JP2000118044A - Imaging system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging system in which gradation skip can be suppressed effectively at the time of outputting a gradation-like CG image. SOLUTION: Maximum value of random number data generated from a random number generating section 210 is calculated at a random number maximum value calculating section 220 and a random number additional amount is calculated depending on the gradation at a random number additional amount calculating section 230 by adjusting the maximum value of random number calculated at the random number generating section 210 according to the gradation of image. Depending on the gradation of an input image data, a random number additional amount selecting section 240 selects and outputs a random number data in a section corresponding to the gradation of image data among the random number data determined for every section at the random number additional amount calculating section 230. Subsequently, a random number adding section 250 adds the random number data to the input image data. A random number addition control section 280 controls a selector 260 depending on the image processing (image data) and selects and outputs one of the input image data or an image data subjected to random number addition processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus and an image forming method for forming an image of input image data.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable development of a digital copying machine for copying an image by electrically reading an original and outputting the obtained image data on paper.
With the rapid growth of technology in the copier industry, color digital copiers capable of processing color images have also appeared, and it has become possible to provide users with higher quality and higher precision beautiful color images.

[0003] One of the problems in improving the image quality of a copying machine is a problem of image gradation skipping (pseudo contour).
This is because the toner characteristic does not change in proportion to the image gradation, so that the toner density difference differs between the preceding and following gradations for each gradation, and the portion where the density difference is large becomes streaks. Is a phenomenon that appears in

Conventionally, in order to solve the problem of gradation skip,
Once, the test image data in the image processing section is printed out, the output image data is placed on the platen, scanned, the image data is captured, the toner characteristics of the device are grasped from the captured image data, and the gradation is obtained. Between the two.

[0005]

However, even this conventional method does not sufficiently suppress the gradation skip. In particular, this phenomenon becomes remarkable when a smooth gradation pattern created on a computer is printed out by a copying machine via a controller.

Therefore, in order to further improve the image quality of the copying machine, it is necessary to establish a new technique for solving the problem of the gradation skipping.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has, for example, the following arrangement as one means for achieving the above objects.

That is, image input means for inputting image data, random number adding means for adding random number data to the image data input by the image input means and outputting the same, and random number data from the random number adding means are added. Image forming means for forming an image of the image data.

For example, the image input means inputs a computer image from a connected external device.

Further, for example, the image forming means prints out an image on a transfer material by an electrophotographic method.

Further, for example, there is provided a random number addition control means for controlling whether or not to add random number data to the image data by the random number addition means. Alternatively, the random number addition control means controls whether or not to add random number data to the image data by the random number addition means in accordance with an instruction received from a user. Alternatively, the random number addition control means controls whether to add random number data to image data in the random number addition means in accordance with an instruction from another external device connected via a communication medium. I do.

[0012] For example, the random number addition control means adds random number data to the image data by the random number addition means when the image data to be formed is a gradation CG image.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment] An image transfer means for transferring an image generated on a computer to an image forming apparatus, and random number data for image data sent from the image transfer means. And random number addition control means for performing addition control of irregular random numbers by the random number addition means, and outputs appropriate random number data to image data sent from the host computer. By adding and outputting, especially in the form of gradation C
A first embodiment of the present invention according to the present invention will be described in detail, which effectively suppresses the gradation skip that occurs when outputting a G image.

FIG. 1 is a schematic sectional view of a color image forming apparatus to which an embodiment of the present invention is applied. The example shown in FIG. 1 has a digital color image reader unit at the top and a digital color image printer unit at the bottom.

In the reader section shown in FIG. 1, an original 30 is placed on an original platen glass 31, and an optical system reading drive motor 35 is provided.
A known document scanning unit including the exposure lamp 32 is exposed and scanned at a constant speed determined according to a preset copy magnification. The reflected light image from the document 30 is condensed by a lens 33 onto a full color sensor (CCD) 34 to obtain a color separation image signal.

As the full-color sensor, R (red), G (green), B
A three-line CCD 34 with a (blue) filter is used. The color-separated image signal is supplied to an image processing unit 36.
The image processing is performed by the controller 37, and the image is sent to the printer.

An operation section is provided around the platen glass 31, and switches for setting various modes related to a copy sequence, a display and a display are arranged.

In the printer section of FIG. 1, a photosensitive drum 1 as an image carrier is rotatably supported in the direction of an arrow, and a pre-exposure lamp 11, a corona charger 2,
Laser exposure optical system 3, potential sensor 12, four developing units 4y, 4c, 4Bk of different colors, on-drum light amount detecting means 1
3. The transfer device 5 and the cleaning device 6 are arranged.

In the laser exposure optical system 3, an image signal from a reader section is converted into an optical signal by a laser output section (not shown), and the converted laser light is reflected by a polygon mirror 3a, and a lens 3b and a mirror 3c, and is projected on the surface of the photosensitive drum 1.

At the time of image formation in the printer section, the photosensitive drum 1 is rotated in the direction of the arrow, and the photosensitive drum 1 after having been neutralized by the pre-exposure lamp 11 is uniformly charged by the charger 2 so as to emit light for each separated color. The image E is irradiated to form a latent image.

Next, by operating a predetermined developing device, the latent image on the photosensitive drum 1 is developed, and a toner image is formed on the photosensitive drum 1 using a resin as a base material. The developing device has an eccentric cam 24.
By the operations of y, 24m, 24c, and 24Bk, the photosensitive drum 1 is selectively approached in accordance with each of the separated colors.

Further, the toner image on the photosensitive drum 1 is
The image is transferred from one of the preselected recording material cassettes 7a, b, and c to the recording material supplied to a position facing the photosensitive drum 1 via the conveyance system and the transfer device 5. The selection of the recording material cassette is performed by driving any one of the pickup rollers 27a, 27b, and 27c according to a control signal from the controller unit 37 in advance according to the size of the recording image.

In the present embodiment, the transfer device 5 includes a transfer drum 5a, a transfer charger 5b, a suction roller 5g opposed to a suction charger 5c for electrostatically sucking a recording material, an inner charger 5d, and an outer charger. A recording material carrying sheet 5f made of a dielectric is integrally stretched in a cylindrical shape in a peripheral opening area of the transfer drum 5a which is rotatably driven and has a container 5e. The recording material supporting sheet 5f uses a dielectric sheet such as a polycarbonate film.

A drum-shaped transfer device, that is, a transfer drum 5a
As the is rotated, the toner image on the photosensitive drum 1 is transferred by the transfer charger 5b onto the recording material carried on the recording material carrying sheet 5f.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the recording material carrying sheet 5f to form a full-color image.

In the case of forming a full-color image, when the transfer of the toner images of four colors is sequentially completed in this way, the recording material is separated from the transfer drum 5a by the action of the separation claw 8a, the separation push-up, the roller 8b and the separation charger 5h. Then, the sheet is discharged to the tray 10 via the heat roller fixing device 9.

On the other hand, the post-transfer photosensitive drum 1 is subjected to the image forming process again after the residual toner on the surface is cleaned by the cleaning device 6.

When images are formed on both sides of a recording material,
Immediately after the fixing device 9 is ejected, the conveyance path switching guide 19 is driven, and once guided to the reversing path 21a via the conveyance vertical path 20, the rear end of the reversing roller 21b is moved forward by the reverse rotation of the reversing roller 21b. And is retracted in the direction opposite to the direction in which the sheet is fed, and stored in the intermediate tray 22. Thereafter, an image is formed on the other surface again by the above-described image forming step.

Further, in order to prevent scattering of powder on the recording material supporting sheet 5f of the transfer drum 5a and adhesion of oil on the recording material, the fur brush 14 and the recording material supporting sheet 5f are used. 14, a backup brush 15, an oil removing roller 16, and a recording material carrying sheet 5.
Cleaning is performed by the action of the backup brush 17 facing the roller 16 via f. Such cleaning is performed before or after image formation, and when a jam (paper jam) occurs.
It is performed at any time when it occurs.

Further, in the present embodiment, the eccentric cam 25 is operated at a desired timing to transfer the transfer drum 5a.
By operating the cam follower 5i integrated with the photosensitive drum 1, the gap between the recording material carrying sheet 5a and the photosensitive drum 1 can be arbitrarily set. For example, during standby or when the power is off, the interval between the transfer drum 5a and the photosensitive drum 1 is increased.

(Image Processing Block) FIGS. 2A and 2B show the detailed configuration of the image processing unit 36, the controller unit 37, and the peripheral controlled units shown in FIG. Hereinafter, the detailed configurations of the image processing unit 36, the controller unit 37, and the peripheral controlled units in the present embodiment will be described with reference to FIGS. 2A and 2B.

The image processing section 36 of the present embodiment can be constituted by a one-chip programmable image processing processor such as a DSP. In the following description, the case where the image processing unit 36 is configured by a one-chip programmable image processor such as a DSP will be described.

2A and 2B, a full-color sensor (CCD) 34 is composed of three lines of CCDs 101, 102, and 103 of red, green, and blue, and separates one line of light information from a document into color information. 40
R, G, B electrical signals are output at a resolution of 0 dpi.
In this embodiment, the maximum is 297 mm as one line.
To read (A4 portrait), for example, the CCD 34
Output a 4677 pixel image per line for each of R, G and B.

Reference numeral 104 denotes a synchronizing signal generation circuit, which comprises a main scanning address counter, a sub scanning address counter, and the like. The main scanning address counter is cleared line by line by a BD signal which is a synchronization signal for laser recording on the photosensitive drum 1 line by line, and the pixel clock generator 105
And outputs a count output H-ADR corresponding to each pixel of one line of image information read from the CCD 34.

The H-ADR ranges from "0" to "500".
It counts up to "0", and the image signal for one line from the CCD 34 can be sufficiently read. The synchronization signal generating circuit 104 outputs various timing signals such as a line synchronization signal LSYNC, a main scanning effective section signal VE and a sub-scanning effective section signal PE of an image signal.

