JPH01176175A - High vision print making device - Google Patents

Abstract

PURPOSE:To obtain a picture whose contour is ideally emphasized by converting a spatial frequency of an input picture while photographing condition, photographing object and print size into account. CONSTITUTION:A High Vision picture inputted by a picture input means 1 is converted into a digital signal form an analog signal by a digitizing means 2 such as an A/D conversion circuit and stored in a storage means 3. The High Vision picture stored in the storage means 3 is subject to contour emphasis processing by a contour emphasis processing means 5 by means of a correction function decided by a correction function decision means 4 based on the photographing condition, object and size of printed matter and result is outputted from an output means 6. Thus, the rate of emphasis is varied depending on the print size and the content of pattern whether it is a scene or a portrait and the photographing condition of High Vision.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high-definition plate-making apparatus that produces a plate for printing from a high-definition image signal.

<Prior Art> Conventionally, there have been apparatuses for producing four-color separation plates for printing from video signals. Most of the forms of use required news and breaking news at a decisive moment. The current television system has problems with image quality due to the amount of information, making it difficult to produce large prints.

The image quality of high-definition television, which has more than five times the amount of information available on current televisions, is extremely good, and it has become possible to produce large prints.

Not all high-definition images with a large amount of information will result in high-quality printed matter. Things that you wouldn't notice with a moving image become problems when you print a still image (
Ru.

Particularly big problems are thick contours and what is called ringing, which is waving around the contours.

In high-definition, the edges are generally emphasized at the very end of the shadows so that they look good even when projected on a large projector. In a large-screen video, sharp outlines make the apparent main image clear, but it is quite difficult to remove these thick outlines when creating four-color separation plates for printing.

Therefore, for works that are likely to be applied to printing, we ask them to photograph them without contour enhancement, and then emphasize the edges during platemaking.

However, even if the outline is emphasized at the time of plate making, it is not possible to produce printed matter that is always emphasized in the same way. The emphasis ratio must be changed depending on the darkest conditions of high-definition, the content of the picture, such as landscape or a human face, and the print size.

Means for Solving Problems - The present invention has been made in view of the above-mentioned current situation, and provides a digitization means for capturing a high-definition television image signal by an image input means and converting it from analog to digital data. In high-definition plate-making equipment that has a storage means for storing digitized data and creates plates for printing, correction is performed to perform ideal outline enhancement based on photographing conditions, photographic subject, and print size. To provide a high-definition plate-making device capable of performing ideal edge enhancement, comprising a correction function determining means for determining a function and replacing the correction function with a spatial filter, and an edge enhancement processing means for carrying out edge enhancement processing using the correction function. It is.

<Example> An example of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram of an apparatus according to the invention.

In FIG. 1, a high-definition image is input by an image input means (1). As the image input means (1), a high-definition camera, a high-definition VTR, etc. can be considered.

The high-definition image input by the image input means (1) is digitized by an A/D conversion circuit (2).
is converted from analog to digital and stored in the storage means (3). The storage means (3) may be anything such as a memory or a magnetic disk.

Based on the correction function determined by the correction function determining means (4) based on the photographing conditions, the object, and the size of the printed matter, the high-definition image stored in the storage means (3) is contour-enhanced by the contour enhancement processing means (5). Emphasis processing is performed and the output means (6
) is output. As an output means, it may be outputted to an image plate making scanner to obtain a four-color separation plate, or it may be outputted to a hard copy device such as a film. Also, -
It is also possible to output the data to a second storage means and perform other processing.

The correction function determining means will be explained using FIG.

Spatial frequency characteristic MTF (Mod
ulation Transfer Function
) is used.

Here, explanation will be given using cough MTF.

M T F A (f) of the input image is shown in (41). The horizontal axis of the figure is the spatial frequency f, and the vertical axis is the response A (f) to the spatial frequency f.

To obtain M T F A (f) of the input image, input a sine wave chart with varying periods from the image input means (1), and compare each period with the data stored in the storage means (3). It is obtained by taking the contrast ratio for each. However, even if the same equipment is used, the MTF changes depending on photographing conditions such as the distance to the object to be photographed, the degree of focusing, and the aperture of the lens. Therefore, it is necessary to measure M TF on the screen actually printed. For this purpose, clear edges such as the edges of buildings in the input image are obtained by Fourier transform. In this way, M T F A (f) of the input image under certain shooting conditions is obtained.

Next, you need to consider the print size. M T F A of the input image (fl is the output of 10 mm per millimeter)
This is required on the premise that this is done using pixels. The number of pixels in high-definition is 1035 pixels vertically and 1840 pixels horizontally, so when outputting at 10 pixels per millimeter, the output service will be 103.5 mm in size and 184 mm in width. If the print size is the same as this standard size, there is no change in MTF. If it is necessary to double the magnification, the spatial frequency f may be tripled. The spatial frequency characteristic B (f) when enlarged twice is shown in (42). In this way, the spatial frequency characteristic B (f) in consideration of the print size can be obtained by multiplying the spatial frequency by the reciprocal of the enlargement rate.

On the other hand, the ideal MTF is determined for each object to be photographed ((43) is the ideal MTF for landscape images, (44)
shows the ideal MTF of a person image. For landscape images,
Emphasis is placed on high spatial frequencies so that fine details can be seen clearly, and in the case of human images, it is thought to appear smooth.

Only two types are shown here, but the classification is finer,
It is a good idea to prepare an ideal MTF for each. Further, it is better to prepare R, G, and B separately for each classification. These ideal MTFs are preferably stored in a memory by a storage means in the correction function determining means so that they can be accessed and read out as needed.

Next, the MTF after expanding the ideal M T F C (f)
By dividing by B(f), the corrected MTF D(f)
(45) can be obtained.

In the frequency domain, an output image with ideal frequency characteristics can be obtained by Fourier transforming an input image, applying this correction MTF, and performing inverse Fourier transform. However, it is necessary to perform two-dimensional Fourier exchange for 2,000 pixels. Therefore, even if fast Fourier exchange FFT is used, the calculation time is extremely long, which poses a problem in practical use.

Hardware dedicated to FFT is also commercially available, but it is expensive.

Therefore, in this device, we decided to perform filter processing in the spatial domain by executing calculation processing by a computer. Assume that the input image is f(x, y), the filter t(k, l), the output image is g(x, y), and the filter size is 3×3.

It is expressed as This can be easily done with a computer.

Hardware implementation using shift registers is also easy.

The 3×3 rotationally symmetric filter t(k, fi) is shown in Figure 3 (
By setting the central value of a to 112 or less, the ratio of emphasis on the low frequency attenuation characteristic can be varied in various ways.

The spatial frequency characteristics when the value of a is set to -12, -20, and -30 have a graph curve as shown in FIG. 3(b).

3. Corrected MTF obtained in advance as described above
An operator arbitrarily operates a terminal such as a keyboard to pre-store a shape similar to D(f) in the memory of the storage means in the correction function determination means, and reads out data that is a variable a of the spatial filter. and filter t
(k, which performs arithmetic processing on images.

<Effects of the Invention> As explained above, in a high-definition plate-making apparatus that creates four-color separation plates for printing from high-definition image signals, the spatial frequency of the input image is adjusted in consideration of the photographing conditions, the object to be photographed, and the print size. By converting the image, an ideal image with enhanced contours can be obtained, and the printed matter based on this image can be of high quality.

[Brief explanation of the drawing]

FIG. 1 shows the device according to the present invention with function realizing means (1).
Image input means (2) Digitization means (3) Storage means (4) Correction function determination means (5) Contour enhancement processing means (6) Output means (41) MTF of input image (42) MTF after enlargement (43) Ideal MTF for Landscape Images (44) Ideal MTF for Portrait Images (45) Corrected MTF Patent Application Representative of Toppan Printing Co., Ltd. Kazuo Suzuki Figure 1

Claims (1)

[Scope of Claims] 1) For printing by having a digitizing means for capturing a high-definition television image signal by an image input means and converting it from analog to digital data, and a storage means for storing the digitized data. In a high-definition plate-making apparatus for producing plates, the correction function determining means determines a correction function for ideal contour enhancement based on photographing conditions, photographic object, and print size, and replaces the correction function with a spatial filter; A high-definition plate-making device comprising: an edge enhancement processing means that performs an edge enhancement process using a function.