JP3251988B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for performing digital image processing such as a printer and a facsimile.

[0002]

2. Description of the Related Art An image forming unit reads an original image by an image reading unit, converts the digital image into a digital signal by performing signal processing, and sends the digital signal to an image processing unit to perform image processing to copy the original image. An example of the device will be described. The image forming apparatus includes an image reading unit 1 and an IP as an image processing unit, as shown in FIG.
U2 (image processing apparatus) and a write processing unit (not shown). In this case, the image reading unit 1 includes a CCD 3, a clamp circuit 4, an S / H (sample and hold) circuit 5,
AGC (Auto Gain Control) circuit 6 and A / D
A conversion circuit 7 and an LUT (Look Up Tab) for performing logarithmic conversion
le) 8).

In such a configuration, digital image processing in the image reading section 1 is performed in the following procedure. First, the analog data read from the CCD 3 in the main scanning direction is adjusted in the base level of the waveform by the clamp 4, and the S / H circuit 5 samples and holds the data in synchronization with the pixel clock. Next, AGC processing is performed to vary the data amplification factor in accordance with the read exposure amount and the data level. Then, the A / D conversion circuit 7 converts the analog data into 6-bit digital data.
Logarithmic conversion is performed by the input / output 6-bit / dot LUT 8 so that the read data linear with respect to the document reflection density read by the CCD 3 can efficiently handle gradation in accordance with the visibility. In this case, the analog data output from the CCD 3 is divided into two systems, EVEN and ODD, for high-speed transfer and output, and is synthesized into a serial analog signal by a switching IC composed of analog switches. The image transfer speed of one pixel after the combination is about 10 MHz. In synchronization with this, the A / D conversion circuit 7 converts the signal into a digital signal of 6 bits 64 gradations or more.

Next, a digital signal for each pixel indicating the above-mentioned image density is input to the IPU 2 and subjected to image processing. This IPU 2 is composed of a plurality of LSIs, and in addition to image processing, shading correction as described below,
MTF correction, magnification change in the main scanning direction, γ correction, writing processing, and the like are performed. First, the shading correction will be described.
Using a linear light source such as a fluorescent lamp and focusing by a lens, C
The light amount becomes maximum at the center of the CD 3 and decreases at the end, and the CCD 3 has a variation in sensitivity of each element. Therefore, both of them are configured to correct the original read data by the reference white plate read data for each pixel. Next, the MTF correction will be described. In an optical system using a lens or the like, the read output by the CCD 3 is read as if the peripheral pixel information had been affected by the performance of the lens or the like. Therefore, when one piece of pixel data is obtained, by correcting the pixel data based on the peripheral pixel level,
An image with high reproducibility can be obtained. Next, magnification in the main scanning direction will be described. The resolution of image reading and writing is the same 400 DPI,
The reading pixel frequency is about 10 MHz and the writing pixel frequency is about 1
Since the frequency is different at 2 MHz, frequency conversion is performed and 25
The magnification is changed in the main scanning direction in the range of% to 400%. In this case, the former is realized by read / write of the line memory, and the latter is calculated by calculation using peripheral pixel data in the main scanning direction. Next, gamma correction will be described. The density reproducibility (γ characteristic of the printer) of the laser printer using the electrophotographic method is not linear, and the original density cannot be faithfully reproduced with the data as it is. Thus, the conversion table is used to convert the write exposure light amount to the print characteristic. In addition, it can be realized by changing the value at the time of manual density adjustment. The IPU 2 also performs image conversion such as masking, trimming, mirroring, black-and-white reversal, document size and density detection, marker detection, and the like.

[0005] Next, the image data from the IPU 2 as described above is sent to the writing processing unit. In this writing processing unit,
Image data is converted into light energy by an LD (laser diode). The optical writing in the printer section is performed by deflecting and scanning the laser beam from the LD with a polygon mirror and exposing the photosensitive member to an electrostatic latent image. In this case, the LD modulation method includes a binary writing method in which the light emission intensity is controlled in two stages of ON and OFF, and a power modulation method (multi-value writing method) in which the light emission intensity is modulated for each dot. . In the power modulation system, a large amount of data is required for writing. For example, in the case of laser beam writing in an electrophotographic system, the density is expressed for each writing dot. In addition to the power modulation method that mainly modulates the exposure intensity, there is a pulse width modulation method that modulates the exposure time within one dot.

