JPH08156326A - Device and method for processing image - Google Patents

Abstract

PURPOSE: To provide excellent images having smooth outlines also in character images with output resolution fully utilized, regardless of resolution of an original image data. CONSTITUTION: A smoothing means 1 for substituting an input data so as to smooth an edge of a processing image data, a plurality of substitution data tables 3-5 which previously hold a substitution data for referring in smoothing processing at the smoothing means 1, a scaling means 2 for scaling an image signal from the smoothing means 1, and a scaling factor setting means 6 for setting a scaling factor of the scaling means 2 are provided. Accordance to the scaling factor of the scaling means 2, an optimal substitution data table is made accessible from the smoothing means 1, and the substitution data of the smoothing means 1 is switched.

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 method.

[0002]

2. Description of the Related Art Recently, in the field of office machines, printers, facsimile machines (FAX), digital copying machines,
Electronic file devices, etc. are being integrated and networked. In such a system, image information data with different numbers of gradations and different resolutions are mixed,
It is necessary to convert the resolution and the number of gradations between each device. For example, the number of gradations of a laser beam printer (LBP) or a facsimile machine is binary, and the number of gradations in a digital copying machine is multivalued. Actually, in addition to this, due to various standards of each office equipment and high resolution due to improvement of digital processing technology and electrophotographic process, there are many resolutions, and the connected equipments are different from each other in most cases.

By the way, as described above, LBP, FAX
And the like handle binary image data, and thus jaggies occur in the contour of a character image or the like. A smoothing process is generally used to eliminate this jaggy. FIG. 3 shows the effect of general smoothing processing. 3A shows the state before the smoothing process is executed, and FIG. 3B shows the state after the smoothing process is executed. In the smoothing process shown in FIG. 3, as shown in FIG. 7, one pixel of white or black is converted into one pixel of white, black, or an intermediate level, and the same number (pixel size) of pixel data as the input image is obtained. Is output as.

Also, due to systematization, LBP, FAX
When outputting a binary image such as
Not only the resolution conversion is performed by the scaling process, but also the required scaling process is performed at the same time. As shown in the block diagram of FIG. 5, the smoothing means 11 converts the binary image which is the input image into the replacement table 1 as shown in FIG.
After performing the smoothing process by replacing with the replacement data registered in 5, the scaling means 12 adjusts the image data from each input to the resolution of the digital copying machine at the scaling ratio set by the scaling ratio setting means 20. Magnification processing is performed.

FIG. 11 shows the result of performing the scaling processing on the image after the smoothing processing of the conventional FIG. 3 (b).
FIG. 11 shows an example in which the magnification is changed by about (4/3) times. With the resolution conversion technique described above, the LB
Even if image data such as P and FAX is output from a digital copying machine, a good image quality with little jaggies is obtained.

[0006]

However, in the above-described conventional example, when the resolution of the input image is relatively low with respect to the output system, the diagonal high frequency band of the smoothed image data is sufficiently large. Since it was not wide, it was not possible to express a curve that was smooth enough to match the resolution of the output system.

FIG. 9 is an image showing a result of scaling the image after the smoothing processing shown in FIG. 3 (b) by a scaling factor close to 2 times. It shows that a sufficient smoothing effect is not obtained compared to the image. In the smoothing processing shown in FIG. 3, the registered replacement data in the replacement data table 15 is not replaced with the replacement data shown in FIG. 7, but one pixel shown in FIG. 10 is replaced with replacement data that replaces a plurality of pixels with an appropriate pixel density. By performing the smoothing process by doing
It is possible to add sufficient diagonal high frequency components to the image data. However, even if conversion is performed using the replacement data shown in FIG. 10, the conventional device of this type uses only one replacement data table 15 as shown in FIG. There was a problem that an appropriate smoothing process could not be performed according to the above.

