and additional processing such as rotation in the image direction or image synthesis is performed at the time of reading from the memory MEM, the data transferred from the IPP to the CDIC passes from the CDIC via the parallel bus Pb. And transmitted to an image memory access control IMAC (hereinafter simply referred to as IMAC). Here, access control of the image data and the memory module MEM (hereinafter simply referred to as MEM) is performed based on the control of the system controller 6, and an external personal computer PC
It expands print data (hereinafter simply referred to as PC) (character code / character bit conversion) and compresses / decompresses image data for effective use of memory. The data sent to the IMAC is stored in the MEM after data compression, and the stored data is read as necessary. The read data is expanded, returned to the original image data, and returned from the IMAC to the CDIC via the parallel bus Pb.

After the transfer from the CDIC to the IPP, the IPP
The image forming unit 5 performs the image processing and the pulse control with the VDC, and the image forming unit 5 forms a visible image (toner image) on the transfer paper.

In the flow of the image data, the composite function of the digital copying machine is realized by the bus control by the parallel bus Pb and the CDIC. The FAX transmission function, which is one of the copying functions, transmits the image data read by the scanner 200 to the IPP.
Performs image processing on CDIC and parallel bus Pb
FAX control unit FCU (hereinafter simply referred to as FCU)
(Referred to as). Public line communication network PN at FCU
(Hereinafter simply referred to as PN), and the data is transmitted to the PN as FAX data. In FAX reception, line data from the PN is converted into image data by the FCU, and is transferred to the IPP via the parallel bus Pb and the CDIC. In this case, no special image quality processing is performed, dot rearrangement and pulse control are performed in the VDC, and a visible image is formed on the transfer paper in the image forming unit 5.

In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function, and a printer output function, operate in parallel, the allocation of the reading unit 4, the imaging unit 5, and the right to use the parallel bus Pb to the job is performed by the system. It is controlled by the controller 6 and the process controller 1.

The process controller 1 controls the flow of image data, and the system controller controls the entire system and manages the activation of each resource. This digital copying function is selected and input on the operation board OPB to select the function of the copying machine, and set the processing contents such as the copying function and the FAX function.

FIG. 3 shows an outline of the image processing function of the IPP. The read image data is transmitted from the SBU via the CDIC to the scanner image processing 12 from the input I / F (interface) 11 of the IPP. Scanner image processing 12 is mainly intended to correct the deterioration of image information due to reading.
Are shading correction, scanner γ correction and MTF
Make corrections and so on. Although not a correction process, a scaling process for enlargement / reduction is also performed. After the correction processing of the read image data is completed, the image data is transferred to the CDIC via the output I / F 13.
For output to transfer paper, input image data from CDIC.
/ F14, and performs area gradation processing in image quality processing 15. The data after the image quality processing is output to the VDC via the output I / F 16. The area gradation processing includes density conversion, dither processing, error diffusion processing and the like, and the main processing is area approximation of gradation information.

Once the image data subjected to the scanner image processing 12 is stored in the memory MEM, various reproduced images can be confirmed by changing the processing performed in the image quality processing 15. For example, try shaking the density of the reproduced image,
The atmosphere of the reproduced image can be changed by changing the number of lines of the dither matrix. At this time, it is not necessary to read the image again by the scanner 200 every time the processing is changed.
If the stored image is read from the EM, different processing can be performed on the same data any number of times.

FIG. 4 shows an outline of the internal configuration of the IPP. I
The PP has a plurality of input / output ports with respect to data input / output with the outside, and inputs and outputs can be set arbitrarily, respectively. A local memory group is provided inside, and a memory control unit controls a memory area to be used and a data path. For the input data and the data for output, a local memory group is allocated as a buffer memory, stored in each, and an I / F with the outside is controlled. Various processing is performed on the image data stored in the local memory in the processor array unit, and the output result is stored again in the local memory. The processing procedure of the processor, parameters for the processing, and the like are exchanged between the program RAM and the data RAM. The contents of the program RAM and data RAM are downloaded from the process controller via the serial I / F. Alternatively, the process controller reads the contents of the data RAM and monitors the progress of the processing.
When the contents of the processing are changed or the processing form required by the system is changed, the contents of the program RAM and the data RAM referred to by the processor array are updated and corresponded.

