JPH10341330A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce image degradation by controlling an arbitrary angle rotating function in accordance with the features of original image data, even when a character image and a photograph image exist mixedly by operating a smoothing means only in the halftone image area of image processed by the arbitrary angle rotating means. SOLUTION: In the case of original on which character images and photographic images (halftone images) mixedly exist, the arbitrary angle rotating function is controlled corresponding to the features of original image data. Image quality is degraded by arbitrary angle rotation, but the degradation in image quality is increased especially in the photograph image and the degradation in image quality is increased with respect to the enlargement of rotation angle. Then, a memory unit part 30 judges whether an input image is a simple binary image or a photographic image, in order to perform smoothing processing to the photographic image and when it is the photographic image, smoothing processing is performed. Thus, since processing is changed in accordance with the attribute of the input image, the degradation of image quality in the photographic area is reduced and even when the character image and the photographic image exist mixedly, the appearance of original image is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
The present invention relates to an image forming apparatus such as a facsimile and a multifunction peripheral.

[0002]

2. Description of the Related Art When a document placed on a document glass for reading a document image is erroneously tilted, it is desirable to correct the tilt of the document to form a document image. For this reason, an arbitrary angle rotation processing function of two-dimensional image data to be output from the image reading device has been proposed (for example, Japanese Patent Publication No. 63-9266). In the arbitrary angle rotation processing, the inclination of the original placed on the original glass is detected, the image data is rotated in a normal direction, and an image is formed using the corrected image data. This allows
Documents placed by the user inadvertently tilted can be automatically corrected for image tilt and output.

[0003]

However, in the conventional inclination correction processing based on arbitrary angle rotation, the input image data is automatically converted to a simple binary image such as a character image or a halftone image such as a photographic image. To process. In addition, the same processing is performed regardless of the magnitude of the rotation angle. At this time,
In the case of a character image, the image after the arbitrary angle rotation process is
The image quality hardly changes (for example, if the resolution is about 400 dpi or more). However, there is a disadvantage that the image quality of the image after the halftone image has been subjected to the arbitrary angle rotation processing is deteriorated. For example, roughness occurs in the halftone image portion. Especially when the rotation angle is large (for example, about 10 °).
Above) the deterioration of the image quality becomes severe. Since there are many types of halftone images and various intentions of the user,
Collective judgment is difficult. If the image is subjected to the arbitrary angle rotation processing as multi-valued data (data with gradation), the deterioration of the image quality can be suppressed to some extent. However, in that case, a complicated configuration is required, the processing speed is reduced, and the cost is greatly increased. In the case of a document in which a halftone image and a character image are mixed, if a smoothing process is performed on a character (simple binary) image, the image quality may be degraded. It is convenient for the user to be able to make a copy by automatically correcting the inclination of the document, but there is a problem that the image quality is deteriorated. In particular, since a halftone image often requires image quality, it is necessary to perform correction by smoothing or the like. In the case of a document in which a halftone image and a simple binary image are mixed, the deterioration of the image quality of a character (simple binary) image is small. For this reason, the image quality after the rotation processing is remarkably different between the character portion and the halftone image portion, and an image formed on one sheet is not good in appearance.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having an arbitrary angle rotation function, which can control the arbitrary angle rotation function according to the characteristics of original image data even when a character image and a photographic image are mixed. It is to provide a device.

[0005]

An image forming apparatus according to the present invention comprises a rotation angle setting means for setting a rotation angle of an input image from a two-dimensional input image, and a rotation angle set by the rotation angle setting means. An arbitrary angle rotating means for rotating a two-dimensional input image; a smoothing means for performing smoothing processing on an image rotated by the arbitrary angle rotating means; and only in a halftone image area of an image processed by the arbitrary angle rotating means. Control means for operating the smoothing means. Preferably, the image forming apparatus further includes a determination unit that determines whether the input image data is a simple binary image or a halftone image, and the control unit determines that the determination unit is a halftone image. Then, the smoothing means is operated. Preferably, the image forming apparatus further includes a mode setting unit for setting an image quality mode, and when the mode set by the mode setting unit is a photograph mode, the control unit is processed by the arbitrary angle rotation unit. The smoothing means is operated only in the halftone image area of the image. A second image forming apparatus according to the present invention includes a rotation angle setting unit that sets a rotation angle of an input image from a two-dimensional input image, and rotates the two-dimensional input image at a rotation angle set by the rotation angle setting unit. An arbitrary angle rotation unit, an attribute determination unit that determines an attribute of an image in the input image, and a control unit that inhibits operation of the arbitrary angle rotation unit when the attribute determination unit determines that an image having a different attribute is included. Is provided. Preferably, in the above-described image forming apparatus, the image forming apparatus further includes an image reading unit that reads an image on the original glass, and the rotation angle setting unit is arranged on the original glass based on image data input from the image reading unit. The rotation angle is set by detecting the angle of inclination of the document placed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital copying machine as an embodiment of the image forming apparatus of the present invention will be described below with reference to the accompanying drawings. (1) Configuration of Copying Machine FIG. 1 schematically shows the overall configuration of a digital copying machine 1. The digital copying machine 1 includes a reading device 200, a printer device 300, a document transport unit 500, an operation panel (see FIG. 2), and a re-feed unit 600. The document transport unit 500 automatically transports the document set on the document feed tray 510 to a reading position on the document glass 18 and, after the reading device 200 reads the document, discharges the document to the discharge tray 5.
Discharge to 11 The size of the original is determined by sensors 551 and 55
2 detected. The reading device 200 includes a scanning system, the image processing unit 20, and the like. In the scanning system, the original glass 18
The upper document is read, and image data corresponding to each pixel of the image of the document is generated. That is, the original is irradiated by the exposure lamp 12 attached to the scanner 19 that moves below the original glass 18. Light reflected from the document passes through a first mirror 12, fixed mirrors 13a and 13b, and a condenser lens 14, and is incident on a line sensor (photoelectric conversion element) 16 using a CCD array or the like. The scanner position sensor 17 is provided to detect that the scanner 19 reaches the document reading area (image area). The line sensor 16 has a large number of photoelectric conversion elements arranged in a direction (main scanning direction) orthogonal to the paper surface of FIG. 1. The line sensor 16 reads an image at 400 DPI, for example, and outputs reflected light corresponding to each pixel of the image of the document. The signal is converted into an electric signal and output to the image signal processing unit 20. The image signal processing unit 20 processes the input electric signal and outputs image data to the memory unit 30. Here, the image signal processing unit 20 can detect the inclination of the document. The memory unit section 30 compresses and temporarily stores the image data input from the image signal processing section 20, and then performs decompression processing and transmits it to the printer device 300. At the time of decompression, if necessary, editing processing such as rotation of the inclined document by an arbitrary angle is performed. Further, the memory unit section 30 includes an external device interface section described later, and is connected to an external device through an external cable 51 via an external device connection connector 50.

