JPH05191642A - Picture output device - Google Patents

Abstract

PURPOSE:To improve the picture quality of image data such as character data or line drawing data and the picture quality of image data such as pattern data. CONSTITUTION:This device is provided with a latch means 207a latching plural picture elements, a 1st picture quality improvement processing means 207b comparing plural picture elements with a comparison pattern and converting binary image data of a noted picture element into multi-value image data when they are coincident and outputting the binary image data as they are when noncoincident, a 2nd picture quality improvement processing means 207d receiving plural picture elements and converting the binary image data of the noted picture element into the multi-value image data through the use of spatial filtering processing and outputting the converted data, an area discrimination means 207e discriminating whether plural picture elements are resident in a character/line drawing area or in a pattern area, and a selection output means 207f outputting selectively the processing result of the 1st picture quality improvement processing means 207b or that of the 2nd picture quality improvement processing means 207d based on the result of the discrimination by the area discrimination means 207e.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image output device such as a printer or a facsimile device, and more particularly to an image output device for improving print quality of an output image.

[0002]

2. Description of the Related Art In recent years, an image output device for converting binary image data into multiple values and printing by using a laser beam has been developed. For example, there is a device disclosed in Japanese Patent Laid-Open No. 2-112966. .. This device inputs image data of a bit pattern image (binary image data) and compares the peripheral m × n region of the pixel of interest with a comparison pattern of the m × n region stored in advance by pattern matching processing. Then, when they match, the binary image of the pixel of interest is converted into a multi-valued image and printed. As a result, the quality of the output image can be improved.

[0003]

However, according to the conventional image output apparatus which multi-values binary image data and prints it by using the laser beam, the comparison pattern of the m × n area used in the pattern matching process is obtained. In reality, since there are only continuous patterns such as characters and line drawings, there is a problem in that the image quality cannot be improved for image data such as pictures read by a scanner or the like.

Further, if all the patterns in the m × n area are stored so that the image quality of image data such as a picture can be improved, a memory capacity of 2 ^mn bits is required, resulting in an increase in cost. However, since the number of comparison patterns increases, the processing speed decreases.

The present invention has been made in view of the above, and it is an object of the present invention to improve the image quality of image data such as characters and line drawings and the image quality of image data such as patterns.

Further, the present invention has been made in view of the above, and it is an object of the present invention to improve the image quality of image data such as a pattern without causing an increase in cost and a decrease in processing speed.

[0007]

In order to achieve the above object, the present invention provides a holding means for holding a plurality of pixels adjacent to a target pixel, and a comparison pattern stored in advance with the plurality of pixels held by the holding means. Are compared in a pattern matching process, and if they match the comparison pattern, the binary image data of the pixel of interest are converted into multi-valued image data, and if they do not match, the binary image data is output as it is. Second image quality improvement processing means for inputting image quality improvement processing means and a plurality of pixels held by the holding means, converting binary image data of a pixel of interest into multivalued image data using spatial filtering processing, and outputting the multivalued image data Based on the determination result of the area determination means and the area determination means for determining whether the plurality of pixels held by the holding means is a character / line drawing area or a pattern area. Te, there is provided an image output device that includes a selection output means for outputting the processing result of the first image quality enhancement means or the second image quality enhancement means selectively.

In order to achieve the above object, the present invention shows a first processing mode indicating that the original has many characters and line drawings, and that the original has many pictures such as photographs and halftone dots. The second mode and the designation means for selectively designating the three processing modes of the third processing mode indicating that the original is a mixture of characters, line drawings, photographs, halftone dots, etc. Storage means for storing certain binary image data,
The optimum image quality improving process is selected from a plurality of image quality improving processes based on the processing mode specified by the specifying means, and the optimum image quality improving process is executed on the binary image data.
Image quality improvement processing means for outputting binary or multi-valued image data, and multi-valued laser writing means for performing laser writing based on the binary or multi-valued image data input via the image quality improvement processing means. And an image output device.