FIG. 5 shows an outline of the functional configuration of the CDIC. The image data input / output control 21 inputs the read image data from the SBU and outputs the data to the IPP. The image data input controller 22 receives the image data subjected to the scanner image correction by the scanner image processing 12 by the IPP. The input data is subjected to data compression in the data compression unit 23 in order to increase the transfer efficiency on the parallel bus Pb. The compressed image data is parallel data I /
It is sent to the parallel bus Pb via F25. Image data input from the parallel data bus Pb via the parallel data I / F 25 is compressed for bus transfer, and is expanded by the data expansion unit 26. The decompressed image data is transferred to the IPP by the image data output control 27. The CDIC has a function of converting parallel data and serial data. System controller 6
Transfers data to the parallel bus Pb, and the process controller 1 transfers data to the serial bus Sb.
For communication between the two controllers 6 and 1, the data conversion unit 24 and the serial data I / F 29 use a parallel /
Performs serial data conversion. Serial data I / F28
Are for IPP, and also perform serial data transfer with IPP.

FIG. 6 shows an outline of a functional configuration of the VDC.
The VDC performs additional processing on the image data input from the IPP according to the characteristics of the imaging unit 5. The rearrangement process of the dots by the edge smoothing process and the pulse control of the image signal for the dot formation are performed, and the image data is output to the image forming unit 5. Apart from the conversion of the image data, it has the parallel data and serial data format conversion functions 33 to 35, and the VDC alone can support the communication between the system controller 6 and the process controller 1.

FIG. 7 shows an outline of the functional configuration of the IMAC. The parallel data I / F 41 manages input / output of image data to / from the parallel bus Pb, stores / reads image data to / from the MEM, and converts code data mainly input from an external PC to image data. Control deployment. The code data input from the PC is stored in the line buffer 42. That is, the data is stored in the local area, and the code data stored in the line buffer 42 is supplied to the video controller 43 based on the expansion processing command from the system controller 6 input via the system controller I / F 44. Expand to image data.
Expanded image data or parallel data I / F4
The image data input from the parallel bus Pb via the P1 is stored in the MEM. In this case, the data conversion unit 45
In step (2), image data to be stored is selected, data compression is performed in the data compression section 46 to increase the memory use efficiency, and image data is stored in the MEM while the memory access control section 47 manages the address of the MEM. I do.
When reading the image data stored in the MEM, the memory access control unit 47 controls the read destination address, and the read image data is expanded by the data expansion unit 48. When transferring the expanded image data to the parallel bus Pb, the data transfer is performed via the parallel data I / F 41.

FIG. 8 shows an outline of the functional configuration of the FCU. F
The AX transmission / reception unit FCU converts the image data into a communication format and transmits it to the external line PN, and converts the data from the external line PN back to the image data and creates the image data via the external I / F unit 51 and the parallel bus Pb. The image is recorded and output in the image unit 5. The FAX transmitting / receiving unit FCU includes a FAX image processor 52, an image memory 53, a memory control unit 55, a facsimile control unit 54, an image compression / decompression 56, a modem 57, and a network control device 5.
Consists of eight. Among them, regarding the FAX image processing 52, the binary smoothing processing on the received image is performed in the edge smoothing processing 31 of the VDC. As for the image memory 53, a part of the output buffer function is completed by the IMAC and the MEM.

FAX transmission / reception unit FCU thus configured
Then, when the transmission of the image information is started, the facsimile control unit 54 instructs the memory control unit 55 and the image memory 53
, The stored image information is sequentially read. The read image information is restored to the original signal by the FAX image processing 52, is subjected to density conversion processing and scaling processing, and is applied to the facsimile control unit 54. The image signal applied to the facsimile control unit 54 is code-compressed by the image compression / decompression unit 56, modulated by the modem 57, and transmitted to the destination via the network control device 58. The transmitted image information is stored in the image memory 5.
3 is deleted.

At the time of reception, the received image is temporarily stored in the image memory 5.
3, if the received image can be recorded and output at that time, it is recorded and output when the reception of one image is completed. When a call is made during the copying operation and reception starts, the image memory 53 is stored in the image memory 53 until the usage rate of the image memory 53 reaches a predetermined value, for example, 80%.
When the usage rate reaches 80%, the writing operation being executed at that time is forcibly interrupted, and the received image is read from the image memory 53 and recorded and output. At this time, the received image read from the image memory 53 is deleted from the image memory 53, and the usage rate of the image memory 53 becomes a predetermined value, for example, 10
When the writing operation has been suspended, the writing operation which has been interrupted is resumed, and when all the writing operations have been completed, the remaining received image is recorded and output. Further, after the write operation is interrupted, various parameters for the write operation at the time of the interruption are internally saved so that the write operation can be resumed, and the parameters are internally restored at the time of restart.

In the above example, the CDIC as the image bus management means and the IMAC as the memory management means are connected by a parallel bus Pb as a set of image buses. The independent SBU as image reading means, VDC as writing means and IPP as image signal processing means are connected directly to image bus management means CDI without being directly connected to image bus Pb.
C, the use management of the image bus Pb is substantially controlled by the image bus management means CDIC and the memory management means IMA.
Only done by C. Therefore, arbitration and transfer control of the bus Pb are easy and efficient.

FIG. 9 shows a flow of a process of storing an image in the MEM and a process of reading an image from the MEM. (a)
Is a processing or transfer process Ip of the image data until the image data generated by the image scanner 200 is written into the MEM.
(B) shows the processing or transfer process Op1 to Op13 of the image data from reading out the image data from the MEM to outputting it to the printer 400. CD
The data flow between such buses and units is controlled by controlling the IC. Regarding the read image data, the scanner image processing Ip1 to Ip13 in the IPP (FIG.
12) is applied to the image data to be output to the printer 400 with the image quality processing Op1 to Op13 (FIG.
15) is carried out independently.

In the present embodiment, the “background removal processing” Op 10 indicated by the block divisions in FIG. 9 is performed by reading the image data from the MEM and outputting it to the printer 400.
Step 13 is performed.

FIG. 10 shows a part of the contents of the “background removal process” Op10. Go to "Background Removal" Op10 and I
The PP checks whether the "density area" key 80h of the operation OPB is on (Step 1). In the following, the word "step" is omitted in parentheses,
Step No. Write only numbers. "Density area" key 80
When h is off, the IPP proceeds to the quantization processing (6), and does not execute the “one-pixel background removal processing” BDP.

When the "density area" key 80h is on,
The IPP performs “one pixel background removal processing” BDP shown in FIG. 10 on image data of each pixel.

At the beginning of the processing BDP, the primary background level JODn is calculated as follows (2): JODn = (1−K) · JODn−1 + K · IDn... JODn: main scanning direction The calculated density of the nth pixel (primary background level) IDn: input image density of the nth pixel in the main scanning direction (image data to be processed) K: tracking coefficient (0 <K ≦ 1); "
A processing characteristic adjustment parameter whose value can be adjusted by operating the key 801. "." Means multiplication and "/" means division. The same applies to the following.

FIG. 12A shows an example of image data IDn to be processed, the calculated primary background level JODn, and the following secondary background level M · JODn. The background level calculation value JODn is calculated based on the value of the weight K and the original data IDn.
The speed of following changes. As can be seen from the equation, K
Is larger, the closer to the original data IDn, the higher the following speed. The smaller K is, the slower the following speed becomes, and it becomes closer to a constant value. By appropriately adjusting the value of K, FIG.
As shown in FIG. 2A, the primary background level JODn that follows only a large change in the background other than the peak can be obtained.

Next, the IPP subtracts (removes) the background level.
The calculated primary image data AODn is calculated as follows (3): AODn = IDn−M · JODn IF (AODn <0) THEN AODn = 0 M: background density calculation coefficient (0 <M ≦ 1) ); "Adjust" key 8
0l is subtracted from the original image data IDn by a processing characteristic adjustment parameter capable of adjusting the value, that is, a secondary background level M · JODn which is a product of the primary background level JODn and the adjustment coefficient M. FIG. 12B shows an example of the primary image data AODn.

Although the background removal is completed by this, the density of the background removal M · JODn is reduced as it is, and in particular, in the case of characters and the like, legibility is reduced. Therefore, the contrast is corrected. Here, the IPP is “dark priority”,
It is checked which of the keys 80i to 80k of "light priority" and "dark &light" is on (4, 8).

When the "dark priority" key 80i is on,
The PP corrects the primary image data AODn to the secondary image data CODn by the next contrast correction 1 (5).

Contrast correction 1: CODn = AODn.HD / (HD-PM.JODn)... CODn: Adjusted density at the nth pixel in the main scanning direction (secondary image data) P: Input saturation density adjustment Parameter; "Adjust" key 80l
, Which can be adjusted to adjust the value, HD: the maximum value that a digital value can take. For example, 255 for 8-bit image data. However, it is not always necessary to fix the value to the maximum value, and the value can be changed by operating the "adjustment" key 80l. This is also one of the processing characteristic adjustment parameters.
FIG. 13A shows an example of the secondary image data CODn obtained by performing the contrast correction 1. This correction is performed by the ratio HD / (HD−P−M · JODn) of the difference (denominator) between the full scale HD of the digital value, the adjustment parameter P + the secondary background level M · JODn, and the full scale value HD (numerator). Is multiplied by the primary image data AODn, which is the value after the background is removed. By the above processing, FIG.
As shown in (a) of FIG. 3, the difference between a portion where the background level is dark and a portion where the background level is light is removed, and a change point (character or the like) on the background is extracted. The density change and the saturation density of the image quality can be adjusted by the parameter “P”. Increasing P increases the slope and darkens the image.

FIG. 13B shows the state of binary image data, that is, an image signal, obtained by quantizing the secondary image data CODn into a binary value with the threshold value TH2. As can be seen from the figure, the binary image data "1" of the image portion can be reproduced well in the region where the background is dark. When the image is binarized without performing the background removal in Steps 2 and 3, the binary image data, that is, the image signal, is continuously "1" in the region where the background is dark as shown in FIG.
(Black), and the image is completely blackened.

However, 2 processed by contrast correction 1
When the next image data CODn is quantized into two values, the image is clearly represented in a region where the background is dark. However, the binary image data of the region where the background is thin continuously becomes “0”, and a thin image cannot be reproduced. If the threshold value TH2 is lowered, the binarized data in a portion where the background is dark may be crushed (almost “1” and crushed in black). Therefore, Contrast Correction 1 converts the image of a document with a dark background
It is suitable for clearing the image by removing the background.

“Dark Priority”, “Light Priority” and “Dark & Light”
When it is checked which one of the keys 80i to 80k is on (4, 8), if the "light priority" key 80j is on, the IPP performs AODn is converted to secondary image data COD
is corrected to n (9).

Contrast correction 2: CODn = AODn.HD / M.JODn... CODn: adjusted density of the nth pixel in the main scanning direction (secondary image data) According to this contrast correction 2, the input image density ( ID
n) is high (if JODn is large), the amplification factor HD / M
Since JODn decreases and the amplification rate increases when the JODn is low, the image data of the thin portion of the background is emphasized, and the image data of the dark portion of the background is suppressed.

FIG. 14A shows an example of the secondary image data CODn processed by the contrast correction 2. FIG. 14B shows an image signal after binarization. It can be seen that the image of the thin portion of the background is binarized without missing or crushing.

Meanwhile, in the above equation used in the contrast correction 2, the amplification factor of the image data in the portion where the background density is high is reduced, so that the image in the area where the background density is high becomes thin. When expressed by the area density gradation, the density becomes low. Therefore, in the present embodiment, even if the background is dark, the contrast correction 1
And a mode in which contrast correction 2 is automatically applied to an area having a low background density. The contents of the automatic mode will be described below.

“Dark Priority”, “Light Priority” and “Dark & Light”
When it is checked which one of the keys 80i to 80k is on (4, 8), if the “dark & light” key 80k is on, the IPP will
Next image data AODn is corrected to secondary image data CODn (10-12).

Automatic correction: when JODn ≧ TH1, CODn = AODn.HD / (HD-PM.JODn)... TH1: threshold for separating dark or light region; operating “adjust” key 801 A processing characteristic adjustment parameter whose value can be adjusted. When JODn <TH1, CODn = AODn · HD / (M · JODn)...

That is, the IPP is set to the “dark & light” key 80 k
Is on, the primary background level JODn is equal to the threshold TH.
It is checked whether it is equal to or greater than 1 (10). If it is greater than or equal to the threshold value TH1, the primary image data AO
Dn is corrected to secondary image data CODn (11).
If the difference is less than the threshold value TH1, the correction is made by the contrast correction 2 (12).

FIG. 15A shows the secondary image data CODn obtained as a result of processing by the "automatic correction". Binary image data (image signal) obtained by binarizing the secondary image data CODn with a threshold value Th2 is shown in FIG.
This is shown in FIG. In this manner, both the dark region and the light region image are satisfactorily binarized. As described above, according to the “automatic correction”, it is possible to obtain image data representing the images of the dark region and the light region in a well-balanced manner with good contrast. The quantization (TH2) is not limited to binarization. Halftone processing (error diffusion, dither)
And so on. Also, the secondary image data COD before quantization
n may be output from the IPP.

Since the above processing can be completely expressed by an arithmetic expression, a digital signal processor (DSP) such as IPP
One of the features is that it is suitable for processing in P).

As shown in FIG. 11, the operation unit OPB includes a liquid crystal touch panel 79, a numeric keypad 80a, a clear / stop key 60b, a start key 60c, a mode clear key 60e, a test print key 80f, a "copy" function, There is a function selection key 80g for selecting a “scanner” function, a “print” function, a “facsimile” function, a “storage” function, an “edit” function, a “register” function, and other functions and indicating that the function is being executed. The liquid crystal touch panel 79
An input / output screen determined by the function specified by the function selection key 80g is displayed. For example, when the "copy" function is specified, a function key 79a and a message indicating the number of copies and the state of the image forming apparatus are displayed. The test print key 80f is a key for printing only one copy regardless of the set number of print copies and confirming a print result.

The "density area" designation key 80h is a key for designating "background removal processing" Op10 for processing an image with high contrast. When this key is pressed, the display is switched to the selected display and the "density area" is turned on. Is saved in the register,
In addition, the on input of each of the keys 80i to 80l of "dark priority", "light priority", "dark &light" and "adjustment" is received. The "density area" designation key 80h is used when the background is of high density, when there is unevenness in the background density, or when the high-density image is preferentially extracted, for example, when copying a blue-printed copy.
It is turned on by the operator to sharpen the image when there is considerable density on the background and it is relatively difficult to sharply print out the image, such as when preferentially extracting a low density image.

When the "dark priority" designation key 80i is pressed, the display is switched to the selected one, "dark priority" ON is saved in the priority register, and "light priority", "dark &light" and "adjustment" are performed. Are cleared off. In this state, in the “background removal processing” BDP shown in FIG. 10, the contrast correction 1 (expression) is executed in step 5 in the order of step 2-3-3-5-6.

When the "light priority" designation key 80j is pressed, the display is switched to the selected one, "light light" ON is saved in the priority register, and "light priority", "light &light" and "adjustment" are performed. Are cleared off. In this state, in the “background removal processing” BDP shown in FIG. 10, the contrast correction 2 (formula) is executed in step 9 in the order of steps 2-3-4-8-9-6.

When the "dark &light" designation key 80k is pressed, the display is switched to the selected display, and the "dark &light" ON is saved in the priority register, and "dark priority", "light priority" and "adjustment" are set. Are cleared off. In this state, the “background removal processing” BDP shown in FIG. 10 is performed in the order of Step 2-3-4-8-10- “11 or 12” -6, and when the background level JODn is equal to or larger than the threshold value TH1, Step 11 is performed. , The contrast correction 1 (expression) is executed, but when the difference is smaller than the threshold value TH1, the contrast correction 2 (expression) is executed in step 12.

When the "adjustment" designation key 80j is pressed, the display is switched to the selected display, and the above-mentioned parameters K, M, H
An input screen for adjusting D, P, TH1, and TH2 is displayed on the liquid crystal touch panel 79. The operator can change the value of each parameter by designating each parameter item key appearing on this input screen and pressing an up / down designation key appearing on the input screen. This input screen is deleted when the "adjustment" designation key 80j is pressed again and when each of the "dark priority", "light priority" or "dark &light" keys 80i to 80k is pressed. .

When the "density area" designation key 80h is turned on again while the "density area" ON is saved in the register, the register addressed to the "density area" is cleared and the data is turned off. It will be shown.

FIG. 16 shows a schematic configuration of a SIMD processor required for image processing adopted in the IPP. SIMD allows a single instruction to be executed in parallel with respect to a plurality of data, and a plurality of (8 in the example shown, for 1-byte parallel processing) P
E (processor element) PE1 to PE8. Each PE has a register (Reg) for storing data, a multiplexer (MUX) for accessing a register of another PE, and a barrel shifter (Shift Expa).
nd), a logical operation unit (ALU), an accumulator (A) for storing a logical result, and a temporary register (F) for temporarily comparing the contents of the accumulator. Each register is connected to an address and a data bus, and stores an instruction code defining a process or data to be processed.

The data to be processed by the register is AL
It is input to U, and the result of the arithmetic processing is stored in A. The result is temporarily saved in F to be taken out of the PE.
By extracting the contents of F, a processing result for the target data can be obtained. The instruction code is given to each PE with the same content, the data to be processed is given in a different state for each PE,
By referring to the contents of the Reg in the MUX, the calculation results are processed in parallel and output to each A. For example, image data 1
By arranging the contents of the line in the PE for each pixel and performing arithmetic processing with the same instruction code, a processing result of one byte can be obtained in a shorter time than processing one pixel at a time. IPP
Is performed by these PEs.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an outline of a mechanism of a digital color copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of a configuration of an electric control system of the copying machine shown in FIG.

FIG. 3 is a block diagram illustrating a functional configuration of the image signal processing device IPP illustrated in FIG. 2;

FIG. 4 is a block diagram showing an outline of hardware of the image signal processing device IPP shown in FIG. 2;

5 is a block diagram showing a functional configuration of a compression / decompression and data interface control unit CDIC shown in FIG. 2;

FIG. 6 is a block diagram showing a functional configuration of a video data control VDC shown in FIG. 2;

7 is an image memory access control IMAC shown in FIG.
FIG. 2 is a block diagram showing a functional configuration of the first embodiment.

FIG. 8 is a block diagram illustrating a functional configuration of a facsimile transmitting / receiving unit FCU illustrated in FIG. 2;

9A is a flowchart showing the flow and processing of image data until the image data read by the scanner 200 shown in FIG. 2 is written into the image memory MEM; FIG.
9 is a flowchart showing the flow and processing of image data from reading image data from the image memory MEM to outputting the image data to the printer 400.

FIG. 10 is a flowchart showing the processing content of “background removal processing” Op10 shown in FIG. 9;

11 is a plan view of an operation unit OPB of the copying machine shown in FIG.

FIG. 12A shows image data IDn read by a scanner 200 on a document in which a dark background and a light background are mixed, and its primary background level JODn and secondary background level M · J.
It is a graph which shows ODn typically. (B)
From the image data IDn shown in FIG.
It is a graph which shows the image data AODn after background removal which subtracted JODn.

FIG. 13A shows image data AODn after background removal.
11 is a graph showing output image data CODn, which is corrected by contrast correction 1 shown in step 5 of FIG.
(B) is a graph showing binary image data (image signal) obtained by binarizing the output image data CODn with the threshold value TH2.

FIG. 14A shows image data AODn after background removal.
11 is a graph showing output image data CODn, which is corrected by contrast correction 2 shown in step 9 of FIG.
(B) is a graph showing binary image data (image signal) obtained by binarizing the output image data CODn with the threshold value TH2.

FIG. 15A shows image data AODn after background removal.
Is output image data COD corrected by the combined use of contrast corrections 1 and 2 shown in steps 10 to 12 in FIG.
9 is a graph showing n. (B) shows the output image data CO
13 is a graph showing binary image data (image signal) obtained by binarizing Dn with a threshold value TH2.

FIG. 16 is a block diagram showing a partial configuration of a processor array PAU shown in FIG. 4;

FIG. 17 is a graph showing image data IDn obtained by reading an image of a blue-printed original and binary image data (image signal) obtained by binarizing the image data with a fixed threshold THp.

[Explanation of symbols]

200: Document scanning scanner 400: Full color printer IPP: Image signal processing device CDIC: Compression / decompression and data interface control unit VDC: Video data control IMAC: Image memory access control FCU: FAX transmission / reception unit SBU ： Sensor-Bo
Do Unit PN: Public line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B047 AA01 AB02 DA03 DC07 DC11 5C062 AA05 AB02 AC61 AE04 BA01 5C077 LL19 PP25 PP47 PQ08 PQ12 PQ18 PQ20 TT06

Claims (6)

[Claims] A background level defined by at least image data of interest and image data preceding said image data of interest;
Calculating means for calculating the background level addressed to the image data of interest by weighting and adding; and calculating means for multiplying the difference between the background level of the image data of interest and the background level by a coefficient defined by the background level. Data processing device. 2. The image data processing apparatus according to claim 1, further comprising means for adjusting a weight K of said weight. 3. The image data processing apparatus according to claim 1, wherein the coefficient is a ratio that can be represented by a fraction including a product of a denominator and the background level multiplied by an adjustment value M. 4. A first ratio which can be represented by a fraction including a value obtained by subtracting a product obtained by multiplying an adjustment value M from a set value by a denominator to the denominator; There is a second ratio which is the product of multiplication by the value M,
2. The method according to claim 1, wherein the first ratio is multiplied by the second ratio when the background level is equal to or higher than the set value TH1, and the second ratio is multiplied by the density difference represented by image data with respect to the background level when the background level is lower than the set value TH1.
Or the image data processing device according to claim 2. 5. An image data processing apparatus according to claim 1, 2 or 3; and reads an original surface, converts the original surface into digitally converted image data, and sends the image data to the image data processing apparatus. Means for providing an image. 6. An image reading apparatus according to claim 5, and
A printer for forming an image represented by image data output by the image data processing device on a sheet of paper.