The printer device 300 includes a print processing unit 40,
It comprises a laser optical system 60, an image forming system and the like. The print processing unit 40 controls the laser optical system 60 based on the image data received from the memory unit 30. In the laser optical system 60, the semiconductor laser 61 emits a laser beam modulated by a signal from the print processing unit 40, and the polygon mirror 65 deflects the laser beam and scans the laser beam on the photosensitive drum 71. That is, the deflected laser beam is guided to the exposure position on the photosensitive drum 71 via the f-θ lens 66 and the reflection mirrors 67 and 68, and the scanning of the original image on the photosensitive drum 71 is performed by this scanning. An image is formed.

Image formation is performed by an electrophotographic method in an image forming system, and a latent image formed on a photosensitive drum 71 is developed, transferred and fixed on paper to form an image on paper. Here, the photosensitive drum 71 rotated and driven in the counterclockwise direction in FIG. 1 is uniformly charged by the charging charger 72 and then exposed, and the latent image is developed by the developing unit 73.
(Only one developing device is shown for simplicity of illustration, but a color image can be developed by providing developing devices for four colors of cyan, magenta, yellow, and black.) Then, the toner image is guided from the cassettes 80a and 80b to the photosensitive drum 71 through the sheet guide 81 and the timing roller 82, and the toner image obtained by the development is transferred to the sheet by the transfer charger 74. Next, the sheet is separated by the separation charger 75 and is conveyed to the fixing roller 84. The fixing roller 84 fixes the image on the sheet by heat, and then the sheet is discharged through the re-feed unit 600.

FIG. 2 is a plan view of the operation panel of the copying machine. The operation panel includes a liquid crystal touch panel 91 for status display and various mode settings, a numeric keypad 92 for inputting numerical values (number of sheets, magnification, etc.), a clear key 93 for returning numerical values to standard values, and a copy mode. A panel reset key 94 for initializing, a stop key 95 for instructing to stop copying, a start key 96 for instructing to start copying, an interrupt key 97 for designating interrupt activation and return, an image quality mode ( An image quality mode key 98 for designating (photo / text), a key 102 for designating an arbitrary angle rotation correction mode, and the like are arranged. Key 10
By pressing 2, on the liquid crystal touch panel 91,
Various choice settings (mode setting, etc.) related to the arbitrary angle rotation function can be performed. FIG. 3 shows a plurality of digital copying machines 1,
1 shows an example of a system configuration in which 1 ′ is connected on a network. The digital copiers 1 and 1 ′ are connected to an external device interface connector 50 via an interface cable 5.
1, a controller 2, which is an example of an external device,
2 '. Controller 2 is Ethernet
computer 3 via a general-purpose interface such as
And to another digital copying machine 1 'through the controller 2'. As an example, various settings (paper size, magnification, number of prints, staples,
When a condition such as sorting) and an output command are input, the command is sent to the controller 2 in a printing process on the computer 3. The controller 2 generally converts image data (such as PostScript data) sent from the computer 3 into raster data. for that reason,
The controller 2 has a memory for at least one screen. When converted into bitmap data, the image data is transmitted to the digital copying machine 1 (at the same time, various setting conditions are also transmitted via the controller 2). Processing is performed. It should be noted that the present invention is not limited to this system form, but also includes a system such as a facsimile apparatus connected to a modem through a telephone line.

(2) Copying Machine Control System FIGS. 4 and 5 show a control unit 100 for controlling the copying machine 1. The control unit 100 is mainly composed of eight CPUs 101 to 107. Each of the CPUs 101 to 107 has a ROM 111 to 117 storing a program and a RAM 121 to 117 serving as a work area for executing the program.
127 are provided. Note that the CPU 103 is provided in the memory unit 30.

The first CPU 101 controls input of signals from various operation keys on an operation panel (see FIG. 2) and display on a liquid crystal touch panel. The second CPU 102 controls driving of a scanning system of the reading device 200 and controls each unit of the image signal processing unit 20. Here, the inclination of the document is detected from the read image. The third CPU 103 compresses the read image data by controlling the memory unit 30, temporarily stores the read image data in the code memory 303, then reads out the image data and outputs it to the print processing unit 40. Here, at the time of reading, rotation editing of image data including image tilt correction is performed. The memory unit 30 has a function of interfacing with an external device, and transmits and receives image data and control data. The fourth CPU 104 controls the print processing unit 40, the optical system 60, and the image forming system of the printer device 300. The fifth CPU 105 controls the control unit 10
Processing for adjusting the overall timing of 0 and setting the operation mode is performed. The sixth CPU 106 controls the document conveying unit 50
0 is controlled. The seventh CPU 107 controls the sheet re-feed unit 600. These CPUs 101 to 10
Between 7, serial communication is performed by interruption, and commands, reports, and data are transmitted and received.

FIG. 6 is a block diagram of the controller 2 controlled by the CPU 105. The first external interface 700 exchanges signals with the external computer 3. The interpreter 702 translates data (for example, postscript data) sent from the computer 3 and develops the data into raster data,
2 stores raster data. When one page of image data is stored, the image data is output to the printing unit via the second external interface 704.