Reference numeral 106 denotes a CCD drive signal generation unit.
-ADR is decoded and a CCD-DRIVE which is a set pulse or a transfer clock from a shift pulse of the CCD 34 is used.
Generate a signal. As a result, the R, G, and B color separation image signals for the same pixel are sequentially output from the CCD 34 in synchronization with VCLK. An A / D converter 107 converts red, green, and blue image signals into 8-bit digital signals.

Reference numeral 150 denotes a shading correction circuit.
This is a circuit for correcting variations in signal output for each pixel in the CCD. In the shading correction circuit,
Each line of R, G, and B signals has a memory for one line, and an image of a white plate having a predetermined density is read by an optical system and used as a reference signal.

Reference numeral 151 denotes a sub-scanning connection circuit, which is a CCD
34 is a circuit for absorbing the displacement of the image signal read by the scanning line in the sub-scanning direction by eight lines.

Reference numeral 152 denotes an input masking circuit for removing dust from the colors of the input signals R, G, and B.

Reference numerals 153 and 163 denote buffers and ZO-
When the ED signal is at the L level, the image signal is passed and the ZO-ED
When the signal is at the H level, the image signal is not passed. Normal,
It is at the L level when the editing function is used.

155 of the editing circuit 154 is a filter for smoothing the image signal, and performs a 5 × 5 matrix operation. Reference numeral 156 denotes a color conversion circuit, which has a function of converting an RGB image signal into HSL color space coordinates, converting a previously designated color into another designated color, and returning the color to the RGB color space again. . It is also possible to convert a multi-value signal into a binary signal at a fixed threshold value.

Reference numeral 159 denotes an external device, which comprises a memory device for storing image signals up to A3 size, a computer for controlling the memory device, and the like. The image signal of the external device 159 is a red, green, blue (RGB) signal or a cyan, magenta, yellow, black (C
MYK) signal and a binary signal.
The external device 159 is, for example, a gradation C
A G image or the like can be output.

Reference numeral 158 denotes an interface (I / F) circuit for adjusting the timing and speed of an image signal from an external device and an internal image signal. 160
Is an area generation circuit that generates and stores an area specified by an editor or the like.

A MARKER signal obtained by extracting an image of a marker pen or the like drawn on a document is also stored in the memory as an area. An SC-BI signal obtained by binarizing the image signal read by the CCD 34 is represented by Z
-Used for BI output signal. This area generation circuit 16
The memory write unit and the memory read unit for the area out of 0 will be described later in detail.

Reference numeral 157 denotes an RGB synthesizing circuit.
4 and the external device 159
This is a circuit for synthesizing the RGB image signals from. It is also possible to combine an RGB image signal from the CCD 34 with a binary image from an external device.

The area to be synthesized is specified by the AREA signal from area generation circuit 160 or by the IPU-BI signal from an external device. In addition, for the synthesis, replacement synthesis in which the image signal from the CCD 34 and the external image signal are independently synthesized for each area, and watermark synthesis in which two images are simultaneously overlapped and watermarked and synthesized are also possible. In this watermark synthesis, it is also possible to specify a watermark rate of which of two images is to be watermarked and synthesized.

Reference numeral 161 denotes a contour generating circuit,
, An SC-BI signal obtained by binarizing the image signal read by the above, an IPU-BI signal which is binary data from the external device 159, or a binary data Z-B from the area generating circuit 160.
A contour is extracted from the I signal to generate a shadow.

Reference numeral 162 denotes a black character judging circuit which judges the characteristics of the input image signal, and outputs eight kinds of character thickness signals (thickness degree) FTMJ, edge signal EDGE, and color signal I
Outputs RO.

A color space compression circuit 108 performs the following matrix operation (1).

[0051]

(Equation 1)

R ′ R a11 a12 a13 a14 a15 a16 a17 a18 R−X G ′ = G + a21 a22 a23 a24 a25 a26 a27 a28 × G−X B ′ B a31 a32 a33 a34 a35 a36 a37 a38 BX (RX) × (GX) (GX) × (BX) (BX) × (RX) R × G × B (155-R)) × (255-G) × (255-B) where X is R, G, B Represents the minimum value of.

By setting in advance whether or not to perform color space compression in the color space compression circuit 108, ON / OFF of the color space compression is performed by the area signal AREA.
Can be switched.

In FIGS. 2A and 2B, reference numeral 109 denotes a light-density converter (LOG converter) which converts red, green, and blue 8-bit light signals by logarithmic conversion into cyan (C), magenta (M), The density signal is converted into a yellow (Y) 8-bit density signal.

Reference numeral 173 denotes a buffer that passes an image signal when the ZO-PRV signal is at an L level and blocks an image signal when the ZO-PRV signal is at an H level. Normally, the level is H level, and when the preview function is used, the level is L level.

Reference numeral 174 denotes a thinning control circuit which is used when a preview function is used. At the time of preview, the same signal is output every four lines by writing the input image signal to the FIFO memory one line at a time for every four lines.

