JPS61272747A - Method for dotting of color photograph for electronic form manufacture - Google Patents

Abstract

PURPOSE:To save labor and time by using dots constituted of many and minute picture elements to make halftone forms of respective original colors and then converting the halftone forms into the picture element arrangements of electronic forms by thinning the picture elements. CONSTITUTION:When scanning line density is set up to a large value, the values of the density and angle of a dot string are increased, and a dot string angle and a dot pitch which are almost equal to the required and sufficient accuracy for a color halftone form can be selected. However, it is impossible under said state to embedded the color halftone frame in a discription part formed by low scanning line density and form a paper image containing the color halftone photograph. Therefore, the color halftone photograph with low scanning line density is formed by a picture element thinning method or the like. Since the dot pitches of the formed respective color forms are slightly different each other, stripe-like moires may be generated when the color forms are superposed. Therefore, plural patterns indicating thinning methods are prepared in accordance with picture element group having the required number of picture elements and a required shape and a required pattern is selected at random out of the plural ones to suppress the generation of moires.

Description

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

[Conventional technology]

When creating typesetting for paper such as newspapers that include articles and color photos, first use a computer to create electronic typesetting while displaying the edited layout on a display for the article portion excluding the color photo portion. Then, a full-page film version is created from this electronic typesetting. Naturally, images are printed in the places where color photos should be placed on this block, and for this space, four sheets of yellow, magenta, cyan, and ink were created separately using a color scanner, etc. Shading films are individually laminated to create four different full-page films, and individual printing plates are created from the four full-page films.

[Problem that the invention seeks to solve]

The pasting work of the color/mesh film has conventionally been carried out manually. There are two reasons why color photographs cannot be typeset together with articles.

■ Color photographs require clear reproduction, so the number of shading lines used is, for example, 85 lines/inch, compared to 65 lines/inch for black and white photographs, which are often used in newspapers. There are many. One electronic typesetting system for newspapers is set so that 50 pixels are included in one screen for black and white photos, but the number of screen lines is increased to 85 lines/inch like for color photos. Since the pixel size is already determined, the number of pixels in one mesh is reduced, resulting in a disadvantage that the gradation of the photograph that can be reproduced is reduced.

■ In order to prevent moiré from being noticeable when overprinting a four-color typesetting of a color photograph, the angles of the halftone dot rows of each color must be individually tilted by a predetermined angle with respect to the horizontal direction. By the way, the scanning line density is 454LPI.
In the case of electronic typesetting, it is necessary to create a halftone version of a color photograph using pixels with a fineness of 454 LPI, but for each color, the angle of the halftone dot row must be matched as much as possible to the specified angle described above. If halftone dots are formed on the paper, the pitch of the halftone dots must be different for each color, and if these are overprinted, there is a problem in that this may cause moiré.

For this reason, in the past, color photographs were recorded on film separately from the article section of the paper, and then manually pasted onto the film for the article section, but this required a great deal of labor and time. In some cases, such as when a printing factory is located in a remote location, it is necessary to create a color halftone photograph on photographic paper using a color scanner and then send the created halftone photograph to the printing factory by facsimile, which may cause a decrease in image quality. It had become.

The present invention solves the above-mentioned problems and makes it possible to extract color halftone photographic data from color photographs that is compatible with electronic typesetting, which has scan line density insufficient for color photographs, thereby saving labor and time. The purpose is to provide a color-saving method for shading color photographs.

[Means for solving problems]

In the present invention, the means for solving the above-mentioned problems is to increase the scanning line density and use halftone dots made up of a large number of very small pixels to shade each part. This is a halftone method in which a halftone plate of primary colors is created and then converted to the pixel arrangement of electronic typesetting, which generally uses a low scanning line density, by pixel thinning or pixel density conversion method.

Pixel thinning can be considered as a method of pixel density conversion (,
The size of the format does not change due to thinning, but the size of the pixels changes.

[Effect]

The reason why shading in color photographs is inconvenient when applied to electronic typesetting that uses a low scanning line density is that the pixel area is large due to the low scanning line density, and if that area becomes smaller,
In other words, if the scanning line density is increased, the possible values of the density and angle of the halftone dot array will increase, and it is possible to select the halftone dot array angle density and halftone pitch that are close to the necessary and sufficient precision for a color halftone plate. . However, since the halftone photographs created in this way have a high scanning line density, they can be embedded in an article section made with a low scanning line density to create a paper image incorporating the color halftone photographs. I can't. Therefore, a method such as image thinning is used to create a color halftone photograph with a low scanning line density, but because the halftone dot pitch of each color plate is slightly different from each other, when overprinting is performed, striped images may appear. Since moiré may occur, moiré can be prevented by preparing multiple patterns indicating the thinning method corresponding to pixel groups having the desired number and shape of pixels, and selecting these patterns at random. be able to.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to examples and drawings.

FIGS. 1 to 11 are front views showing an example of halftone dots and pixel configuration of electronic typesetting. In the electronic typesetting in this embodiment, the size of pixel 1 is determined to be a square of 2.2 mils x 2.2 mils, and when a photo is to be typesetting, the photo is first divided into 50 pixels by "shading". A pattern is created in which halftone dots 2 are regularly arranged.

The shading of the part of the photo corresponding to each halftone dot of this pattern is
Halftone photographic information is created by replacing the number of ink-applied pixels within a halftone dot, and then predetermined positional coordinates in the forme are given to this pattern. The density of the dot rows in FIG. 1 is 64.28 lines/inch, and the angle 5 is 45 degrees with respect to the horizontal direction.

In color photographic typesetting, four versions of one photograph, yellow, magenta, cyan, and ink, are created as described above.
In printing, ink corresponding to each plate is applied and overprinted,
Each version of this book is 1. In order to avoid moiré caused by overlapping of each plate, halftone dot rows with the same density and different angles are used.

Figures W and 2 are diagrams showing an example of such angles, where a shows a yellow version, b shows a magenta version, C shows a cyan version, and d shows a black version. This is shown in more detail in Figure 3~
FIG. 6 is a front view of FIG. 6;

Figure 3 shows the halftone dots and pixel configuration of the yellow version.
The pixel size is 2.2 x 10/16 mils square, the density of the halftone dot row is 65.84@/inch, and one halftone dot 2
contains 122 pixels 1, and the angle 3 of the halftone dot row is 5 degrees.

Similarly, Fig. 4 shows the halftone dot and pixel configuration of the magenta version, the pixel size is 2.2 x 10/16 mils square, the density of the halftone dot row is 6479 lines/inch, and each halftone dot is 1
Thirty pixels are included, and the angle of the halftone dot array is 75 degrees.

Similarly, FIG. 5 shows the halftone dots and pixel configuration of the cyan version,
The pixel size is 2.2 x 10/16 mils square, the density of the halftone dot row is 64.28 lines/inch, 128 pixels are included per halftone dot, and the angle of the halftone dot row is 45 degrees. It is.

Similarly, Figure 6 shows the halftone dot and pixel configuration of a black plate, the pixel size is 2.2 x 10/16 mils square, the density of the halftone dot row is 6579 lines/inch, and one halftone 13 per point
0 pixels are included, and the angle of the halftone dot array is 15 degrees.

In the case of electronic typesetting, the pixel positions are arranged like the eyes of the substrate, so if the shape of the halftone dots is fixed to one shape for each plate, it is usually difficult to take into account the density and angle of the halftone dot rows. The obtained values will be different from each other, and it will be difficult to set an arbitrary uniform value for each edition, making it impossible to satisfy the condition of the same dot density mentioned above. The density of a halftone dot row can be thought of as the number of pixels from the center of a center pixel in a halftone dot to the center of the center pixel in the next halftone dot, but
.

The prime numbers must be chosen to be different values as shown in FIGS. 3 to 6. In this case, if the number of pixels within one halftone dot is further increased, the density of the halftone dot array approaches a constant value.

The reason why electronic typesetting causes such inconvenience is that the area of the pixel is large, and when it is made small, the density and angle of the halftone dot row can have many possible values.

If the pixels of each initial version are not small enough, moiré may occur after typesetting due to differences in the halftone dot pitch of each created version, but pixel thinning can reduce this possibility. It can be reduced. If you prepare multiple thinning patterns in advance for a pixel group with a certain number of pixels and a certain shape, assign addresses to them, and randomly select them using something like a random number table, you can perform thinning. Since the subsequent halftone dot position moves irregularly and small, the regularity of the halftone dot arrangement is disrupted, reducing moiré. Figure 7 is an explanatory diagram of the thinning process and process in four-color plate production.
This shows a case where the pattern is composed of 4 pixels, and the first halftone is divided into pixel groups determined by the thinning ratio (for example, 4:1), and then the thinning pattern number is randomly assigned to each pixel group (pattern ■ to pattern ■). +ii, extract information on whether part i is white or black, and create a four-color plate for electronic typesetting.

Electronic typesetting work according to the present invention is performed as follows. First, a color photograph is run through a color scanner and a shaded output signal is sent out. At this time, for example, in the yellow version,
As explained in Fig. 3, a pixel within one halftone dot is 2.2×1
Since it is o/16 mils square, the above-mentioned shaded output signal may be made such that the pixel is 2.2 mils square. One example of a specific method is to add 4 pixels to every 16 pixels in the output signal of a color scanner to make 20 pixels, and then remove every other pixel, resulting in one halftone dot. The pixels within are Z2 Mils square.

When the image signal adjusted in this way is incorporated into electronic typesetting,
Compatible formatting data that does not involve film can be obtained. [Effects of the Invention] As explained above, according to the present invention, data that is compatible with electronic typesetting and can be transmitted and received can be collected from a color photograph, thereby saving labor and time. A color photo shading method can be provided.

[Brief explanation of the drawing]

Figure 1 is a front view of halftone dots and pixels of electronic typesetting, Figure 2 is an explanatory diagram of the slope of halftone dots for each color, Figures 3 to 6 are front views of halftone dots and pixels of each color plate, FIG. 7 is an explanatory diagram of the thinning process. 1... Pixel, 2... Halftone dot, 3... Inclination angle of halftone dot row. Agent Patent Attorney Kubo 1) Ryo Akira Figure 1 Figure 2 Figure 3 Fang Figure 4 Figure 5

Claims (1)

[Claims] A color photo shading method used in electronic typesetting, in which the color photo is shaded using halftone dots made up of extremely small and large numbers of pixels, and each version of yellow, magenta, cyan, black, etc. is created. A color photograph shading method for producing electronic typesetting, characterized in that the color photograph is then converted into a pixel arrangement for electronic typesetting by pixel thinning or pixel density conversion method.