JP3400874B2 - 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 rotating device for rotating an image at an arbitrary angle.

[0002]

2. Description of the Related Art Generally, when an image is rotated at an arbitrary angle, it can be realized by directly executing an affine transformation shown in the equation (1) described later. However, since high-speed processing is difficult with this method, as a conventional method for performing high-speed rotation, a microprocessor is used to convert image data into an oblique axis conversion as shown in, for example, Japanese Patent Laid-Open No. 60-97473. It is proposed that the scaling is performed after that, and further the oblique axis conversion is performed. In addition, as disclosed in Japanese Patent Laid-Open No. 60-97474, by using a microprocessor, coordinate data is updated from image data to perform one-direction oblique change axis conversion and enlargement / reduction conversion, and further another direction oblique change axis conversion. A method of performing scaling conversion has been proposed.

[0003]

However, in the above-described conventional image rotation method, since italic conversion and magnification conversion are performed using a microprocessor, it is impossible to perform processing in real time that matches the speed of the transfer paper, for example. There is a problem. Further, there is a problem that new hardware must be added in order to realize the image rotation processing function in an existing digital copying machine, for example.

In view of the above-mentioned conventional problems, the present invention can perform processing in real time so as to match the transfer paper conveyance speed, and can be processed in an existing digital copying machine without adding new hardware. It is an object of the present invention to provide an image rotation device capable of performing.

[0005]

In order to achieve the above-mentioned object, the first means is to read the read original document for each scan.
Image stored in the frame memory and stored in the frame memory
An image that reads data and forms a visible image on a recording medium
In an image forming apparatus including a forming unit, a magnification conversion circuit that performs magnification conversion in the main scanning direction of image data, an italic conversion circuit that performs italic conversion of the image data processed by the magnification conversion circuit, and the frame memory, The image data processed by the italic conversion circuit is rotated by 90 °.
And an image rotation circuit capable of causing the image data processed by the image rotation circuit in the preceding stage of the magnification conversion circuit.
Select whether to return or to return to the latter stage of the italic conversion circuit, and again
By returning to the magnification conversion circuit and the italic conversion circuit,
Set whether to perform magnification conversion and italic conversion again respectively
And an image bus including a switch for switching .

The second means is to scan the read original by one scan.
Each frame is stored in the frame memory and stored in the frame memory
The image data that has been read is read and a visible image is formed on the recording medium.
Image forming apparatus equipped with an image forming unit
Magnification conversion in the main scanning direction of image data and italic conversion
It includes a magnification conversion / shift circuit and a frame memory.
Image data processed by the magnification / shift circuit
Image rotation circuit that can rotate the image in 90 ° increments
And the image data processed by the image rotation circuit
Whether to return to the previous stage or the subsequent stage of the magnification conversion / shift circuit
By selecting and returning to the magnification conversion / shift circuit again
Whether to perform the magnification conversion and italic conversion again.
Image bus including switches to set, and pre-magnification conversion / shift
Control circuit that outputs scaling control data to the
The magnification conversion / shift circuit includes an interpolation calculation circuit and
Includes a FIFO memory that toggles.
The data input to the magnification conversion / shift circuit is as it is,
Data thinned out by the interpolation calculation circuit at the time of reduction
However, when expanding, the data interpolated by the interpolation calculation circuit is
Data is input to the FIFO memory and the next write
Read out from the FIFO memory and re-interpolate
It is input to the selector before the arithmetic circuit and FIFO memory.
Selected by the selector according to the same size, reduction, or enlargement.
Data from the selected interpolation calculation circuit or FIFO memory
Data is output from the magnification conversion / shift circuit.
It is characterized in that an image is formed based on the applied data .

[0007]

In the first means, the image is rotated at an arbitrary angle by the hardware composed of the magnification conversion circuit, the italic conversion circuit, the image rotation circuit and the image bus. Therefore, since the processing can be performed at high speed, the processing can be performed in real time so as to match the transfer speed of the transfer sheet.

In the second means, the magnification conversion and the italic conversion are processed by the common FIFO memory, so that they can be processed in an existing digital copying machine without adding new hardware.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of an image processing apparatus having an image rotating function according to the present invention, and FIG. 2 is a block diagram showing a scanner and a printer of a digital copying machine to which the image processing apparatus of FIG. 1 is applied. .

First, the structure of a scanner of a digital copying machine to which the image processing apparatus of this embodiment is applied will be described with reference to FIG. A contact glass 1 for placing a document is provided on the upper surface of the apparatus, and the document on the contact glass 1 is reflected by a light source 2, and the reflected light is reflected by mirrors 3, 4, and 5.
Is sequentially reflected by 90 ° and is read by the CCD line image sensor 7 via the lens 6. The light source 2 and the mirror 3 are supported by the traveling body 8, and the mirrors 4, 5 are supported by the traveling body 8 and are movable in the sub scanning direction.

The image signal read by the line image sensor 7 is a VPU (Video Processing U) shown in FIG.
A / D after being given proper gain by nit) 100
The 8-bit digital data DATA0 to 7 that are converted and are synchronized with the clock CK1 are applied to the IPU (Image Processing Unit) 110. In addition, IPU110
Therefore, to the VPU 100, the CCDSTN signal that determines the read timing of the CCD line image sensor 7 and the clock CK1 of 10 MHz are applied.

The IPU 110 is a black offset correction circuit 11
1, shading correction circuit 112, MTF correction circuit 1
13, a main scanning direction magnification conversion circuit 114, a γ conversion unit 11
5. It has an image quality correction circuit 116. EDU (EDiting Un
it) 120 is for iterative, black and white inversion, with respect to the image data that has been γ corrected by the γ conversion unit 115 when performing editing processing
Edit processing such as shading is performed, and the processed data is γ
It returns to the latter stage (illustration A) of the conversion unit 115.

The IPU 110 will be described in detail.
First, the black offset correction circuit 111 subtracts the black level of the dark current of the CCD line image sensor 7 from the image data. Next, the shading correction circuit 112 detects the light amount unevenness of the light source 2 in the main scanning direction and the CCD line image sensor 7.
In order to eliminate the unevenness due to the difference in sensitivity between the pixels, a white plate having a uniform density is read in advance before scanning the document and stored for each pixel, and the read data of the document is divided by the reference data of the white plate. The MTF correction circuit 113 corrects the deterioration of the frequency characteristic of the optical system by a spatial filter, and the image quality correction circuit 1
16 performs character processing, error diffusion processing, dither processing, etc. according to the mode.

The FMU (Frame Memory Unit) 130 is
Data of 5000 x 6800 pixels covering 3 sizes can be stored with a depth of 8 bits per pixel, and in addition to the normal mode (FIFO) for reading the data written in the frame memory in the writing order, the X direction It has a rotation mode in which an image is rotated in 90 ° units by reading out the address of and the address in the Y direction. This F
The data processed by the EDU 120 (B in the figure) is applied to the MU 130, and the processed data is the image bus 11
It is selected by the changeover switch 131 of No. 7 and selectively output to the magnification conversion circuit 114 (B ′ in the drawing) or the image quality correction circuit 116 (B in the drawing).

Although not shown, the IPU 11
0 is the CPU and address bus of the main control circuit of the copying machine,
Communication is performed with the CPU by sharing the data bus. The main control circuit controls the scanner and printer motors, and also various clutches,
Control the solenoid. The output data SDT0 to 7 of the IPU 110 are speed-converted according to the write clock and then sent to the LD modulation circuit. In the LD modulation circuit, according to the image data of 8 bits (256 gradations), as shown in FIG.
The pulse width (PWM) of the current applied to the semiconductor laser generator 17 and the amount (PW) of the current are controlled.

In the printer shown in FIG. 2, the laser generator 1
When the laser beam from 7 reaches the photoconductor 20 that has been charged by the charging charger 21 through the optical system 18 and the reflection mirror 19, a latent image is formed on the surface of the photoconductor 20. This latent image is developed with toner by the developing roller 22, the toner image is transferred to a sheet, and then the residual toner on the photoconductor 20 is removed by the cleaning unit 32.

Paper is fed from cassettes 24 and 25 to the paper feed roller 2.
7 is fed by the registration roller 23 to the photoconductor 2
0 is transferred so that the toner image is transferred so that the toner image is transferred by the transfer charger 28.
The toner image is separated from the photoconductor 20 by 9 and is transported by the transport belt 30, and the toner image is fixed by the fixing unit 31 and discharged onto the discharge tray 33.

In the above-mentioned structure, in the normal original reading mode, when the start button is pressed while the original is placed on the contact glass 1 with the image surface facing downward, the CPU sends the scan signal SS to the IPU 110.
CAN is applied, and the signal FGATEN indicating the image effective range in the sub-scanning direction becomes active. Then, the traveling bodies 8 and 9 start moving in the sub-scanning direction, and the document is scanned. In this case, the traveling body 9 moves at half the speed of the traveling body 8.

The reflected light (reading light) of the document illuminated by the light source 2 is photoelectrically converted by the line image sensor 7 via the mirror 3 → mirror 4 → mirror 5 → lens 6 and A / D converted by the VPU 100. , IPU110
Applied to. In the IPU 110, each processing is performed by the black offset correction circuit 111, the shading correction circuit 112, the MTF correction circuit 113, the magnification conversion circuit 114 in the main scanning direction, the γ conversion unit 115, and the image quality correction circuit 116.
It is output to the printer. Here, at the time of normal copying, almost simultaneously with the generation of the signal FGATEN indicating the image effective range in the sub-scanning direction, the printer operation start signal DFGATEN
Becomes active and writing is performed by the printer.

On the other hand, the frame memory (FMU13
0) in the high speed mode, the black offset correction circuit 111, the shading correction circuit 112, the MT
An F correction circuit 113, a magnification conversion circuit 114 in the main scanning direction,
After each processing is performed by the γ conversion unit 115, the signal FGA
Data for one scan is stored in the frame memory in synchronization with TEN. After this, the printer operation start signal DF
GATEN becomes active, image data is read from the frame memory, and is output to the image quality correction circuit 116 (B in the figure) via the bus switch 131. Hereinafter, when copying the second and subsequent sheets, the image data stored in the frame memory is repeatedly read.

Next, the principle of rotating at an arbitrary angle will be described. Normally, affine transformation represented by the equation (1) is generally used for rotation. However, since this method has a problem in terms of cost and speed with the current hardware, in this embodiment, the equation (2) obtained by expanding the equation (1) is sequentially executed.

[0022]

[Equation 1]

[0023]

[Equation 2]

Here, the first item in equation (2) indicates that magnification conversion and italic conversion are performed with respect to the x-axis (main scanning direction axis), and the coefficient A is sin θ, which is reduction conversion.
Since the coefficient B is cos θ, it is an italic transformation less than 45 °. The second item represents a 90 ° rotation with respect to the origin. The third item indicates that magnification conversion and italic conversion are performed with respect to the x-axis (main scanning direction axis). The coefficient C is 1 / sin θ, which is expansion conversion, and the coefficient D is cot θ, which is italic conversion. is there.

Next, the operation of rotating the image will be described. First, when the rotation angle θ is set by the user via the operation panel (not shown), the coefficients A, B, C, and D in the equation (2) are set to C of the main control unit according to the rotation angle θ.
Calculated by PU. Next, when the start button is pressed, the document is read and the VPU 100 changes to the IPU 110.
, 8-bit digital data DATA0 to 7 synchronized with the clock ck1 are applied, and each processing is performed by the black offset correction circuit 111, the shading correction circuit 112, and the MTF correction circuit 113.

Next, in the magnification conversion circuit 114, equation (2)
The electrical scaling in the main scanning direction is performed by the factor A times in the main scanning direction, and γ is corrected by the γ conversion unit 115 as in the normal mode. Then, in the image rotation mode, the image bus 117 is switched so that the image data flows to the EDU 120, and the EDU 120 performs the italic transformation of the angle φ that satisfies tan φ = cos θ, whereby the first item in the equation (2). Is executed.

The image data processed by the EDU 120 is input to the FMU 130 via the IPU 120, and when the data for one scan is stored in the FMU 130, the addresses of x and y are exchanged and read out. Is executed and rotated by 90 °. Then F
The image data processed by the MU 130 is returned to the magnification conversion circuit 114 (B ′ in the drawing) via the bus switch 131, and the electric magnification in the main scanning direction by the coefficient C times in Expression (2) is performed. Next, as in the normal mode, the γ conversion unit 11
Γ is corrected by 5.

In the image rotation mode, the bus 117 is switched so that the image data flows to the EDU 120, and the EDU 120 performs the italic transformation of the angle φ (90−θ) that satisfies tan φ = cot θ. The third item in (2) is executed. Then EDU
The image data processed by 120 is the image quality correction circuit 11
6 and output to the printer. Therefore, since the transformation of this example is equivalent to the affine transformation in the equation (1), it can rotate at an arbitrary angle.

Next, a second embodiment will be described with reference to FIGS. In FIG. 3, the magnification conversion circuit 114 shown in FIG.
Instead of this, a magnification conversion / shift circuit 114a as shown in detail in FIG. 4 is provided. Further, a CPU 140 is used instead of the EDU 120, and the CPU 140 converts the magnification via an address bus 141 and a data bus 142.
It is connected to the shift circuit 114a.

Magnification conversion / shift circuit 114a shown in FIG.
Is 25% to 5 in interpolation by cubic function convolution
12% (in 1% increments) scaling in the main scanning direction,
By setting the shift direction and the shift amount by a command, the image is shifted in the main scanning direction in units of one pixel and with a different shift amount for each line to perform italic transformation. Enlargement or reduction is selected by a command kakdi from the CPU 140, and actual scaling operation control is performed by the scaling control data written in the internal RAM of the 512 × 4 bit CPU 140.

In FIG. 4, SKD <7: 0> is the circuit 11
4a input data, HKD <7: 0> is output data of the circuit 114a, and BOUT <7: 0> is FIFO memory (F
Output data to IFO1, 2), BIN <7: 0> is F
Input data from the IFO memory (FIFO1, 2), S
MPL <7: 0> indicates resampling position data from the internal RAM. bout <7: 0>, bin <7: 0
> Is a 5k × 8 bit FIFO memory (FIFO1,
2) are connected in parallel and operate as a toggle.

The flip-flops FF2 and FF3 are provided with an enable terminal en, and the FF1 and FF4 are normal 8-bit flip-flops. Also, the selector SEL1
3 to 8 are 8 bits, and the interpolation calculation circuit (hokan25
69 interpolates 8-bit multi-valued data. The read enable signal ren for the FF3 and the write enable signal wen for the FF2 are H / L controlled by the scaling control data of the internal RAM of the CPU 140.

Enlargement / reduction selection command kak at the same size
di = L is set, and both the read enable signal ren and the write enable signal wen are set to inactive as shown in FIG. In this case, when the input data SKD <7: 0> is fetched by the FF1, the input data SKD <7: 0> passes through the interpolation calculation circuit (hokan256) and the output data B
OUT <7: 0> is written to the FIFO memory (FIFO 1 or 2). This data is read out as data BIN <7: 0> on the next line and output as output data HKD <7: 0> via FF3 and FF4.
In this case, since ren = wen = L, speed conversion is not performed, and the same-magnification operation is performed.

At the time of reduction, kakdi = L is set, and as shown in FIG. 6, the write enable signal wen is set active and the read enable signal ren is set inactive. In this case, the input data SKD <7: 0
> Is taken in by FF1, the interpolation calculation circuit (ho
kan256) interpolated by cubic convolution. The sampling position when performing the interpolation is obtained by reading the scaling control data previously written in the internal RAM of the CPU 140.

The interpolated data is thinned out by the write enable signal wen in FF2 and written in the FIFO memory (FIFO 1 or 2). This data is read in the next line, is multiplied by FF3 (ren = L), and is output as output data HKD <7: 0> via FF4.

At the time of enlargement, kakdi = H is set, and as shown in FIG. 7, the write enable signal wen is set inactive and the read enable signal ren is set active. In this case, the input data SKD <7: 0
> Is taken in by FF1, FF2 (wen =
L) and is written to the FIFO memory (FIFO 1 or 2). This data is read in the next line, speed converted by the read enable signal ren by the FF3, and interpolated by cubic function convolution in the interpolation calculation circuit (hokan256).

The sampling position for interpolation is CP
It is obtained by reading the scaling control data written in advance in the internal RAM of U140, and the sampling position is changed with respect to the data whose reading is stopped, and the data is enlarged by performing interpolation a plurality of times. The interpolated data is FF
It is output after passing through 4.

The circuit 114a is also capable of shifting in the main scanning direction by a variable shift amount to perform italic conversion by changing the read time for each line of the FIFO memory. FIG. 8 shows the case of shifting to the right (leftward italic) and FIG. 9 shows the case of shifting to the left (rightward italic). When shifting to the right, the write enable signal wen and the write reset signal wres are generated as they are, and the read enable signal ren and the read reset signal rres are delayed by the shift amount. When shifting to the left, the write enable signal wen and the write reset signal wres are delayed by the shift amount, and the read enable signal ren and the read reset signal rres are generated at normal timing.

Therefore, in this embodiment, the italic conversion is performed by the FIFO memory for the magnification conversion, so that the magnification conversion and the italic conversion can be performed without adding new hardware. Therefore, the same FIFO memory is used. Can be used to rotate at any angle.

[0040]

The invention of claim 1, wherein, as described in the foregoing can be magnification conversion circuit, italic conversion circuit, the image rotation circuit, and image bus images by hardware configured to rotate at any angle Therefore, it is possible to perform processing in real time so as to match the conveyance speed of the recording medium .

According to the second aspect of the present invention, since the magnification conversion and the italic conversion are processed by the common FIFO memory, image formation is performed.
It can be processed without adding new hardware in a device such as an existing digital copying machine.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image rotation device according to the present invention.

2 is a configuration diagram showing a scanner and a printer of a digital copying machine to which the image rotating device of FIG. 1 is applied.

FIG. 3 is a block diagram showing an image rotation device of a second embodiment.

FIG. 4 is a block diagram showing the magnification conversion / shift circuit of FIG. 3 in detail.

5 is a timing chart showing main signals at the same magnification in the magnification conversion / shift circuit of FIG.

6 is a timing chart showing main signals at the time of reduction in the magnification conversion / shift circuit of FIG.

7 is a timing chart showing main signals at the time of enlargement in the magnification conversion / shift circuit of FIG.

8 is a timing chart showing main signals at the time of rightward shifting in the magnification conversion / shift circuit of FIG.

9 is a timing chart showing main signals at the time of leftward shift in the magnification conversion / shift circuit of FIG.

[Explanation of symbols]

114 Magnification Conversion Circuits 114 and 114a Magnification Conversion / Shift Circuit 120 EDU (EDiting Unit) (Italic Conversion Circuit) 117 Image Bus 130 FMU (Frame Memory Unit) (90 ° Rotation Circuit) FIFO1, FIFO Memory

Claims (2)

(57) [Claims] 1. The scanned original is framed for each scan.
Image data stored in the frame memory.
An image type that reads data and forms a visible image on a recording medium
In an image forming apparatus including a forming unit, a magnification conversion circuit that performs magnification conversion in the main scanning direction of image data, an italic conversion circuit that performs italic conversion of the image data processed by the magnification conversion circuit, and the frame memory, Image data processed by the italic conversion circuit can be rotated in 90 ° increments.
An image rotation circuit Noh, the image data processed by the image rotation circuit the multiplying
Return to the previous stage of the rate conversion circuit or return to the latter stage of the italic conversion circuit.
Select either one, and again the magnification conversion circuit and italic conversion circuit
, And the italic conversion is performed again.
An image forming apparatus , comprising: an image bus including a switch for setting whether or not to displace the image. 2. The scanned original is framed for each scan.
Image data stored in the frame memory.
An image type that reads data and forms a visible image on a recording medium
In the image forming apparatus equipped with the image forming means, the main scanning direction of the image data is scaled and the diagonal conversion is performed.
The magnification / shift circuit includes a frame conversion / shift circuit for converting the frame and the frame memory.
Rotate the processed image data in 90 ° increments
Image rotation circuit capable of performing the above, and the image data processed by the image rotation circuit
Select whether to return to the front stage or the rear stage of the rate conversion / shift circuit
Then, return it to the magnification conversion / shift circuit again.
Set whether to perform magnification conversion and italic conversion again respectively
Outputs the scaling control data to the image bus including the switch and the pre-magnification conversion / shift circuit
And a control circuit for performing the multiplication , the magnification conversion / shift circuit includes an interpolation calculation circuit and a toggle.
Includes an operating FIFO memory, and at the same magnification, the magnification change
When data is input to the conversion / shift circuit as is , when reducing
The data thinned by the interpolation calculation circuit is expanded
Sometimes the data interpolated by the interpolation calculation circuit is
Each is input to the FIFO memory, and the next line
The interpolation operation circuit is read again from the FIFO memory and is again
And input to the selector in the previous stage of the FIFO memory, etc.
Selected by the selector according to double, reduce, enlarge
Data from the interpolation calculation circuit or FIFO memory
Output from the magnification conversion / shift circuit, and output
Image formation is performed based on the data
Image forming apparatus.