[0006]

As described above, the original image read by the image reading section 1 is subjected to image processing by the IPU 2 and optical writing is performed by the writing processing section. Various problems as described occur. Faithful reproduction of a document is an important factor in improving image quality in a copying machine, and a copy is often copied again as a document.
In repeated copying, deterioration occurs in the generation image. In particular, in a character image, the character becomes thick and thin, and the image is degraded. This is caused by the characteristics and limitations of the copying process, or by machine accuracy, etc.
Degradation and fluctuation of gradation.

[0007] In particular, in an electrophotographic image forming system, there are physical limitations on resolution and gradation.
The density reproducibility varies due to changes in image forming process conditions and the like, and changes with time are unstable. For this reason, resolution,
It is difficult to faithfully reproduce both gradations, and if the gradation of characters is faithfully reproduced, characters and line images are blurred and easily interrupted.

Further, in an electrophotographic digital copying machine, it is difficult to repeatedly reproduce an original, and the image is generally deteriorated from an allowable range by the number of generation copies. Basically, the generation image can be improved by faithfully reproducing each copy, but the original information cannot be completely preserved in the image copy. In particular, in a character image, generation appears as fatness, roundness, and space filling of a character due to added density. In addition, the thinning of the character due to the insufficient density appears as a blur or cut.
The fatness of a character is easily determined by artificial guess according to its shape. In addition, thinning of characters is lost, which is fatal for information transmission.

Therefore, in order to solve such a problem, thinning, blurring, and cutting of characters are performed by increasing the copy density or applying a filter processing 9 to the read image using a coefficient matrix as shown in FIG. This can be reduced by enhancing the edges of the character. But in this case,
Increasing the copy density increases the fatness, roundness, and filling of the space due to the added density and degrades the generation image.On the other hand, emphasizing the edges of the characters emphasizes the moire of the halftone dot manuscript, Deteriorate the image. In both cases, the density increases and the gradation of the document is lost. In addition, the text and photo parts of the manuscript are separated,
There is a method in which the text portion is subjected to density addition or MTF correction, and the photographic portion reproduces gradations faithful to the document density. However, it is difficult to perform complete text / photo separation.

[0010]

According to the first aspect of the present invention, an image reading unit reads an original image, performs signal processing and digitizes the image, and sends the digitized signal to the image processing unit to perform image processing. Then, in an image forming apparatus that forms an image by performing binary writing by a writing processing unit, in the main scanning direction or the sub-scanning direction of the noted binary data of the digitized pixels. the Rukoto and the logical sum of the neighboring binary data adjacent to />
The adjacent binary data is added to the target pixel data to
Pixel data of interest to the extent that
Is provided with a binary data inflating means. in this case,
In the main scanning direction and the sub-scanning direction of the read original image,
Any of horizontal, vertical, vertical and horizontal directions or cancellation of image expansion
May be selected.

According to the second aspect of the present invention, the image reading unit reads the original image in multiple gradations, performs signal processing and digitizes the image, and sends the digitized signal to the image processing unit to perform the image processing. After that, in the image forming apparatus which forms an image by performing multi-tone writing by the writing processing unit, the noted multi-tone data of the digitized pixels and the main scanning direction of the multi-tone data or
Has multivalued data expansion means which takes the maximum density data of the adjacent multi-tone data adjacent in the sub-scanning direction and uses it as the density data of the pixel data of interest. In this case, the read
Regarding image expansion in the main scanning direction and sub-scanning direction of the original image
And select any of horizontal, vertical, vertical and horizontal directions or cancel
You may do it.

According to the third aspect of the present invention, the image reading unit reads the original image, performs signal processing to digitize the image, sends the digitized signal to the image processing unit, performs the image processing, and then performs the writing process. In an image forming apparatus that forms an image by performing binary writing by a unit, a delay unit that delays binary data in the main scanning direction or the sub-scanning direction to an extent that reduces thinning, blurring, or cutting of characters is provided. Delay 2 delayed by this delay means
A binary data expanding means for obtaining image data by taking a logical sum of the value data and the binary data of the target pixel is provided.

According to the fourth aspect of the present invention, the image reading unit reads the original image in multiple gradations, performs signal processing and digitizes the image, and sends the digitized signal to the image processing unit to perform the image processing. Thereafter, in an image forming apparatus that forms an image by performing multi-tone writing by a writing processing unit , thinning, blurring, or cutting of characters is reduced.
A delay means for delaying the multi-gradation data in the main scanning direction or the sub-scanning direction to the extent that the maximum density data of the delayed multi-gradation data delayed by the delay means and the multi-gradation data of the target pixel is provided. Density data of the pixel data of interest
Multivalued data expansion means to provided.

According to the fifth aspect of the present invention, the image reading unit reads the original image, performs signal processing to digitize the image, sends the digitized signal to the image processing unit, performs the image processing, and then performs the writing process. an image forming apparatus for forming an image by writing a part, sentence
The data of the read original image is delayed in the main scanning direction to such an extent as to reduce the thinning, blurring or breakage of characters, and the logical sum of the delayed plurality of delayed data or the
Maximum concentration inflated more main scanning direction by replacing the pixel of interest, the expanded data expanded in the main scanning direction is delayed in the sub-scanning direction, the delayed plurality of delayed data is logical OR or Focus on maximum concentration in delay data
It provided an image expansion means for expanding more in the sub-scanning direction by replacing the pixel.

[0015]

According to the first aspect of the present invention, the binary data is expanded by the binary data expanding means and the binary data in the main scanning direction.
Alternatively , the image can be processed so as to expand by taking the logical sum of the binary data adjacent to the sub-scanning direction and the binary data of the image of interest, and further expanded by the directionality of a specific pixel adjacent to the pixel of interest. The direction and amount of processing can be arbitrarily changed.

According to the second aspect of the present invention, the multi-value data expansion means sets the maximum density data of the multi-tone data and the adjacent multi-tone data as the multi-value data of the target pixel, thereby expanding the image. And the direction and amount of expansion processing can be arbitrarily changed depending on the directionality of a specific pixel adjacent to the target pixel.

According to the third aspect of the present invention, the binary data is delayed in the main scanning direction by the delay means, and the binary data expansion means obtains the logical sum of the delayed binary data and the binary data of the target pixel. Thus, the image can be expanded in the main scanning direction with a simple circuit configuration, and the binary data can be delayed in the sub-scanning direction by the delay means, and the delayed binary data and the target pixel can be processed by the binary data expansion means . By calculating the logical sum with the binary data, it is possible to process the image to expand in the sub-scanning direction with a simple circuit configuration.

In the invention described in claim 4, the multi-gradation data is delayed in the main scanning direction by the delay means, and the logical multiplication of the delayed multi-gradation data and the multi-gradation data of the target pixel is performed by the multi-value data expansion means. In this way, the image can be processed so as to expand in the main scanning direction without losing image information, and the multi-gradation data is delayed in the sub-scanning direction by the delay means, and the delay is increased by the multi-value data expansion means. Gradation data and attention
By taking the logical sum with the multi-gradation data of the pixel, it is possible to process the image so as to expand in the sub-scanning direction without losing the image information.

According to the fifth aspect of the present invention, not only the main scanning direction or the sub-scanning direction but also the
The image can also be expanded at a point connecting the expansion points in the main scanning direction and the sub-scanning direction on a rectangle , so that a more uniform and natural expansion processing can be performed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention will be described with reference to FIGS. In this embodiment, an image reading unit reads a document image, performs signal processing to digitize the image, sends the digitized signal to an image processing unit, performs image processing, and then performs binary writing by a writing processing unit. The present invention relates to an image forming apparatus that forms an image by performing. Note that the image reading unit, the image processing unit,
Regarding the write processing unit, the conventional example described above (see FIG. 10)
, The description is omitted here.

First, the configuration of the operation display unit of the present apparatus will be described with reference to FIG. The image expansion selection unit 10 includes an image thickening key 11 for instructing image expansion processing, and indicators 12, 13, and 14 including LEDs for displaying horizontal, vertical, vertical and horizontal directions. Further, the image expansion amount designation unit 15 includes a width setting key 16 and a vertical width setting key 17 for designating the expansion width (thickness width) of the image, a width display 18 including 7-segment LEDs,
19 and a numeric keypad 20.

Now, when the image thickening key 11 for instructing the image expansion processing is pressed, the image thickening direction is changed to horizontal, vertical, vertical and horizontal.
The display changes to a release state, and the indicators 12, 13, and 14 are sequentially turned on according to the input mode. When the image expansion processing mode is input, the expansion width is displayed on the width indicators 18 and 19 in dot units, and the display in the direction in which expansion is not instructed is 0 or no display. At the beginning of the expansion mode, the expansion width is set to one dot both vertically and horizontally, and the input direction of the fat width is selected by the width setting key 16 and the height setting key 17 independent of the length and width.

