JPH08314124A - Moire evaluation method and image output system used therefor - Google Patents

Abstract

(57) [Abstract] [Purpose] Evaluate whether moiré occurs when gravure printing is performed using image data for gravure printing. [Structure] C, M, Y, and K image data for gravure printing is color-printed for each color plate by a color printer.
In addition, the C, M, Y, and K image data for gravure printing are subjected to scaling processing to form image data of the same size, and these image data are supplied to a color printer to perform full-color printing. By observing these images, when the cylinder engraving is performed using the image data for the gravure printing, and when printing is performed, which color plate has a moiré pattern, and when the moiré pattern is superimposed on four plates, It can be confirmed at the image data stage how it appears.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moire evaluation method and an image output system used therefor.

[0002]

2. Description of the Related Art The process of gravure printing is as schematically shown in FIG. First, each document is set on the plate-making scanner and image input is performed (step S1). When image input is completed, image processing such as plate collection for page make-up and color correction is performed (step S2).

The C, M, Y, and K image data obtained by the step 2 has the same number of pixels. That is, the size of these image data is as shown in FIG.
It is the same as shown in b, c and d. Note that FIG.
b, c, and d are C, M, Y, and K image data, respectively, and a rectangular area in the drawing indicates data of one pixel.

Next, engraving machine conversion processing is performed (step S
3). This step is a step for creating image data for gravure printing from the C, M, Y, K image data obtained in step S2, and the C, M, Y, K obtained in step S2.
The image data is subjected to a predetermined filtering process and a scaling process for performing pixel density conversion. These processes are well known and will not be described.

By this step, image data having different numbers of pixels for each of C, M, Y and K plates can be obtained. 5a, b,
c and d are diagrams showing examples of image data obtained by the process of step S3, and C, M, Y, and K, respectively.
The image data of is shown. In addition, the area shown by the rectangle in the figure shows the data of one pixel. From the figure, it can be seen that the number of pixels is different for each plate.

After the image data for gravure printing is obtained in this way, the cylinder is engraved for each plate using the image data obtained in step S3 (step S4). As a result, C, M, Y, and K gravure plates are obtained, respectively, as shown in FIGS. 6a, b, c, and d. It goes without saying that the sizes of these plates are all the same. Figure 6
In each of a, b, c, and d, a rectangle represents one gravure cell and has a one-to-one correspondence with a pixel. That is, it can be seen that the pixel length is different for each plate, that is, the pixel density is different. The cylinder has a cylindrical shape, but FIG. 6 shows a diagram in the case of being developed for convenience.
Further, the shape and size of the cell are usually different for each plate, but in FIG. 6, the shape and size are represented by a rectangular shape for convenience.

When the engraving of the cylinder is completed in this way, printing is performed using this cylinder (step S
5). This gives a gravure full-color print.

[0008]

By the way, although moiré may occur also in gravure printing, conventionally, whether or not moiré occurs by looking at the printed matter obtained by performing the printing step of step S5 of FIG. I was deciding.

However, since it can be determined only in the printed matter whether or not the moire is generated, if it is confirmed that the moire is generated in the printed matter, the engraved cylinder is subjected to chemical treatment to be flat and again. Step S3 in FIG.
Carry out the engraving machine conversion process. In the engraving machine conversion process at this time, it is natural to perform an operation such as changing the characteristics of the filter that performs the filter process in order to suppress the occurrence of moire.

Then, a step of engraving the cylinder again after the image data for gravure printing is created again in this way is required.

Therefore, in the past, when moire was generated in the gravure printed matter, the steps as described above had to be performed, so that the labor of the operator was large and the cost was also very large.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a moire evaluation method capable of determining whether or not moire occurs at the stage of image data.

Another object of the present invention is to provide an image output system capable of determining whether or not moire occurs at the stage of image data.

[0014]

In order to achieve the above object, in the moire evaluation method according to claim 1, image data having the same pixel density for each color is scaled at different scaling rates. It is characterized in that at least one color plane image data of the resulting image data is supplied to the color printer or the display means and the moire is evaluated based on the output image.

According to a second aspect of the present invention, in the moire evaluation method, image data obtained as a result of performing scaling with different scaling factors on image data having the same pixel density for each color is scaled to an image having the same output size. Then, the moire is evaluated based on the color image obtained by supplying the image data of all the color plates obtained by the scaling processing to the color printer or the display means.

According to another aspect of the image output system of the present invention, there is provided a first means for performing scaling with different scaling factors for image data having the same pixel density for each color, and all the colors obtained by the first means. A color printer for making a hard copy for each color plate based on the image data of the plate and / or a color display device for displaying for each color plate based on the image data of all the color plates obtained by the first means. Is characterized by.

In the image output system according to the present invention, the image data obtained as a result of scaling the image data having the same pixel density for each color at different scaling factors is scaled to an image having the same output size. And a color printer for performing full-color hard copy based on the image data of all the color plates obtained by the first means and / or the image data of all the color plates obtained by the first means. And a color display device for performing full-color display based on the above.

[0018]

The present invention proposes two methods as a moire evaluation method. One is the method according to claim 1, in which at least one color in image data obtained as a result of performing scaling with different scaling factors for image data having the same pixel density for each color. Moire is evaluated using the image output by supplying the image data of the plate to the color printer or the display means.

As described above, in this method, each color image is separately output as a hard copy or displayed on a monitor. Therefore, by observing these images, it is possible to determine which color plate has moire. It can be confirmed in advance at the data stage.

A system for performing this method is claimed in claim 3.
The image output system described above, which comprises a first means and a color printer and / or a color display device.

The first means carries out scaling with different scaling rates for image data having the same pixel density for each color, and the image data of all color plates obtained by this first means is hard. It is hard-copied for each color plate by a copy or color display device, or is displayed for each image data of each color plate.

Therefore, for example, when the moire evaluation method according to claim 1 and the image output system according to claim 3 are applied to the case of creating image data for gravure engraving, an image for each color plate of the image data for gravure engraving is applied. Is separately output as a hard copy or displayed on a monitor, so observing these images will cause moire in which color plate when engraving in a cylinder using the image data and printing. It is possible to confirm in advance at the stage of image data before performing the cylinder engraving, and it is possible to avoid the situation in which moire occurs as a result of printing as in the conventional case in advance.

Another method is the method according to claim 2, in which the image data obtained as a result of performing scaling with different scaling factors for image data having the same pixel density for each color is the same. The image having the output size is subjected to the scaling process, and the image data of all the color plates obtained by the scaling process is supplied to the color printer or the display means to evaluate the moire by using the output image.

Therefore, according to this method, first, the image data obtained as a result of scaling the image data of the same pixel density for each color with different scaling factors is subjected to a scaling process to an image of the same output size. In addition, since the image data of each color plate that has been subjected to the scaling processing and has the same size is superimposed and hard-copied or displayed as a full-color image,
By observing these images, it is possible to confirm in advance at the image data stage whether or not moire occurs as a whole.

As described above, when this moire evaluation method is applied to the case of creating image data for gravure engraving, the image data for gravure engraving obtained by the scaling process is used to engrave on a cylinder. By printing C,
It is possible to confirm in advance at the image data stage whether or not moire occurs as a whole when the Y, M, and K inks are superposed, and moire occurs as a result of printing in the conventional manner. This situation can be avoided in advance.

A system for performing this method is claimed in claim 4.
The image output system described above, which comprises a first means and a color printer and / or a color display device.

The first means is to perform scaling processing on image data obtained as a result of scaling the image data having the same pixel density for each color at different scaling rates, into an image having the same output size. The image data of all the color plates obtained by the first means is output as a hard copy in full color by the color printer, or displayed on the color display device in full color.

As described above, if this image output system is applied to the case where image data for gravure engraving is applied, it is checked whether or not moire occurs in the gravure printed matter at the stage of image data before cylinder engraving. You can check.

It should be noted that the present invention can be generally applied to a printing method using image data that has been scaled at different scaling rates.

[0030]

Embodiments will be described below with reference to the drawings.
Note that the present invention can be generally applied to a printing method using image data that has been scaled with a different scaling rate for each color as described above, but here, a case where it is applied to gravure printing will be described.

FIG. 1 is a diagram showing the configuration of an embodiment of an image output system according to the present invention. In the figure, 1 is a control unit, 2 is an input unit, 3 is a color printer, 4 is a scanner, and 5 is a memory. Reference numeral 6 denotes a monitor.

The control unit 1 centrally manages the overall operation of the image output system, and comprises a CPU and its peripheral devices. Then, here, the control unit 1 performs the processing of step S2 of FIG. 3, the engraving machine conversion processing of step S3, and the scaling processing for realizing the moire evaluation method in gravure printing according to the present invention. The input unit 2 is composed of a keyboard, a mouse and the like.

As the color printer 3, it is desirable to use a sublimation transfer type color printer or the like capable of expressing gradation for each output pixel, but it is also possible to use an area modulation type color printer.

The scanner 4 is for inputting an image in step S1 of FIG. 3, and a conventional one can be used. The storage unit 5 stores image data input by the scanner 4,
It is for storing the image data and the like obtained in the steps S2 and S3 of FIG. 3, and is preferably composed of a large-capacity storage device such as a hard disk device. The monitor 6 is composed of an appropriate display device such as a color CRT.

Next, the operation of the image output system shown in FIG. 1 will be described. Note that here, in step S3 of FIG.
It is assumed that the steps up to are completed and the C, M, Y, and K image data for gravure printing shown in FIGS. 5A, 5B, 5C, and 5D are generated and stored in the storage unit 5. That is, it is assumed that the storage unit 5 stores image data obtained as a result of scaling with different scaling factors for each color.

There are two moire evaluation methods in gravure printing, as described below. Which method is used for evaluation is selected by operating the input unit 2.

Now, in order to evaluate whether or not a moiré will occur on the printed matter when the user performs cylinder engraving with the image data for gravure printing and performs printing, a first moiré evaluation method is performed by the input unit 2. Suppose you have selected.

At this time, the control unit 1 controls the storage unit 5 from the C,
Image data for gravure printing of four colors of M, Y, and K are read one by one in a predetermined order, transferred to the color printer 3, and individually hard-copied for each image data of each color plate. The color printer 3 naturally makes a hard copy of cyan C image data in cyan. The same applies to image data of other colors.

By performing such an operation,
Although four images of C, M, Y, and K are output as hard copies, the color printer 3 hard copies the transferred image data as image data of square pixels. The image size ratios are the same as those shown in FIGS. 5a, b, c, and d.

By observing the image thus hard-copy output, it is checked for each color plate whether or not moire occurs on the printed matter when the cylinder engraving is performed using the image data for gravure printing and printing is performed. You can judge. This has been confirmed by the present inventor.

The reason why moire can be evaluated for each color plate by such a method is as follows. That is, when performing gravure printing, the scaling processing is performed in the step S3 of FIG. 3 as described above. However, since this scaling processing itself is a process that causes moire, it is likely that moire will occur on the printed matter. This is because it can be predicted with a very high probability that moire may be generated in images of each plate. And it is actually confirmed that the prediction is correct.

In the above description, the color printer 3 outputs as a hard copy, but it goes without saying that it may be displayed on the monitor 6. The input unit 2 can select whether the color printer 3 outputs or the monitor 6 displays. It should be noted that, for example, when the image data of cyan C is displayed on the monitor 6, it is naturally converted into R, G, B. The same applies when displaying M, Y, and K images on the monitor 6.

However, when displaying on the monitor 6, the number of vertical and horizontal pixels of the image to be displayed must be less than the number of vertical and horizontal pixels of the screen of the monitor 6. This is because, for example, when the number of pixels in the horizontal direction of the image is larger than the number of pixels in the horizontal direction of the screen of the monitor 6, it is necessary to thin out at least the horizontal direction when the image is displayed on the monitor 6. This is because there is a possibility that another moire may occur due to the thinning in the case of.

The first moire evaluation method has been described above. Next, another moire evaluation method will be described.

Now, in order to evaluate whether or not a moire will occur in the printed matter when the user performs cylinder engraving with the image data for gravure printing and performs printing, a second moire evaluation method is performed by the input unit 2. Suppose you have selected.

At this time, the control unit 1 controls the storage unit 5 from the C,
The image data for gravure printing of four colors of M, Y, and K is read, and a scaling process is performed to make the output sizes of the images of the four color plates of C, M, Y, and K the same. The scaling factor at this time is the reciprocal of the scaling factor of the scaling process in the engraving machine conversion process of step S3 in FIG. For example, if the horizontal scaling factor is r _HC and the vertical scaling factor is r _VC when the cyan C image data for gravure printing is obtained in the process of step S3 of FIG. 1 / r in the horizontal direction for cyan C image data for gravure printing
_The magnification is changed to _HC and then to 1 / r _VC in the vertical direction. The same applies to image data of other color plates.

As a result, the sizes of the C, M, Y and K image data are the same as shown in FIGS. 2a, 2b, 2c and 2d. That is, all of these image data have the same number of pixels.

As a scaling method used in the scaling process at this time, a function having a good frequency characteristic such as a sinc function or a Cubic Spline function may be used as the interpolation function, but the calculation speed is Considering the above, it is appropriate to use a cubic spline function as an interpolation function, which can perform calculation faster than the sink function.

When the output sizes of the image data of all C, M, Y and K color plates are made the same in this way, the control unit 1
Transfers the image data of these four colors to the color printer 3 and makes a hard copy of the full-color image in which the four colors are superimposed.

In addition to the above-described first moire evaluation method, the second moire evaluation method is also adopted. Even when the moire for each color plate cannot be confirmed by the first moire evaluation method, four plates are used. When full-color gravure printing is performed by overlapping, there is a possibility that new moiré will occur due to the overlapping of the 4 plates, so it is necessary to check whether such moiré occurs. First
This is because it is necessary to confirm how the moire appears when full-color gravure printing is performed by superimposing the four plates when the moire is confirmed on a certain color plate by the moire evaluation method described in 1.

Therefore, by observing the image thus hard-copy output, cylinder engraving is performed using the image data for gravure printing, and when full-color gravure printing is performed, a new image is created by superimposing four colors. It is possible to judge whether or not the moire occurs, and how the moire appears in the full-color printing when the moire occurs in a certain plate by the first moire evaluation method. This has been confirmed by the present inventor.

The size of each image data shown in FIG. 2 is the size of the image data shown in FIG. 4 obtained as a result of the step S2 of FIG. 3, that is, the scaling is performed by the engraving machine conversion process of step S3 of FIG. Although the size is the same as the size of the image data before processing, the image data shown in FIG. 4 cannot be used in the second moire evaluation method. This is because the cause of moire as described above is mainly shown in FIG.
This is because the scaling processing is performed in step S3, and it is necessary to perform the scaling processing with the inverse scaling on the image data that has been subjected to the scaling processing in step S3.

In the above description, the color printer 3 outputs as a hard copy, but it goes without saying that it may be displayed on the monitor 6. The input unit 2 can select whether the color printer 3 outputs or the monitor 6 displays. However, when displaying on the monitor 6, the number of vertical and horizontal pixels of the displayed image are both
It is the same as described above that the number of pixels needs to be equal to or less than the vertical and horizontal pixels of the screen.

Further, when displaying a full-color image on the monitor 6, the image data of C, M, Y, K is R, G, B.
It is natural that it is converted to.

As described above, according to the present invention, before the cylinder engraving, the occurrence state of moire for each color plate or the occurrence state of moire when four plates are overlaid is checked at the image data stage. You can

In the above example, C, M, Y,
Although the scaling factors of the K image data are all different, the present invention is not limited to such a case.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining a second moire evaluation method.

FIG. 3 is a diagram for explaining a process of gravure printing.

FIG. 4 is a diagram conceptually showing an example of image data obtained in the process of step S2 of FIG.

5 is a diagram conceptually showing an example of image data obtained in the process of step S3 of FIG.

FIG. 6 is a development view showing an example of a state of an engraved cylinder.

[Explanation of Codes] 1 ... Control unit, 2 ... Input unit, 3 ... Color printer, 4 ... Scanner, 5 ... Storage unit, 6 ... Monitor.

Claims (4)

[Claims] 1. Image data of at least one color plate among image data obtained as a result of scaling image data having the same pixel density for each color at different scaling factors to a color printer or display means. A moire evaluation method, characterized in that moire is evaluated based on an image supplied and output. 2. Image data obtained as a result of performing scaling with different scaling factors for image data having the same pixel density for each color is scaled to an image of the same output size, and the scaling process is performed. A moiré evaluation method characterized in that moiré is evaluated based on a color image obtained by supplying image data of all the obtained color plates to a color printer or a display means. 3. A first means for changing the magnification of image data having the same pixel density for each color at different magnifications, and each color based on the image data of all color plates obtained by the first means. An image output system comprising: a color printer for performing hard copy for each plate and / or a color display device for displaying each color plate based on image data of all color plates obtained by the first means. 4. A first means for performing scaling processing on image data obtained as a result of performing scaling with different scaling rates for image data having the same pixel density for each color. A color printer for performing full-color hard copy based on image data of all color plates obtained by the first means and / or a color display device for displaying full color based on image data of all color plates obtained by the first means An image output system comprising: