JPH0766976A - Picture processing unit - Google Patents

Abstract

PURPOSE:To provide the picture processing unit in which longitudinal and lateral 2-dimensional optional variable magnification processing is attained with high quality, an input binary picture is subjected to multi-valued processing and variable magnification processing, and picture quality deterioration is solved through the print by a multi-value processing engine. CONSTITUTION:The processing unit is provided with a binary image area separate means 401 applying image area separate processing to a binary picture and a multi-value processing means 402 applying multi-value processing of edge interpolation type to a picture recognized as a character and line drawing area and applying multi-value processing to an area recognized as a photograph or a graphic picture with an averaging filter.

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 of a printer having a multi-valued engine, and more particularly to an image processing apparatus characterized by a resolution conversion processing technique when the resolutions of a printing section and an input image are different. .

[0002]

2. Description of the Related Art FIG. 13 is a system configuration diagram of a general digital copying machine. In FIG. 13, 100 is a printer unit, 101 is a floppy disk device in which the floppy disk 300 is set, and 102 is a general-purpose I / F such as SCSI I / F.
/ F, 103 is a modem, and 200 is a scanner unit. The printer unit 100 uses a floppy disk device 101 in which a document created on a computer is stored.
Read in, print with the printing section in the printer section 100,
Directly receives and prints documents from a computer connected to the general-purpose I / F 102, or through the modem 103,
It has a printer function for receiving and printing a facsimile document.

[0003]

In such a digital copying machine system, print images of various formats are input targets. In particular, the following problems occur. For example, in a conventional system that outputs a binary image, for example, jaggies cannot be removed in a character or line drawing image, and in a photographic or graphic image, an original image of a uniform halftone image is represented by black and white dots. Therefore, the image will be rough. Further, in such a system, for example, when the resolution of the recording engine in the printer unit 100 is 400 dpi, enlargement processing of 167% and 133% is required for emulation images of 240 dpi, 300 dpi, etc., respectively. In such a conventional binary output system, simple insertion enlargement, SPC enlargement, smoothing enlargement,
Although such methods were often used, for example, moiré may occur on the halftone screen, jaggies may appear in enlarged characters, and reduced small letters and thin lines may be cut off, so good scaling is not always necessary. No image was obtained.
However, in the current system, the input device is binary data in many cases, whereas the output device is multivalued. In that case, high-quality image output utilizing the characteristics of the multivalued engine is desired. . Further, the functions of the digital copying machine include vertical and horizontal independent variable magnification, but the printers currently on the market do not have such a function. This is because the scaling function of the digital copying machine realizes vertical scaling at a scanning linear velocity of 200, and thus vertical scaling cannot be realized for a document created on a computer. . Therefore, it is necessary to develop a vertical and horizontal two-dimensional scaling function.

An object of the present invention is to provide a multi-value output system,
It is intended to solve the above-mentioned image quality deterioration by performing multi-value conversion using filters suitable for characters, line-drawing images, photographs, and graphic images, and printing with a multi-value engine. An object is to provide an image processing device that enables double processing.

[0005]

SUMMARY OF THE INVENTION The above object is to provide a binary image for performing image area separation processing on the binary image in an image processing apparatus of a system for inputting a binary document image and printing with a printer having a multivalued engine. Edge-interpolation-type multi-value processing is performed on the area separation means and images recognized as characters and line drawing areas, and multi-value conversion is performed on areas recognized as photographs or graphic images with an averaging filter. It is achieved by the first means including a multi-value quantization means for

Further, in an image processing apparatus of a system in which a binary document image is input and is printed by a printer having a multi-valued engine, a filter close to the reading element characteristic of a scanner for converting a binary image into a multi-valued image and a binary value are used. This is achieved by the second means including a multi-value image area separation means for performing image area separation processing of an image.

Further, according to the first means, the multi-valued multi-valued data is subjected to multi-valued two-dimensional scaling processing to obtain a multi-valued scaling processing result. To be achieved.

In the third means, the image of the area recognized as the character or line drawing area is subjected to level correction processing in consideration of the dot reproducibility of the multi-valued engine, and recognized as a photograph or graphic image. This is achieved by the fourth means for performing the multivalue gradation processing and the level correction processing on the formed area.

[0009]

In the first means, the binary image is subjected to the image area separation processing, and the image recognized as the character or line drawing area is subjected to the edge interpolation type multi-valued processing to obtain the photographic or graphic image. Averaging /
By using a filter to multi-value, jaggies in characters and line drawing areas are removed, and multi-value density of an original image of a photograph or graphic image can be reproduced.

In the second means, a binary image is multivalued by a filter having a characteristic close to the reading element characteristic of the scanner, and the image area separation processing of the binary image is performed by the multivalued image area separation processing to perform digital copying. Since the image area separation chip built in the device can be used and the image area separation chip dedicated to the binary image does not have to be developed, new development investment can be suppressed.

In the third means, the image quality deterioration in the conventional binary-to-binary scaling processing can be improved by converting the scaling result into multiple values.

In the fourth means, the image of the area recognized as a character or line drawing area is subjected to level correction processing in consideration of the dot reproducibility of the multi-valued engine, and the area recognized as a photographic or graphic image. In contrast, by performing multi-value gradation processing and the level correction processing, a stable image can always be printed by changing the content of the level correction depending on the type and state of the printer.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an internal block diagram of the printer section according to the embodiment. Floppy disk device 101, general-purpose I /
The print information obtained through F102 and the modem 103 is stored in the CPU.
It is decoded by 104 and expanded in the binary memory unit 120. Then, the image is printed by the multi-value engine unit 110 through the binary multi-value arbitrary scaling unit 400 according to the present invention. In addition, 105 is RO
M and 106 are RAMs.

FIG. 2 is an internal block diagram according to the first embodiment of the binary multi-value arbitrary scaling unit. The binary image area separation unit 401 performs binary image area separation processing on the binary data in the memory unit 120, and the multi-value conversion unit 402 separates the character, line drawing area 403 and photograph or graphic area 404. , Multivalued processing is performed for each area, then multivalued scaling processing unit 405 performs multivalued scaling processing, and further, multivalued gradation processing unit 406 performs multivalued gradation processing. The result is the multi-value engine
Transfer to 110 to get print image.

A detailed description will be given below for each block. First, various companies have proposed various methods for the binary image area separation processing of the binary image area separation unit 401. For example, it is performed by comprehensive judgment of edge separation processing, halftone dot separation processing, and white background detection processing. Methods etc. are known. However, instead of using such a method of providing an image area separation block dedicated to a binary image, the multivalued image area separation processing built in the digital copying machine may be diverted.

FIG. 3 is an internal block diagram of a binary multi-value arbitrary scaling unit according to the second embodiment, and FIG. 4 shows a filter matrix used in the binary multi-value arbitrary scaling unit of the second embodiment. It is an explanatory view shown. In this embodiment, the binary image in the memory unit 120 is multi-valued by a filter 407 (in consideration of CCD characteristics which is an optical reading element), and the multi-valued image area separation unit 408 multi-values based on this data. Image area separation processing is performed, and the binary information in the general-purpose I / F 102 is multivalued using the separation result information. Although this method cannot be used in an ordinary laser printer, it is effective in the system configuration of the present invention.

Next, the multi-value quantization unit 402 will be described. In this embodiment, Max density of 255, that is, multi-valued conversion into an 8-bit image has been described. First, the character and line drawing area 40
In the multi-value conversion of 3, edge interpolation type multi-value conversion is performed. This will be described with reference to FIG. FIG. 5A shows a part of a character, and the pixels at the edges are multivalued as shown in FIG. 5B. By this processing, the edge portion of the character is multi-valued to an intermediate density (density 85, 170), and edge jaggies are removed. Meanwhile, the photo / graphic area 404
The image recognized as is multi-valued by a smoothing filter as shown in FIG. FIG. 6B shows an example of the smoothing filter. In this case, the binary image shown in FIG. 6A is converted into an intermediate density of 113, 142 as shown in FIG. 6C. This is considered to be a state close to the original image information before binarization. After the binary image is converted into an 8-bit image by the multi-value conversion, an arbitrary scaling process is performed by the next-stage multi-value scaling algorithm.

FIG. 7 shows an example of a two-dimensional scaling process for a multi-valued image, where a, b, c and d are original pixels and p is a converted pixel. 8A is a numerical representation of FIG. 5B, and FIG. 8C is a numerical representation of FIG. 6C including its peripheral pixels. (D) is 75 for each
% Is the result of reduction. Further, the results of the conventional method of performing the scaling process on the binary image as it is, not according to the present invention, are shown as comparative examples in FIGS. 9 and 10 and will be described first. 9,
FIG. 10B shows the processing result of the simple thinning-out method, and FIG. 10C shows the processing result of the SPC method for the image of FIG. As compared with the images of (c) and (d) of FIG. 8, it can be seen that the step of the edge portion changes, jaggies are not removed, and the texture of the photographic image changes. Although not shown in this embodiment, fine lines or the like may disappear, or moire may occur in a photographic image.

On the other hand, it can be seen that the scaling result according to the present invention realizes the scaling process with the jaggies caused by the step of the character removed. Further, it can be seen that the scaling processing without image quality deterioration is realized in the state where the density of the binarized photographic image is restored to the original multivalued image. However, in a printer that cannot faithfully reproduce the result of multi-value scaling according to the present invention, for example, a laser printer, multi-value gradation processing or the like is performed on a multi-valued image, and the printer can perform stable dot reproduction. As described above, multi-value gradation processing and level correction are performed. Also in this case, the processing is divided into two types according to the above-mentioned separation result. In the present embodiment, the multi-valued engine unit 110 has six
The following explanation is given assuming that there are only four gradations of dot reproduction. First, in the character and line drawing areas, the preprocessing result is subjected to linear interpolation processing to convert 256 gradation data into 64 gradation data [FIG. 11 (a)]. And, for example, in FIG.
By performing the level correction shown in FIG.
1 (a) is level-corrected as shown in FIG. 11 (c).
This level correction is performed in consideration of the gamma characteristic of the printer so that the halftone densities of the edge portions are evenly spaced. This is because if the print density changes abruptly with a certain density value as a boundary, the density of the edge portion may undulate, and as a result, jaggies may be induced. On the other hand, with respect to the area determined to be a photographic image, multi-value gradation processing is performed to convert 256 gradation data into 64 gradation data [FIG.
(B)]. For the multi-value gradation processing, for example, a matrix having a priority order as shown in FIG. Further, for example, by performing the level correction (FIG. 11B) described above, the 64 gradation data of FIG. 12C can be obtained. Considering that the original original image has a uniform halftone, a density value closer to that of the original image can be obtained as compared with the case of FIG.

The image in the area recognized as a character or line drawing area is subjected to level correction processing in consideration of the dot reproducibility of the multi-valued engine, and the area recognized as a photograph or graphic image is processed. By switching between the multi-value gradation processing and the gradation correction processing method for performing the level correction described above according to the output printer, a stable image can always be printed.

Further, the binary multi-value arbitrary scaling processing circuit is arranged between the binary page memory and the multi-valued engine so that the binary multi-value arbitrary scaling processing can be performed in real time. It becomes possible to execute.

In the above embodiment, in the image processing apparatus of the system in which the binary document image is input and the image is printed by the printer having the multi-valued engine, the binary image area separation is performed on the binary image. The means 401 and an image recognized as a character or line drawing area are subjected to edge interpolation type multi-valued processing, and an area recognized as a photo or graphic image is multi-valued by an averaging filter. Since the multi-value conversion means 402 is provided, the image area separation processing is performed on the binary image, the edge interpolation type multi-value processing is performed on the image recognized as the character or line drawing area, and the image or the graphic image is obtained. Since the recognized area is multi-valued by the averaging filter, the jaggies in the character and line drawing areas are removed, and it is possible to reproduce the multi-valued density of the original image of the photograph or graphic image. In the above embodiment, 2
In an image processing apparatus of a system that inputs a value document image and prints with a printer having a multivalue engine, a filter 407 that multivalues a binary image and that is close to the reading element characteristic of the scanner 200 and an image area of the binary image. Since the multivalued image area separating means 401 for performing the separation processing is provided, the binary image is multivalued by the filter 407 having a reading element characteristic close to that of the scanner 200, and the image area separation of the binary image is performed by the multivalued image area separation processing. Since the processing is performed, the image area separation chip built in the digital copying apparatus can be used, and it is not necessary to develop the image area separation chip dedicated to the binary image, and new development investment can be suppressed.
In the above-described embodiment, multi-valued multi-valued data is subjected to multi-valued two-dimensional scaling processing to obtain a multi-valued scaling processing result. It is possible to improve image quality deterioration in the scaling process. In the above-described embodiment, the level correction processing with dot reproducibility of the multi-valued engine is performed on the image of the area recognized as the character or line drawing area, and the area recognized as the photographic or graphic image is processed. Since the multi-value gradation process and the level correction process are performed, stable images can always be printed by changing the level correction contents depending on the type and state of the printer.

[0024]

According to the first aspect of the invention, the image area separation processing is performed on the binary image, and the edge interpolation type multi-value processing is performed on the image recognized as the character or line drawing area. By averaging the area recognized as a photo or graphic image with an averaging filter, jaggies in the text and line drawing areas can be removed, and the multi-value density of the original image of the photo or graphic image can be reproduced. It will be possible. According to the second aspect of the present invention, digital copying is performed by converting the binary image into a multi-valued image with a filter having a characteristic close to the reading element of the scanner and performing the image area separation process of the binary image with the multi-valued image area separation process. The image area separation chip built into the device can be used,
Since it is not necessary to develop an image area separation chip dedicated to the value image, new development investment can be suppressed. Claim 3
According to the above-described invention, the image quality deterioration in the conventional binary-to-binary scaling process can be improved by converting the scaling result into multi-valued. According to the invention described in claim 4, level correction processing is performed on an image of a region recognized as a character or line drawing region in consideration of dot reproducibility of a multi-valued engine, and a region recognized as a photographic or graphic image. In contrast, by performing multi-value gradation processing and the level correction processing, a stable image can always be printed by changing the content of the level correction depending on the type and state of the printer.

[Brief description of drawings]

FIG. 1 is an internal block diagram of a printer unit according to an embodiment of the present invention.

FIG. 2 is an internal block diagram according to a first embodiment of a binary multi-value arbitrary scaling unit.

FIG. 3 is an internal block diagram according to a second embodiment of a binary multi-value arbitrary scaling unit.

FIG. 4 is an explanatory diagram showing a matrix of filters used in the second embodiment.

FIG. 5 is an explanatory diagram showing edge interpolation type multi-leveling.

FIG. 6 is an explanatory diagram showing a state in which an image in a photograph or graphic area is multivalued by a smoothing filter.

FIG. 7 is an explanatory diagram showing an example of a state of two-dimensional scaling processing of a multivalued image.

FIG. 8 is an explanatory diagram showing pixels that have been digitized and vertical and horizontal reduction results.

FIG. 9 is an explanatory diagram showing, as a comparative example, a result of a conventional method of performing a scaling process on a binary image as it is.

FIG. 10 is an explanatory diagram showing, as a comparative example, a result of a conventional method of performing a scaling process on a binary image.

FIG. 11 is an explanatory diagram showing a state of level correction of gradation data in a character / line drawing area.

FIG. 12 is an explanatory diagram showing a state of multivalue gradation processing in a photographic image area.

FIG. 13 is a system configuration diagram of a general digital copying machine.

[Explanation of symbols]

 100 Printer unit 101 Floppy disk device 102 General-purpose I / F 200 Scanner unit 300 Floppy disk 400 Binary multi-value arbitrary variable magnification unit 401 Binary image area separation unit (binary image area separation means) 402 Multi-value conversion unit (multi-valued) 407 filter 408 multi-value image area separation unit (multi-value image area separation means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 5/00 H04N 1/40 8420-5L G06F 15/66 355 L 9191-5L 15/68 310 310 J 4226-5C H04N 1/40 F

Claims (4)

[Claims] 1. An image processing apparatus of a system for inputting a binary document image and printing with a printer having a multi-valued engine, a binary image area separating means for performing image area separation processing on the binary image, a character and a line drawing. The image recognized as a region is subjected to edge interpolation type multi-valued processing, and the region recognized as a photograph or graphic image is provided with multi-valued conversion means for multi-valued by an averaging filter. An image processing device characterized by the above. 2. An image processing apparatus of a system for inputting a binary document image and printing with a printer having a multi-valued engine, wherein a binary image is multi-valued and a filter close to a reading element characteristic of a scanner and a binary value. An image processing apparatus, comprising: a multi-valued image area separation unit that performs image area separation processing of an image. 3. The method according to claim 1, wherein multivalued multivalued data is subjected to multivalued two-dimensional scaling processing to obtain a multivalued scaling processing result. Image processing device. 4. The area recognized as a photograph or graphic image according to claim 3, wherein a level correction process with dot reproducibility of a multi-valued engine is performed on an image of an area recognized as a character or line drawing area. The image processing apparatus is characterized by performing multi-value gradation processing and the level correction processing.