JP2001018352A - Halftone plate forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a halftone plate forming device which saves time required from the determination of a print sample upto the format start of printing and a material and consequently, reduces printing cost. SOLUTION: The halftone plate forming device comprises an image reading means which reads an image 14a of a print sample and an image 14a corresponding to an image of a print sample in a proof sheet, a dot percent measuring means which measures the dot percent of the print sample which is read by the image reading means and the dot percent of the image corresponding to the proof sheet which is read by the image reading means and a halftone dot forming means which calculates the difference between the dot percent of the image of the print sample and the dot percent of the image corresponding to the proof sheet and forms halftone dots which have such an area as to eliminate the difference on a printing plate for printing the image corresponding to the image of the print sample.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone forming apparatus for forming halftones for printing.

[0002]

2. Description of the Related Art Conventionally, when a printed material is printed using halftone printing, halftone printing corresponding to the image is formed by a halftone forming apparatus based on an image of a print sample, and test printing is performed. The test print image has a slightly different color tone from the print sample image according to various factors such as the external environment such as the temperature and humidity at the time of the test print, the characteristics of the printing machine used for the test print, and the characteristics of the ink. .

[0003] Conventionally, a print engineer who has seen a test print has, based on his or her experience, corrected the color tone of the test print image so as to match the color tone of the print sample image, specifically, the dot area. The increase / decrease of the ratio is added to the halftone forming apparatus, and the halftone modified with the above correction is newly formed by the halftone forming apparatus, and the trial printing is performed again with the new halftone printing.

[0004] Such a correction operation is repeated until the color tone of the test print image matches the color tone of the print sample image.

[0005]

In the conventional halftone printing apparatus as described above, the number of times of the halftone correction work repeated until a test print image whose color tone substantially matches the tone of the print sample is obtained. Tend to increase. Therefore, the time and materials required until the start of formal printing are increased, and the printing cost is increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the time and materials required from the determination of a print sample to the start of formal printing, thereby reducing the printing cost. An object of the present invention is to provide a plate forming apparatus.

[0007]

In order to achieve the above-mentioned object of the present invention, a halftone printing apparatus according to the present invention comprises: a print sample image and an image corresponding to a print sample image in a test print. An image reading unit to be read; a halftone dot area ratio of the image of the print sample read by the image reading unit, and a halftone dot area ratio of the corresponding image of the test print printed matter read by the image reading unit. Dot area ratio measurement means; and calculates the difference between the dot area ratio of the image of the print sample and the dot area ratio of the corresponding image of the test print, and prints an image corresponding to the image of the print sample. Dot forming means for forming a dot having an area that eliminates the above difference on the printing plate.

[0008] In the halftone printing apparatus according to the present invention having the above-described configuration, to print a printed material having an image having a color tone substantially matching the color tone of a print sample image. First, an image of the print sample and an image corresponding to the image of the print sample in the first test print are read using the image reading unit. Next,
The dot area ratio of the image of the print sample read by the image reading unit and the dot area ratio of the corresponding image of the test print printed matter read by the image reading unit are measured by the dot area ratio measuring unit. . Further, the dot forming means calculates the difference between the dot area ratio of the image of the print sample and the dot area ratio of the corresponding image of the test print, and prints the image corresponding to the image of the print sample. A halftone dot having an area that eliminates the difference is formed on the printing plate.

Hereinafter, an embodiment of the halftone printing apparatus of the present invention will be described in detail with reference to the accompanying drawings.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 in the accompanying drawings is a schematic diagram showing the main parts of a common configuration between a print sample and a printed matter printed by a halftone print formed by a halftone print forming apparatus according to the present invention. FIG. 2A is an enlarged schematic plan view showing a halftone dot in a predetermined area of a color separation image in a print sample; and FIG.
Is a predetermined pattern of a color separation image formed corresponding to the color separation image in the printing sample in a printed matter printed by the halftone printing formed based on the printing sample by the halftone forming device according to the present invention. It is a schematic plan view which expands and shows the halftone dot in an area.

FIG. 1 schematically shows the main parts of a printed sample. In the print sample, a desired main image 12a is printed in a predetermined area on the paper 10a, and color separation of various colors used for printing the main image 12a is performed in a predetermined area of a margin on the paper 10a. Image 14a is printed. The main image 12a and the color separation image 14a of the print sample are formed by halftone printing.

When substantially the same print sample is to be printed, first, a halftone plate for the first trial printing is formed on the basis of the print sample by a halftone printing apparatus according to the present invention. The first test printing is performed using the halftone printing for the first test printing. In the first trial printing, the same paper 10b as the print sample paper 10a as well as the print sample
The first test print image 12b corresponding to the desired main image 12 of the print sample is printed in the upper predetermined range, and
0b in the predetermined range of the margin on the first trial print image 12b
The color separation images 14b of various colors used for printing are printed.

Next, various color separation images 14 of the print sample will be described.
a and various color separation images 14b of the first trial printing
Are read by known image reading means. The publicly known image reading means includes various color separation images 1 of a print sample.
4a and various color separation images 14 of the first trial printing
Each predetermined area range of b is read in an enlarged manner. FIG. 2A schematically shows one of the various color separation images 14a of the print sample read by the image reading means, and FIG. 2B shows the image reading means. Various color separation images 1 of the first test print read by
4b schematically shows one of them.

As shown in detail in FIGS. 2A and 2B, the size (ie, size) of a halftone dot in a predetermined area of one color separation image 14a of a print sample is determined. Normally, the size of the halftone dots in the predetermined area range of one color separation image 14b of the first test printing, that is, the area ratio, is different. This is because various conditions when the printing of the print sample is executed and the various conditions when the first test printing is executed are different, and these various conditions include, for example, the printing machine. The characteristics, the external environment (temperature, humidity, etc.) at the time of printing, and the characteristics of the ink are included.

Next, in the halftone forming apparatus according to the present invention, the halftone dot area ratio of the various color separation images 14a of the print sample read by the image reading means in the predetermined area range, and the image reading are performed. The dot area ratio in each of the predetermined area ranges of the various color separation images 14b of the first test print read by the means is measured by the dot area ratio measuring means.

The halftone dot area ratio measuring means performs a binarization operation on each of the various color separation images 14a of the read print sample and each of the various color separation images 14b of the first trial printing. The halftone dot area ratio in these predetermined area ranges is measured.

The dot area ratio is measured by measuring the density of the image in the above-mentioned predetermined area range with a microscope-like measuring machine.
It can also be executed by using a formula for converting the measured density into a dot area ratio.

The halftone forming apparatus according to the present invention further includes a halftone dot area ratio and a halftone dot in each of the predetermined area ranges of the various color separation images 14a of the print sample measured by the halftone dot area ratio measuring means. First measured by the area ratio measuring means
The difference between each of the various color separation images 14b of the trial printing and the halftone dot area ratio in the predetermined area range is calculated. Then, based on the halftone screen used for the first trial printing, a correction for increasing or decreasing the area ratio by the difference is made, and a halftone screen for the second trial printing is created by the halftone dot forming means. .

For example, various color separation images 14 of a print sample
The halftone dot area ratios of cyan, magenta, and yellow of a in the predetermined area ranges are 70%, 60%, and 5%, respectively.
0%, and various color separation images 14b of the first trial printing
Are respectively 75%, 55%, and 45% in the predetermined area ranges of cyan, magenta, and yellow.
%, The halftone area ratios of cyan, magenta, and yellow halftones formed in the halftone printing formed for the second test printing are formed for the first trial printing. In the halftone screen, the halftone dot area ratios of cyan, magenta, and yellow are -5%, + 5%, and + 5%, respectively.

Then, the second test printing is performed using the halftone printing for the second test printing. Thereafter, in the same manner as when the first trial printing is performed, each of the various color separation images of the second trial printing is read by a known image reading unit, and the second trial reading read by the image reading unit is performed. The dot area ratio in each of the predetermined area ranges of the various color separation images of the printing is measured by the dot area ratio measuring means, and the various colors of the printed sample already measured by the dot area ratio measuring means are measured. The difference from the dot area ratio in each of the predetermined area ranges of the decomposed image 14a is calculated. If there is a difference, based on the halftone used for the second test printing, the area ratio is corrected to be enlarged or reduced by the difference, and the halftone for the third test printing is changed to halftone. Created by forming means.

In this manner, halftone printing for test printing is performed until the difference between each of the various color separation images 14a of the print sample and the halftone dot area ratio in the predetermined area range is substantially eliminated. Is repeated, but the number of times of halftone printing for test printing is much smaller than in the conventional case described above.

The halftone dot area ratio of each of the various color separation images of the test print in the above predetermined area range and the halftone dot area ratio of each of the various color separation images 14a of the print sample in the above predetermined area range are shown. The halftone for the test printing, which was used when the difference substantially disappeared, is used for the actual halftone.

[0023]

As is apparent from the above description, the halftone printing apparatus according to the present invention can reduce the time and materials required from the determination of a print sample to the start of formal printing. As a result, the printing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a main part of a configuration common to a print sample and a printed matter printed by a halftone print formed by a halftone print forming apparatus according to the present invention.

FIG. 2A is a schematic plan view showing halftone dots in a predetermined area of a color separation image in a print sample in an enlarged manner; and FIG. 2B is a halftone plate according to the present invention. A halftone dot in a predetermined area of a color-separated image formed corresponding to the color-separated image in the print sample in a printed matter printed by a halftone formed based on the print sample by a forming apparatus is shown in an enlarged manner. It is a schematic plan view.

[Explanation of symbols]

 12a main image 12b main image 14a color separation image 14b color separation image

Claims (1)

[Claims] An image reading means for reading an image of a print sample and an image corresponding to the image of the print sample in a test print, a halftone dot area ratio of the image of the print sample read by the image reading means, and an image reading means A dot area ratio measuring means for measuring a dot area ratio of the corresponding image of the test print read by the computer; and a dot area ratio of the image of the print sample and the corresponding image of the test print. A halftone dot forming means for calculating a difference between the halftone dot area ratio and a halftone dot having an area that eliminates the difference in a plate for printing an image corresponding to the image of the print sample;
Halftone forming apparatus comprising: