JP2000175045A - Image processor and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor and its control method where deterioration in quality can be prevented by applying smoothing to an outputted image depending on an instruction as to whether or not smoothing processing is to be applied to the outputted image. SOLUTION: Image data are received from an external device 101, a pattern matching circuit 102 analyzes a pattern of the image data, and when the pattern is coincident with a prescribed pattern, a smoothing processing circuit 103 interpolates pixels of the data so that the resolution of the image data is converted from 400 dpi into 800 dpi and density of the image data is corrected so as to be smoothed. A selector 105 selects and outputs an output of the smoothing processing circuit 103 or the output from the external device 101 on the basis of an SST-ON/OFF signal whose level is designated by the user.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to a method for smoothly processing and printing bitmap data representing characters and figures output from a personal computer or the like, thereby printing printed characters and characters. The present invention relates to a color copying machine capable of improving the printing quality by smoothing the outline of a figure.

[0002]

2. Description of the Related Art The resolution of characters of a printer such as a color copying machine is generally 400 dpi and 63.5 u.
Printed in m units. On the other hand, in order to further increase the resolution of the character portion, a technique of outputting the character at 800 dpi twice has been proposed. Even if such a printer is used, when characters and graphics created by a personal computer or the like are output in mono-color print, it is inevitable that jagged feeling occurs when rasterizing a vector image such as PostScript (trademark). Did not.

In such a case, by increasing the resolution and correcting the density of the pixels near the outline, the outline of the character can be made smoother and the image quality can be further improved.

[0004]

However, as the resolution increases, the expressiveness of gradation generally decreases.
When outputting image data of 6 gradations, 800 lines (800 lines)
(dpi) Depending on the gradation characteristics of the output, the reproducibility of the image may be significantly deteriorated.

[0005] The present invention has been made in view of the above-described conventional example, and it is possible to prevent a decrease in quality by performing smoothing in accordance with an instruction whether or not to perform smoothing processing on an output image. It is an object to provide an image processing apparatus and a control method thereof.

[0006]

In order to achieve the above object, the present invention has the following arrangement. That is, an image processing apparatus that forms an image, an instruction input unit that inputs an instruction signal as to whether to perform an image contour smoothing process,
Smoothing processing of the image contour according to the pattern of the input image data, and smoothing processing means for outputting image data, and when the instruction input means instructs to perform smoothing processing, the smoothing processing means Forming an image based on the output image data, and forming an image based on the input image data when not instructed.

[0007] Preferably, the smoothing means includes:
Attention is paid to a region of a predetermined size including a pixel of interest from the input image data, and it is determined whether or not to perform smoothing according to a pixel arrangement pattern in the region. The pixels are interpolated for each pixel, and the density of the step-like pixels is changed so that the density changes smoothly.

Preferably, the instruction signal is input from an external device.

Preferably, the instruction signal is issued in accordance with a manual input corresponding to a screen display for asking a user whether or not to perform a smoothing process before forming an image.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, based on a preferred embodiment,
The present invention will be described.

[First Embodiment] FIG. 1 is an external view of an apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 201 denotes an image scanner which reads a document and performs digital signal processing. Reference numeral 200 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner 201 on a sheet in full color.

In the image scanner section 201, 20
Reference numeral 2 denotes an original platen, and an original platen glass (hereinafter, platen) 2
The original 204 on the document 03 is irradiated with light from a halogen lamp 205. The reflected light from the original is guided to mirrors 206 and 207, and a three-line sensor (hereinafter referred to as CC) is
D) Form an image on 210. The lens 208 is provided with an infrared cut filter 231.

The CCD 210 separates the light information from the original into colors to obtain full-color information red (R), green (G),
The blue (B) component is read and sent to the signal processing unit 209.

Each color component reading sensor row of the CCD 210 is composed of 5000 pixels. As a result, 297 mm in the short side direction of the A3 size document, which is the maximum size among the documents placed on
Read at 0 dpi resolution.

It should be noted that 205 and 206 are speeds v and 207
Scans the front surface of the original by 1 / 2V mechanically moving in a direction perpendicular to the electrical scanning direction (hereinafter, main scanning direction) of the line sensor (hereinafter, main scanning direction).

Reference numeral 211 denotes a standard white plate.
Correction data of the read data of the R, G, B sensors of -1 to 210-3 is generated.

