JP2001296644A - Image-processing apparatus and printing cylinder forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-processing apparatus which processes an original image, so as to smooth the contour segments of an exposure region relating to a machine plate of a laser exposure system and a method for forming a printing cylinder, according to the processed image. SOLUTION: The original image expressed by binary values, as shown in (a) is inputted from an image input section 1, and the binary original image is inputted as 'white' as is in the case of the 'white' like a pixel A, is converted to 'black' if the image is 'black' like a pixel B and the 'white' pixel exists near 8 thereof, and the original image is converted into 'gray' which is a neutral tint, if the image is 'black' like a pixel C and all near 8 thereof are 'black', by which the grayscale image having three values as shown in (b) is formed. The formed grayscale image is outputted from an image output section 3 and is delivered to a laser printing machine, by which the formation of the printing cylinder is conducted.

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 for producing a printed matter having a smooth contour and a method for producing a printing cylinder.

[0002]

2. Description of the Related Art Gravure printing is known as one of printing methods. With gravure printing, a recess is formed for placing printing ink on the surface of the printing cylinder, and the printing ink is placed on this recess and transferred to paper.
This is a technique for creating printed matter. In addition, there are several printing plate methods for forming recesses on the printing cylinder surface, such as engraving printing plate methods in which the cylinder surface is directly shaved, and curing of necessary portions by laser,
The laser printing method that corrodes other parts is famous.

[0003] Among them, in the laser printing system, an original image is input to a laser printing machine, and it is determined whether or not to perform laser exposure on a printing cylinder according to a pixel value in each area of the original image. Further, for an area where laser exposure is to be performed, the ratio of exposure to be performed is determined based on the pixel values of the original image. For example, assume that exposure is performed at a rate of 50%. At this time, the laser plate printing machine does not uniformly expose the area so as to expose 50%, but exposes 100% inside a cell of a predetermined size and does not expose outside the cell due to its characteristics. In this manner, the exposure is performed so that the exposed portion in the entire area becomes 50%.

[0004]

When printing is to be performed based on a binary original image, usually, the portion where no ink is applied is formed as data of 0% density, and the portion where ink is applied is formed as data of 100% density. . However, if a portion on which ink is applied is formed at a density of 100%, there is a problem that the ink filled in this portion is scraped out by a doctor during printing. Therefore, the area where the ink is placed is 100% density.
It is performed to form using less than, for example, about 98% of data. When data of less than 100% is used as described above, a cell is formed. However, by forming a cell, a so-called bank-shaped portion is formed between cells. And a large amount of ink is not scraped out by the doctor. However, for example, if the laser beam is 10 × 1
In the case of 0 μm, the cell is 10 × 10
It is often set as large as 100 × 100 μm. For this reason, the contour portion of the exposed region becomes jagged and saw-like due to the influence of the cell shape, which causes another problem that so-called jaggies are noticeable.

In view of the above, the present invention provides an image processing apparatus for processing an original image so as to smooth the outline of an exposure area, and a method for creating a printing cylinder based on the processed image. The task is to provide

[0006]

In order to solve the above problem, according to the first aspect of the present invention, a first value (for example,
An original image represented by binary values of a black value and a second value (for example, white) is input, and an outline of a region having the first value in the input original image is extracted. A gradation image is obtained by setting a third value (for example, gray) between the first value and the second value that the image can take. According to the first aspect of the present invention, a contour processing is performed on a binary original image for printing, and a gradation image having three values is created by setting the inside to an intermediate value. Therefore, by creating a printing cylinder using this image, it is possible to prevent a large amount of ink from being scraped out during printing, and
It is possible to create a printed matter having a smooth outline.

According to a second aspect of the present invention, the generation of the gradation image according to the first aspect of the present invention is performed such that, for each pixel in the original image, when the pixel has the second value, When the pixel has the first value, when there is a pixel having the second value in the vicinity, the value is used as it is, and all the peripheral pixels have the first value. Is set to the third value, the process of creating a gradation image having three values from a binary original image is quickly performed.

According to the third aspect of the present invention, an original image represented by binary values of a first value and a second value is input, and a contour of an area having the first value in the input original image is input. Extraction is performed, and a gradation image is created by setting the inside thereof to a third value between the first value and the second value, and a third image is created from the created gradation image. The region with the value
Exposure data is formed by dividing a cell having a predetermined size having a value of and a bank portion having a second value other than the cell such that the ratio corresponds to the third value as a whole inside the region. The printing cylinder is produced by exposing the portion having the second value to laser light. According to the invention of claim 3, a gradation image having three values is created from the binary image, and an area having an intermediate value is divided into a cell portion and a bank portion in the gradation image, Since the printing cylinder is formed by exposing the bank portion and the outside of the region, the formed printing cylinder is formed with a concave portion for placing ink on a portion corresponding to the contour and the cell. For this reason, at the time of printing, a large amount of printing ink is not scraped out from the printing cylinder, and a smooth outline is expressed in the printed matter to be created.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration in an embodiment of an image processing apparatus according to the present invention. In FIG. 1, 1 is an image input unit, 2 is an arithmetic processing unit, 3 is an image output unit, and 4 is an image display unit. The image processing apparatus shown in FIG. 1 is realized by a computer equipped with dedicated software and its peripheral devices. The image input unit 1 is for inputting a binary original image, and is realized by a reading device for an electronic recording medium such as an FD or an MO. The arithmetic processing unit 2 includes a contour extraction unit 5 and a gradation processing unit 6, and performs a contour extraction process on the input original image.
By performing the gradation processing, a gradation image having three values is created. The arithmetic processing unit 2 is realized by a CPU and a memory of a computer, and the contour extraction unit 5 and the gradation processing unit 6 are realized by dedicated software. The image output unit 3 is for outputting a gradation image having three values, and is realized by a writing device for an electronic recording medium such as an FD or an MO. The image display unit 4 is realized by a display device such as a CRT display and a liquid crystal display.

Next, the processing operation of the image processing apparatus shown in FIG. 1 will be described. FIGS. 2A and 2B are diagrams showing a state of image processing by the arithmetic processing unit 2, wherein FIG. 2A shows an original image before processing,
(B) shows a corresponding portion of the processed gradation image. In FIG. 2A, a pixel shown in black indicates that the pixel value is large, and a pixel shown in white indicates that the pixel value is small. The original image is read into the buffer line by line according to the scanning direction. A total of three types of buffers, a PRE buffer for the immediately preceding column, a NOW buffer for the column currently being processed, and a POST buffer for the next column, are prepared. A pixel is processed by being compared with its eight neighboring pixels.

The way each pixel is processed depends on the state of that pixel. Specifically, when the pixel value corresponds to white, the processed pixel value also becomes white. If the pixel value corresponds to black, it depends on the state of the surrounding eight neighboring pixels. If at least one pixel value corresponding to white exists in the eight neighboring pixels, the pixel value after processing remains black. If all the pixel values in the vicinity of eight correspond to black, the pixel value after processing becomes a color (for example, gray) located between white and black. For example, since the pixel A corresponds to white in the original image shown in FIG. 2A, the pixel A is also white in the gradation image shown in FIG. Further, the pixel B corresponds to black in the original image, and a white pixel exists near 8 so that the pixel B is also black in the gradation image.
The pixel C corresponds to black in the original image, and all the pixel values in the vicinity of 8 are black, so that it is gray in the gradation image.

FIG. 3 shows the state of the original image and the entire gradation image obtained by processing the original image. FIG. 3A shows an original image, and FIG. 3B shows a gradation image. As can be seen from a comparison between the two, the original image is a binary image in which the inside of a certain area is blacked out and the outside of the area is white. And the outside of the area is white.

As a work flow, an operator inputs an original image from the image input unit 1 and displays it on the image display unit 4 as shown in FIG.
The image is displayed in the state shown in FIG. 3A, and the image processing is performed by giving an instruction to execute the image processing from a keyboard, a mouse, or the like, and the gradation image shown in FIG. 3B is displayed. Become. At this time, by displaying the created gradation image side by side on the same screen as the original image, it is possible to easily confirm whether or not the contour processing has been performed well. In the displayed image, white pixels are 0
%, 100% black pixels, 50% neutral pixels
It is preferable to set the degree. This is because by providing a predetermined density difference between the white pixel and the black pixel, the operator can easily confirm on the screen of the image display unit 4 whether or not the intermediate color portion is correctly created.

The tone image thus obtained is output from the image output unit 3 and passed to a laser printing machine (not shown). At this time, the intermediate color portion of the gradation image passed to the laser printing machine is practically converted to 98%. This 98
When the image is confirmed on the image display section 4, the numerical value of about 50% is easier to confirm, but when printing is actually performed, it is sufficient that 100% can be avoided. Is 100%, so that in order to reproduce the original image, it has been determined to satisfy the desire to approach 100% as much as possible.

Then, using the image data in which the intermediate color has been converted to 98%, the laser printing press exposes the printing cylinder with a laser beam. As a characteristic of a laser plate printing machine, for a region of 0%, exposure is performed in units of laser beams, and for a region of more than 0% and less than 100%, a cell of a predetermined size is formed. Perform exposure. No exposure is performed on the 100% area. Here, consider a case where a horizontally long elliptical area as shown in FIG. 4 is formed in a printing cylinder. FIG.
In (a), D is an outline having a density of 100%, E inside the area is a middle color area, and the area outside the outline is an area having a density of 0%.
This intermediate color area B is actually formed as shown in FIG. That is, a large number of square cells E1 are formed, and a bank portion E2 other than the cell E1 (here,
The part that remains without being finally corroded is referred to as a “bank”. ). The inside of the cell E1 is 100%, and the bank portion E2 outside the cell E1 is 0%, and is set to be 98% in the entire intermediate color area E. further,
FIG. 5 shows a state in which a portion F indicated by a rectangle in FIG. 4B is enlarged.

In FIG. 5, the same components as those in FIG. 4 are denoted by the same reference numerals. In FIG. 5A, the smallest square forming a lattice shape indicates a unit of exposure of the laser beam. Here, the exposed portions are shown in white, and the unexposed portions are shown in black. The contour D has a thickness in the unit of a laser beam, and is formed by not exposing this portion. The cell E1 has a size of 41 laser beams in the example of FIG. 5, and is formed by not exposing this portion. Embankment part E2, outline G of contour
Are all exposed. In FIG. 5A, the exposure unit of the laser beam is shown in a lattice shape for the sake of convenience of explanation, and in actuality, as shown in FIG. , G are all exposed, leaving no grid-like traces. Thereafter, the exposed printing cylinder proceeds to a corrosion process, where the exposed and hardened portion remains, and the unexposed portion is corroded. In the example of FIG. 5B, the areas E2 and G shown in white remain, and the areas D and E1 shown in black are depressed by corrosion.

In the example shown in FIG. 5, one cell has a size of 41 laser beams for the sake of drawing restrictions and for convenience of explanation. As described above, the size of one cell is about 100 laser beams. for that reason,
One side of the cell is about 10 times the width of the contour, and the contour processing increases the smoothness.

Printing is performed by placing printing ink on the printing cylinder obtained in this way. At this time, the printing ink is applied only to the depressed portions as shown in the areas D and E1.

[0019]

As described above, according to the present invention,
An original image represented by binary values of a first value and a second value is input, and an outline of a region having a first value in the input original image is extracted, and the inside of the original image is converted to the first value. A gradation image is created by setting a third value between the second value and the second value, and a region having a third value in the created gradation image has a first value. Exposure data is formed by dividing a cell having a predetermined size and a bank portion having a second value other than the cell such that the ratio thereof corresponds to the third value as a whole inside the region, Since the printing cylinder was created by exposing a portion having a value of 2 to a laser beam, a recess was formed in the created printing cylinder to apply ink to a portion corresponding to the contour and the cell, and during printing, , A large amount of printing ink is scraped from the printing cylinder DOO no, also, in the printed matter is created, smooth contour is an effect that will be expressed.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment of an image processing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a state of image processing performed by an arithmetic processing unit 2.

FIG. 3 is a diagram showing a state where an original image and a gradation image are compared.

FIG. 4 is a diagram showing an area formed in a printing cylinder.

FIG. 5 is a diagram showing a state in which a portion F in FIG. 4 is enlarged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image input part 2 ... Operation processing part 3 ... Image output part 4 ... Image display part 5 ... Contour extraction part 6 ... Gradation processing part

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Claims (3)

[Claims] 1. An image input means for inputting an original image represented by binary values of a first value and a second value, and extracting an outline of a region having a first value in the input original image. Contour extraction means, and gradation processing means for setting the inside of the contour to a third value between the first value and the second value that the original image can take;
An image processing apparatus comprising: an image output unit that outputs a gradation image obtained by being processed by the contour extraction unit and the gradation processing unit. 2. The method according to claim 1, wherein the contour extracting means and the gradation processing means keep the value of each pixel in the original image as it is when the pixel has the second value. When there is a pixel having the second value in the vicinity, the value remains as it is, and when all the surrounding pixels have the first value, the third value is used. The image processing apparatus according to claim 1, wherein the image processing apparatus is set to: 3. A step of inputting an original image represented by binary values of a first value and a second value, and extracting an outline of a region having the first value in the input original image, Creating a gradation image by setting the inside thereof to a third value between the first value and the second value; and setting the third value of the created gradation image to Partitioning the region into cells having a predetermined size having a first value and a bank portion having a second value other than the cell such that the ratio corresponds to the third value as a whole in the region. Forming exposure data by laser exposure and laser exposure of the portion having the second value to form a print cylinder.