Further, in order to achieve the above object, the present invention provides a document having a large number of characters such as a first processing mode indicating that the document has many characters and line drawings, a photograph, and halftone dots. Designating means for selectively designating two processing modes of the second mode shown, storage means for storing binary image data which is an original image, and holding for holding a plurality of pixels adjacent to the pixel of interest Means and a plurality of pixels held by the holding means and a comparison pattern stored in advance are compared by a pattern matching process, and if they match the comparison pattern, the binary image data of the pixel of interest is converted into multivalued image data. However, if they do not match, the first image quality improvement processing unit that outputs the binary image data as it is and a plurality of pixels held by the holding unit are input, and two pixels of the target pixel are input using the spatial filtering process. A second image quality enhancement means for converting the multivalued image data to image data of,
Based on the processing mode designated by the designating means, a selection output means for selectively outputting the processing result of the first image quality improvement processing means or the second image quality improvement processing means, and 2 inputted via the selection output means. An image output device provided with a multi-valued laser writing means for performing laser writing on the basis of value or multi-valued image data.

In the above-mentioned structure, it is desirable that the selection output means selectively outputs the processing result of the first image quality improvement processing means in the first processing mode.

In the second processing mode, it is desirable that the selection output means selectively outputs the processing result of the second image quality improvement processing means.

In addition to the above-mentioned structure, the plurality of pixels held by the holding means are provided with area judging means for judging whether the area is a character / line drawing area or a pattern area. The designating means is capable of designating a third processing mode indicating that the original is a mixture of characters, line drawings, photographs, halftone dots, etc., and the selecting and outputting means is a region in the case of the third processing mode. Based on the determination result of the determination means, the first
It is desirable to selectively output the processing result of the image quality improvement processing means or the second image quality improvement processing means.

Further, the area determination means detects the continuity of white and black pixels in the vertical and horizontal directions of a plurality of pixels adjacent to the pixel of interest, and expands the result to a desired size to continue the black and white pixel continuation. And a white background detecting means for detecting a cluster of white pixels of a plurality of pixels adjacent to the pixel of interest and expanding the result to a desired size. The expansion processing result of the black and white pixel continuity detecting means, Based on the expansion processing result of the white background detecting means and the comparison result of the pattern matching processing in the first image quality improving processing means, whether the area of the pixel of interest is a character / line drawing area or a pattern area is determined. It is desirable to judge.

Further, when the target pixel is a pixel detected by the white background detecting means and the comparison result of the pattern matching processing of the first image quality improving processing means with respect to the target pixel is coincident, the area determining means determines that It is desirable that the area of the pixel of interest is determined to be a character / line drawing area, and the selection output means outputs the processing result of the first image quality improvement processing means when the determination result of the area determination means is the character / line drawing area. ..

In the area determining means, when the pixel of interest is a pixel detected by the white background detecting means and detected by the black and white pixel continuity detecting means, the area of the pixel of interest is a character / line drawing area. It is desirable that the selection output means outputs the processing result of the first image quality improvement processing means when the determination result of the area determination means is a character / line drawing area.

The area determining means is a pixel in which the target pixel is not detected by the white background detecting means but is detected by the black and white pixel continuity detecting means, and the pattern matching processing of the first image quality improving processing means is performed. If the comparison results do not match,
It is desirable that the area of the pixel of interest is determined to be the picture area, and the selection output means outputs the processing result of the second image quality improvement processing means when the judgment result of the area judgment means is the picture area.

[0017]

In the image output apparatus of the present invention, the selective output means selectively outputs the processing result of the first image quality improvement processing means or the second image quality improvement processing means based on the determination result of the area determination means. .. As a result, the optimum image quality improving process is selected from the plurality of image quality improving processes, and the optimum image quality improving process is executed for the binary image data.

Further, in the image output apparatus of the present invention, when the corresponding processing mode is designated based on the type of the original document via the designating means, the image quality improving processing means is based on the processing mode designated by the designating means. The optimum image quality improvement process is selected from a plurality of image quality improvement processes, and the optimal image quality improvement process is executed for the binary image data.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser printer to which an image output device of the present invention is applied will be described below in detail with reference to the drawings.

