JPH052225B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for shading photographs published in publications such as newspapers and magazines, and in particular, when the publications are created by electronic typesetting, The present invention relates to a method of shading a photo for electronic typesetting, which is carried out to convert the pixel arrangement to a pixel arrangement corresponding to the typesetting.

[Conventional technology]

Traditionally, photo manuscripts published in publications that require typesetting, such as newspapers and magazines, are shaded using halftone dots made up of a large number of minute pixels that correspond to the typesetting, and then printed. However, in recent years, various processing techniques using computers have developed, and typesetting processing has come to be performed electronically. In that case, generally speaking, the code or ID (identification number) of the paper components such as text and photographs and the dimension attributes of the elements are used to lay out these elements on the paper and display the intermediate results. While displaying the screen, electronic typesetting data is created, and image data such as characters and photographs are arranged according to the created electronic typesetting data to create paper image data and a block copy is created on a full-page film.

[Problem that the invention seeks to solve]

In the case of halftone dots in electronic typesetting, it is said that if "halftone dots" consisting of P pixels are used to perform halftone dots, it is possible to express (P+1) levels of gradation. A problem that arises when the number of pixels per halftone dot P decreases is the occurrence of "false contours." This is because the gradation level is low in areas in the image where the density level should normally change smoothly.
It changes in a step-like manner, appears in the form of contour lines, and has an unclear outline.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a method for shading photographs for electronic typesetting, which matches the pixel arrangement of electronic typesetting and has excellent gradation characteristics.

[Means for solving problems]

In the present invention, the means for solving the above-mentioned problems is as follows: First, when hatching a photograph, a halftone dot is made up of Q times the number of pixels (where Q is a positive integer) of the electronic typesetting for articles. Use. After creating the required halftone screen, in order to convert it to the pixel arrangement of the electronic typesetting,
In order to thin out the number of pixels after processing for the shaded pixel group to 1/Q of the number before processing, Q types of thinning patterns with different sampling positions are prepared in advance by assigning numbers to Q numbers of pixels. This is a method for shading photographs for electronic typesetting, which performs pixel thinning processing by randomly selecting and applying one of the following methods. Please note that the above photos can be monochrome or color.

[Effect]

In the above pixel thinning process, if you want to reduce the number of pixels after processing to 1/Q of the number before processing, prepare Q patterns for a group of pixels with a certain number and shape and add numbers to them. , using a random number table of the numbers, one of the patterns is randomly selected and converted into a pixel arrangement for electronic typesetting.

〔Example〕

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

In electronic typesetting, for example, the pixel size is determined to be a 2.2 mils x 2.2 mils square. When typesetting a monochrome photograph, first, by "shading", each halftone dot 6 of the pattern shown in Figure 2, in which halftone dots each consisting of 50 pixels are regularly arranged, is marked with the corresponding halftone dot of the photograph. The shading of the minute portion is replaced with the number of ink-applied pixels of the halftone dot to create halftone photographic information, and then the coordinates of a predetermined position in the forme are given. One halftone dot 6 consists of 50 pixels, but if the pixel size is determined as described above, the resulting halftone photograph has a halftone dot row density of 64.28 lines/inch and an angle of 50 pixels. 45 degrees to the direction.

In color photosetting, four versions of yellow, magenta, cyan, and ink are created for one photo, and in printing, each version is overprinted with ink corresponding to each version. At this time, in consideration of moiré caused by the overlapping of each plate, the density of the halftone dot array was the same at 85 lines/inch, and the angles were different as shown in Figure 3. do. If you are trying to format such color photographs electronically,
Since the pixel positions are arranged like a checkerboard, if the shape of the halftone dots is fixed to one shape for each plate, the density and angle of the halftone dot rows can usually be set to the desired values. Moreover, the number of pixels P that constitutes one halftone dot is P=50×(64.28) ² /(85) ² ≒29, which deteriorates the reproducibility of gradation.

In the typesetting method in which the present invention is implemented, the required plate is first created by halftone dots made up of a large number of minute pixels, and then converted to the pixel arrangement of electronic typesetting by pixel thinning. Pixel thinning is used as one method of pixel density conversion, and by thinning, the size of the forme is not changed, but only the pixel size is changed.

In this pixel thinning process, for example, if you want to reduce the number of pixels after processing to 1/Q of the number before processing, prepare Q thinning patterns for a group of pixels with a certain number and shape in advance, and number them. If the pattern numbers are selected randomly using a random number table,
The gradation reproducibility after thinning is determined by the (P+1) level determined by the number of pixels P of each halftone dot, and the 1/(Q-1) level between each of the above levels as a composite effect of the density of neighboring halftone dots. It becomes possible to express In other words, if the target image of the thinning pattern has periodicity in terms of position, the possible states in which the thinned out image can be white or black at positions that match the period are (No. 1) where all pixels are white. Become. (2
(No.) Black occurs at a ratio of 1 pixel to every Q pixel. (3
No.) Black occurs at a ratio of 2 pixels to every Q pixel. ……
[No. (Q+1)] There are (Q+1) ways in which the ratio of Q pixels to Q pixels becomes black. Among these, (1) and (Q
+1) is included in the (P+1) level determined from the number of pixels constituting each halftone dot, so subtracting this will result in (Q-1) levels. (Q) of (2) to (Q)
-1) On the street, as the average value of neighboring halftone dot density,
Each step of the density determined by the number of pixels of each halftone dot can be expressed more precisely down to the 1/(Q-1) level.

FIG. 1 is an explanatory diagram showing an example of pixel thinning processing according to the present invention, in which Q=4, that is, the number of pixels after processing is set to 1/4 of the number before processing. Therefore, as a pixel thinning pattern, four thinning patterns with different sampling positions made up of four pixels are prepared in advance, and four patterns 1 to 4 in the figure are prepared in advance, and one of them is selected using a random number table. do.

The halftone screen created first is divided into pixel groups determined by the thinning rate, and then a thinning pattern number is randomly selected for each pixel group to extract information on whether the unthinned portion 5 is white or black. Create a version for typesetting.

〔Effect of the invention〕

As described above, according to the present invention, a photographic original is shaded using halftone dots made up of a large number of extremely small pixels, and this is subjected to pixel thinning processing to match the pixel arrangement of electronic typesetting. Furthermore, by applying random selection, it is possible to provide a method for shading photographs for electronic typesetting with excellent gradation characteristics.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an example of thinning processing according to the present invention, FIG. 2 is an explanatory diagram of halftone dots in a monochrome photograph,
FIG. 3 is an explanatory diagram of color photographic halftone dot array angles. 1, 2, 3, 4... thinning pattern, 5... portion not thinned out, 6... halftone dot.

Claims (1)

[Claims] 1 A method of shading monochrome photographs and color photographs used in electronic typesetting, in which the photograph is shaded using halftone dots consisting of Q times the number of pixels (where Q is a positive integer) of the electronic typesetting. For the crossed and shaded pixel groups, the number of pixels after processing is reduced to 1/1 of the number before processing.
Numbers are given in advance to prepare Q types of thinning patterns with different sampling positions, which are made up of the number of Q pixels to be thinned out, and the selection of the numbers is thinned out using a random number table to reduce the pixels of the electronic typesetting. A method for shading photographs for electronic typesetting, characterized by converting them into layouts.