An output masking unit 110 extracts a black density signal from the C, M, and Y color density signals by a known UCR process (under color removal process).
A known masking operation for removing color turbidity of the developer corresponding to each density signal is performed. The selector 111 selects a color signal corresponding to the developer currently being used from the density signals M ′, C ′, Y ′, and K ′ thus generated.

The ZO-TONER signal is a 2-bit signal generated from the toner color generation circuit 178 for this color selection. When the ZO-TONER is 0, the M 'signal is output, and when the ZO-TONER is 1, In this case, the signal C '
When −TONER is 2, the Y ′ signal is ZO-TON
When ER is 3, the K 'signal is output as a READ-DT signal.

The toner color generation circuit 178 outputs the SLTNR signal output from the CPU 130 according to the development color during normal copying as a ZO-TONER signal. At the time of preview, a signal sequentially switched to 0123 for each line is output.

2A and 2B, reference numeral 164 denotes a CMYK synthesizing circuit for synthesizing the image signal read by the CCD 34 and the CMYK format image signal input from the external device 159. When performing CMYK synthesis, a color signal corresponding to the developer currently used is input from the external device 159 one page at a time in accordance with the image signal from the CCD 34.

The area to be synthesized is the RGB synthesis circuit 15
Switching is performed by the AREA signal or the IPU-BI signal in the same manner as in 7. Similarly, watermark synthesis is also possible.

Reference numeral 165 denotes a coloring circuit which performs processing such as adding a preset color to a black and white image, for example. In addition, coloring can be performed on the binary image signal IPU-BI from the external device 159. Further, it is possible to create a gradation pattern in which the gradation gradually changes.

An F value correction circuit 166 performs gamma processing according to the developing characteristics of the printer and can set the density for each mode. 114 is a variable power circuit,
It has a memory for one line of an image signal, and performs enlargement and reduction of the image signal in the main scanning direction and italics for outputting an image obliquely. At the time of sampling, the sampling data is stored in a memory and used for creating a histogram.

Reference numeral 168 denotes a texture circuit.
The color image signal read in 4 is combined with a pattern obtained by binarizing the image signal read in advance by the CCD 34 or a binary pattern input from the external device 159 and output. 169 is a smoothing circuit composed of 5 × 5 filters, and 170 is an edge enhancement circuit composed of 5 × 5 filters.

Reference numeral 176 denotes a preview conversion unit which performs a thinning process in the main scanning direction during previewing, for example, 4
The data of the resolution of 00 bpi is converted into the data of 100 bpi, output to the monitor 177 and displayed, and the image formed image can be visually checked on the monitor 177.

Reference numeral 171 denotes an add-on circuit which outputs an image signal in a specific coded pattern. Reference numeral 200 denotes a random number addition block, which will be described in detail later, which adds random number data to the image signal from the add-on circuit 171 and outputs the image signal when performing a specific image processing. Reference numeral 115 denotes a laser and a laser controller, which is an 8-bit density signal VI.
The light emission amount of the laser is controlled according to the DEO signal. This laser light is scanned in the axial direction of the photosensitive drum 1 by the polygon mirror 3a to form a one-line electrostatic latent image on the photosensitive drum.

Reference numeral 116 denotes a photodetector provided in the vicinity of the photosensitive drum 1, which detects the passage of laser light immediately before scanning the photosensitive drum 1 and detects a one-line synchronization signal BD.
Occurs. 141 is an area LUT (look-up table) circuit, which is an ARE from the area generation circuit 160.
Each mode is set according to the A signal.

LOGC which is the output of area LUT 141
The D signal is used to switch the LOG table of the LOG conversion 109 to a through setting or the like. Area LUT1
The UCRCD signal which is the output of 41 is output masking 11
0 is used for trimming and masking. The FCD signal output from the area LUT 141 is used to change the magnitude of the F value of the F value correction 166.

The ACD6 signal is supplied to the coloring circuit 165.
The NCD signal is connected to the MCYK synthesizing circuit 164, and the KCD signal is connected to the black character LUT circuit 172, for setting various modes.

A black character LUT 172 performs various processes according to the output of the black character determination circuit 162. For example, U
The CR-SL signal is output from the UCR of the output masking circuit 110.
For an area determined to be a darker character by changing the amount, processing such as developing with a larger amount of black and a smaller amount of C, M, and Y is performed.

In the EDGE-SL signal, the smoothing circuit 169 and the edge emphasizing circuit 170 are set so as to switch to a filter such that the edge of a black character area is emphasized in a black character area. Further, the SNS-SL signal is a black character L
The output of the UT 172 switches the number of 400/200 lines under PWM control in the laser controller 115. In other words, development is performed with 400 lines to increase the resolution in an area determined to be a black character, and development is performed with 200 lines in other image areas to increase the gradation.

Reference numeral 118 denotes a photo sensor which detects that the transfer drum 5a has reached a predetermined position and detects a page synchronization signal I.
A TOP is generated, a sub-scanning address counter of the synchronization signal generation circuit 104 is initialized, and is input to the CPU 130. Reference numeral 130 denotes a CPU which controls image reading and image recording operations.

Reference numeral 131 denotes a controller for controlling the forward / reverse and speed of the reading motor 35. Reference numeral 132 denotes an I / O port for controlling other sensors and actuators required for controlling the copying operation. The I / O port also includes a PF signal for feeding paper from a paper cassette. As other signals, the size of the sheet is detected by a sheet size sensor (not shown) attached to the sheet cassette, and is input to the CPU 130 from the I / O port.

An operation unit 51 is used to instruct the number of copies and various operation modes. 133 is a ROM, CP
An operation control program of U130 and a predetermined set value are stored. Reference numeral 134 denotes a RAM that temporarily stores data and stores newly set values and the like.

(Addition of Random Number Data) The detailed configuration of the random number addition block in the image forming apparatus of the present embodiment shown in FIGS. 2A and 2B will be described below with reference to FIG. FIG. 3 is a block diagram illustrating a detailed configuration of the random number addition block 200 in the image forming apparatus according to the present embodiment.

In FIG. 3, reference numeral 210 denotes a random number generation unit for generating random number data serving as a source of a random number signal to be added to image data; and 220, a random number maximum value calculation unit for calculating the maximum value of the random number signal. Reference numeral 230 denotes a random number addition amount calculation unit that calculates a random number addition amount according to the gradation in order to adjust and add the maximum value of the random numbers to be added according to the gradation of the image.

Reference numeral 240 denotes a random number addition amount selection unit which corresponds to the gradation of the image data in the random number data obtained for each section by the random number addition amount calculation unit 230 according to the gradation of the input image data. Select and output random number data of the section. 2
Reference numeral 50 denotes a random number adding unit that adds random number data to input image data.

Reference numeral 260 denotes a selector for selecting and outputting one of the image data subjected to the random number addition processing and the input image data. Reference numeral 270 denotes a register unit, which is configured by a register group, and the set value of each block is set as a register value via the CPU. Reference numeral 280 denotes a random number addition control unit that controls the selector 260 to control random number addition.

In the above configuration, the maximum random number value of the random number data generated by the random number generation section 210 is
The random number addition amount calculation unit 230 adjusts the maximum value of the random numbers calculated by the random number maximum value calculation unit 220 according to the gradation of the image, and calculates the random number addition amount according to the gradation. Then, in the random number data obtained for each section by the random number addition amount calculation unit 230 according to the gradation of the input image data by the random number addition amount selection unit 240, the random number data of the section corresponding to the gradation of the image data is extracted. Select and output. Then, the random number adding unit 25
When 0, the random number data is added to the input image data. Then, the random number addition control unit 280 performs image processing (image data).
The selector 260 is accordingly controlled to select and output one of the image data subjected to the random number addition processing and the input image data depending on the image data.

The detailed configuration of the above-described random number generation section 210 will be described below with reference to FIG. FIG. 4 is a detailed block configuration diagram of the random number generation unit 210 according to the present embodiment.

As shown in FIG. 4, a random number generator 210 mainly includes a shift register 211 composed of a large number of shift registers and an exclusive OR circuit (ExOR gate) 212.
It is constituted by. The shift register 211 is reset when the power is turned on. A selector 213 switches a load signal of the shift register 211.

The selector 213 switches the input signal of either A or B according to the value of the select signal 216 set in the register 270 and outputs it as the load signal 215 of the shift register 211.

When the A input is selected by the select signal 216, the load signal 215 is output at the timing when the first line image leading signal arrives, and the register is output at the timing when the first line image leading signal arrives. The load value set in 270 is output as the load signal 215 of the shift register 211.

The select signal 216 is output from the selector 21
When the B input of 3 is selected, the set value to the register 270 is output as the load signal 215 of the shift register 211. This loading is performed for each color.

When the load signal 215 of the shift register 211, which is the output signal of the selector 213, becomes active, the shift register 211 reads the load input signal 217 input to the load input terminal. Load input signal 2
17 can be controlled by the value set in the register 270. The shift register 211 repeats the shift operation in synchronization with the loaded input signal 217 in synchronization with the image clock signal 219.

A part of the output of the shift register 211 is subjected to an exclusive OR (ExO) by the subsequent ExOR gate 212.
R) and is connected to the D input terminal of the D type flip-flop 214. Then, the image clock signal 2
After being delayed by one clock of 19, the shift register 21
It is output as 1 shift input data.

The detailed configuration of the above-described maximum random number calculating section 220 will be described below with reference to FIG. FIG. 5 is a block diagram showing a detailed configuration of the maximum random number calculating unit 220 according to the present embodiment. The maximum random number calculating section 220 of the present embodiment shown in FIG. 5 is mainly configured by a multiplier.

When the random number signal 218 is input from the random number generation section 210, the random number maximum value calculation section 220
18 and the other input signal, a random number maximum value signal 225 from the resist 270, is multiplied, the value indicated by the random number maximum value signal 225 is adjusted to be the maximum value of the generated random number, and output as a random number signal 226. I do.

The value of the maximum random number signal 225 is
130 can be set to an arbitrary value depending on the value set in the register 270.

The detailed configuration of the above-described random number addition amount calculating section 230 will be described below with reference to FIG. FIG. 6 is a block diagram illustrating a detailed configuration of the random number addition amount calculation unit 230 according to the present embodiment, and FIG. 7 is a diagram illustrating a maximum value of random number data to be added to image data according to the present embodiment.

In the present embodiment, as shown in FIG. 7, the value of the random number data to be added to the image data is changed and added for each gradation. That is, the maximum random number signal to be added to the image signal in the section A which is a low gradation part, the section B which is a half gradation part, and the section C which is a high gradation part have a constant value as shown in FIG. Control is performed as follows.

For this reason, the random number addition amount calculating section 230 of this embodiment considers that all gradations are divided into three sections as shown in FIG. 7, and calculates the maximum value of the random number for each section. And outputs the random number data corresponding to it. The number of divided sections is not limited to three, but may be divided into four or more sections, and the slope of the change of the maximum value of the random number signal in each section may be changed.

The random number addition amount calculating section 230 of this embodiment shown in FIG. 6 mainly includes a multiplier 231 (section A), a multiplier 232 (section B), and a multiplier 233 (section C) for each gradation section.
C).

The random number addition amount calculation unit 230 includes a random number signal 226 input from the random number maximum value calculation unit 220 and a gradation threshold signal 23 indicating a gradation change point at which the maximum value of the random number switches.
4 (section A), the gradation threshold signal 235 (section B), the gradation threshold signal 236 (section C) and the image data to be added are multiplied, and the maximum value is calculated for each section, and the calculated value is calculated. Random number data 237, 238, 2 to be the maximum value
39 is output.

The respective threshold data of the gradation threshold signals 234 to 236 are set values to the register 270,
Arbitrary values can be set by U130.

A detailed configuration of the above-described random number addition amount selecting section 240 will be described below with reference to FIG. FIG. 8 is a block diagram illustrating a detailed configuration of the random number addition amount selection unit 240 according to the present embodiment. The random number addition amount selection unit 240 of the present embodiment illustrated in FIG. 8 mainly includes a comparator 241 and a selector 242.

The random number addition amount selecting section 240 of the present embodiment shown in FIG. 8 includes an input maximum random number signal 226, a gradation of an image signal and a gradation threshold signal (image threshold signal) 234 to
The comparator 241 performs comparison with the gradation indicated by 236, and as a result of the comparison, supplies the selector 242 with an interval selection signal 245 indicating which interval the input image signal corresponds to.

The selector 242 outputs the added random number signals 237 to 39 for each gradation section to the random number added amount calculating section 2 shown in FIG.
The selector 242 is switched according to the section selection signal 245 and selects and outputs random number data of a corresponding section.

The detailed configuration of the above-described random number adding section 250 will be described below with reference to FIG. FIG. 9 is a block diagram illustrating a detailed configuration of the random number adding unit 250 according to the present embodiment.
The random number adding unit 250 according to the present embodiment mainly includes a flip-flop group 251, a selector 252, an adder 253, and an addition timing generating unit 254.

In this embodiment, in order to shift the position of the random number to be added to the image, as shown in FIG. 10, the position of the random number to be added for each line is alternately changed by one pixel in the main scanning direction. I do.

Then, in order to cancel the added amount of the random numbers, control is performed such that data having a polarity different from that of the random number data two pixels before is added to a position corresponding to a position two pixels after the added random number in the main scanning direction. It shall be. For example, at a position two pixels after the addition of the random number data, control is performed so that the random number data is subtracted from the input image data.

The input A of the selector 252 in the random number addition unit 250 has the random number signal 24
6 and the polarity signal 255 are input. The input B receives the random number data delayed by one flip-flop 251 two pixels before and the signal obtained by inverting the polarity signal 255 by an inverter circuit. This polarity signal 255 is
30 to the register 270.

An addition timing generator 254 is a block for controlling a select A signal 256 and a select B signal 257, which are timing signals for adding random numbers to image data, and receives an image clock signal 219 and a main scanning synchronization signal. . FIG. 11 shows the generation timings of the select A signal 256 and the select B signal 257 in the addition timing generator 254 in the present embodiment.

The select A signal 256 and the select B signal 257 become active at a period of four pixels, respectively, and the phase relationship between the select A signal 256 and the select B signal 257 is generated so as to have a phase difference of two pixels. Further, the generation phases of the select A signal 256 and the select B signal 257 are controlled so as to be alternately shifted by one pixel in the main scanning direction for each line.

Select A signal 2566 and select B signal 257 generated by addition timing generation section 254
Is the selector 25
2 is input. The selector 252 outputs the select A signal 2
When 56 is active, it outputs the random number signal 246 and the polarity signal 255 input to the A terminal.

The selector 252 outputs the select B signal 2
When the signal 57 is active, random number data two pixels before the flip-flop 251 input to the B terminal and a signal obtained by inverting the polarity signal 255 are selected and output.