FIG. 1 shows the system configuration of a laser printer (image output device) 200 of this embodiment. First, a document (original) created by existing application software on the host computer 100 is sent to the laser printer 200 by a general-purpose communication device (for example, Centronics, RS232C, etc.).

As shown in the figure, the laser printer 200 includes a receiving device 201 that receives data from the host computer 100, a CPU 202 that controls the entire device according to various control programs, and a ROM 203 that stores various control programs used by the CPU 202. And a RAM 204 for temporarily storing and reading data used on the control program, a font ROM 205 storing vector fonts, and image data for one page (here, pixel unit data). Page memory 206 for performing image quality improvement, an image quality improving device 207 that performs image quality improving processing on image data in the page memory 206, and a multi-value laser writing unit that performs laser driving in accordance with image data output from the image quality improving device 207. 208, photosensitive drum, developing device, etc. Electrophotographic processing section 209 made
And a first processing mode indicating that the original has many characters and line drawings, a second mode indicating that the original has many pictures such as photographs and halftone dots, and characters, line drawings, photographs and halftone dots, etc. Operation panel 210 for selectively designating three processing modes of the third processing mode indicating that the originals are mixed with each other.
And an I / I for performing data communication with the operation panel 210.
It is composed of an O device 211 and an internal system bus 212.

FIG. 2 shows an internal block diagram of the image quality improving device 207, and as shown in the figure, the FIFO buffer 207a.
, Smoothing processing unit 207b, and comparison pattern unit 2
07c, a filter processing unit 207d, and an image area separation unit 2
07e and a selector 207f.

The FIFO buffer 207a is a line buffer for storing n lines of binary image data in the page memory 206. Of n lines of data, m (dot) × n (lin with the pixel of interest as the center
e) The data in the area is processed by the smoothing processing unit 207 in the next stage.
b, the filter processing unit 207d, and the image area separation unit 207e.

The smoothing processing unit 207b uses AND,
Logic circuit such as OR, PLD circuit, or ROM
Has a LUT (look-up table) function configured by, for example, the comparison pattern of the m (dot) × n (line) area stored in the comparison pattern unit 207c in advance and the output (m ×) of the FIFO buffer 207a. (n region), and when they match, the binary pixel data of the pixel of interest is converted into desired multivalued pixel data, and when they do not match, the original image data is output as it is. In other words, when the pattern matching process matches the comparison pattern, the binary image data of the pixel of interest is converted into multi-valued image data, and when they do not match, the binary image data is output as it is. It should be noted that the comparison pattern portion 207c stores a plurality of continuous patterns such as characters and line drawings in m × n regions used in the pattern matching process as comparison patterns.

The filter processing unit 207d has a pixel value m centering on the pixel of interest output from the FIFO buffer 207a.
Data in (dot) × n (line) area (plural pixels)
Is subjected to smoothing filtering processing, converted into desired multi-valued data and output.

As will be described in detail later, the image area separation unit 207e is
It is determined whether the m (dot) × n (line) area centered on the pixel of interest output from the FIFO buffer 207a is a character / line drawing area or a pattern area,
In addition to the determination result, a selection signal is output to the selector 207f based on information as to whether the results of the pattern matching processing in the smoothing processing unit 207b match and the processing mode designated via the operation panel 210. To do.

The selector 207f is an image area separation unit 207e.
Smoothing processing unit 207b according to the selection signal from
Either the processing result of (1) or the processing result of the filter processing unit 207d is output to the multilevel laser writing unit 208.

The operation of each unit in the above configuration will be specifically described. The CPU 202 executes the control program stored in the ROM 203, and the host computer 1
A document for one page from 00 is read via the receiving device 201
Stored in AM204, if the character code is font RO
It is converted into binary image data using M205 and stored in a predetermined position of the page memory 206.

The image quality improving device 207 performs an image quality improving process, which will be described later, on the binary image data in the page memory 206 in accordance with a processing mode designated by the operator through the operation panel 210 in advance, and multilevel laser writing is performed. It is transmitted to the unit 208.