[0008]

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following structure as one means for solving the above-mentioned problems. That is, smoothing means for replacing the input data so as to smooth the edges of the processed image data, scaling means for scaling the image signal from the smoothing means, and scaling factor for setting the scaling factor of the scaling means. It is characterized by further comprising setting means and switching means for switching the replacement data of the smoothing means in accordance with the scaling ratio of the scaling means.

Further, smoothing means for replacing the input data so as to smooth the edges of the processed image data, and at least two or more operation modes, the image signals from the smoothing means are changed according to the operation mode. Magnification changing means for changing the magnification according to the magnification, magnification changing means for setting the magnification according to the operation mode of the magnification changing means, and switching for switching the replacement data of the smoothing means according to the magnification changing of the magnification changing means And means.

Further, for example, at least a part of the replacement data of the smoothing means is obtained by calculation. Alternatively, the replacement data of at least part of the smoothing means is obtained by a table prepared in advance.

[0011]

With the above construction, it is possible to provide a good image having a smooth contour even in a character image or the like which makes full use of the resolution of the output system, regardless of the resolution of the original image data.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings. The outline of the smoothing processing and the scaling processing in this embodiment will be described below with reference to FIG.
In FIG. 2, reference numerals 3 to 5 are replacement data tables 1 to 3 in which different replacement data are respectively registered. The optimum replacement data table is selected according to the scaling ratio set by the scaling ratio setting means 6 and the smoothing means 1 is selected. It can be supplied.
That is, the replacement data is supplied from the appropriate replacement data table to the smoothing means by controlling the selector according to the resolution ratio among the plurality of replacement data tables for smoothing processing. The scaling means 2 also performs scaling processing on the data for which smoothing processing has been completed according to the scaling ratio set by the scaling ratio setting means.

In the present embodiment, since a plurality of replacement data tables corresponding to the respective resolution ratios are provided as described above, the resolution of the output system can be fully utilized regardless of the resolution of the original image data. It is possible to provide a good image having a smooth contour even for a character image. In addition, although the case where three data tables are provided as the replacement data table has been described as an example in FIG. 2, the present invention is not limited to the above example, and a configuration including a larger number of replacement tables may be provided as necessary. Is also good. More detailed image output can be realized by supporting each resolution in more detail. Alternatively, the registration content of the replacement table may be changed by the CPU 150, which will be described later, and desired replacement data may be updated prior to the processing.

FIG. 1 shows the construction of a concrete apparatus for realizing the smoothing processing and the scaling processing shown in FIG. FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention. This embodiment will be described with reference to the block diagram of FIG. A document placed on a document table (not shown) is irradiated with a halogen lamp, and the reflected light is photoelectrically converted by a line CCD 101 through an optical system (not shown) to read a document image. In this embodiment, the halogen lamp is scanned in the direction perpendicular to the longitudinal direction, and the image is sequentially read by the CCD 101 line by line. Each of these configurations (not shown) is publicly known, and detailed description thereof will be omitted.

The S / H circuit 102 samples and holds the output signal of the CCD 101, and the A / D conversion circuit 103
Output to. The A / D conversion circuit 103 is the S / H circuit 102.
The analog signal sampled and held by is converted into a corresponding 8-bit digital signal. The correction circuit 104 corrects variations in gain and offset for each pixel due to a halogen lamp, an optical system, sensitivity unevenness of the CCD 101, and the like with respect to the input digital signal.

The output signal from the correction circuit 104 is input to the image processing circuit A 106 via the selector 105. The image processing circuit A 106 performs editing processing such as scaling, negative / positive conversion, and movement on the digital signal corrected by the correction circuit 104. The image processing circuit B107 performs non-linear processing such as logarithmic conversion on the output signal of the image processing circuit A106. The digital signal after the image processing by the image processing circuit B107 is converted into a corresponding analog signal by the D / A conversion circuit 108, pulse width modulated by the modulation circuit 109, and supplied to the laser unit 110.