This standard white plate has a substantially uniform reflection characteristic with visible light, and has a white color when visible. The output data of the visible sensors of the sensors 210-1 to 210-3 is corrected using the standard white plate.

The image signal processing section 29 electrically processes the read signal, decomposes the signals into magenta (M), cyan (C), yellow (Y), and black (BK) components. send. Also, the image scanner unit 20
1 for one original scan (scan), M,
One of the components C, Y, and BK is sent to the printer 200, and one printout is completed by scanning the document four times in total.

The M, C, Y, and BK image signals sent from the image scanning unit 201 are transmitted to the laser driver 21.
Sent to 2. The laser driver 212 responds to the image signal,
The semiconductor laser 213 is modulated and driven. The laser beam starts the polygon mirror 214, the f-θ lens 215, and the mirror 216, and scans the photosensitive drum 217.

Reference numerals 219 to 222 denote developing devices, which are a magenta developing device 219, a cyan developing device 220, and a yellow developing device 2.
21; a black developing unit 222; four developing units alternately contact the photosensitive drum, and develop the electrostatic latent images of M, C, Y, and BK formed on the photosensitive drum 217 with corresponding toners; .

Reference numeral 223 denotes a transfer drum.
4 or 225 to the transfer drum 2
23, and transfers the toner image developed on the photosensitive drum 217 to a sheet.

After the four colors M, C, Y, and BK are sequentially transferred in this manner, the sheet passes through the fixing unit 226 and is discharged.

The rough operation of the apparatus has been described above.

Next, the image scanner 201 will be described in detail.

FIG. 2A shows the CCD 21 used in this embodiment.
0 is shown.

Here, 210-1 is a light receiving element array for reading red light (R), and 210-2 and 210-3 are light receiving element arrays for reading G and B wavelength components in order.

R, G, B of 210-1 to 210-3
Each of the sensors has an opening of 10 μm in the main scanning direction and the sub-scanning direction.

The three light receiving element arrays having different optical characteristics are monolithically mounted on the same silicon chip so that the R, G, and B sensors are arranged in parallel with each other to read the same line of the document. It is configured.

By using a CCD having such a configuration,
An optical system such as a lens is used in common for each color separation reading.

This makes it possible to simplify the optical adjustment for each of the R, G, and B colors.

FIG. 2C is a sectional view taken along the dotted line in FIG.
Shown in

On the silicon substrate 210-5, a photosensor 210-1 for reading R and photosensors 210-2 and 210-3 for reading visible information of each of G and B are arranged.

An R filter 210-for dropping a red wavelength component of the visible light on the R photo sensor 210-1.
7 are arranged. Similarly, a G filter 210-8 is provided on the G photo sensor 210-2, and a B photo sensor 210
-3 is provided with a B filter 210-9. 2
10-6 is a flattening layer formed of a transparent organic film.

FIG. 2B is an enlarged view of the light receiving element. Each sensor has a length of 10 μm per pixel in the main scanning direction. Each sensor measures the short side (297 mm)
There are 5000 pixels in the main scanning direction so that the image can be read at a resolution of 00 dpi.

The distance between the lines of the R, G, and B sensors is 80 μm, and each line is separated by 8 lines for a sub-scanning resolution of 400 dpi.

Next, the density reproduction method of the printer will be described.

In this embodiment, a laser 213 is used to reproduce the density of a printer by using a well-known PWM method.
Is controlled in accordance with the image density signal. As a result, an electrostatic latent image having a potential corresponding to the laser lighting time is formed on the photosensitive drum 217. Then, by developing the latent image with an amount of toner corresponding to the potential of the electrostatic latent image in the developing devices 219 to 222, the density can be reproduced.

FIG. 3 shows the control operation of the printer for reproducing the density in this embodiment.

Reference numeral 10201 denotes a printer pixel clock, which corresponds to a resolution of 400 dpi.

This clock is generated by the laser driver 212.

A triangular wave 10202 of 400 lines is generated in synchronization with the printer pixel clock 10201. This 4
The known triangular wave 10202 of the 00 line is the pixel clock 102.
It is the same as the period of 02.

400 dp sent from the image processing unit 209
M, C, Y, B of 256 gradations (8 bits) at i resolution
The K image data and the 400-line / 800-line switching signal are transmitted in synchronization with the CLOCK signal, and are synchronized with the printer pixel clock 10201 by a not-shown FIFO memory in the laser driver 212.

The 8-bit digital image data is converted into an analog image signal 10203 by a D / A converter.
Then, it is compared with the aforementioned 400-line triangular wave 10202 in an analog manner, and a PWM output 10204 of 400 lines is generated.

The digital pixel data changes from 00H to FFH, and the 400-line PWM output 10204 has a pulse width corresponding to this value. One cycle of the 400-line PWM output is 63.5 μm on the photosensitive drum.

The laser driver 212 generates an 800-line triangular wave 10205 having a double cycle in synchronization with the printer pixel clock 10201 in addition to the 400-line triangular wave.

Then, this 800-line triangular wave 10205
Is compared with an analog image signal 10203 of 400 dpi to obtain a PWM output signal 10206 of 800 lines.
Generate

The 800 line PWM output signal 10206 forms a latent image on the photosensitive drum at a period of 31.75 μm as shown.

In the density reproduction with 800 lines and the density reproduction with 400 lines, the minimum unit for density reproduction for 400 lines is 63.5 μm, which is twice as large as that for 800 lines, so that tone reproduction is better.

As for the resolution point, 800 lines that reproduce the density in units of 31.75 μm are more suitable for high-resolution image recording.

As described above, the 400-line PWM recording is suitable for gradation reproduction, and the 800-line PWM recording is superior in terms of resolution.
The PWM of the 0 line is switched.

A signal for this purpose is a 400-line / 800-line switching signal, and is input from the image processing unit 209 to the laser driver in pixel units in synchronization with an image signal of 400 dpi.

When the 400/800 line switching signal is at the L level, the PWM output of 800 lines is selected, and when it is at the H level, the PWM output of 400 lines is selected.

Next, FIG. 4 will be described. The full-color image signal output from the external device 101 is binarized by the pattern matching circuit 102,
Pattern matching is performed. If the pattern of the image matches the predetermined pattern, "0" is output as a 400/800 line switching signal, and if not, "1" is output. Then, the smoothing circuit 103 performs smoothing (SST processing) by interpolating the steps of the step-like jagged pattern and converting the steps to double resolution. The data to be interpolated is determined according to the density data of the surrounding pixels.

From the smoothing processing unit 103, 400
The interpolated data is passed to the A input of the selector 105 together with the / 800 line switching signal when smoothing is performed and when the smoothing is not performed.
Further, a signal of value “1” is fixedly input to the B input of the selector 105 as a signal for selecting 400 lines.
On the other hand, YMCK data from the external device 101 is also input to the B input of the selector 105.

The selector 105 outputs either the input A or the input B using the SST_ON / OFF signal output from the external device 101 as a selection signal. SS
If the value of the T_ON / OFF signal is 1, smoothing processing is enabled, and the selector 105 selects and outputs the A input from the smoothing processing unit 103. If the SST_ON / OFF signal is 0, the smoothing process is disabled regardless of the result of the pattern matching, and the B input of the selector 105 is output.

The PWM control 104 switches the resolution according to the value of the line number switching signal 10207. If the line number switching signal is 0, it is 800 lines, and if it is 1, it is 400 lines.

FIG. 9 shows an example of a screen (PPD screen) when a printer driver is started for printing on the external device 101 such as a host computer. The user
"Resolution" is manually specified from items such as "paper" and "resolution", and a smoothing process is performed from the "SST process (smoothing process)" pull-down menu ("Yes") or not ("No"). Set. The value set here is stored in the memory of the external device. If “Yes” is set, SST_ON / OFF
1 is output as a signal, and 0 is output if “none” is set. That is, when “Yes” is selected, the PWM control unit 104 receives image data from the smoothing processing unit 103 and a 400/800 line switching signal according to the presence or absence of smoothing, and outputs “No”.
Is selected, image data from the external device 101 and a switching signal fixed to 400 lines are input.

Next, a method of performing the smoothing process by the smoothing processing unit 103 will be described. FIG. 5 is an example of image data output from the external device 101. On the other hand, the result of smoothing by the smoothing processing unit 103 is shown in FIG. In this way, the resolution in the horizontal direction of the entire image is doubled, and the adjacent pixels are directly expanded for the vertical line component and the horizontal line component that are not smoothed. With respect to the step-like oblique line component, the pixel to be interpolated is given a density that smoothly connects the densities of adjacent pixels.

Next, the pattern matching circuit 102 will be described. FIG. 7 is a detailed block diagram. When an image signal of 400 dpi is transmitted from the controller to the printer in synchronization with the image CLK, the image dot data is sequentially stored in the line memories 1 to 9 and, at the same time, a shift is performed using the output of each line memory as an input. The register group 1302 stores dot matrix information of 11 dots for each line (main scanning) × 9 dots for the number of lines (sub-scanning). Each dot data stored in the shift register group 1302 is input to the determination circuit 1301 to detect the feature of the dot matrix information.

FIG. 8 is a diagram for extracting features of a dot pattern from a matrix area of 11 dots in the main scanning direction to 9 dots in the sub-scanning area over the entire area of the matrix area to check whether or not the dot pattern should be smoothed. FIG. 3 is a diagram for explaining each reference area. Hereinafter, this figure will be described.

FIG. 8A is a diagram showing a reference area of 11 dots in the main scanning direction × 9 dots in the sub-scanning direction.
a, b, c, d, e, f, g, h, i, j, k, and 1, 2, 3, 4, 5, 6, 7, 8, 9 in the sub-scanning direction. ing. For example, the center pixel is represented by 5f. The center pixel is a pixel to be changed for smoothing. FIG. 8B shows the reference area of FIG.
8, divided into 17 areas of Y1 to Y8 and 5f. Here, X1 is the pixels 3d, 3e, 3f, 4d,
An area including 4e and 4f, X2 is a pixel 3f, 3g, 3h,
An area including 4f, 4g, and 4h, and X3 represents pixels 6d, 6e,
This area includes 6f, 7d, 7e, and 7f. Figure 8 below
This is as shown in FIG. As described above, the reference area includes eight areas (X1 to X8) composed of six dots and six areas (Y1, Y3, Y4, Y5, Y5) composed of nine dots.
7, Y8) and two areas (Y2, Y2) composed of 10 dots.
6) and the central pixel 5f. here,
The characteristics of each area are represented as Xn and Yn. If the dots in each area have the same value for all the dots, the feature of each area is set to “0”. If the dots in each area are not the same, the feature of each area is set to “1”. In this way, X1 to X8 and Y1 to Y8 are obtained as characteristics of each region. The result of the pattern matching thus obtained is sent to the smoothing circuit 103. Smoothing circuit 10
In 3, if the values of X1 to X8, Y1 to Y8, and f5 match a predetermined pattern, the density of the pixel to be interpolated is determined according to the pattern, the pixel of interest, and the values of pixels in the vicinity thereof. , The pixel of that density is interpolated.

For example, Y3, Y7, X1, X4, X5
Consider a case where the value of X8 is 0 and the others are 1.
In this case, there are regions including pixels of different colors on the diagonal line from the upper right to the lower left, and in each of the other regions, the pixels included therein have the same value. Therefore, it can be estimated that the contour of the image exists from the upper right to the lower left of the target pixel on the boundary line. In this case, since it is desirable to smooth the contour line in the oblique direction, "80/80" is used as the 400/800 line switching signal.
The “0 line” is selected, and smoothing is performed according to the value of the target pixel and its surrounding pixels. As described above, it is determined by pattern matching that an image contour in an oblique direction exists near the target pixel, and if it exists, smoothing is performed.

FIG. 10 shows an example of smoothing of a line of one pixel width of the rasterized density data 255. As described above, the interpolation pixel of the data is replaced as the multi-value data according to the input pattern.
In the example of FIG. 10, pixel values adjacent in the main scanning direction are interpolated for each pixel in the main scanning direction in the image 11 of 400 dpi. Thereafter, the density of each pixel is corrected and smoothed according to the value of the pattern, the target pixel, and the peripheral pixel values. Here, if the density of the three pixels on the upper, left, and lower left of the target pixel is 255, and the density of the three pixels on the lower, right, and upper right is 0, 180 is set as the target pixel, and 180 80 is given as the density value. If the density of the three lower, right, and upper right pixels is 255, and the density of the upper, left, and lower left three pixels is 0, the target pixel has a density value of 180, and the lower pixel has a density value of 80. Given. That is, the smoothing is performed by interpolating pixels for each pixel in the main scanning direction and changing the pixel density so that the density of the staircase-shaped pixels changes smoothly.

As described above, the user selects whether or not to perform smoothing, and only when smoothing is selected, smoothing is performed according to the result of pattern matching. Therefore, if the user does not want smoothing, smoothing is not performed regardless of the characteristics of the image, and the quality of the image may be degraded by the smoothing. Disappears.

Although the setting with or without the SST processing is designated by the PPD on the host side, the user can also make the setting on the operation unit on the main body side of the color copying machine. In this case, the SST_ON / OFF signal is input as a selection signal of the selector 105 from the copying machine according to the setting in the operation unit, not the external device.

In the above-described embodiment, an example has been described in which YMCK density data is received from an external device. However, RGB luminance data may be used.

[0068]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to provide 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 apparatus.
Or MPU) reads and executes 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, The case where the CPU of the function expansion board or the function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing.

[0074]

As described above, whether or not to perform smoothing is set according to a user's instruction. If no smoothing is set, the image itself is the image to be smoothed. Even in the case of a certain determination, no smoothing is performed. Therefore, when the quality of the output image is reduced due to smoothing, it is possible to prevent the quality from being reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color copying machine.

FIG. 2 is a diagram of a color CCD.

FIG. 3 is a diagram showing how a PWM signal is generated.

FIG. 4 is a block diagram of an image processing system according to the present invention.

FIG. 5 is a diagram illustrating an example of an image before smoothing.

FIG. 6 is a diagram illustrating an example of an image after smoothing.

FIG. 7 is a block diagram of a pattern matching circuit.

FIG. 8 is a diagram showing a state of area division for pattern analysis in a pattern matching circuit.

FIG. 9 is a diagram illustrating an example of a screen for designating the presence or absence of smoothing processing.

FIG. 10 is a diagram illustrating an example of pixels before and after smoothing.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B057 AA11 BA02 BA19 CA01 CA08 CA16 CB01 CB08 CB12 CB16 CE03 CE05 CE06 CF03 DA08 DB02 DB09 DC05 DC36 5C077 LL02 MM03 MM27 MP06 MP07 MP08 PP02 PP03 PP09 PP15 PP33 PP43 PP47 PP51 PP58 PQ22 TT02 TT06

Claims (8)

[Claims] 1. An image processing apparatus for forming an image, comprising: instruction input means for inputting an instruction signal as to whether or not to perform an image contour smoothing process, and an image contour smoothing device according to a pattern of input image data. Smoothing processing means for performing image processing and outputting image data, and when it is instructed to perform smoothing processing by the instruction input means, forms an image based on output image data from the smoothing processing means, An image processing apparatus comprising: a forming unit configured to form an image based on the input image data when not instructed. 2. The smoothing means focuses on a region of a predetermined size including a pixel of interest from input image data, determines whether or not to perform smoothing according to a pixel arrangement pattern in the region, and performs smoothing. 2. The image according to claim 1, wherein, when performing the above, the pixel is interpolated for each pixel in the main scanning direction, and the density of the step-like pixels is changed so that the density changes smoothly. Processing equipment. 3. The image processing apparatus according to claim 1, wherein the instruction signal is input from an external device. 4. The apparatus according to claim 1, wherein the instruction signal is issued in accordance with a manual input corresponding to a screen display for asking a user whether or not to perform a smoothing process before forming an image. An image processing apparatus according to claim 1. 5. A method for controlling an image processing apparatus for forming an image, comprising: an instruction inputting step of inputting an instruction signal indicating whether or not to perform an image contour smoothing process; A smoothing step of performing contour smoothing and outputting image data; and, if the instruction inputting step instructs to perform the smoothing processing, an image is formed based on the output image data from the smoothing processing step. Forming an image based on the input image data when not instructed. 6. The smoothing step focuses on an area of a predetermined size including a pixel of interest from input image data, determines whether to perform smoothing according to a pattern of pixel arrangement in the area, and performs smoothing. 6. The image according to claim 5, wherein, when performing the above, the pixel is interpolated for each pixel in the main scanning direction, and the density of the step-like pixels is changed so that the density changes smoothly. A method for controlling a processing device. 7. The method according to claim 5, wherein the instruction signal is input from an external device. 8. The system according to claim 5, wherein the instruction signal is issued in accordance with a manual input corresponding to a screen display for asking a user whether or not to perform a smoothing process before forming an image. 3. The method for controlling an image processing apparatus according to claim 1.