The image quality improving device 207 first inputs binary image data for n lines from the page memory 206 and stores it in the FIFO buffer 207a. The FIFO buffer 207a converts the data of the m (dot) × n (line) area centering on the pixel of interest from the data of n lines to the smoothing processing unit 207b, the filter processing unit 207d, and the image area separation unit 207e of the next stage. Send to.

Here, for example, the m × n area is defined as a 7 × 7 area, and a plurality of 7 × 7 comparison patterns as shown in FIGS. 3A and 3C are stored in advance in the comparison pattern portion 207c. The smoothing processing unit 207b is shown in FIG.
It is assumed that the pixels of interest (lattice-shaped pixels in the drawing) for the comparison patterns of (a) and (c) are converted into the multivalued image data of FIGS. 3 (b) and (d), respectively.

In this case, for example, FIG. 4 (a) and FIG.
Assuming that the image data of (a) is sent from the FIFO buffer 207a, the smoothing processing unit 207b
The processing results of are as shown in FIG. 4 (b) and FIG. 5 (b), respectively. In FIG. 4, the pixels indicated by a, b, c, d, e, and f are converted into multivalued image data, and the stair-like jaggedness (jaggies) generated by diagonal lines, characters, etc. becomes visually smooth.

On the other hand, since the image data of the pattern as shown in FIG. 5A does not match the comparison pattern stored in the comparison pattern section 207c, the original image is output as it is. However, in the image data of FIG. 5 (a), it is considered that 50% of uniform gray data was originally area density modulated by gradation processing such as systematic dither method. Judging from this viewpoint, The smoothing processing unit 207b does not perform the image quality improving process on the image data of the pattern.

As a matter of course, it is only necessary to store in the comparison turn section 207c a comparison pattern capable of performing the image quality improving process on the image data of the pattern. Since there are 2 ^mn patterns of comparison pattern data including the continuous patterns shown in FIGS. 3A and 3C, the memory capacity becomes huge and it is not practical from the viewpoint of cost. Therefore, the smoothing processing unit 207b stores only continuous comparison patterns and performs image quality improvement processing only on image data such as characters and line drawings.

Further, in the present embodiment, for the pixel of interest that coincides with the comparison pattern, the information indicating the coincidence (coincidence information) is sent from the smoothing processing unit 207b to the image area separation unit 2
07e is notified.

Like the smoothing processing unit 207b, the filter processing unit 207d has m (d) centered on the pixel of interest.
Data in the (ot) × n (line) area is input, and smoothing filtering processing is performed on the pixel of interest. For example,
When the smoothing filtering process shown in FIG. 6 is executed with n = m = 3, the image data of FIG.
The image data of FIG. 8A is converted into FIG. 8B, and the image data of FIG.

Characters in the filter processing unit 207d,
As can be seen from FIG. 7, the result of processing the image data such as the line drawing has the effect of removing the jaggies, but the line width becomes thick, resulting in a visually blurred image. On the other hand, with respect to image data such as a picture, the original picture is reproduced faithfully as shown in FIG. 8, and the image quality is improved.

From the above results, the image quality improving process of the smoothing processing unit 207b is suitable for image data such as characters and line drawings, and the image quality improving process of the filter processing unit 207d is suitable for image data such as pictures. It turns out to be suitable.

Therefore, in this embodiment, the smoothing processing section 207b, the filter processing section 207d, and the image area separating section 2
07e are processed in parallel, and the output of the selector 207f is selected based on the processing mode input through the operation panel 210 and the processing result of the image area separation unit 207e, thereby outputting the optimum image quality improvement processing result. I am trying.

The processing mode designated through the operation panel 210 is FC / MODE: the first processing mode designated when the manuscript is almost a character or a line drawing FI / MODE: the manuscript is almost a picture or a pattern such as a halftone dot Second processing mode designated in case of FCI / MODE: There are three modes of third processing mode designated when characters, line drawings, photographs, halftone dots and the like are mixed in the original.

Next, the configuration and operation of the image area separation unit 207e will be described with reference to FIGS. As shown in FIG. 9, the image area separation unit 207e includes a pixel continuity detection unit 501 that detects the continuity of white and black pixels in the vertical and horizontal directions of a plurality of pixels adjacent to the pixel of interest, and pixel continuity detection unit 501. A dilation processing unit 502 that dilates the detection result of the nature detection unit 501 to a desired size, a white background detection unit 503 that detects a group of white pixels (white background) of a plurality of pixels adjacent to the pixel of interest, and a white background detection unit 503. Expansion processing unit 504 for expanding the detection result of the image to a desired size, expansion processing unit 502, and expansion processing unit 5
A comprehensive determination unit 505 that determines whether the region of the pixel of interest is a character / line image region or a pattern region based on the expansion processing result of 04 and the matching information from the smoothing processing unit 207b. ..

In order to simplify the description, the m × n region to be image-area-separated is m = n =, as shown in FIG.
Set to 5. Further, each of the pixels a to y in the figure has a value of "1" when it is a black pixel and has a value of "0" when it is a white pixel.

The pixel continuity detecting section 501 indicates the continuity of black and white pixels in the horizontal and vertical directions within the m × n region (here, 5 × 5 region) as shown in FIG. Detect by logic. The output A in the figure is "1" when three black pixels are continuous in the vertical direction and three white pixels are continuous in the vertical direction among the eight adjacent pixels. The output B is “1” when three black pixels are continuous in the horizontal direction and three white pixels are continuous in the horizontal direction among the eight adjacent pixels.

Similarly, the AND output of the output C and the output D is "1" when five black pixels are continuous in the vertical direction and five white pixels are continuous in the vertical direction among the 24 adjacent pixels. Becomes The AND output of output E and output F is
It becomes “1” when five black pixels are continuous in the horizontal direction and four white pixels are continuous in the horizontal direction among the four.

Further, the AND output of the output C and the output E is "1" when five black pixels are continuous in the vertical direction and five black pixels are continuous in the horizontal direction among the 24 adjacent pixels. Becomes Therefore, the OR output G of these outputs is 1 in the above condition.
When any one of them is applicable, the pixel of interest is regarded as a line drawing,
Outputs "1".

The pixel continuity detecting section 501 operates in this way, so that, for example, (a), (b) of FIG.
The target pixel (center pixel of the 5 × 5 area) of (c) and (d) is regarded as a character / line drawing pixel, and the target pixels of (e), (f), and (g) are regarded as pattern pixels.

The expansion processing unit 502 checks the detection result of the continuity detection unit 501 with respect to the pixel adjacent to the pixel of interest, and if there are n or more pixels that are character / line drawing pixels,
Processing is performed so that the pixel of interest is regarded as a character / line drawing pixel. For example, for the image data of FIG.
The processing result of the pixel continuity detecting unit 501 is as shown in FIG. 7B, and the pixel of interest is not regarded as a character / line-drawing pixel, but by processing with the dilation processing unit 502, adjacent pixels are 3 Since it is regarded as one character / line drawing pixel, the pixel of interest is finally regarded as a character / line drawing pixel (however, n
= 3).

Usually, since a group of white pixels (white background) exists adjacent to the character / line drawing pixels, the white background detecting section 503 detects whether or not the pixel of interest is a part of the white background. Specifically, it is compared with a pattern in which white pixels are gathered as shown in FIGS. Try to select the most suitable one according to the resolution of the target document.

The expansion processing unit 504, for example, as shown in FIG. 15, if at least one pixel in the 32 × 5 area adjacent to the pixel of interest is detected as a white background by the white background detection unit 503,
The pixel of interest is regarded as a white background area.

The comprehensive judgment unit 505 sends a selection signal to the selector 207f based on the processing mode designated on the operation panel 210, the processing results of the expansion processing units 502 and 504, and the matching information of the smoothing processing unit 207b. Output.

First, when FC / MODE (first processing mode) is specified, the expansion processing units 502, 5
The smoothing processing unit 207b is unconditionally irrespective of the processing result of 04 and the matching information of the smoothing processing unit 207b.
The selector 207f is switched so as to selectively output the processing result of.

Next, when FI.MODE (second processing mode) is designated, the expansion processing units 502, 5
The selector 207f is switched so as to unconditionally select and output the processing result of the filter processing unit 207d regardless of the processing result of 04 or the matching information of the smoothing processing unit 207b.

On the other hand, when FCI.MODE (third processing mode) is designated, the processing result of the smoothing processing unit 207b is selected for the pixel that matches the comparison pattern. Further, in the case of a white background pixel (see the processing result of the expansion processing unit 504) and a pixel determined to be a character / line drawing pixel (see the processing result of the expansion processing unit 502), the processing result of the smoothing processing unit 207b is also obtained. Select.
In other cases, in other words, for the pixels that do not match the comparison pattern, and are not determined as white background pixels and character / line drawing pixels, the filter processing unit 207d
Select the processing result of.

As described above, in this embodiment, since the two image quality improving processing means (smoothing processing section 207b and filter processing section 207d) are provided, the operation panel 21
By specifying the type of original (Original with many characters, line drawings, originals with many pictures, originals with mixed characters, line drawings, pictures, etc.) via 0, the optimum image quality improvement processing according to the original type Can be selected.

Further, even in the case of a document in which characters, line drawings, pictures, etc. are mixed, the image area separating section 207e can separate the originals, and the optimum image quality improving processing can be applied to the respective areas. In this embodiment, the three processing modes are specified according to the type of the original, but the optimum image quality improvement processing is selected only by the judgment of the image area separation unit 207e without specifying the processing mode. Even in this case, it goes without saying that the image quality can be improved as compared with the conventional case. However, since the separation of the image area is incomplete at present, the image area separation unit 2
It is possible to further improve the image quality by designating the processing mode as in the present embodiment, as compared with the case of determining only by 07e.

In the present embodiment, the laser printer has been described as an example, but the present invention is not limited to this.
It is obvious that the same effect can be obtained even when applied to an image output device such as a high definition CRT.

[0057]

As described above, the image output apparatus of the present invention includes the holding means for holding a plurality of pixels adjacent to the pixel of interest, the plurality of pixels held by the holding means, and the comparison pattern stored in advance. Compared by pattern matching processing, if it matches the comparison pattern, the binary image data of the pixel of interest is converted into multi-valued image data, and if it does not match, the binary image data is output as it is. Processing means and second image quality improvement processing means for inputting a plurality of pixels held by the holding means, converting binary image data of a pixel of interest into multivalued image data by using spatial filtering processing, and outputting the multivalued image data; Based on the region determination unit that determines whether the plurality of pixels held by the holding unit is a character / line drawing region or a pattern region, and the determination result of the region determination unit, Since the image quality improving processing means of 1 or the selective output means for selectively outputting the processing result of the second image quality improving processing means is provided, the image quality of image data such as characters and line drawings is improved, and the image quality of image data such as patterns is improved. It is possible to improve. In addition, it is possible to improve the image quality of image data such as a picture without increasing the cost and reducing the processing speed.

The image output apparatus of the present invention has a first processing mode indicating that the original has many characters and line drawings, and a second mode indicating that the original has many pictures such as photographs and halftone dots. Also, a designation means for selectively designating the three processing modes of the third processing mode, which indicates that the original includes a mixture of characters, line drawings, photographs, halftone dots, etc., and the original image 2
Optimal image quality improvement processing is selected from a plurality of image quality improvement processings based on the storage means for storing the value image data and the processing mode designated by the designating means, and the optimum image quality for the binary image data. Image quality improvement processing means for executing improvement processing and outputting binary or multi-valued image data;
Since the multi-valued laser writing means for performing laser writing on the basis of the binary or multi-valued image data inputted through the image quality improvement processing means is provided, the image quality of the image data such as characters and line drawings is improved, and the pattern etc. The image quality of image data can be improved. In addition, it is possible to improve the image quality of image data such as a picture without increasing the cost and reducing the processing speed.