The laser section 110 irradiates a photosensitive drum (not shown) with laser light to generate an electrostatic latent image on the photosensitive drum, and copies it onto a recording medium such as paper by a so-called electrophotographic process. Since these configurations are publicly known, detailed description will be omitted. The above is the signal flow of the system having the function as the copying machine of the present embodiment. Next, a signal flow of the system as a printer and a FAX function will be described.

First, the operation mode of the printer will be described. In this case, a computer which is an output information supply source (not shown) is connected to the connector 111 which is an input when operating as a printer, and the output information from the computer is transmitted to the image processing circuit C112 via the connector 111. Is entered. At the same time, a control signal from the computer is also input. The image processing circuit C112 develops the output information signal from this computer into a binary image and outputs it. The binary image signal from the image processing circuit C112 is
It is input to the smoothing circuit 114 via the selector 113. The smoothed signal from the smoothing circuit 114 is sent to the selector 105, and then to the above-described image processing circuit A 106, where the same processing as described above is performed.

On the other hand, in the operation mode as the facsimile apparatus, the selector 113 is controlled so as to select and output the signal from the FAX unit 118. as a result,
The signal is sent from the FAX unit 118 to the signal smoothing circuit 114. The subsequent signal flow is the same as in the printer operation mode. The selectors 105 and 113 are controlled by the CPU 150 that controls the overall control of the apparatus of this embodiment.

Further, in this embodiment, a copying machine, FA
The flow of image data is adjusted by a buffer memory (not shown) so that the X and printer can be used simultaneously. The smoothing circuit 114 described above outputs (255) and (0) for white and black, respectively. Also,
In order to smooth the contour of the image, the pixels adjacent to the boundary between white and black are replaced with (255), (0), or an appropriate halftone level and output.

The characteristic structure of this embodiment will be described below. FIG. 6 is a diagram showing an example of a pixel pattern when the smoothing means 1 of the present embodiment replaces input data with a halftone level and outputs. Each square corresponds to a pixel, and X is D
on'tCare, white circles represent white pixels, and black circles represent black pixels. When the patterns match, the central pixel is replaced with one or four pixels at the halftone level as shown in FIG. 7 or 10.

The replacement data for 1 pixel and 4 pixels are the replacement data tables 115 to 11 corresponding to the replacement data tables 1 to 3 shown in FIG.
It is stored in advance in 7. Replacement data table 115-
Any one of 117 is selected by the selector 119 and connected to the smoothing circuit 114, and supplies replacement data to the smoothing circuit 114. The head address of each table stores the number of vertical and horizontal pixels of the replacement pixel.

The input of the scaling ratio setting unit 120 differs depending on the operation mode of the system. In the copy mode, the scaling ratio setting unit 120 converts a key input by a key button of an operation unit (not shown) into 8-bit scaling ratio information. Further, in the printer mode in which an image is output by a signal supplied from the computer via the connector 111, the CPU 150 detects a control signal from the connector 111 and automatically sets the magnification. Scale setting unit 120
Outputs the set scaling information to the image processing circuit A 106 that performs scaling processing, and the replacement data table 115
It outputs to the selector 119 which selects either of -117.

In the present embodiment, if the scaling factor is 150% or less, the replacement data table 115 is selected by the selector 119, and if the scaling factor is 150% to 200%, the replacement data table 116 is 200% or more. If so, the replacement data table 117 is selected. In this embodiment, three replacement data tables are provided, and 150%
And 200% as a reference, but another value may be used depending on the characteristics of an output system such as an electrophotographic process. If the scaling factor is not so large, two replacement data tables 115 and 116 are provided, and two replacement data tables may be selected depending on whether the replacement data table is 150% or more or 150% or less. .