The random number data and the polarity signal selected by the selector 252 are output to the adder 25 in the subsequent stage together with the input image signal.
3 is input. The adder 253 performs an addition / subtraction process of the random number data selected by the selector 252 on the input image.

The addition / subtraction is controlled by the input polarity signal. When the polarity signal is "L", the addition is performed, and when the polarity signal is "H", the subtraction is performed. The image data subjected to the addition / subtraction processing is subjected to overflow and underflow control, and when the calculation result at the time of addition exceeds the maximum value of the image data ("255" for 8 bits), the maximum value is obtained. When it becomes negative, each is controlled to be zero.

The output of the adder 253 is supplied to the subsequent-stage selector 260 as random number-added image data.

The detailed configuration of the above-described selector 260 is shown in FIG.
2 will be described below. FIG. 12 is a block diagram illustrating a detailed configuration of the selector 260 according to the present embodiment.
The selector 260 of the present embodiment is a block that selects and outputs one of the random number added image data 259 subjected to the random number addition process and the input image data.

A switching terminal of the selector 260 has a random number addition control signal 289 supplied from the random number addition control unit 280.
Is entered. When the random number addition control signal 289 is "L", the input image signal is output as it is as the through image data of the random number addition processing block. On the other hand, when the random number addition control signal 289 is “H”, the image data subjected to the random number addition processing in the random number addition processing block is output as output image data.

With the above configuration, the image forming apparatus of the present invention adds appropriate random number data to image data sent from the host computer via the controller as necessary. By outputting and using the random number addition control unit 280 to control the addition of the random number data, it is possible to appropriately perform the gradation jump correction control.
In particular, it is optimal for correction control of gradation jumps generated when outputting a gradation CG image, and can effectively suppress the gradation jumps generated when outputting a CG image.

[0113] The addition control of the random number data can be performed by an arbitrary operation, and the addition control of the random number data can be performed under its own confirmation.

[Second Embodiment] In the random number addition block 200 of the first embodiment described above, FIG.
Random number addition control signal 2
89 was output. However, the present invention is not limited to the above example, and the random number addition control signal 289 may be configured to be output under another control by, for example, a host computer. The second embodiment according to the present invention thus configured
The embodiment will be described below.

In the second embodiment described below, the basic configuration is the same as that of the above-described first embodiment, and the configuration of the random number addition block 200 is partially different in the second embodiment. ing. For this reason, the same reference numerals are given to the same components as those in the first embodiment described above, and the detailed description will be omitted. 1, 2A and 2 in the image forming apparatus.
The control configuration shown in FIG. 3B and the configurations of the image processing unit, the controller unit, and the peripheral controlled units are the same as those of the first embodiment. A configuration different from the embodiment will be described.

FIG. 13 is a block diagram showing a detailed configuration of a random number addition block in the image forming apparatus according to the second embodiment of the present invention. The same components as those in FIG. 3 described above are denoted by the same reference numerals, and detailed description is omitted.

In the second embodiment shown in FIG. 13, random number addition control is performed by an external device 159 constituted by a host computer or the like and a controller 282. Also in the second embodiment, the configuration of the selector 260 is the same as that of FIG.
The switching terminal of the selector 260 includes:
When the random number addition control signal 289 supplied from the external device 159 via the controller 282 is input, and the random number addition control signal is “L”, the input image signal is output as it is as the through image data of the random number addition processing unit, and the random number addition is performed. When the control signal is "H", image data subjected to random number addition processing is output.

With the above configuration, the image forming apparatus of the second embodiment adds appropriate random number data to image data sent from the external device 159 via the controller 282. By using a host computer and a controller to control the addition of the random number data, it is possible to effectively suppress gradation skipping that occurs when a CG image is output, as necessary.

That is, according to the second embodiment, the additional control of the random number data is performed by another external device 1 that can be connected to the device.
59, it is possible to perform appropriate random number addition control according to the image type supplied by the external device 159 on the information supply side, for example, and to perform appropriate gradation skip suppression control as necessary.

It is to be noted that the random number addition control signal 289 may be controlled not by the external device 159 for outputting, for example, a gradation CG image but by another host computer. The control of the random number addition control signal may be performed by another control, for example, by a control computer.

[Other Embodiments] In the above description of the second embodiment, the controller 282 has been described as an example of a configuration for receiving the added random number control signal from the external device 159 (or the host computer). The image forming apparatus of the present invention is not limited to the controller
An additional random number control signal may be transmitted from another host computer or the like via a network such as an SI.

In the present invention, a full-color copying machine has been described as an example, but it is needless to say that the present invention is not limited to a full-color copying machine.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

An object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, by downloading and reading out a program represented by software for achieving the present invention from a database on a network by a communication program, the system or apparatus can be
It is possible to enjoy the effects of the present invention.

[0130]

As described above, according to the present invention, random number data can be added to an output image.
It is possible to effectively suppress the gradation jump that occurs when an image is output.

[0131] The addition control of the random number data can be performed by an arbitrary operation, and the addition control of the random number data can be performed under its own confirmation.

Further, the additional control of the random number data can be controlled by another external device which can be connected to the device. For example, an appropriate random number addition control according to the type of image supplied by the information supply side can be performed. Appropriate gradation skip suppression control can be performed as necessary.

[0133]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus to which an embodiment of the present invention is applied.

FIG. 2A is a block diagram of an image processing unit, a controller unit, and a peripheral controlled unit shown in FIG. 1 according to the embodiment;

FIG. 2B is a block configuration diagram of an image processing unit, a controller unit, and a peripheral controlled unit shown in FIG. 1 in the embodiment.

FIG. 3 is a block diagram illustrating a detailed configuration of a random number addition block in the image forming apparatus according to the embodiment.

FIG. 4 is a block diagram illustrating a detailed configuration of a random number generation unit in the random number addition block according to the embodiment;

FIG. 5 is a block diagram illustrating a detailed configuration of a random number maximum value calculation unit in the random number addition block according to the embodiment;

FIG. 6 is a block diagram illustrating a detailed configuration of a random number addition amount calculation unit in the random number addition block according to the embodiment;

FIG. 7 is a diagram for explaining control for changing random number data to be added to the gradation of image data in the random number addition amount calculation block according to the embodiment;

FIG. 8 is a block diagram illustrating a detailed configuration of a random number addition amount selection unit in the random number addition block according to the embodiment;

FIG. 9 is a block diagram illustrating a detailed configuration of a random number addition unit in the random number addition block according to the embodiment;

FIG. 10 is a diagram for explaining a random number adding position in the random number adding unit of the embodiment.

11 is a timing chart showing random number addition timings in the addition timing generation unit shown in FIG. 9 of the present embodiment.

FIG. 12 is a block diagram illustrating a detailed configuration of a selector in the random number addition block according to the embodiment.

FIG. 13 is a block diagram illustrating a detailed configuration of a random number addition block in the image forming apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 2 corona charger 3 laser exposure optical system 3a polygon mirror 3a 3b, 33 lens 3c mirror 4y, 4c, 4Bk developing device 5 transfer device 5a transfer drum 5b transfer charger 5c adsorption charger 5d inner charger 5e outer charger Device 5f Recording material carrying sheet 5g Suction roller 5h Separation charger 5i Cam follower 6 Cleaning device 7a, 7b, 7c Recording material cassette 8a Separation claw 8b Roller 9 Heat roller fixing device 10 Tray 11 Pre-exposure lamp 12 Potential sensor 13 Light amount detection on drum Means 14 Fur brush 15 Backup brush 16 Oil removal roller 17 Backup brush 19 Transport path switching guide 20 Transport vertical path 21a Reverse path 21b Reverse roller 22 Intermediate tray 24y, 24m, 24c, 24Bk Eccentric cam 25 Eccentric cam 7a, 27b, 27c pickup roller 30 document 31 image processing unit 37 the controller unit of the platen glass 32 exposure lamp 33 lens 34 full-color sensor (CCD) 35 optical reading driving motor 36

Claims (15)

[Claims] An image input unit for inputting image data, a random number adding unit for adding random number data to the image data input by the image input unit and outputting the same, and the random number data from the random number adding unit are added. An image forming apparatus comprising: an image forming unit that forms an image of the image data. 2. The image forming apparatus according to claim 1, wherein the image input unit inputs a computer image from a connected external device. 3. The image forming apparatus according to claim 1, wherein the image forming unit prints out an image on a transfer material by an electrophotographic method. 4. The apparatus according to claim 1, further comprising random number addition control means for controlling whether to add random number data to the image data in said random number addition means. Image forming device. 5. The image according to claim 4, wherein the random number addition control means controls whether or not to add random number data to the image data by the random number addition means in accordance with an instruction received from a user. Forming equipment. 6. The random number addition control means controls whether or not to add random number data to image data by the random number addition means in accordance with an instruction from another external device connected via a communication medium. The image forming apparatus according to claim 4, wherein: 7. The method according to claim 1, wherein the random number addition control means adds random number data to the image data by the random number addition means when the image data to be formed is a gradation CG image. The image forming apparatus according to claim 4. 8. An image forming method in image forming means for forming an image in accordance with input image data, wherein random number data is added to the input image image data to form image data to which random number data is added. An image forming method comprising: 9. The image forming method according to claim 8, wherein the image data to be formed is a computer image from a connected external device. 10. The image forming method according to claim 9, wherein random number data is added to the image data when the image data to be formed is a gradation CG image. . 11. The image forming method according to claim 8, wherein the image forming of the input image is performed by printing the image on a transfer material by an electrophotographic method. 12. The image forming method according to claim 8, wherein the addition of the random number data to the image data is performed according to an instruction received from a user. 13. The apparatus according to claim 8, wherein the addition of the random number data to the image data is performed in accordance with an instruction from another external device connected via a communication medium. Image forming method. 14. A computer program sequence for realizing the function according to any one of claims 1 to 13. 15. A computer-readable recording medium storing a computer program for realizing the functions according to claim 1. Description: