JPH0822084B2 - Video image processor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention obtains a still image such as a color separation plate or a hard copy of high quality for printing a video image arbitrarily selected from a video signal. Video image processing device for

[Prior art and its problems]

In recent years, due to the rise of television broadcasting in the mass media and the development and spread of video technology, there is an increasing demand for recording desired images from printed images on a printed matter or the like for mass duplication.

Conventionally, when making a printed image that is a still image from a video image,
A method of making a color film obtained by shooting the cathode ray tube surface of a color monitor with a still camera with a plate making scanner, and multiple exposure of R, G, B video images projected on a black and white monitor through R, G, B color filters respectively. There is a method of plate-making the obtained color film with a plate-making scanner, and a method of directly inputting the R, G, B video signals as electrical signals to the plate-making scanner in JP-A-55-74545.

However, with the method of photographing with a color monitor, the color tone and gradation of the video image cannot be reproduced satisfactorily due to the spectral emission characteristics of the R, G, B phosphors of the cathode ray tube and the spectral sensitivity of the color film and the mismatch of the density region. In addition, there is a drawback that the R, G, B phosphor dots and the halftone dots of the printed matter interfere with each other to cause moire. In addition, even in the method of multiple exposure with a black and white monitor, the scanning lines of the video image interfere with the dots of the printed matter to generate moire, and the resolution of the video image deteriorates due to the addition of the step of making a color film and then plate-making. There was a drawback.

Further, in the method of directly inputting the R, G, B video signals of JP-A-55-74545 into the plate-making scanner, the color tone, gradation and resolution represented by the video signal are reproduced almost as they are, but the original image quality of the video image is Is often not sufficient as an original for printing, and it is difficult to obtain a high-quality printed matter by this method.

The reason for this is that the video signal complies with the standard system of color television broadcasting, and NTSC is adopted in Japan among some standard systems, but the video signal of NTSC is compared with the black and white and television broadcasting before that. In consideration of compatibility and the like, the information amount of the image is compressed. The image information compression method uses the characteristics of the human eye for moving images, and even if the image quality appears to be sufficient as a moving image on a monitor TV, the still image does not provide satisfactory image quality. Further, processing applied to a video signal by various devices so that the video image can be better seen by human eyes as a moving image, noise added in recording and transmission system of the video signal, and the like are factors that deteriorate the image quality of a still image.

Excessive contour enhancement is one of the causes of this deterioration.
The edge enhancement will be described with reference to the waveform of the video signal in FIG.

As shown in FIGS. 5 (a) and 5 (b), since the spot of the scanning beam of the image pickup tube of the television camera is not very sharp in the video image, it is not possible to cope with the abrupt change in contrast between the contour and the luminance signal. The sharpness of the contour tends to be deteriorated due to a slight slope in the waveform.

Further, when the image is reproduced, the spot of the scanning beam of the cathode ray tube of the television also has a finite size, so that the high frequency resolution of the image similarly decreases.

Such distortion that makes the sharpness of the contour dull is called aperture distortion, but in general, a kind of contour enhancement circuit called an aperture compensation circuit is installed in the tuner of a TV camera or TV to increase the slope of the signal waveform at the contour part. By doing so, the above-mentioned distortion is reduced and the sharpness of the contour is normally maintained.

This outline emphasis is performed as shown in FIGS.
A primary differential waveform (c) is created based on the luminance change of the original signal (b), and then a secondary differential waveform (d) is created. Next, the inverted waveform (e) of the secondary differential waveform is obtained. This inverted waveform (e)
Is combined with the original signal (b) to make the gradient of the waveform of the contour portion steep.

However, in the video image sharpened through the contour enhancement circuit, there is a preshoot (31) or overshoot (32) (or undershoot (33)) in the contour portion as shown in FIG. 5 (f). In addition, signal distortion such as ringing occurs.

Due to these signal distortions, in the reproduced image, black edges and glare are generated on the outline, but when watching TV, unlike watching printed matter, watching from a distance apart, And because it's a video,
The impression of the entire image is prioritized, and the deterioration of the image quality that occurs in the local portion as described above is not an issue, so it was not considered a problem.

However, when creating a printed material from the video image,
Since the image quality evaluation of a printed matter is a still image, it has been a serious problem that the image quality is deteriorated due to the excessive detail enhancement due to the details. Black spots and color gaps appearing in printed materials obtained from this video image are, for example, 10
A print size of about cm × 10 cm may be about 0.2 mm, and a terrible thing may appear with a width of about 1.0 mm. This width increases as the enlargement ratio of the printed matter increases, and cannot be ignored.

<Objects of the Invention> The present invention has been invented to solve the above-mentioned problems, and removes darkening and color loss of contours from a video image on which contours are excessively emphasized, thereby achieving high-quality stillness. An object of the present invention is to provide a video image processing apparatus capable of obtaining an image, that is, a hard copy or a color separation version for printing.

[Outline of Invention]

The present invention is a video image processing apparatus for obtaining a high-quality hard copy or a color separation version for printing of a video image arbitrarily selected from a video signal, wherein a contour portion is extracted from the video image. In addition, the video image processing apparatus has means for removing overshoot and undershoot of the image signal generated by the contour enhancement processing in the extracted contour portion and preventing image quality deterioration due to darkening and color loss of the contour portion.

Example of Invention

Hereinafter, the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 4. FIG. 1 is a system configuration diagram according to the present invention when a color separation plate for printing is obtained from a video signal, and there are a TV tuner (1) and a VTR (2) as a video signal source representing a video image. When an image to be processed is edited, the image is once recorded on a 1-inch VTR (3) or the like, and then a video signal of a video image for plate making is input to the frame buffer unit (4). The video signal is A / D converted by the frame buffer (4), and the information of the video image is stored as digital data. The computer unit (5) performs digital image processing on the video image stored in the frame buffer unit (4) to improve the image quality of the video image for printing, and outputs the processed video image information to the plate making scanner (6). To obtain a color separated version of the video image.

FIG. 2 is a block diagram of a portion (a portion surrounded by a chain line in FIG. 1) for performing image processing in the video image processing apparatus of the present invention. The video signal generated from the video signal generation source is converted into an RGB video signal and a sync signal by a decoder (not shown) or the like, and then input to the frame buffer unit (4). In the frame buffer section (4)
The RGB video signal is converted into digital data by the A / D converter (10) and sequentially stored at the address designated by the address generator (11) of the frame memory (12). The video image data stored in the frame memory (12) is transferred to the RAM (21) of the computer section (5) via the interfaces (14) (23) of the frame buffer section (4) and the computer section (5). If necessary, it is stored in a magnetic disk (25) as an external memory, and an instruction command is given from a terminal (24) so that the CPU (20) removes the image over-enhancement processing. The processed video image data is stored in the frame memory (12) under the control of the frame memory controller (15) from the RAM (21) via the interfaces (23) and (14) again, and the processed video image is displayed. Can be confirmed as a RGB video signal on a color monitor (not shown) by a D / A converter (not shown) connected to the frame memory (12). It is also possible to perform interactive processing using the digitizer (16) while looking at the color monitor.

The ROM (22) stores a processing program including a program for controlling the entire system, and the memory controller (13) controls writing and reading of video signal data in the frame memory (12).

Next, a description will be given of the contour over-emphasized removal processing, which is a feature of the present invention.

FIG. 3 shows a process in which distortion of a video signal whose contour is excessively emphasized is corrected by a program stored in the magnetic disk (25). This process will be described based on the flowchart shown in FIG. First, since the edge enhancement is performed on the luminance signal, the frame memory RGB primary color signals taken into E _R, E _G, the E _B the following formulas (1) to (3), the luminance signal E _Y E _Y = 0.30E _R + 0.59E _G + 0.11E _B (1) E _I = 0.74 (E _R- E _Y ) -0.27 (E _B- E _Y ) (2) E _Q = 0.48 (E _R- E _{Y ) +0.41 (E B -E Y)} (3) and E _I signal, separated into E _Q signal (S1). Then, for each pixel, the difference between the luminance signal E _Y and the luminance signal of the pixel which is a constant distance away in the scanning line scanning direction is calculated (S2). Next, the change in the difference value is examined in the horizontal direction similarly to the scanning beam of the CRT tube. At this time, the portion where the absolute value of the difference value exceeds a predetermined constant value is considered to be the contour. In this way, the contour is extracted (S3). Next, looking at the change in the difference value between the extracted contour portion and the pixels before and after the contour portion, it is checked whether there is distortion such as preshoot (31), overshoot (32) or undershoot (33). Detection is performed based on the difference value (S4). Regarding the distorted portion, the state of the luminance signal level of each pixel is investigated in the direction opposite to the contour, and a waveform (h) without distortion is created based on the level (S5). As an example of the distortion correction method, a regression line obtained by the least square method can be used.

Since the corrected waveform may lack naturalness, the corrected waveform is combined with the uncorrected waveform to adjust the shape (S6). Basically, this smoothing is performed by combining the correction signal in a portion extremely close to the contour (edge portion), and the waveform before correction is prioritized as the distance from the contour increases. Is kept. This waveform is shown in FIG. 3 (i). If unnaturalness remains in the correction waveform obtained as described above, the contour to be corrected is extracted, the correction waveform is created, or the fitting parameters and method are changed (S8), and immediately Feedback can be applied to obtain the best image quality. The corrected luminance signal (i) thus obtained is the E- _I separated by the Y-C separation.
Recycled to RGB signals by decoding from the signal and E _Q signal ends the image processing. As a result of the above processing, a good image can be obtained.

By inputting the image data thus obtained into a plate-making scanner engraving plate-making device as an output means, a color hard copy device such as an inkjet printer, a high-quality still image is output from the output means. Can be output.

<Advantages of the Invention> As described above, according to the present invention, it is caused by excessive edge enhancement in obtaining a still image from a video image. There is an effect that it is possible to easily and quickly remove defects such as black edges and glare on the contour portion, which makes it possible to provide a still image such as an inexpensive and high-quality printed matter.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a model diagram showing the overall structure of a video plate making apparatus of the present invention, and FIG. 2 shows the structure of an image processing unit of the video plate making apparatus. FIG. 3 is a block diagram, FIG. 3 is an explanatory diagram showing a state of contour overemphasized removal, FIG. 4 is a flowchart of contour overemphasized removal processing, and FIG. 5 is an explanatory diagram showing signal formation of contour enhancement. (1)… TV tuner, (10)… A / D converter (2)… VTR, (14) (23)… Interface (3)… 1 ″ VTR (4)… Frame buffer (5)… Minicomputer (6) )…scanner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kotoshi Naito 1-5-1, Taitō, Taito-ku, Tokyo Toppan Printing Co., Ltd. Judgment body for referee Judge Masuda Yamada Judge Tanabe Toshiji Keiichi Hashimoto (56 ) References JP-A-58-10741 (JP, A)

Claims (1)

[Claims] 1. A video image processing apparatus for producing a hard copy or a color separation plate for printing based on a video signal composed of R, G, B signals, and A / D conversion means for converting the video signal into a digital signal. Storage means for storing the video signal digitized by the A / D conversion means, contour extraction means for extracting a contour portion of the video signal stored in the storage means, and the contour extraction means A video image processing apparatus, comprising: a correction unit that extracts a contour overemphasized portion from the image signal of the contour portion that has been extracted and removes the contour overemphasized portion.