JPS62210784A - Netting method for electronic form generating color photograph - Google Patents

Abstract

PURPOSE:To prevent the generation of moire due to a laminated print, by applying a prescribed netting on a picture signal, providing a photographing picture signal processing system to send the signal to an electronic form as a color dividing print picture signal, developing an inputted color dividing print picture signal on a memory, rotating it with a prescribed angle, and performing an electronic netting with the dot string angle of 45 deg.. CONSTITUTION:An output size is inputted and processed by a keyboard 6, and out of a yellow print, a magenta print, a cyan print, and a black print, the consecutive tone picture signal of the yellow print is rotated by 45-alpha deg. in counterclockwise direction by an image processor 20. Next, the electronic netting is performed by the image processor 20 so as to set the dot string angle at 40 deg., and a dot string density at a prescribed value. After a netting process, the picture signal is rotated by 45-alpha deg. in a clockwise direction by the image processor 20, and the netting process of the yellow print is completed. Similarly, the netting processes for the magenta print, the cyan print, and the black print, are performed in order, and netted picture signals are sent to and processed at an electronic form system 3. Therefore, it is possible to equalize the dot string density regardless of the dot string angle, and the moire is not conspicuous.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for shading color photographs used in electronic typesetting for paper such as newspapers.

[Conventional technology]

In the conventional newspaper plate-making process, when typesetting a monochrome photograph, a diagonal screen with 5 lines per inch is used, as shown in Figure 7 (a), but in electronic phototypesetting systems, the same figure (CI) is usually used. ), 454 horizontal scanning lines per inch are used, and the width of the scanning lines is converted to 2.2.
Become Milus.

This is made compatible with conventional halftone dots and is used as a halftone dot shape with a dot structure as shown in FIG. That is, halftone dots consisting of 50 pixels are regularly arranged by hatching, divided into four fordrants Q1 to Q4 as shown in the figure), and each fordrant unit is sampled for density. Converts pixel density to halftone information. Next, the coordinates of a predetermined position within the electronic typesetting are given.

One halftone dot consists of 50 pixels, but since the pixel size is already determined, the resulting halftone photograph has a halftone dot row density of 64.28 lines/inch and an angle relative to the horizontal direction. Te4
It is 5 degrees. When the dot array angle is 45 degrees with respect to the horizontal direction, there is an advantage that the dot configuration is simple and the dot logic is also simple.

Currently, electronic typesetting of color photographs is not carried out, but as color typesetting, four shaded films of one photographic image, yellow, magenta, cyan, and black are created using a color scanner etc. Based on this, printing plates are made, and during the printing process, inks corresponding to each plate are applied and overprinted.

[Problem that the invention seeks to solve]

In the above-mentioned overprinting of color photographs, in order to make the moiré caused by rL71 of each plate less noticeable, the dot row density is the same for each color separation plate at 85 lines/inch, and the dot row angle is set as shown in FIG. As shown, the magenta version is 75 degrees and the cyan version is 4 degrees.
5 degrees, 15 degrees for the black version, 0 degrees for the yellow version, etc., are changed for each color separation plate.

However, when creating a typesetting for a color photograph electronically, the positions of the pixels in the document created with a color scanner etc. are arranged like the eyes of the substrate, so the halftone dot shape is uniform for each plate. Specifically, if the halftone dots are configured so that the halftone dot array angle for each color separation plate is adjusted to a predetermined angle, the halftone dot array density must be made different for each color. As a result, when overprinting is performed, there is a problem that this causes moiré.

The present invention has been made to solve the above problems,
To provide a method for shading a color photograph for electronic typesetting, in which the dot row angle can be freely selected and the dot row density can be made the same regardless of the dot row angle vibration.

[Means for solving problems]

An image signal of a color photographic color separation plate is added to the image signal, and the image signal is subjected to predetermined shading and sent to electronic typesetting as a color separation image signal. The system is constructed by providing a computer graphics means for logically developing the separated color image signal on a memory and rotating the developed signal on the memory by a predetermined angle, and an electronic halftone dot row angle of 45 degrees. Ru.

[For production]

The image signal of the color separation plate created by scanning an image original with a color scanner is manually input to a color photographic image processing system, and in this system, the image signal of the color separation plate is logically developed in memory by an image processor. Then, the expanded image signal on the memory is logically rotated counterclockwise by (45-α) degrees (where α is the halftone dot array angle of the color separation plate) using computer graphics means.

The above-mentioned image processor processes the rotated image signal by
Electronic halftone processing with a predetermined halftone dot row density is performed at a halftone dot row angle of 45 degrees. The image signal after shading is logically (45-α)
The halftone dot array is rotated clockwise to form a halftone dot array having an angle α and a predetermined halftone dot array density. The image signals subjected to the shading processing of each color separation plate are sent to an electronic typesetting system.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, which includes a color photographic image processing system 1 and a color scanner 2. As shown in FIG. The magenta, cyan, black, and yellow color separation image signals subjected to predetermined shading processing in the processing system 1 are sent to the electronic typesetting system 3. FIG. 2 is a block diagram of the color photographic image processing system 1, which is mainly composed of a CPU 10, an image processor 20, and a multipath 11.

The CPU 1o has a memory of 12tm, and a hard disk unit 13 serves as a small and large-capacity storage device.
Connected to 1. Command display display 4 is C
Displays commands etc. input to PUIG.

A scanner 2 that scans a color photograph and sends out color separation image signals outputs the scanned image signals to an image processor 20 having an image memory 22.

The image processor 20 performs image rotation calculations and shading processing. An image monitor display 5 is connected to the multipath 11 via a graphic memory 51 and displays a real image of image data to be output to a host processor (not shown), and simultaneously records the data on an output device 52. . The host processor and the multipath 11 are connected by a dedicated interface 15 as a communication means. In addition, a function keyboard 6 and a tablet-type keypad for inputting commands for shading and image rotation are connected to the multipath 1 via an interface 14.
1, and a stylus pen 8 is attached to the key matsu door.

Next, the shading processing operation of this embodiment will be explained.

Prior to the explanation, (1) electronic halftone processing, (2) setting of line processing parameters, and (3) setting of halftone angle parameters for color separation plates will be described.

FIG. 3 is a flowchart of Makiko shading processing. First of all, ■ 1ilii in a row! ii Express the coordinates of the image as X and Y,
The units of X and Y are made to correspond to the dot spacing in the X-axis and Y-axis directions. Let the coordinates of the color separation image after the shading process be X', Y',
A relationship of x-kx, yz, . . . ky (k is a constant) is established. ■The dimensions of the continuous tone photo are A (horizontal) x B (vertical)
Assume that When doing the shading, first select position X-01.
Start from y=o. Select Fordrant Qt-Qt, read the density value of Fordrant Qs from the image data, select the halftone dot pattern corresponding to Qs and its density value from the file, and set the coordinates X', Y of the color separation image. Set the halftone pattern to ′. (Four run) Qu
・Repeat with E/Q4t. Thus, create the mesh on the right side in the X-axis direction one after another, and repeat with the horizontal dimension Ai of the continuous tone photograph.

After this is completed, the halftone dots in the X-axis direction are sequentially created by moving from the start point of the previous halftone dot creation to the upper right halftone dot. Next, move from the previous start point to the diagonally upper left halftone dot, and create halftone dots in the X sleeve direction one after another. Thereafter, halftone dots are created by repeating the start point diagonally above and to the upper right of the previous start point, then diagonally above and to the left of the previous start point, and repeating until the vertical dimension B of the continuous tone photograph is completed, completing the halftone dots of the entire image.

(2) Figure 4 shows an example of line processing parameter settings 70
-It is a chart. As shown in the figure, instructions in line processing are given to either the gradation curve, K [or white/black density, or halftone dot row density].

In continuous-tone photographs, brightness must be quantified in accordance with the density of the original, and the brightness must be changed to the size of the halftone dots. The concentration information is 256 in the case of Fordrant concentration data.
The level is sampled, and the correction of the output relative to the input can be indicated by a gradation curve. Also, image data f
:A, and its surrounding pixel data is B, then if we logically synthesize the values at a constant ratio such as [composition level] A + K (A - B), the density difference will be can be increased to increase the sharpness of the output image.

As for the operation, when you instruct "line processing" on the keyboard,
The parameter display shows the gradation curve and the value and white/
Since it asks you about the black density and halftone row density, KlfL and halftone row density are 3-digit numerical values, the gradation curve can be entered using a digitizer, etc., and the white density, black density and clip level values can be entered using the keypad. It can be set as a value from 0 to 255 from the mat.

Note that each of the above processes can be done with default values unless there is a particular change.

(3) When setting the halftone dot row angle inverse parameter for the color separation plate, the halftone dot row angle α of the color separation plate should be set as shown in FIG.
For example, the magenta version is 75 degrees to the horizontal direction, and the cyan version is 4 degrees.
5 degrees, a black version of 15 degrees, and a yellow version of 0 degrees.

Therefore, as shown in Fig. 5, it is determined whether or not to change the above αit, and if it is to be changed, the screen for correcting the halftone dot row angle α value is displayed on the parameter display using the keyboard, and the α value is changed. Instructs to make corrections, and if it is 0/K, Natsuko instructs input. Note that if no special changes are required, the default values can be used.

As shown in FIG. 6, the halftone processing according to the embodiment of the present invention is performed by sequentially selecting and setting the above-mentioned "halftone dot array angle parameter settings for color separation plates" and "line processing parameter settings". A continuous tone image is displayed on the display and trimmed, and the output size is input and processed using the keyboard. Yellow version (M-1), magenta version (M-2)
, cyan version (M-3), and black version (M-4), the system automatically sets the processing parameters for the yellow version, and the continuous tone image signal of the yellow version is processed by the image processor (45-α). Rotate the skin clockwise. Next, electronic halftone processing is processed by the image processor so that the halftone dot row angle becomes 45 [ and the halftone dot row density becomes a predetermined value. After the shading process, the image signal is processed by an image processor (45-α
) degree clockwise to complete the shading process on the yellow plate. Similarly, magenta version (M-2).

The cyan version (M-5) and the black version (M-4) are sequentially shaded and the shaded image signals are sent to an electronic typesetting system for processing.

〔effect〕

In the conventional method, it was not possible to arbitrarily set the values of the halftone dot row angle and the halftone dot row density so that the halftone dot shape for each color separation plate was the same. The halftone dot row angle is 4
Since it is 5 degrees, the halftone dot array density is the same. Further, when an image signal is logically rotated, although the dot of a certain pixel does not necessarily take an integer value after rotation, it is only necessary to process fractions below the decimal point, so there is little change in the halftone dot shape.

Therefore, (1) the halftone dot row angle can be freely selected;
The dot row density can be made the same regardless of the dot row angle, and therefore,
The effect is that the dot row angle and dot row density can be freely selected so that moiré is not noticeable.

(2) Since the color separation plates are created with halftone dot row angles that have traditionally been used because the moiré caused by overprinting of each color plate is not noticeable, there is an effect that moire does not occur due to overprinting of the color separation plates.

(3) In the conventional method, in order to make moiré less noticeable on printed matter, each halftone dot shape is designed to be different, and the combinations of different halftone dots are made irregular and the halftone dots are repeated It was extremely difficult to do so because it required a large repetition period. In contrast, the present invention has the effect of preventing moiré by means that are easy to implement.

(4) Since only one type of program is required for shading processing, there are practical effects such as simple processing.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of the configuration of a color photographic image processing system, Fig. 3 is a flowchart of electronic halftone processing, and Fig. 4 is an example of halftone processing parameter settings. 5 is a flowchart for setting the halftone dot array angle parameter, FIG. 6 is a flowchart for the shading process according to the embodiment of the present invention, and FIG. 7 (A) to ←)
8 is a diagram for explaining the creation of halftone dot rows, and FIG. 8 is a diagram showing the halftone dot row angles of color separation plates. 1...Color photo image processing system 2...Color photo scanner 3...Electronic typesetting system 4...Command) Display fIslay 5...Image monitor display 6...Function keyboard 7.・・Command input 8・・Stylus pen 10・・・CPU11・・
・Multipath 12...Memory 13...Hard disk unit 14, i5...Interface 20...Image processor 22...Image memory 51...Graphic memory 52...Output device agent Patent attorney Kubo 1) Ryo Akira Figure 1 Display Figure 7 (A)

Claims (1)

[Claims] The image signal of the color photographic color separation plate, which is obtained by dividing the original image into pixels, is added to the color photographic image processing system, and the system uses the central processing unit to logically store the image signal of the color separation plate in memory. The developed memory signal is logically rotated counterclockwise by (45-α) degrees (where α is the halftone dot array angle of the color separation plate) using a computer graphic method, and the image after this rotation is Dot array angle 4 for signal
Performing electronic halftone processing with a predetermined halftone dot row density at 5 degrees, and logically rotating the halftone image signal clockwise by (45-α) degrees to have a halftone dot row angle α degrees; 1. A color photographic halftone method for creating electronic typesetting, characterized in that a color separation halftone image signal having a predetermined halftone dot array density is created, and the created image signal is sent to an electronic typesetting system.