Next, processing of image data will be described. FIG. 7 illustrates an image signal processing unit 20. The image signal processing unit 20 includes a timing control unit 21, an amplifier 23, an A / D
Converter 25, shading correction unit 26, density conversion unit 2
7, an electric scaling section 28, an editing section 29, etc.
It is controlled by the PU 102. The image signal processing unit 20 converts the input signal from the line sensor 16 into an amplifier 23
And amplified by the A / D converter 25 for each pixel.
It is quantized to bit image data. The image data is then subjected to various processes such as shading correction, conversion to density data (gamma correction), electric scaling, and editing, and then sent as image data to the memory unit 30 or a printer device. The CPU 102 controls the image signal processing unit 20
Of the scanner unit of the laser scanning system, communication with the CPU 105, and the like, and controls the entire reading apparatus 200. The document size and the orientation of the document are detected as follows. In determining whether or not the read image is a document, for example, the document placed on the document glass 18 is scanned by setting the document cover of the document feeder 500 to a mirror-like surface, and a portion where the amount of reflected light is large is determined as the document. to decide. If the mirror surface is used, the amount of reflected light is very small, so that the determination is easy. Therefore, scanning may be performed with the document cover opened. C
When receiving an instruction of the document size detection operation from the CPU 105, the PU 102 performs a preliminary scan. CPU10
2 controls a scanner motor that drives the scanner 19 based on position information from the scanner position sensor 17;
The scanner 19 is caused to scan in the sub-scanning direction. At the timing corresponding to the sub-scanning position, the document size and the portrait / landscape orientation are detected from the content of the image data and the monitor position information, and the detection result is transmitted to the CPU 105. The CPU 102
Based on the magnification information transmitted from the PU 105, at the time of image reading, the speed of the scanner motor is controlled at a scan speed that matches the magnification information.

FIG. 8 is a block diagram of the memory unit 30. The switching unit 301 switches the route of image data to the image signal processing unit 20, the print processing unit, and the external interface 310. The area determination unit 303 determines whether input image data is simple binary data or halftone data for each area (pixel). Based on the parameter settings from the third CPU 103, the binarization processing unit 302 converts the image data into binary data within a range that can be restored to multivalued image data by error diffusion, dithering, or the like. The image memory 304 has a capacity for two pages.
The binary data is stored in the image memory 304. Next, the binary data read from the image memory 304 is compressed by the compressor 311 in the code processing unit 305 and stored in the code memory 306. The code memory 306 is, for example, a multi-port memory having a capacity of one page of A4 size at 400 DPI. The code memory 306 temporarily stores read data of a document image of a plurality of pages. The data in the code memory 306 is managed by a code management table provided in the RAM 126.

At the time of printing, the compressed image data in the code memory 306 is expanded by an expander 312. If image editing is required, the editing control unit 307 performs editing processing (rotation, scaling, movement, etc.) at the time of decompression, and performs the editing processing and decompression processing simultaneously. If necessary, a tilt angle rotation is also performed at the time of extension. The decompressed data is transferred to the image memory 304. When the data of one page is decompressed, the binary data read from the image memory 304 is converted into multi-value data by the multi-value processing unit 308.
If necessary, after the smoothing processing is performed in the smoothing processing unit 309, the data is transferred to the print processing unit 40 or the external device via the switching unit 301. CPU103
Sends control parameters to the multi-value processing section 302 and the smoothing processing section 309.

Next, the operation sequence of the copying machine 1 in image reading and printing will be described with reference to the CPUs 101 to 106.
Command (Q), report (A) exchanged between
And the flow of data. FIG. 9 shows a schematic sequence of the memory write operation. First, the fifth CPU 105, which manages the entire sequence, requests the third CPU 103, which controls the memory unit 30, to prepare for memory. In response, the CPU 103
Setting of a bus connection state for transferring image data from the image signal processing unit 20 to the image memory 304 to the internal hardware, setting of a mode for binarization processing, start address of a writing area in the image memory 304 , X
Make settings such as Y-length information. When these settings are completed and the preparation is completed, the CPU 103
05 is notified of the completion of memory preparation. Next, CP
U105 requests the CPU 103 and CPU 102 to read. In response, the CPU 102 requests the document scanning unit of the reading device 200 to scan. In this way, when the scanning of the original is started and the scanner 19 reaches the original reading area on the original glass, the read data is read according to the image processing mode set by the CPU 102.
(Image data D2) is transferred from the image signal processing unit 20 to the memory unit unit 30. When the scan is completed, a scan end signal is sent to the CPU 102, and the CPU 102
103 notifies the CPU 105 of the completion of the reading. Next, the CPU 105 requests the CPU 103 to compress the data. In response to this, the CPU 103 sets the read address from the image memory 304, the XY length information, the write address to the code memory 306,
Eleven modes (for example, arithmetic coding system and MH system) are set, and each unit is started. This allows the compressor 3
11 is performed, and the code data is stored in the code memory 306. When the compression process is completed, the CPU 1
03 notifies the CPU 105 of the completion of compression. At this time, if the code memory 306 is full of data, a compression completion report to which a parameter indicating that compression is impossible is added is sent to the CPU 105. Thus, the CPU 105 can know that the code memory 306 has become full.

FIG. 10 shows a schematic sequence of a memory read operation. In the memory read operation, image data is read from the image memory 304, and a copy image is printed on a sheet based on the image data. CPU10
5 requests the CPU 103 to decompress data. In response, the CPU 103 reads the address from the code memory 306, the amount of data, the write address to the image memory 304, the XY length information, the mode of the decompressor 312 (for example, the arithmetic coding method and the MH method), Set the edit processing mode such as angular rotation and start each unit. As a result, decompression (editing) processing is performed, and the image data is written to the image memory 304.
When the decompression process is completed, the CPU 103 notifies the CPU 105 of the completion of the decompression. Next, the CPU 105
The PU 103 is requested to prepare a memory for reading an image from the image memory 304. In response, CP
U103 is the image memory 3 for the internal hardware.
04, the setting of the bus connection state for outputting the image data to the print processing unit 40, the setting of the start address of the read area of the image memory 304, the XY length information, and the like are performed, and the CPU 105 is notified of the completion of the memory preparation. next,
The CPU 105 controls the CPU 103 and the printing unit 40
Request a print. From the print processing unit 40 to the CPU 105
Then, a paper feed report notifying the paper transport state is sent to the printer, and thereafter, the image data read from the image memory 304 is output to the print processing unit 40, and printing is performed. When printing is completed, the CPU 103 and the print processing unit 40
A print completion report and an ejection completion report are sent to the PU 105. C who received these reports
The PU 105 gives a memory clear request to the CPU 103 as needed.