In the procedure for setting the expansion width, for example, when the horizontal direction is set, the width setting key 16 is pressed. Thus, the mode is set to the lateral expansion width setting mode, and the numerical value of the width display 18 blinks. Then, the operator operates the screen of the width display 18.
By pressing the numeric keypad 20 while setting the horizontal expansion width, and pressing the enter key 21, the numerical value of the width display 18 changes from blinking to lighting, and the set value is determined.

To set the vertical direction, use the vertical width setting key 1
By pressing 7, the mode becomes the expansion width setting mode in the vertical direction, and the numerical value of the width display 19 flashes. So the operator
Is set by pressing the numeric keypad 20 while viewing the screen of the width display 19, and by pressing the enter key 21, the numerical value of the width display 19 changes from blinking to lighting, and the set value is changed. Determine.

In the case of the vertical and horizontal expansion mode, the width setting key 1
6 or the vertical width setting key 17 is pressed. This allows
The mode is set to the expansion width setting mode, and the numerical values of both the width indicators 18 and 19 blink. Then, the operator operates the width indicators 18, 1
Pressing the numeric keypad 20 sets the horizontal expansion width while viewing the screen 9, and pressing the enter key 21 causes the same numerical value to light on both the width indicators 18 and 19, and the same set value in the vertical and horizontal directions is determined. I do. The set values of these expansion widths in the vertical and horizontal directions are transmitted to the IPU control board, so that the IPU performs expansion processing of the image data based on the data.

Next, the main part of the invention of the present apparatus will be described. Here, of the digitized pixels, there is provided binary data expansion means for obtaining a logical OR of certain binary data of interest and adjacent binary data adjacent to the binary data to obtain target pixel data. (Claim 1). Further, a delay means for delaying the binary data in the main scanning direction or the sub-scanning direction is provided, and the binary data obtained by taking the logical sum of the delayed binary data delayed by the delay means and the current binary data is obtained. Data expansion means is provided (claim 3).

Hereinafter, as a specific configuration example including a delay unit and a binary data expansion unit, one bit after binarization processing will be described.
A description will be given based on FIGS. 1 and 2 by taking as an example binary writing in which write data of each dot of 1 bit expanded from data is created.

FIG. 1 shows the configuration of a binary data image data expansion processing circuit. First, the image expansion in the main scanning direction is performed by delaying and sampling the read data for a plurality of dots in the main scanning direction using a plurality of latches (DF / F) 22 as delay means according to the amount of image expansion. I do. Here, the maximum image expansion amount in the main scanning direction can be reduced to about 1 mm in 1/16 mm steps, and has 15 delay elements. In FIG. 1, the black pixel is set to HIG.
Ri Contact with the H level, the expansion of the image data using an OR circuit 23 as binary data expansion means. In other words, adjacent or previous pixels in the main scanning direction (main scanning direction or sub-scanning
The pixel data of interest is determined from a logical sum with adjacent binary data adjacent in the direction, and if there is a black pixel, the pixel data of interest is determined as a black pixel. The expansion amount is converted from a 4-bit value set from 0 (unprocessed) to 15 by a decoder (not shown) based on the operation input value of FIG. 9 described above and input to T1 to T15. Mask the delay data. As a result, the logical sum of the delayed pixels of the image expansion amount becomes the data of the pixel of interest, and if there is a black pixel between them, it is converted to a black pixel, and the image is extended in the main scanning direction until there is no black pixel in the delayed data. .

The image expansion in the sub-scanning direction is performed by a plurality of line memories (F
(IFO) 25 to delay and sample read data for a plurality of lines in the sub-scanning direction. Also in this case, the maximum pixel expansion amount in the sub-scanning direction can be reduced to about 1 mm in 1/16 mm steps, and has 15 delay elements. The expansion width is based on the operation input values in FIG.
A 4-bit value set from 0 (unprocessed) to 15 is converted by a decoder (not shown), input to Y1 to Y15, and the AND circuit 24 masks each delay data. As a result, the image is extended in the sub-scanning direction.

Further, data in the main scanning direction or the sub-scanning direction is delayed, and sampling pixels within a predetermined range (delay 2
Value data) and the target pixel ( binary data of the target pixel ) can be used to independently expand the image in the main scanning direction or the sub-scanning direction. Are expanded in both directions. Also, a binary image is obtained as expanded 1-bit data in the vertical and horizontal directions according to the independent set width.

FIG. 2 shows an example of the configuration of an image data expansion processing circuit for binary data when a black pixel is set to a LOW level. Here, to expand the image data,
AND circuit (logical product) 26 as binary data expansion means
Is used. As a result, the target pixel data is determined based on the adjacent or previous pixels in the main scanning direction and the sub-scanning direction, and if there is a black pixel in the sampling area, the target pixel data is set as a black pixel. The expansion amount is converted from a 4-bit value set from 0 (unprocessed) to 15 by a decoder (not shown) based on the operation input value in FIG.
15, Y1 to Y15 are inverted and input, and the OR circuit 27 masks each delay data. As a result, the logical sum of the delayed pixels of the image expansion amount becomes the data of the pixel of interest, and if there is a black pixel between them, it is converted to a black pixel, and the image is extended in the designated direction until there are no more black pixels in the delayed data.

Next, an embodiment in which the invention described in claim 5 is applied to binary writing will be described with reference to FIG. here,
The data of the read original image is delayed in the main scanning direction, the expanded plurality of delayed data is expanded in the main scanning direction, and the expanded data expanded in the main scanning direction is delayed in the sub-scanning direction. Image expanding means for expanding in the sub-scanning direction from the plurality of delayed data obtained.

Hereinafter, as a specific configuration example of the image expansion means, an image data expansion processing circuit for binary data capable of expanding an image not only in the main scanning direction and the sub-scanning direction but also in an oblique direction will be described. And will be described with reference to FIG. In the image data expansion processing circuits of FIGS. 1 and 2 described above, expansion in one direction in the main scanning direction and the sub-scanning direction is performed from T1 to T1.
5. It is possible by setting (masking) one of Y1 to Y15 to 0 or FH. However, when the dot expands in both directions, the isolated dot extends from that point by a set amount only in the main scanning direction and the sub-scanning direction, and thus becomes an “L” -shaped image. In such a case, the expansion is preferably performed not only in the main scanning direction and the sub-scanning direction, but also in a diagonal direction, that is, up to a point connecting the expansion points in the main scanning direction and the sub-scanning direction on a rectangle.

Therefore, for such a reason, an image data expansion processing circuit as an image expansion means as shown in FIG. 3 is provided. This circuit is an OR circuit, and the OR circuit 28 performs OR operation on the result of the expansion processing in the main scanning direction with a delay in the sub-scanning direction. As a result, the expansion data in the main scanning direction further expands in the sub-scanning direction to have a rectangular shape.

It should be noted that a similar result can be obtained even if the processing order is reversed. That is, as a modified example of the image expansion means, the data of the read original image is delayed in the sub-scanning direction, the delayed plurality of delayed data is expanded in the sub-scanning direction, and the expanded data expanded in the sub-scanning direction is obtained. May be delayed in the main scanning direction, and the plurality of delayed data may be expanded in the main scanning direction. Also,
In this circuit, more suitable expansion processing is possible, and the above-described expansion in one direction is also possible.

Next, an embodiment of the present invention will be described with reference to FIGS. Here, among the digitized pixels, multi-valued data is obtained by taking the maximum density data of a certain multi-tone data of interest and the adjacent multi-tone data adjacent to the multi-tone data. Data expansion means is provided (claim 2). Further, a delay unit for delaying the multi-gradation data in the main scanning direction or the sub-scanning direction is provided, and the maximum density data of the delayed multi-gradation data delayed by the delay unit and the multi-gradation data of the target pixel is provided. A multi-value data expanding means for obtaining density data of the pixel data is provided (claim 4).

Hereinafter, as a specific configuration example including the delay means and the multi-value data expansion means, multi-value writing in which write data of each dot of 6 bits is created from read data of each dot of 6 bits will be described as an example. This will be described with reference to FIGS.

FIG. 4 shows the configuration of a multi-value data image data expansion processing circuit. Now, from the dot positional relationship shown in FIG. 5, when the target pixel D _{m, n} , the expansion width X in the main scanning direction, and the expansion width Y in the sub-scanning direction, D _{mx, ny} and _{the target} pixel D _{m, n} The maximum density value of the data in the rectangular area surrounded by is defined as the output density data of the target pixel D _{m, n} . First,
The image expansion in the main scanning direction is performed by a plurality of latches (D / F / F) as delay means having a configuration of several bits according to the image expansion amount.
22 is performed by delaying read data for a plurality of dots in the main scanning direction in synchronization with the image data clock. Here, the maximum image expansion amount in the main scanning direction is 16
It is possible to reach about 1 mm in 1 / mm step.
It has five delay elements. In FIG. 4, the larger one of the data is defined as a black pixel, and the maximum detection circuit (MAX-SE
L) The target pixel data is determined by the adjacent or previous pixels in the main scanning direction using 29a to 29c, and the maximum density pixel data of the designated pixel is set as the density data of the target pixel data.

The image expansion in the sub-scanning direction is performed by using a plurality of line memories (FIFOs) 25 as delay means having a structure of several bits corresponding to the amount of image expansion, by using read data for a plurality of lines in the sub-scanning direction. In the data line cycle. Also in this case, the maximum image expansion amount in the sub-scanning direction can be reduced to about 1 mm in 1/16 mm steps, and has 15 delay pixels. The expansion width is based on the operation input value of FIG. 1 described above, and the value set from 0 (unprocessed) to 15 of 4 bits is set to the maximum detection circuit 29a to 29.
29c to mask each delay data. In the circuit of FIG. 4, the larger one of the data is defined as a black pixel, and the maximum detection circuits 29a to 29c
However, in an adaptation example in a system in which data with higher density is smaller, a target pixel may be determined from its minimum value using a minimum detection circuit (not shown).

FIGS. 6 and 7 show the maximum detection circuit 29a of FIG.
29 shows an example of a multi-valued data comparison circuit of FIG. In this case, the circuits 30 within the broken-line frame of FIG. 6 are constituted by 15 circuits in the maximum detection circuits 29a and 29b, and one circuit in the maximum detection circuit 29c. For comparison of image data, a 6-bit D-COMP (digital comparator) 31 is used.
Using TOR (selection circuit) 32, data with high density data is selected. Further, the input data uses the delay data A to P shown in FIG.
16 to mask the input data.

In the circuit of FIG. 6, a plurality of D-COs
The MP 31 is connected in series, the comparison result data is compared with the next data, and the comparison is sequentially repeated. If this is compared with A and B, and C and D, and the results are compared with each other, and the parallel processing is performed, the processing time is reduced to 1 / N 2, where N is the number of delayed sampling data. You. In the circuit of FIG. 7, the delay data is input to one input A of the D-COMP 31, and the higher density data obtained from the comparison result is fed back to the other input B and input again. By repeating the designated number of times, a set of maximum detection circuits 29a to 29c can be configured.

Next, an embodiment in which the invention described in claim 5 is applied to multi-level writing will be described with reference to FIG. here,
The read document image data is delayed in the main scanning direction, the plurality of delayed data is expanded in the main scanning direction, and the expanded data expanded in the main scanning direction is delayed in the sub-scanning direction. Image expanding means for expanding the plurality of delayed data in the sub-scanning direction.

Hereinafter, as a specific configuration example of the image expansion means, an image data expansion processing circuit for multi-value data capable of expanding an image not only in the main scanning direction and the sub-scanning direction but also in an oblique direction will be described. And will be described with reference to FIG. In the image data expansion processing circuit of FIG. 4, when the image is expanded in the main scanning direction and the sub-scanning direction, expansion in the oblique direction is not performed as in the case described with reference to FIG. In order to solve such a problem, an image data expansion processing circuit as shown in FIG. 8 is provided. In this circuit, the result of performing the expansion processing in the main scanning direction is expanded in the sub-scanning direction. Therefore, up to a point connecting the expansion points in the main scanning direction and the sub-scanning direction on a rectangle is filled with the maximum density data of the designated area pixel.

It is to be noted that the processing order can be reversed, and the expansion processing in the sub-scanning direction can be performed in the same manner when the expansion processing in the main scanning direction is performed on the data after the expansion processing is performed first. That is, the data of the read original image is delayed in the sub-scanning direction, the plurality of delayed data is expanded in the sub-scanning direction, and the expanded data expanded in the sub-scanning direction is delayed in the main scanning direction. The delayed plurality of delayed data may be expanded in the main scanning direction.

As described above, by providing the image data expansion processing circuit, the image can be expanded in one of the main scanning direction and the sub-scanning direction, and the character or the character having a thin horizontal line such as Mincho can be used. Without increasing the density of the image edge portion, it is possible to reduce fineness and blurring in copying, and furthermore, cut off. In addition, by expanding the image in both the main scanning and sub-scanning directions, thinning and blurring in copying, and further reducing cutting, regardless of the directionality of the set original,
Information loss can be prevented and legible copying can be performed.
Further, in general, in an electrophotographic apparatus, since charging, exposure, development, and transfer are performed on a rotating drum, line (horizontal line) reproducibility in the main scanning direction tends to be inferior to line reproducibility in the sub-scanning direction. Can be corrected.

Further, the provision of the image expansion selecting unit 10 for selecting the image expansion in the main scanning direction and the sub-scanning direction makes it possible to reduce the width of the characters and the width of the horizontal and vertical lines as in Mincho. It is possible to correct the copied document irrespective of the setting direction of the document and retain the image information, and it is also possible to cope with the limitation in the vertical and horizontal feeding directions of the transfer paper.

Further, by providing the image expansion amount designating section 15 for designating the image expansion amount, it is possible to specify and correct the expansion amount in accordance with the degree of thinning of the characters of the copy original, and to further correct the image information. Can be retained so as to be distinguished, and the generation of copying can be improved.

In the specific examples described above, data in the main scanning direction or sub-scanning direction is sampled after delaying the data in the main scanning direction or sub-scanning direction, and the maximum density data is used as target pixel data. Can be specified independently, and bidirectional expansion is also possible. Further, this makes it possible to obtain natural and suitable multivalued data with less gradation unevenness in any expansion processing.

[0049]

According to the first aspect of the present invention, an image reading unit reads an original image, performs signal processing and digitizes the image, and sends the digitized signal to the image processing unit to perform image processing. In an image forming apparatus in which an image is formed by performing binary writing by a writing processing unit, a noticeable 2 of the digitized pixels
The Rukoto and the logical sum of the neighboring binary data adjacent to the binary data in the main scanning direction or sub-scanning direction Toko value data
The adjacent binary data is added to the target pixel data to
Pixel data of interest to the extent that
It is provided with the binary data expansion means for expanding the image that can be processed to expand, moreover, is possible to change the direction and amount of expansion processing by the direction of a particular pixel adjacent to the pixel of interest as desired You can do it.

According to the second aspect of the present invention, the image reading section reads the original image in multiple gradations, performs signal processing and digitizes the image, and sends the digitized signal to the image processing section to perform image processing. After that, in the image forming apparatus which forms an image by performing multi-tone writing by the writing processing unit, the noted multi-tone data of the digitized pixels and the main scanning direction of the multi-tone data Or
Since multi-value data expansion means for taking the maximum density data of the adjacent multi-tone data adjacent in the sub-scanning direction and setting it as the density data of the pixel data of interest is provided, the image can be processed so as to expand, In addition, the direction and amount of expansion processing can be arbitrarily changed depending on the directionality of a specific pixel adjacent to the target pixel.

According to a third aspect of the present invention, a document image is read by an image reading section, signal processing is performed to digitize the image, and the digitized signal is sent to the image processing section to perform image processing and then write processing. In an image forming apparatus that forms an image by performing binary writing by a unit,
Delay means for delaying the binary data in the main scanning direction or the sub-scanning direction so as to reduce the thinning, blurring or breakage of characters; and providing the binary data delayed by the delaying means and the binary data of the target pixel. Since the binary data expansion means for obtaining the image data by taking the logical sum of the two is provided, the processing can be performed with a simple circuit configuration so as to expand the image in the main scanning direction and the sub-scanning direction.

According to a fourth aspect of the present invention, an image reading unit reads an original image in multiple gradations, performs signal processing to digitize the image, and sends the digitized signal to the image processing unit to perform image processing. Thereafter, in an image forming apparatus that forms an image by performing multi-tone writing by a writing processing unit, the thinning, blurring, or cutting of characters is reduced.
A delay means for delaying the multi-gradation data in the main scanning direction or the sub-scanning direction each time, and the maximum density data of the delayed multi-gradation data delayed by the delay means and the multi-gradation data of the target pixel is provided. And the density data of the pixel data of interest
Since the multivalued data expansion means is provided, the image can be processed so as to expand the image in the main scanning direction or the sub-scanning direction without losing image information.

According to a fifth aspect of the present invention, an image reading unit reads an original image, performs signal processing to digitize the image, sends the digitized signal to the image processing unit, performs image processing, and then performs a writing process. an image forming apparatus for forming an image by writing a part, character
The data of the read original image is delayed in the main scanning direction to such an extent as to reduce the thinning, blurring or cutting, and the logical sum of the delayed plurality of delayed data or the
Inflated more main scanning direction by replacing the pixel of interest at the maximum density, the expansion data that is expanded in the main scanning direction is delayed in the sub-scanning direction, the logical sum or a plurality of delay of the delayed plurality of delayed data is Attention image at maximum density in data
Since there is provided an image expansion means for expanding more in the sub-scanning direction by replacing the original, not the main scanning direction and the subscanning direction only, connecting the expansion point of the main scanning direction and the sub-scanning direction on a rectangular
The image can also be expanded to a point , so that a more uniform and natural expansion process can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a binary data image data expansion processing circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating another configuration example of a binary data image data expansion processing circuit;

FIG. 3 is a block diagram showing a configuration example of a binary data image data expansion processing circuit according to an embodiment of the invention described in claim 5;

FIG. 4 is a block diagram showing a configuration of an image data expansion processing circuit of multi-value data according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a dot positional relationship.

FIG. 6 is a block diagram illustrating a configuration example of a multi-value data comparison circuit.

FIG. 7 is a block diagram illustrating another configuration example of the multi-value data comparison circuit.

FIG. 8 is a block diagram showing a configuration example of a multi-value data image data expansion processing circuit according to an embodiment of the present invention;

FIG. 9 is a schematic diagram illustrating a state of an operation display unit of the image forming apparatus of the present invention.

FIG. 10 is a block diagram showing a state of data processing of a reading scanner in digital PPC.

FIG. 11 is a schematic diagram illustrating a configuration of a secondary differential filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading part 2 Image processing part 22 Delay means 23 Binary data expansion means 25 Delay means 26 Binary data expansion means 29a-29c Multi-value data expansion means

Claims (6)

(57) [Claims] An image reading unit reads an original image, performs signal processing to digitize the image, sends the digitized signal to an image processing unit to perform image processing, and then performs binary writing by a writing processing unit. In the image forming apparatus for forming an image by performing the above, a certain binary data of the digitized pixels and this binary data
Attention image the adjacent binary data and the Rukoto a logical sum with adjacent binary data adjacent in the main scanning direction or sub-scanning direction
Reduces thinning, blurring or cutting of characters in addition to raw data
An image forming apparatus further comprising a binary data expanding means for expanding target pixel data to such an extent that the target pixel data is expanded . 2. An image reading section reads an original image in multiple gradations, performs signal processing to digitize the image, sends the digitized signal to an image processing section to perform image processing, and then performs writing processing by a writing processing section. In an image forming apparatus that forms an image by performing multi-tone writing, a certain multi-tone data of interest among the digitized pixels is adjacent to the multi-tone data in a main scanning direction or a sub-scanning direction . An image forming apparatus comprising: a multi-value data expansion unit that takes maximum density data of adjacent multi-tone data and sets density data of target pixel data. 3. An image reading unit reads an original image, performs signal processing to digitize the image, sends the digitized signal to an image processing unit to perform image processing, and then performs binary writing by a writing processing unit. In an image forming apparatus that forms an image by performing the process , thinning, blurring, or
Is provided with a delay means for delaying the binary data in the main scanning direction or the sub-scanning direction to the extent that cutting is reduced, and ORs the delayed binary data delayed by the delay means with the binary data of the pixel of interest. An image forming apparatus comprising a binary data expanding means for obtaining image data. 4. An image reading section reads an original image in multiple gradations, performs signal processing to digitize the image, sends the digitized signal to the image processing section, performs image processing, and then writes the digitalized signal to the image processing section. In an image forming apparatus that forms an image by performing multi-gradation writing , fine characters are used.
Ri, blur or to the extent of reducing the cutting a delay means for delaying the multi-tone data in the main scanning direction or sub-scanning direction, multi-tone data of the pixel of interest and the delayed delay multi-tone data by the delay means An image forming apparatus comprising multi-value data expansion means for taking maximum density data among the above and taking the maximum density data as density data of target pixel data . 5. An image reading unit reads an original image, performs signal processing to digitize the image, sends the digitized signal to the image processing unit, performs image processing, and writes by a writing processing unit. by the image forming apparatus for forming an image, a character thinning, blurred or switching
The data of the read document image to the extent of reducing Les delayed in the main scanning direction, the delayed plurality of delayed data were
The target pixel is determined by the logical sum or the maximum density in the multiple delayed data.
Inflated more main scanning direction by replacing the expanded data expanded in the main scanning direction is delayed in the sub-scanning direction, the logical sum or a plurality of the delayed plurality of delayed data is
Replace the pixel of interest with the maximum density in the delay data
An image forming apparatus characterized by providing an image expansion means for expanding more in the sub-scanning direction. 6. A main scanning direction of the read document image and
Regarding image expansion in the sub scanning direction, horizontal, vertical, vertical and horizontal directions or
It is characterized in that one of the cancellations is selected.
The image forming apparatus according to claim 1.