JPS6120949A - Image processing method of computer graphics - Google Patents

Abstract

PURPOSE:To print computer graphics CG images of high quality easily without the degradation of the image quality by subjecting CG image data to required processings as they are and inputting this data directly to a scanner. CONSTITUTION:Image data generated by a CG device 1 is recorded on a floppy disc FD or a magnetic tape MT in a prescribed format as it is. A computer 21 reads out image data from the FD or the MT and subjects this data to required processings such as the image data processing. Processed image data is supplied to an output scanner 23 through an interface 22, and image data is recorded on an unexposed film to obtain separated plates of four colors, namely, yellow Y, magenta M, cyan C, and Indian ink K.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for processing image data created by computer graphics, and in particular to a process for directly obtaining separated plates for printing from the image data created in this way. Regarding the method.

[Background of the invention]

The technique of creating various animations and figures using a computer is also called computer graphics (hereinafter referred to as CG), and has become widely used as a method of creating images suitable for the visual age. It's here.

By the way, the following method has conventionally been used to print images created by such a CG system. That is, as shown in Figure 2, image data created by a CG device is displayed on an image monitor, and the displayed monitor image is photographed to obtain an original image, or the image data is output to a film plotter. An original image is obtained using the process, and printed matter is then obtained from this original image using standard printing and plate-making techniques.

However, among these methods, in the method of taking photographs, the image is once displayed on the image monitor, resulting in distortion of the screen, blurring of edges, changes in color, etc.
Alternatively, there are disadvantages in that deterioration of image quality is unavoidable due to the occurrence of moiré due to scanning lines during halftone screening, and on the other hand,
In the method of using an image plotter, it is possible to minimize the deterioration of image quality by using a high-grade plotter, but this requires a large increase in cost and sacrifices economic efficiency. There was a drawback that it had to be done.

[Purpose of the invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to
To provide a C0 image processing method that allows printing images with high quality and at low cost.

[Summary of the invention]

In order to achieve this objective, the present invention provides a method for performing appropriate processing on image data produced by a CG device without performing any image conversion, and directly inputting the data into a scanner to obtain separated plates. It is characterized by the following points.

[Embodiments of the invention]

Hereinafter, the C0 image processing method according to the present invention will be explained in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, where l is a CG device.

2 is a color separation scanner system, 21 is a computer for data processing and scanner control, 22 is an interface, and 23 is an output scanner for exposing color separation plates.

In this embodiment, first, the image data created in the CGG station 1 is recorded as is on an FD (floppy disk) or MT (magnetic tape) in a predetermined format.

Next, this FD or MT is transferred to the color separation scanner system 2.
The data is set in a predetermined input device for reading data provided in the computer 21.

The convenitor 21 reads image data from the FD or MT and performs ■ format conversion, zero color/gradation correction, and ■
After performing necessary processing such as size change and other image data processing, the processed image data is supplied to the output scanner 231C via the interface 22, the unexposed film IC-I data is recorded, and Y (yellow), M (maze/red), C (cyan), K (black) 4
Obtain color separations.

Therefore, according to this embodiment, the image data created by the CG device is input as is to the output scanner 23 in the form of image data, and during that time, no imaging process using an image monitor or positive film is performed. As a result, there is no deterioration in image quality due to single image formation. Furthermore, as a result, the process is simplified and an expensive plotter is not required, so there is no risk of cost increase.

Next, the content of image data processing by one computer 21 will be explained.

(2) Format conversion processing This processing is for converting the format of the image data output from the CG device and provided via the FD or MT into a suitable format in the scanner system 2. . Therefore, the content of this process is
Although the configuration may vary depending on the type of scanner system 2 installed, an example is shown in FIG. 3.

(a) of FIG. 3 shows that FD or M
This is an example of the storage format recorded in T. RGB (
The image data for selecting and displaying 256 types of colors from 8 bytes (2 types of colors) for each color (red, green, blue) is stored in a 256 x 3 byte LUT' ( Look Up Table) and pixel data of 1 byte per pixel are arranged in a format, and as shown in Figure 3 (b) K, this is a general format consisting of 1 byte for each RGB pixel. Convert to image data. Therefore.

In this example, for each pixel in FIG. 3(a), from the numerical value of that pixel, UTl is
.

When the original pixel data is restored and the pixel data is sequentially arranged, format conversion processing is performed starting from k.

0 color/gradation correction process This process is based on printing characteristics and consists of the following 311 processes.

(a) A process of calculating the ink density (or dot %) of each separated plate for each color, Y, M, C, from RGB image data.

(b) Color selection and adjustment processing for color correction according to preference and color matching for colors on the image monitor surface.

(c) Correction processing of gradation power based on the same reason as above (b).

■Size change C processing is for adjusting the print finish size to a predetermined size, and consists of the following two types of processing.

(b) Processing for changing the size, for example.

15 CG images consisting of 512 x 512 pixels
87 when offset printing with a resolution of 0 lines/inch
Since the size is 87 mm x 87 millimeters square, when printing an image of a size other than this, the image must be enlarged or reduced in order to be printed at the desired size. This processing can be realized by pixel interpolation, pixel thinning, or the like. In addition.

For interpolation, a method is used in which adjacent pixels are used as they are, or a new pixel is created by averaging surrounding pixels.

1) 1 in the process of correcting the aspect ratio of the 00 image and the printed image
For example, in a 640 x 200 pixel CG image, the pixel aspect ratio is approximately 2 = 1, but the "degree pixel" on the printed matter (with offset, the aspect ratio of the pixels is approximately 2 = 1). (in gravure, 1) is 1 (in gravure), the aspect ratio is 1. Therefore, this process is necessary.

Aspect ratio correction is essentially the same technique as interpolation processing,
What is necessary is to make the ratio of enlargement and reduction in the vertical direction and the horizontal direction different.

(2) Other image data processing This processing includes additional processing as necessary in addition to the above (1) to (2).For example, processing for the purpose of improving uniform quality, such as contour smoothing, etc., is included.

It should be noted that various methods are known for each of the above-mentioned processes (1) to (2), and therefore, further detailed explanation will be omitted.

[Effects of the Invention] As explained above, according to the present invention, all the processing necessary for outputting C0 image data as a color separation plate by a scanner is performed on the image data as it is at 5V, which eliminates the need for the prior art. Except for the disadvantages of , there is no screen distortion, blurring at edges, or moire, and it is possible to print high-quality CG images at low cost, and digital image processing immediately before color separation is possible. Therefore, it is possible to provide a 00 image processing method that can provide high (Z) added value.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a computer graphic image processing method according to the present invention, FIG. 2 is an explanatory diagram showing an example of a conventional image processing method, and FIGS. FIG. 2 is an explanatory diagram of format conversion operation in FIG. 1... Computer graphics device, 2
...Color separation scanner system, 21...
... Computer, 22 ... Interface, 23 ... Output scanner for exposure, FD
······floppy disk. MT...Magnetic tape.

Claims (1)

[Claims] In an image processing method using a computer, the image data stored in the memory is supplied to a printing plate-making scanner to obtain separated plates for printing, and the image data stored in the memory is converted into RGB image data. calculation of CMYK image data representing the printing ink density from the above RGB image data, color/gradation correction processing to give the required color characteristics and gradation characteristics, and adjustment to the print size. A computer graphics image processing method comprising: a size change process for enlarging/reducing the CMYK image data and changing the aspect ratio; .