(3) Document Reading When Document is Tilt Next, image reading when the document read on the document glass 18 is tilted will be described. As shown in FIG. 11, the document 10 is placed with its copy surface facing downward on a document glass 18 with reference to the upper right end (indicated by a triangle). The longitudinal direction of the original glass 18 is the sub-scanning direction of scan reading, and the direction perpendicular thereto is the main scanning direction. In the example shown in FIG. 11, the document is placed away from the image reference, and its position is not parallel to the sub-scanning direction. In this example, the document does not protrude from the reading area. FIGS. 12 and 13 show images of a read image when the document 10 (shown by a broken line) does not protrude from a reading area (a rectangle shown by a solid line). (Since the document 10 is viewed from the copy surface side, the image reference is at the upper left corner.) The image signal processing unit 20 processes image data of a rectangular area including at least the range of the document and processes the image data of the document area where the document exists. Perform detection,
From all the coordinates around the original (that is, the edge),
As shown in the figure, the coordinates of the four corners of the rectangular document are detected. Here, the main scanning direction is the X axis, and the sub scanning direction is the Y axis. X _max and X _min are the maximum and minimum X coordinates. Of the remaining two X coordinates, the larger _one is X ₁ and the smaller _one is X ₂ . Y _max and Y _min are the maximum and minimum Y coordinates, of which the larger _one is Y ₁ and the smaller _one is Y 2. In the example of FIG. 12, the X and Y coordinates of the four corners of the document are (X ₁ , Y _min ),
(X _max, Y _2), a _{(X min, Y 1),} (X 2, Y max). The lengths a, b, c, and d of the four sides of the document 10 can be calculated as follows from the coordinates of the document. a = {(X _max −X ₁ ) ² + (Y ₂ −Y _min ) ² } b = {(X ₁ −X _min ) ² + (Y ₁ −Y _min ) ² } (1) c = √ {(X ₂ −X _min ) ² + (Y _max −Y ₁ ) ² } d = {(X _max −X ₂ ) ² + (Y _max −Y ₂ ) ² } In the example of FIG. Unlike the case of FIG. 12, the coordinates of the four edges of the document are (X _min , Y ₁ ),
(X ₁ , Y _min ), (X ₂ , Y _max ) and (X _max , Y ₂ ). Also in this case, the lengths a, b, c, and d of the four sides can be calculated by the same formula. Here, the editing processing parameters for correcting the tilted image are as follows. First, X ₁ −X _min <
In the case of Y ₁ −Y _min (FIG. 12), rotation coordinates: (X ₁ , Y _min ) Rotation angle θ: tan ⁻¹ {(X ₁ −X _min ) / (Y ₁ −Y _min )} (2) Destination Nation address (pmmax, pmday): (−X ₁ , −Y _min ) When X ₁ −X _min > Y ₁ −Y _min (FIG. 13), rotation coordinates: (X _min , Y ₁ ) Rotation angle θ : Tan ^-1 {(Y ₁ −Y _min ) / (X ₁ −X _min )} (3) Destination address (pmdx, pmday): (−X _min , −Y ₁ ) The rotation coordinates are the upper left corner of the figure. Are the coordinates of the corner near. The rotation angle θ is a rotation angle for rotating the original with reference to the rotational coordinate position to make the original parallel to the reading area. The destination address is the coordinates of the transfer destination to the memory, and corresponds to the length from the upper left position to the image reference.

(4) Tilt Correction by Arbitrary Angle Rotation When the tilt of the read document is detected, the image is automatically rotated by the tilt angle to obtain an image that does not tilt. Therefore, when the user places the document on the document glass and erroneously places the document on the document glass, the image is automatically rotated by the tilt angle, so that a normal image can be obtained. Hereinafter, the arbitrary angle rotation processing will be described. The arbitrary angle rotation is performed in the editing processing unit 307 in the memory unit 30 based on the editing parameters detected by the image reading. First, the editing processing unit 307 will be described.
FIG. 14 shows a portion related to the arbitrary angle rotation of the edit processing unit 307 in the memory unit 30 and the image memory 304.
Editing such as rotation by the editing processing unit 307 is performed by using the image memory 304 and combining shift processing, XY conversion processing, and bit swap processing (FIG. 15, FIG.
See FIG. 16). When the rotation process is not performed (0 ° rotation), only the bit swap process is performed, and only the signals W2 and R2 are accessed, as indicated by the broken line.

In the case of performing the rotation processing, the input image data transferred from the decompression unit 312 is 16 bits, and is converted into 32 bits by the edit processing unit 307 by the 16 → 32 conversion unit 3070 first. In order to process the internal operation of the edit processing unit 307 and access to the image memory 304 at high speed, all data processing is performed in 32 bits. First
The shift unit 3071 performs a shift process if data after bit conversion is necessary, and
The data is written to the slice area 3040 and the 1-2 slice area 3041. The 1-1X-Y conversion section 3072 and the 1-2X-Y conversion section 3073 respectively include a 1-1 slice area section 3040 and a 1-2 slice area section 30.
An XY conversion process is performed on the data R1 read from 41. The second shift unit 3074 performs a shift process on the data after the XY conversion, if necessary. The first bit swap unit 3075 performs bit swap processing on the data from the 16 → 32 conversion unit 3070 or the data from the second shift unit 3074 if necessary, and edits the virtual paper area 3042 (maximum) in the image memory 304. To write to A3 size capacity). The second XY conversion unit 3076 outputs the second bit swap unit 3 if necessary at the time of printout.
077, the X of the R2 data read from the print output virtual paper area 3042 in the image memory 304
After performing the -Y conversion process, the data is written to the second slice area 3043 in the image memory 304. The R2 data read from the virtual paper area 3042 or the R3 data read from the second slice area 3043 during the print output operation is converted into one bit by the 32 → 1 conversion unit 3078 and sent to the multi-value processing unit 308. Will be transferred. During continuous operation, access to the image memory 304 (signals W1 to W3,
R1 to R3) are processed in parallel on a 32-bit bus line in a time division manner.

Next, referring to FIG.
The 0 ° rotation processing will be described. The image of the input image transferred from the decompression unit 312 is received with the upper left end as the image reference, as shown in FIG. The input image data is, as shown in (b) at the upper right, the first to the first in the line unit.
The data is read from the slice area unit 3040 in units of 32 bits × 32 bits from data of 32 bits × 32 lines, and is edited by the 1-1X-Y conversion unit 3072. Next, for 90 ° rotation, the center (c)
Is read out as shown in FIG.
The data is written in the virtual paper area 3042. At this time, image reference (destination address (pmdax, pmday))
Expand the data so that is at the lower left. 1-1 slice area section 3040 and 1-2 slice area section 3
No. 041 is a pair, and the above processing is performed by a double buffer operation. Next, referring to FIG. 16, first bit swap unit 3075 and second bit swap unit 3077
A bit swap process of image data according to will be described. In this process, as shown in the upper part of the figure, the arrangement of the 32-bit data is reversed. Then, as shown in the lower part of the figure, the inverted data is written in the virtual paper area 3042 such that the image reference (destination address) is at the lower right corner. In addition, by combining the 90 ° rotation and the bit swap processing, it is also possible to rotate 270 °. At this time, the data is developed so that the image reference is at the upper right end. The editing processing unit 307 can simultaneously process the parallel movement of the image by changing the transfer destination (destination address) to the virtual paper area based on the image. Although not described, processing such as erasing, copying, and pasting of an image in a specific area is also possible.

Next, the calculation for the arbitrary angle rotation will be described. The following equation shows a rotation process in the affine transformation. As shown in Expression (4), the coordinates (X, Y) are rotated by the angle θ to become coordinates (U, V). This operation is
It is decomposed as shown in Expression (5), and becomes a combination of the first shift, the 90 ° rotation, the second shift, and the −90 ° rotation. The above-described editing processing unit 307 performs an operation by combining these processes. In the first shift and the second shift, only the X-axis parameter is processed with the Y-axis parameter fixed.

(Equation 1)

Next, the inverse operation of the above-described rotation address operation will be described. Equations (6) and (7) show the inverse transform of Equations (4) and (5).

(Equation 2)

In the arbitrary angle rotation processing of the image data, the image data is processed according to the above-described calculation for the arbitrary angle rotation. An arbitrary angle rotation process (shift shift method) of image data will be described with reference to FIG. In the editing processing unit 307, the image of the input image transferred from the decompression unit 312 is received on the basis of the upper left corner as shown in the upper left of FIG. The input image data is subjected to a first shift process in the above-described first shift unit 3071 in accordance with the set rotation angle θ, as shown in the upper part of the center of FIG.
1 slice area 3041 and 1-2 slice area 3
042 is written in line units. Next, a 1-1 slice area 3041 and a 1-2 slice area 304
The data is read out in units of 2 to 32 × 32 bit blocks, and processed by the 1-1X-Y conversion unit 3072 and the 1-2X-Y conversion unit 3073. Next, based on the data for the two blocks, the second shift unit 3074 performs a second shift process according to the set rotation angle θ, and writes the data to the virtual paper area 3042. The two slice areas 3040 and 3041 form a pair, and the above operation is performed by a double buffer operation. With the processing so far, the image is rotated by (90 ° + θ). When printing out from the virtual paper area 3042, -90
The rotation by 270 ° (270 ° rotation) is processed using the second XY conversion unit 3076 and the second bit swap unit 3077, buffered (bit converted) to the second slice area unit 3043, and then multi-valued. Output to the unit 308. In the rotation process by the shift method, θ is desirably as small as possible in consideration of the image quality after the process.
<Θ <45 °. 90 ° rotation for more angles
Process by combining with unit rotation.

Next, a logical expression for simultaneously processing the arbitrary angle rotation and the scaling process of the image data is shown. Equation (8) is
The rotation processing and the scaling processing in the affine transformation are shown, and the coordinates (X, Y) are rotated by an angle θ and multiplied by α to become coordinates (U, V). This is decomposed as shown in equation (10), and the first shift, the rotation by 90 °, the second shift, −90
° rotation. In the first and second shifts, only the X-axis parameter is processed while the Y-axis parameter is fixed.

(Equation 3) Next, an inverse operation of the above-described rotation address operation will be described. Equation (1
(0) and (11) show the inverse transformations of equations (8) and (9).

(Equation 4)

FIG. 18 shows the above-described arbitrary rotation processing of image data. This processing includes shift processing, 90 ° rotation, shift processing, and −90 ° rotation. The scaling is performed in the editing processing unit 307 shown in FIG. 14 by associating the scaling parameters in the first and second shift units. However, depending on the magnification, it is necessary to increase the number of slice areas. At this time, only the scaling is processed,
If not, the rotation angle may be set to 0 °.

(5) Tilt Angle Rotation Correction According to Image Properties In the present copying machine, even in the case of a document in which a character image and a photographic image (halftone image) are mixed, an arbitrary angle rotation is performed according to the characteristics of the document image data. Control functions. Although image quality is degraded by rotation at an arbitrary angle, image quality is particularly degraded especially for photographic images. As the rotation angle increases (for example, when the rotation angle is about 15 ° or more), the image quality deteriorates more seriously. (Because there are many types of photographic images and the user's intentions are various, it is difficult to judge image deterioration collectively.) Therefore, it is desirable to perform smoothing processing on photographic images. For this reason, for example, it is determined whether the input image is a simple binary image or a photographic image,
If it is a photographic image, a smoothing process is performed. Since the processing is changed in accordance with the attribute of the input image in this manner, the image quality is not deteriorated in the photographic area, and even if the character image and the photographic image are mixed on one original, the original image formed on one sheet Looks better. When the user sets the image quality mode, and when the set image quality mode is the photograph mode, the smoothing processing is performed only on the halftone image area of the image subjected to the arbitrary angle rotation processing.

(6) Control of Copying Machine The control flow of the copying machine will be described below. FIG.
5 is a main flowchart of a first CPU 101 that controls an operation panel. When the power is turned on, first, an initialization for initializing a RAM, a register, and the like is performed (step S11). Thereafter, an internal timer that defines the length of one routine is set (step S12), key input processing for accepting key operation is performed (step S13), and panel display processing for performing display according to the key operation is performed (step S14). ). Then, a choice setting process is performed for the tilt angle rotation process (step S15, see FIG. 26). And
After performing other processing (step S17), the process waits for the end of the internal timer (YES in step S18), returns to step S12, and repeats the above processing. In addition, communication with another CPU is performed as interrupt processing at an appropriate time.

FIG. 20 is a flowchart for setting the image quality mode. If the image quality mode key is depressed (step S171), if the current image quality mode MD is the photo mode (YES in step S172), the character mode is set (step S173), and if not, the mode is not the photo mode (step S172). And NO), set the photograph mode (step S174), and return.

FIG. 21 is a flowchart of the choice setting (FIG. 25, step S15). First, the smoothing mode (RYO or GA) input from the operation panel
SITU) is registered in S_HANTEI (step S)
151). Next, the area determination comparison data is registered in REF (step S152). Further, other processing is performed (step S153), and the process returns.

FIG. 22 is a main flowchart of the second CPU 102 for controlling the image signal processing section 20. RA
After initial settings for initializing M and registers are performed (step S21), an internal timer that defines the length of one routine is set (step S22). Next, image data is input (step S23), document detection processing is performed (step S24, see FIG. 23), image processing is performed (step S25), and image data is output (step S2).
6). Then, other processing is performed (step S27),
Wait for the end of the internal timer (YE in step S28).
S), the process returns to step S22, and the above processing is repeated.

FIG. 23 is a flowchart of the document detection process (FIG. 22, step S24). Here, the coordinates of the edge portion are extracted in the document area, and a straight line composed of the extracted coordinates is regarded as each side of the document area (step S2).
41). Next, the coordinates of the X _min point and the X _max point and the coordinates of the Y _min point and the Y _max point (see FIGS. 12 and 13) are extracted (steps S242 and S243). X ₁ −X _min <Y ₁ −
If Y _min (YES in step S244), -ta
n ⁻¹ ((X ₁ −X _min ) / (Y ₁ −Y _min )) is defined as the inclination angle θ ′ (step S 245). X ₁ −X _min > Y ₁ −Y
If it is _min (YES in step S246), -tan
⁻¹ ((Y ₁ −Y _min ) / (X ₁ −X _min )) is defined as the inclination angle θ ′ (step S247). X ₁ −X _min = Y ₁ −Y _min
If it is (YES in step S248), the inclination angle θ ′ is set to 0 (step S249). If none of the above applies, the inclination angle θ ′ is set to 45 ° (Step S
250).

FIG. 24 is a main flowchart of the third CPU 103 for controlling the memory unit 30. First, initial settings for initializing a RAM, a register, and the like are performed (step S31). Next, a command receiving process for receiving a command from the fifth CPU (step S32), a status transmitting process for transmitting a status to the fifth CPU (step S33), an image memory writing process (step S34), an area determining process (step S35, 26, smoothing determination processing (step S36, FIG. 26)
), Compression control processing (step S37), decompression control processing (step S38), edit control processing (step S3).
9, see FIG. 27), smoothing control processing (step S
3A, see FIG. 28), image memory read processing (step S3B), and other processing (step S3C).
do. Then, the process returns to step S32, and the above processing is repeated.

FIG. 25 is a flowchart of the area determination process (FIG. 24, step S35). When the image input is completed (YES in step S351), the area determination result is read, and the text area is MOJI and the photograph area is SYASIN.
(Steps S352 and S353), and the ratio of the photographic area to the whole SYASIN / (SIASIN + MO)
JI) is set as HANBETU (step S354).
Next, the calculation result HANBETU is stored in the area determination comparison data R
EF (step S355), and the calculation result HANB
If the ETU is larger, the photographic image (SYASIN_
IMG) is set to IMAGE (step S356),
If it is smaller, the character image (MOJI_IMG) is IMAG
It is set to E (step S357).

FIG. 26 is a flowchart of the smoothing determination process (FIG. 24, step S36). First, the process branches according to the smoothing determination mode (S_HANTEI) set by the choice or the operation panel (steps S361 and S362). If the smoothing determination mode is the mode RYO based on the area determination, the
The process branches depending on the content of the GE (step S363). When the smoothing determination mode is a photograph image (SYASIN_IM
If G) or in the photo mode, a smoothing process is performed (step S364). When the smoothing determination mode is the character image MOJI_IMG,
Alternatively, in the case of the character image mode, the process immediately proceeds to step S36A, and SMOOTH_0 is set to the smoothing parameter SMOOTH_PARA (step S36).
365).

FIG. 27 shows the editing control (FIG. 24, step S
39 is a flowchart of FIG. If print data is stored in the code memory 306 (step S39)
1 is YES), a 90 ° unit rotation parameter (90θ) is set (step S392), and the arbitrary angle rotation parameter θ
Is set (step S393), and destination parameters (pmmax, pmday) are set (step S394). Then, other parameters are set (step S395). Next, an arbitrary angle rotation process is executed based on the set destination and rotation angle (step S396). Next, when it is determined that rotation is to be performed by 90 ° (YES in step S397), a 90 ° unit rotation is performed (step S398). And it returns.

FIG. 28 is a flowchart of the smoothing control process (FIG. 24, step S3A). If print data is stored in code memory 306 (YES in step S3A1), smoothing parameter S
If MOOOTH_PARA is SMOOTH_0 (YES in step S3A2), smoothing process disable setting is performed (step S3A3). If smoothing parameter SMOOTH_PARA is not SMOOTH_0 (NO in step S3A2), smoothing process enable setting is performed (step S3A2). S3A4). Then, other parameters are set (step S3A5).

FIG. 29 shows a fourth CP for controlling the printer unit.
It is a main flowchart of U104. After the initialization for initializing the RAM and the registers is performed (step S41), an internal timer that defines the length of one routine is set (step S42). Next, control of the development / transfer system (step S43) and control of the transport system (step S43)
44), control of the fixing system (step S45), and control of the print processing unit (step S46). Then, other processing is performed (step S47). Next, after waiting for the end of the internal timer (YES in step S48), step S4
2 and repeat the above processing. FIG. 30 is a main flowchart of the fifth CPU 105 for controlling the entire copying machine. After the initialization for initializing the RAM and the registers is performed (step S51), an internal timer that defines the length of one routine is set (step S51).
52). Next, an input data analysis process for checking input data from another CPU (step S53), a mode setting process for determining an operation mode according to the operation content (step S54), an interrupt switching process (step S55), and a mode Command setting processing (step S56), output data setting for making the command wait in the communication port (step S57), and other processing (step S58).
do. Next, waiting for the end of the internal timer (YES in step S59), the process returns to step S52, and the above-described processing is repeated.

In the above, the arbitrary angle rotation processing of the image data input from the document reading apparatus has been described. Similarly, it is also possible to process image data (with angle parameters) communicated from an external device on the network. . For example, image data input from an external device can be rotated by an arbitrary angle and printed by the print processing unit. Further, the image data read by the image reading device can be subjected to an arbitrary angle rotation process and output to an external device. In addition, image data input from an external device can be subjected to arbitrary angle rotation processing and output to the external device again.

(7) Second Embodiment In the copying machine according to the second embodiment, as in the copying machine according to the first embodiment, when a document in which a character image and a photographic image (halftone image) are mixed exists, a photographic image Is subjected to a smoothing process. The feature of this copying machine is that the attribute of the document image data is determined at the time of printing, and the smoothing function is controlled according to the attribute. That is, for the image data read from the image memory, the type (character / photo) of the image is determined in each area in the original image, and the smoothing processing is performed on the image data after the rotation processing only in the photographic area. This copying machine is different from the copying machine of the first embodiment in that the memory unit 30
Therefore, the memory unit will be described below. In the memory unit 30, when image data is read during printing, an image attribute is determined for each region (pixel), and a smoothing process is controlled for a photographic image in accordance with the determination result. FIG.
In the memory unit 30 shown in FIG.
Switches the route of image data to the image signal processing unit 20, the print processing unit, and the external interface 310. 2
Based on the parameter setting from the third CPU 103, the binarization processing unit 302 converts the image data into binary data within a range that can be restored to multi-valued image data by error diffusion, dithering, or the like. The image memory 304 has a capacity for two pages. The binary data is stored in the image memory 304. The binary data read from the image memory 304 is
Next, the data is compressed by the compressor 311 in the code processing unit 305 and stored in the code memory 306. Code memory 3
Reference numeral 06 denotes a multiport memory having a capacity of one page of A4 size at 400 DPI, for example. The read data of the document image of a plurality of pages is temporarily stored in the code memory 306.
It is managed by a code management table provided in M126.

At the time of printing, the compressed image data in the code memory 306 is expanded by the expander 312. If image editing is required, the editing control unit 307 performs editing processing (rotation, scaling, movement, etc.) at the time of decompression, and performs the editing processing and decompression processing simultaneously. If necessary, a tilt angle rotation is also performed at the time of extension. The decompressed data is transferred to the image memory 304. When the data of one page is expanded, the binary data read from the image memory 304 is used by the area determining unit 303 'to determine whether the input image data is simple binary data or halftone data. The region is determined, and a timing signal is sent to the multilevel smoothing processing unit 309 '. The data is converted into multi-value data by a multi-value smoothing unit 309 ', and if the image is a halftone image, smoothing processing is performed by a timing signal. Then, the switching unit 3
01 to the print processing unit 40 or an external device. The CPU 103 sends control parameters to the multi-value processing section 302 and the smoothing processing section 309.

The flowchart of the control of the copying machine has many parts in common with the copying machine of the first embodiment shown in FIGS. 19 to 30, and only the differences will be described below. The flow of the first CPU 101 for controlling the operation panel is the same as in FIG. The contents of the choice settings are different,
Here, the description is omitted. FIG. 32 is a main flowchart of the third CPU 103 for controlling the memory unit 30. First, initial settings for initializing a RAM, a register, and the like are performed (step S31). Next, the fifth CPU
Command receiving process for receiving a command from the CPU (step S32), status transmitting process for transmitting a status to the fifth CPU (step S33), image memory writing process (step S34), and compression control process (step S3).
7), decompression control processing (step S38), edit control processing (step S39), image memory read processing (step S3B ', see FIG. 33), and other processing (step S3C). Then, the process returns to step S32, and the above processing is repeated. In the image memory reading process, the smoothing process is controlled at the time of printing according to the attributes of the image.

FIG. 33 is a flowchart of the image memory reading process (FIG. 32, step S3B '). If print data is stored in the image memory 304 (YES in step S3B1), print settings are made (step S3B2), the data is read from the image memory 304, and pixels (areas) are stored in the area determination unit 303 '. Attribute. When it is determined that the attribute of the pixel is halftone (step S3B3), enable setting of the smoothing process is performed (step S3B4), and a timing signal (see FIG. 31) is generated. If it is determined that the attribute of the image data is a character (step S3B3), disable setting of the smoothing process is performed (step S3B).
5), no timing signal is generated. This is repeated until the processing is completed for all image data (YES in step S3B6).

(8) Third Embodiment In the copying machine according to the third embodiment, the attribute (character / photo) of the input image is determined (see FIG. 34). Correction is prohibited (see FIG. 36) to prevent image quality deterioration due to image rotation. This copier has a configuration similar to that of the first embodiment. The flowchart of the control of the copying machine has many parts in common with the copying machine of the first embodiment shown in FIGS. 19 to 30, and only different points will be described below.

FIG. 34 is a main flowchart of the third CPU 103 for controlling the memory unit 30. First, initial settings for initializing a RAM, a register, and the like are performed (step S31). Next, a command receiving process for receiving a command from the fifth CPU (step S32), a status transmitting process for transmitting a status to the fifth CPU (step S33), an image memory writing process (step S34), and an area determining process (step S35 ') , FIG. 35
3), arbitrary angle rotation determination processing (step S36 ', FIG. 3)
6), compression control processing (step S37), decompression control processing (step S38), edit control processing (step S3).
9), smoothing control processing (step S3A ′, FIG. 3)
7), image memory read processing (step S3)
B) and other processing (step S3C). Then, the process returns to step S32, and the above processing is repeated.

FIG. 35 is a flowchart of the area determination control (FIG. 34, step S35 '). When the image input process is completed (YES in step S1351), the area determination result is read, and the character area is set to MOJI (step S135).
1352), the photo area is set to SYASIN (step S1353). If SYASIN and MOJI exist (YES in step S1354), HA
NBETU is set to 0 (step S1355), otherwise, HANBETU is set to 1 (step S135).
6). The determination result HANBETU is used in the arbitrary angle rotation processing shown in FIG. 36 and the smoothing control shown in FIG.

FIG. 36 is a flowchart of the arbitrary angle determination process (FIG. 34, step S36 '). Determination result HANBETU set in area determination processing (FIG. 35)
Is zero (YES in step S1361), that is, if different attributes are mixed, the arbitrary angle rotation is prohibited (step S1362). Otherwise, the arbitrary angle rotation is permitted (step S1363).

FIG. 37 is a flowchart of the smoothing control (FIG. 34, step S39 '). If data for printing is stored in the image memory 304 (YES in step S1391), it is determined whether the determination result HANBETU is 0 (step S13A2). H
If ANBETU is 0 (if different attributes are mixed), the smoothing process is prohibited (step S13A).
3). On the other hand, if HANBETU is not 0 (in the case of a single attribute), smoothing processing is permitted (step S1).
3A4). Then, make other settings and return.

[0049]

According to the present invention, by performing various processes on an image after rotation of an arbitrary angle in image rotation for correcting a tilt angle on a photographic image, image quality deterioration can be reduced. For example, when the input image data is a halftone image, the image quality is prevented from deteriorating by performing smoothing. Further, in the case where the attributes of different images are included in one document, the arbitrary angle correction is prohibited, thereby preventing the image quality of the halftone image from deteriorating and improving the appearance of the single image.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a copying machine according to the present invention.

FIG. 2 is a plan view of an operation panel of the copying machine.

FIG. 3 is a diagram illustrating an example of a system configuration including a copying machine;

FIG. 4 is a block diagram of a part of a control unit of the copying machine.

FIG. 5 is a block diagram of a part of a control unit of the copying machine.

FIG. 6 is a block diagram of a controller.

FIG. 7 is a block diagram of an image signal processing unit.

FIG. 8 is a block diagram of a memory unit.

FIG. 9 is a diagram of a memory write operation.

FIG. 10 is a diagram of a memory read operation.

FIG. 11 is a diagram for explaining input of a document image by scanning.

FIG. 12 is a diagram illustrating an example of an image of a read image.

FIG. 13 is a diagram illustrating an example of an image of a read image.

FIG. 14 is a block diagram of an edit processing unit in the memory unit.

FIG. 15 is a diagram illustrating a 90 ° rotation process of image data.

FIG. 16 is a diagram for explaining bit swap processing of image data.

FIG. 17 is a diagram for explaining an arbitrary angle rotation process (shift shift process) of image data.

FIG. 18 is a diagram illustrating a process of simultaneously performing an arbitrary angle rotation process (shift shift process) and a scaling process on image data.

FIG. 19 is a main flowchart of the first CPU.

FIG. 20 is a flowchart of image quality mode setting.

FIG. 21 is a flowchart of choice setting.

FIG. 22 is a main flowchart of the second CPU.

FIG. 23 is a flowchart of document detection.

FIG. 24 is a main flowchart of the third CPU.

FIG. 25 is a flowchart of an area determination.

FIG. 26 is a flowchart of smoothing determination.

FIG. 27 is a flowchart of editing control.

FIG. 28 is a flowchart of smoothing control.

FIG. 29 is a main flowchart of the fourth CPU.

FIG. 30 is a main flowchart of the fifth CPU.

FIG. 31 is a block diagram of a memory unit of a copying machine according to a second embodiment.

FIG. 32 is a main flowchart of a third CPU according to the second embodiment.

FIG. 33 is a flowchart of image memory reading in the second embodiment.

FIG. 34 is a main flowchart of a third CPU according to the third embodiment.

FIG. 35 is a flowchart of area determination control.

FIG. 36 is a flowchart of an arbitrary angle rotation determination process.

FIG. 37 is a flowchart of smoothing control.

[Explanation of symbols]

30 memory unit section, 101 first CPU, 1
03 third CPU, 200 image reading unit, 303,
303 'area discriminating section, 307 editing processing section, 30
9 'Multi-level / smoothing processing unit.

Claims (5)

[Claims] 1. A rotation angle setting means for setting a rotation angle of an input image from a two-dimensional input image; an arbitrary angle rotation means for rotating a two-dimensional input image at a rotation angle set by the rotation angle setting means; It is characterized by comprising smoothing means for performing smoothing processing on an image rotated by the arbitrary angle rotating means, and control means for operating the smoothing means only in a halftone image area of the image processed by the arbitrary angle rotating means. Image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising: a determination unit configured to determine whether the input image data is a simple binary image or a halftone image. An image forming apparatus, wherein the smoothing means is operated when the means determines that the image is a halftone image. 3. The image forming apparatus according to claim 1, further comprising: a mode setting unit for setting an image quality mode, wherein when the mode set by the mode setting unit is a photograph mode, the control unit includes: An image forming apparatus which operates the smoothing means only in a halftone image area of the image processed by the arbitrary angle rotating means. 4. A rotation angle setting means for setting a rotation angle of an input image from a two-dimensional input image; an arbitrary angle rotation means for rotating a two-dimensional input image at a rotation angle set by the rotation angle setting means; An attribute discriminating means for discriminating an attribute of an image in an input image, and a control means for prohibiting the operation of the arbitrary angle rotating means when the attribute discriminating means determines that an image having a different attribute is included. Image forming device. 5. The image forming apparatus according to claim 1, further comprising: an image reading unit that reads an image on a document glass; An image forming apparatus for detecting a tilt angle of a document placed on a document glass from image data input from a reading unit and setting a rotation angle.