Further, the image output apparatus of the present invention has the first processing mode indicating that the original has many characters and line drawings, the photograph, and the second processing mode indicating that the original has many pictures such as halftone dots. Designation means for selectively designating two processing modes of modes, storage means for storing binary image data which is an original image, holding means for holding a plurality of pixels adjacent to the pixel of interest, and holding The plurality of pixels held by the means and the previously stored comparison pattern are compared by a pattern matching process, and if they match the comparison pattern, the binary image data of the pixel of interest is converted into multi-valued image data and does not match. In this case, the first image quality improvement processing means for outputting the binary image data as it is and a plurality of pixels held by the holding means are input, and the binary image of the pixel of interest is subjected to the spatial filtering processing. Second image quality improvement processing means for converting the data into multi-valued image data and outputting it, and the first image quality improvement processing means or the second image quality improvement processing means based on the processing mode designated by the designating means. Since the selective output means for selectively outputting the processing result of 1) and the multi-value laser writing means for performing laser writing based on the binary or multi-valued image data inputted through the selective output means are provided,
In addition to improving the image quality of image data such as characters and line drawings, it is possible to improve the image quality of image data such as pictures.
In addition, it is possible to improve the image quality of image data such as a picture without increasing the cost and reducing the processing speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a system configuration of a laser printer (image output device) of this embodiment.

FIG. 2 is an explanatory diagram showing an internal block diagram of an image quality improving device.

FIG. 3 is an explanatory diagram illustrating an operation of a smoothing processing unit.

FIG. 4 is an explanatory diagram showing an operation of a smoothing processing unit.

FIG. 5 is an explanatory diagram illustrating an operation of a smoothing processing unit.

FIG. 6 is an explanatory diagram showing an operation of a filter processing unit.

FIG. 7 is an explanatory diagram showing an operation of a filter processing unit.

FIG. 8 is an explanatory diagram illustrating an operation of a filter processing unit.

FIG. 9 is an explanatory diagram showing the configuration and operation of the image quality improving apparatus.

FIG. 10 is an explanatory diagram illustrating an operation of the image quality improving device.

FIG. 11 is an explanatory diagram showing the logic of a pixel continuity detection unit.

FIG. 12 is an explanatory diagram showing a specific operation example of a pixel continuity detection unit.

FIG. 13 is an explanatory diagram showing processing results of a pixel continuity detection unit and an expansion processing unit.

FIG. 14 is an explanatory diagram illustrating a specific operation example of a white background detection unit.

FIG. 15 is an explanatory diagram showing a processing result of an expansion processing unit.

[Explanation of symbols]

100 Host Computer 200 Laser Printer 201 Receiver 202 C
PU 203 ROM 204 R
AM 205 Font ROM 206 Page memory 207 Image quality improving device 207a
FIFO buffer 207b Smoothing processing unit 207c
Comparison pattern section 207d Filter processing section 207e
Image area separation unit 207f Selector 208 Laser writing unit 209 Electrophotographic process unit 210 Operation panel 211 I
/ O device 212 Internal system bus 501 Pixel continuity detection unit 502 Expansion processing unit 503 White background detection unit 504 Expansion processing unit 505 Overall determination unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G06F 15/68 9191-5L 15/70 450 9071-5L

Claims (10)

[Claims] 1. A holding means for holding a plurality of pixels adjacent to a pixel of interest, a plurality of pixels held by the holding means and a comparison pattern stored in advance are compared by a pattern matching process, and when the comparison patterns match. , A first image quality improving processing means for converting binary image data of a pixel of interest into multi-valued image data and outputting the binary image data as it is when they do not match, and a plurality of pixels held by the holding means. Second image quality improvement processing means for inputting and converting binary image data of a pixel of interest into multi-valued image data using spatial filtering processing, and a plurality of pixels held by the holding means are character / line drawing. A region,
Alternatively, area determining means for determining whether the area is a picture area,
An image output, comprising: a selection output unit that selectively outputs the processing result of the first image quality improvement processing unit or the second image quality improvement processing unit based on the determination result of the area determination unit. apparatus. 2. A first processing mode indicating that the original has many characters and line drawings, a second mode indicating that the original has many pictures such as photographs and halftone dots, and characters, line drawings, photographs,
Designating means for selectively designating the three processing modes of the third processing mode indicating that the original has halftone dots and the like, and storage means for storing binary image data which is an original image. , An optimum image quality improving process is selected from a plurality of image quality improving processes based on the processing mode specified by the specifying means, and the optimum image quality improving process is executed on the binary image data to obtain a binary value. Alternatively, an image quality improvement processing means for outputting multivalued image data and a multivalued laser writing means for performing laser writing on the basis of the binary or multivalued image data input via the image quality improvement processing means are provided. An image output device characterized by the above. 3. Two processing modes are selected: a first processing mode indicating that the original has many characters and line drawings, a photograph, and a second mode indicating that the original has many pictures such as halftone dots. A designating means for designating a single image, a storage means for storing binary image data which is an original image, a holding means for holding a plurality of pixels adjacent to a target pixel, and a plurality of pixels held by the holding means A comparison pattern stored in advance is compared by a pattern matching process. If the comparison pattern matches, the binary image data of the pixel of interest is converted into multi-valued image data, and if it does not match, the binary image data Is input to the first image quality improving processing means and a plurality of pixels held by the holding means are input, and binary image data of the target pixel is converted into a multivalued image by using spatial filtering processing. The processing result of the first image quality improving processing means or the second image quality improving processing means is selected based on the second image quality improving processing means for converting the data and outputting the data, and the processing mode specified by the specifying means. Image output including selective output means for selectively outputting and multivalued laser writing means for performing laser writing based on binary or multivalued image data input through the selective output means. apparatus. 4. The image output device according to claim 3, wherein the selection output means selectively outputs the processing result of the first image quality improvement processing means in the first processing mode. 5. The image output apparatus according to claim 3, wherein the selection output means selectively outputs the processing result of the second image quality improvement processing means in the second processing mode. 6. An area determination means for determining whether the area of a plurality of pixels held by the holding means is a character / line drawing area or a pattern area, and the designating means is a character , A line drawing, a photograph, a halftone dot, and the like can be designated as a third processing mode indicating that the original is present, and the selection output means, in the case of the third processing mode, of the area determination means. 4. The image output device according to claim 3, wherein the processing result of the first image quality improvement processing means or the second image quality improvement processing means is selectively output based on the determination result. 7. The black-and-white pixel continuation for detecting the continuity of white and black pixels in the vertical and horizontal directions of a plurality of pixels adjacent to the pixel of interest and expanding the result to a desired size. And a white background detecting means for detecting a group of white pixels of a plurality of pixels adjacent to the pixel of interest and expanding the result to a desired size. The expansion processing result of the black and white pixel continuity detecting means Whether the area of the pixel of interest is a character / line drawing area or a pattern area based on the expansion processing result of the white background detection means and the comparison result of the pattern matching processing in the first image quality improvement processing means. The image output device according to claim 6, wherein 8. The area determination unit is a case where the pixel of interest is a pixel detected by the white background detection unit, and the comparison result of the pattern matching process of the first image quality improvement processing unit with respect to the pixel of interest is a match. , The area of the pixel of interest is determined to be a character / line drawing area, and the selection output means
8. The image output apparatus according to claim 7, wherein the processing result of the first image quality improvement processing means is output when the determination result of the area determination means is a character / line drawing area. 9. When the pixel of interest is a pixel detected by the white background detecting unit and detected by the black and white pixel continuity detecting unit, the region determining unit determines that the region of the pixel of interest is a character / line drawing region. 8. The selection output means determines that there is, and outputs the processing result of the first image quality improvement processing means when the determination result of the area determination means is a character / line drawing area. Image output device. 10. The area determining means is a pixel in which a target pixel is not detected by the white background detecting means but is detected by the black and white pixel continuity detecting means, and the pattern matching of the first image quality improving processing means is performed. If the comparison results of the processes do not match, it is determined that the area of the pixel of interest is the pattern area,
The image output apparatus according to claim 7, wherein the selection output unit outputs the processing result of the second image quality improvement processing unit when the determination result of the region determination unit is a pattern region.