In the embodiment described above, the replacement data table for the smoothing process is selected on the basis of the scaling information, but the CPU 150 or the like can directly use the information on various modes such as the printer or FAX standard. It may be configured to control. The output signal from the smoothing circuit 114 is scaled by the image processing circuit A 106 so as to have an appropriate amount of data suitable for the resolution of the electrophotographic process. In the scaling process of the image processing circuit A106, since the output resolution of the printer portion is 400 DPI, if the original image is image data equivalent to 300 DPI, 4
Magnify to 3 times. In this case, since the scaling factor is 150% or less, the replacement data table 115 is selected in the smoothing process.

If the original image is image data corresponding to 240 DPI, the scaling factor is 5 in order to obtain 400 DPI.
Since it is / 3 times, it exceeds 150%, so the replacement data table 116 is selected in the smoothing process. In this case, since the magnification has been doubled by the smoothing process, the image processing circuit A106 performs (1/2) * (5/3) = 5/6 times.

The images shown in FIG. 3A are subjected to smoothing processing by the replacement data tables 115 and 116, and the scaled images are shown in FIGS. 11 and 8, respectively.
In FIG. 8, a smoother contour is obtained as compared with the conventional image of FIG. 9. After the image processing circuit A106, the same processing as in the copy mode in which the image signal from the CCD is output is performed, a laser is irradiated by pulse width modulation to form a latent image, and a medium such as paper is formed by an electrophotographic process. Copy to.

Further, in the present embodiment, indexes are assigned to the respective patterns as shown in FIG. 6 in the smoothing process, and the selected table is based on the index information and the information of the number of replacement pixels. Access the replacement data from. For example, when the replacement data from the replacement data table 115 is supplied to the smoothing circuit 114, as shown in FIGS. 7A and 7B, (255) and (0) are set for the white and black pixels. The pixel of is output. Further, when a specific pattern as shown in the example of FIG. 6 is matched, in order to smooth the contour of the image, the pixels adjacent to the boundary between the white and black pixels are adjusted to an appropriate halftone as shown in FIG. 7C. The pixel of the level is replaced and output.

On the other hand, when the replacement data from the replacement data table 116 is supplied to the smoothing circuit 114, FIG.
As shown in (a) and (b) of 0, four (255) and (0) pixels are output for white and black, respectively. Also, if a specific pattern is matched, as shown in FIG. 10C, it is replaced with four (255), (0) or an appropriate halftone level pixel for output.

Similarly, the replacement data table 117 may be configured to output 9 pixels of 3 × 3 for each of white and black so that an optimum smoothing result for the resolution can be selected. Images obtained by smoothing the input data shown in FIG. 3A by the replacement data tables 115 and 116 using the above replacement data tables are shown in FIGS. 3B and 4, respectively.

In the present embodiment, there are three replacement data tables, but the replacement pixels are different in combination or 4 according to various scaling factors such as 1 × 2, 4 × 4 pixels.
You may prepare more than one table. Further, in the above description, the ROM is used as the replacement data table, but it may be directly incorporated into a hardware logic circuit by using an IC or the like, or may be configured as a RAM and loaded from a CPU or the like.

From the data having a large number of replacement pixels,
The smaller data may be calculated by low-pass filtering. Further, the contour information is extracted from the coordinate information of the pixel, the contour information is smoothed by filtering, and when the pixel data is calculated from the contour information, the number of pixels to be extracted is changed according to the input / output resolution ratio. The data may be calculated.

Although the office equipment system has been described in the above embodiments, the present invention can be applied to any display system such as a display as long as it is an output system expressing pixels in multiple values.
Further, other input system such as an electronic file may be used as the input of the binary image. As described above, according to the present embodiment, the number of replacement pixels for smoothing processing and the density data table or the method for calculating density data are switched according to the ratio of the input and output resolutions to change the output system. It is possible to obtain a smoothing effect that makes full use of the resolution, and it is possible to make good use of the resolution of the output system and provide a good image with a smooth outline such as a character image, regardless of the resolution of the original image data. .

The present invention may be applied to a system including a plurality of devices or an apparatus including a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0035]

As described above, according to the present invention, regardless of the resolution of the original image data, the resolution of the output system is fully utilized, and a good image having a smooth outline such as a character image is provided. You can

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an outline of smoothing processing and scaling processing according to the present embodiment.

FIG. 3 is a diagram showing pixel patterns before and after execution of a smoothing process at a normal size.

FIG. 4 is a diagram showing an example of a pixel pattern on which smoothing processing has been performed using the replacement data table of this embodiment.

FIG. 5 is a block diagram showing an outline of conventional smoothing processing and scaling processing.

FIG. 6 is a diagram showing a pixel pattern when an input pixel is replaced with a halftone level and output using the replacement data table of the present embodiment.

FIG. 7 is a diagram showing an example of pixel replacement by smoothing.

FIG. 8 is a diagram showing an example of a pixel pattern that has been subjected to smoothing processing and scaling processing using the replacement data table of this embodiment.

FIG. 9 is a diagram showing a pixel pattern in which the pixel shown in FIG. 3B is scaled by a scaling factor of 2 × in each of the vertical and horizontal directions.

FIG. 10 is a diagram showing an example of pixel replacement by smoothing.

11 is a diagram showing a pixel pattern in which the pixel shown in FIG. 3b is scaled with a small magnification.

[Explanation of symbols]

 1, 11 smoothing means 2, 12 variable magnification means 3, 4, 5, 15 replacement data table 6, 20 variable magnification setting means 101 CCD (photoelectric conversion element) 102 sample and hold circuit 103 A / D conversion circuit 104 shading correction circuit 105, 113, 119 Selector 106, 107, 112 Image processing circuit 108 D / A conversion circuit 109 PWM modulation circuit 110 Laser section 111 Connector 114 Smoothing circuit 115, 116, 117 Replacement data table 118 FAX section 120 Scale setting section 150 CPU

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G06T 5/00 G09G 5/36 520 C 9377-5H H04N 1/409 G06F 15/66 355 P 15/68 350 H04N 1/40 101 D

Claims (8)

[Claims] 1. A smoothing unit that replaces input data so as to smooth edges of processed image data, a scaling unit that scales an image signal from the smoothing unit, and a scaling ratio of the scaling unit. An image processing apparatus, comprising: a scaling ratio setting unit that performs the scaling process; and a switching unit that switches replacement data of the smoothing unit according to the scaling ratio of the scaling unit. 2. A smoothing means for replacing the input data so as to smooth the edges of the processed image data, and at least two or more operation modes, wherein the image signal from the smoothing means is varied at different scaling factors. Scaling means for multiplying, scaling ratio setting means for setting the scaling ratio of the scaling means according to the operation mode, and switching means for switching the replacement data of the smoothing means according to the scaling ratio of the scaling means. An image processing apparatus comprising: 3. The image processing apparatus according to claim 1, wherein at least a part of the replacement data of the smoothing unit is calculated. 4. The image processing apparatus according to claim 1, wherein at least a part of the replacement data of the smoothing unit is obtained by a table prepared in advance. 5. An image processing method, wherein after performing smoothing processing for replacing input data so as to smooth edges of processed image data, the replaced image signal is scaled at a set scaling ratio. An image processing method, characterized in that replacement data of the input data is switched according to a scaling factor at the time of multiplication. 6. After performing a smoothing process for replacing the input data so as to smooth the edges of the processed image data, at least two or more operation modes having different scaling factors are used to obtain the smoothed image signal. An image processing method for scaling, wherein a scaling ratio is set according to an operation mode during the scaling process,
An image processing method, characterized in that replacement data in the smoothing process is switched according to a set scaling ratio. 7. The image processing method according to claim 5, wherein at least a part of the replacement data in the smoothing process is calculated. 8. The image processing method according to claim 5, wherein at least a part of the replacement data in the smoothing process is obtained by a table prepared in advance.