JPS635682A - Video signal processing method - Google Patents

Abstract

PURPOSE:To enable the reduction of a television picture with the simple constitution of a circuit by reducing blocks from an input composite video signal sampled by phase synchronizing to a color subcarrier by frequency which is N(interger)-fold of the subcarrier on a unit which is a block consisting of N- pieces of continuous sampled points at a specified rate. CONSTITUTION:From a composite video signal converted into a digital signal, in a memory 105 controlled by a memory control circuit 106 blocks are reduced at a specified rate on a unit which is a block consisting of N-pieces of continuous sampled points so as to reduce a picture. The composite video signal of the reduced picture is converted into an analog signal in a D/A converter 9 and outputted from a composite video signal output terminal 10. For example in case of reducing the picture to one-third, the blocks are reduced in horizontal and vertical directions to one-third on a unit which is block consisting of N(=4) pieces of sampled points, which is enclosed with a thick line. Namely, the picture elements 11A-11D, 12A-12D and 21A-21D, etc. illustrated in figure(a) are arranged like the figure (b), so that the sampled points of the composite video signal which is reduced to one-third of the picture are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal processing method for reducing television images.

BACKGROUND OF THE INVENTION In recent years, digital technology has often been used to reduce the size of television images and display them in combination with other screens.

The conventional video signal processing method for reducing an image separates the composite video signal of the image to be reduced into a luminance signal and a color signal, demodulates the color signal into two color difference signals, and then extracts a sample of each signal. The points are thinned out and reduced, and the points are modulated and combined to obtain a composite video signal of the reduced image.

FIG. 3 is an example of a video signal processing device capable of reducing an image using the conventional video signal processing method described above.

In FIG. 3, a composite video signal input manually from a composite video signal input terminal 1 is converted into a digital signal by an A/D converter 2. Composite video signal converted to digital signal
/C separation filter 3 separates the luminance signal Y and 111 color sending signal C, and further sends the carrying color signal C to the color signal demodulator 4.
The signal is demodulated into an RY signal and a BY signal. The luminance signal Y, color signals R-Y and B-Y obtained in this way are stored in the memory 5 controlled by the memory control circuit 6, and when reducing the image to 1/3, for example, the sample points of each signal are horizontally Then, the image is reduced by thinning out every third image in the vertical direction. Color signal R-Y of the reduced image
The B-Y signal is modulated again into a carrier color signal C by the color signal modulator 7, and combined with the luminance signal Y of the reduced image in the Y/C synthesizer 8 to form a composite video signal, which is then D/A converted. Analog with device 9. In this way, a composite video signal of the reduced image can be obtained. (For example, "Broadcasting Technology" July 1983 issue, p. 67) Problems to be Solved by the Invention However, in the above conventional method, the composite video signal is separated into a luminance signal and a chrominance signal, and the chrominance signal is further divided into two. In order to perform reduction processing after demodulating into two color difference signals, a Y/C separation filter, Y/C combiner, and color signal modulator/demodulator are required.
Further, there is a problem in that the circuit size of the device becomes large, such as requiring a large memory capacity.

The present invention has focused on the above-mentioned problems, and an object of the present invention is to provide a video signal processing method that enables reduction of television images with a simple circuit configuration.

Means for Solving the Problems In order to solve the above problems, the video signal processing method of the present invention uses an input sampled in phase synchronization with the color subcarrier at a frequency N (an integer) times the color subcarrier. The image is reduced by thinning out a composite video signal at a predetermined ratio in units of blocks each consisting of N consecutive sample points.

Since the effect sampling is performed in phase synchronization with the color subcarrier,
In this way, if thinning is performed in units of blocks consisting of N consecutive sampling points, that is, in units of one period of the color subcarrier of the input composite video signal, the phase relationship between each sampling point and the color subcarrier can be maintained. Reduction is possible without drooping or color demodulation, and can be realized with a simple circuit configuration.

Example Below, a video signal processing method according to an example of the present invention will be described.
This will be explained with reference to the drawings.

FIG. 2 shows a configuration example of a video signal processing device that reduces an image by the video signal processing method of the present invention.

In FIG. 2, blocks having the same functions as those in the conventional example shown in FIG. 3 are given the same numbers. In FIG. 2, a composite video signal input from a composite video signal input terminal 1 is sampled by an A/D converter 2 at a frequency N (an integer) times the color subcarrier in phase synchronization with the color subcarrier. and convert it into a digital signal. The composite video signal converted into a digital signal is stored in the memory 105 controlled by the memory control circuit 106, and the image is reduced by thinning out the block at a predetermined ratio in units of blocks each consisting of N consecutive sample points. . The composite video signal of the reduced image is converted back to an analog signal by the D/A converter 9 and outputted from the composite video signal output terminal 10.

Next, the thinning performed in the memo January 05 and the memory control circuit 106 in units of blocks each consisting of N consecutive sample points will be further explained with reference to FIG. FIG. 1(a) shows part of the arrangement of sampling points on an image in a certain field of an input composite video signal when sampling is performed at a frequency of N=4, that is, four times the frequency of the color subcarrier. Here, the small squares are sample points, and the rectangles made up of N (=4) sample points surrounded by thick lines indicate blocks that serve as units when reducing the image. Now, for example, when reducing an image to 173, the block is made up of N (=4) sample points surrounded by a thick gland, and the block is divided horizontally and vertically by 1/3.
thin out. That is, the pixel 11A shown in FIG. 1(a)
~IID, 12A ~ 12D, 21A ~ 21D, etc. are arranged as shown in the same figure (bl) to obtain sample points of a composite video signal that reduces the image to 1/3. Since the thinning is performed in phase synchronization with the carrier wave, if thinning is performed in units of blocks each consisting of N consecutive sample points, that is, in units of one period of the color subcarrier of the input composite video signal, each The phase relationship between the sampling point and the color subcarrier is maintained, and it can be reduced without color demodulation.

Note that in FIG. 1, N=4 and the reduction ratio is 1/3, but the present invention is not limited to this.

Effects of the Invention As described above, according to the video signal processing method of the present invention, it is possible to easily reduce an image without color demodulating the input composite video signal, and this can be achieved with a very simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1(a)(1)) is an explanatory diagram showing the arrangement of sample points on an image to explain the video signal processing method of the present invention, and FIG. 2 is an illustration of an image whose image is reduced by the video signal processing method of the present invention. FIG. 3 is a block diagram of a video signal processing device that reduces an image using a conventional video signal processing method. 2... A/D converter, 105... Memory, 106... Suburb ν ″ hill

Claims (1)

[Claims] An input composite video signal sampled in phase synchronization with the color subcarrier at a frequency N (an integer) times the color subcarrier is divided into blocks at a predetermined ratio in units of blocks each consisting of N consecutive sampling points. A video signal processing method characterized by reducing an image by thinning out.