JPH03179890A - Television receiver - Google Patents

Abstract

PURPOSE:To convert a current television signal into a picture with high definition and high quality and to display the picture by utilizing a scanning line in a field even in a moving picture part so as to double number of scanning lines as the prescribed processing thereby obtaining the picture with less deterioration due to the movement. CONSTITUTION:The television receiver is provided with detection circuits 14, 15, 19 obtaining movement information of a picture from an inter-frame difference signal of an interlaced television signal, 1st interpolation circuits 16, 17, 18, 21 utilizing the scanning line in a field, and a 2nd interpolation circuits 15, 22 utilizing a scanning line of a preceding field at least. Moreover, mixing circuits 20, 21, 22 controlling the ratio of the mixture with the output of the interpolation means with an output of the detection circuits 14, 15, 19 obtaining the movement information of the picture and time axis conversion circuits 24, 25 compressing the time axis of the mixed output to 1/2 are provided. Thus, the reproduced picture with less deterioration in the picture due to the movement of the picture is realized by using a television signal whose scanning line number is doubled with respect to that of the input television signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a television receiver that receives a television signal and obtains a television image with twice the number of scanning lines through interpolation. Regarding.

Currently, television receivers with larger screen sizes are being developed. When the screen size is enlarged, the displayed television image will naturally have a scan line spacing, and the resolution of one image will be insufficient, making it impossible to obtain a high-quality image. There is an increasing demand to obtain high-quality images.

In response to these demands, high-definition televisions with double the number of scanning lines are being developed. In this case, a high-resolution, high-quality television image can be obtained, but changing the number of scanning lines from imaging requires changing the existing transmitter and receiver, so it is difficult to put it into practical use. There are many technical and economic issues to be solved, and it will take a long time.

on the other hand,]! I! A high-resolution television receiver that receives a current television broadcast signal and interpolates between the scanning lines to substantially double the number of scanning lines is being considered.

That is, in order to double the number of transmitted scanning lines, the received signal is subjected to time compression processing, and the scanning lines spanning two fields are made into a single frame signal. The NTSC television signal currently broadcast in Japan is sent by interlace scanning a field signal with 262.5 scanning lines every 1/60 seconds, and a frame signal with 525 scanning lines in 2 fields. configured. Therefore, when two fields of image signals separated by 1760 seconds are combined to form a single frame, if one image is stationary or has little movement, an image with double the number of high-definition scanning lines will be used. However, if the image changes over time, 1/60
This results in a composite of two images that moved for a second, which causes a problem in that the image quality deteriorates.

Therefore, one object of the present invention is to provide a television receiver that receives an interlace-scanned television signal and pseudo doubles the scanning lines inside the receiver, so that there is little deterioration of the reproduced image even when the image moves. The object of the present invention is to realize a television receiver that can reproduce high-definition images.

In order to achieve the above object, the present invention provides a method for generating an interpolated scanning signal from a received television signal.

The present invention is characterized in that it is configured to detect motion information of an image of a television signal, and to select an optimal one from a plurality of types of interpolation means based on the detection signal.

That is, a detection circuit that obtains image motion information from an interframe difference signal of an interlaced television signal, a first interpolation circuit that uses scanning lines within a field, and a detection circuit that obtains image motion information from an interframe difference signal of an interlaced television signal, a first interpolation circuit that uses scanning lines within a field, and a detection circuit that uses at least a previous field (or a previous and subsequent field). a second interpolation circuit that uses scanning lines; and a mixing ratio in which the mixing ratio of the output of the first interpolation means and the output of the second interpolation means is controlled by the output of a detection circuit that obtains motion information of the image. and a time axis conversion circuit that compresses the time axis of the mixed output to 1/2, thereby obtaining a television signal with twice the number of scanning lines of the input television signal. It is a machine.

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

FIG. 1 shows a general configuration of a television receiver in which the scanning lines of an input television signal are artificially doubled by interpolation.

Regarding the current NTSC television broadcast signal as a signal source, a television signal with 525 scanning lines, a horizontal frequency of 15.75 kHz, a vertical frequency of 60 Hz, and a 2:1 interlace is used for normal NTSC television reception. A demodulator 1 similar to that of the machine obtains a Y signal, an engineering signal, a Q signal, a horizontal synchronizing signal H1, and a vertical synchronizing signal V. Y
,I.

Each signal of Q is input to the time axis conversion circuit 2 as explained in FIG. 2, and the signals of Y', I', and
It is converted into each signal of Q' and sent to the video amplification circuit and chroma circuit 4.
added to. Further, the H and V signals are converted into H' and V' by a synchronizing signal converter 3, and are applied to the display device 5 as a drive signal of a television signal with doubled scanning lines.

FIG. 2(A) shows the conventionally known time axis conversion circuit 2.
FIGS. 2A and 2B are diagrams illustrating the states of scanning lines of an input television signal and an interpolated television signal, respectively. The time axis conversion circuit 2 shown in FIG. 1 includes circuits as shown in FIG. 2(A) for each of the Y, I, and Q signals.

The Y signal will be explained below to simplify the explanation.

A Y signal corresponding to a current television signal interlaced every 1/60 seconds is applied to the input terminal 6 as shown in FIG. A part of the signal is delayed by one field period (1/60 second) by the field memory 7, and both the input signal and the input signal are input to the time axis conversion circuit 8.9.The time axis conversion circuits 8 and 9 convert the time axis to 1 Convert to a signal compressed to /2H. These output signals are converted to 1/2H by the switching circuit 10.
By switching each time, a time-base converted signal with a horizontal scanning period of 172H is obtained at the output terminal 11.

Therefore, as a reproduced image, a television image in which the horizontal scanning lines are doubled (525 lines) is obtained every 1760 seconds as shown in FIG. Furthermore, if the horizontal and vertical rotation signals are created so that the second and third fields are interleaved, the number of horizontal scanning lines in one frame (two fields) becomes one.
050 images are obtained.

However, of the 525 scanning lines in each field in Figure (C), half of the scanning lines, 262.5, are from the previous field, i.e. 1
Since it is a pseudo signal created by interpolating an image signal from 760 seconds ago, in the case of an image (subject) that moves and has many temporal changes, it is a composite of the previous field image and the current field image. Therefore, when there is a change in the image (movement of the image, change in brightness of one color, etc.) for 1/60 seconds, the image quality deteriorates.

In order to explain the principle of the signal processing circuit of the television receiver according to the present invention, FIG. 3 is a perspective view showing the state of the scanning lines of three consecutive fields of the current television signal in isolation. In the figure, the broken line in the first field, the dotted line in the second field, and the solid line in the third field are actually transmitted signals, and from these signals, for example, a pseudo When creating a scanning line signal m, depending on the motion information of one image, the scanning MrQt n of the second field is used, or the signal of the scanning line of the first or third field located at the same position as m is used. be. More specifically, when creating a pixel Y on a scanning line m that is created by interpolation, when the subject is moving, interpolation is performed from the upper and lower scanning lines Q and n of the same field, which are most similar in terms of time. In addition, if the subject is close to a still image with little movement, the closest one in the spatial domain, that is, the pixels x and z at the same position as the above-mentioned pixels in the first and third fields are used.

Note that if the subject is moving, the resolution will in principle deteriorate because pixels from different areas are used, but human vision has a characteristic that the resolution decreases for moving objects. Therefore, the reduction in resolution due to the interpolation described above does not substantially pose a problem.

FIG. 4 is a block diagram showing the main part of an embodiment of a device implementing the signal processing method for a television receiver according to the present invention, that is, the structure of a time axis conversion circuit. The television signal (for example, luminance signal Y) input from the input terminal 12 is stored in the field memories 14 and 15 as 262H.

It is delayed by 263H (H is the horizontal scanning period).

If the input signal is pixel Z (signal level is represented by Z) in the third field in FIG. 3, the output of the field memory 15 will be X (signal level is represented by X) of the first field exactly one frame before. , the signals X and Z are applied to the subtraction circuit 19, and a difference signal of (Z-X), i.e., the second
It is converted into a signal representing the movement of pixel Y in the field.

On the other hand, the output of the field memory 14 is the scan signal i1n of the second field, which is sent to the line memory 16 by I1n.
By delaying by H, a signal corresponding to the scanning line is obtained. An average value of the pixel values of the scanning lines n and a is obtained from the addition circuit 17 and the coefficient circuit 18.

This is the interpolated value a from the signal in the same field. Using this interpolated value a, the interpolated value b from the previous field, and the motion coefficient obtained by the motion coefficient circuit 20, the value of the pixel to be interpolated. Y as Y=k −b+ (1−k) ・a・・・・・・
...=-(1). Multiplication circuits 21, 22.
The adder circuit 23 is a circuit for calculating the above equation.

The signal of the scanning line n of the second field and the signal of the new scanning line m consisting of the interpolated signal Y obtained above are input to the time conversion circuit 24.25, and the output thereof is input to the switching circuit 20.
By switching at a 2H cycle, a high-definition television signal with twice the desired number of scanning lines can be obtained at the output terminal 13.

In the above embodiment, the interpolation value of the still image is the signal X of the previous field, but it can also be the average value of X and Z using the addition circuit and the 1/2 coefficient circuit. In this way, minute noise components cancel each other out, making it possible to obtain a higher quality image.

As described above, according to the present invention, in the portion of the television signal where the subject is stationary, information on all the scanning lines of two fields spanning the frame is used to create a high-definition image with twice the number of scanning lines. is obtained. Furthermore, in the moving image part, the scanning lines in the field are used to double the number of scanning lines, so images with less deterioration due to movement can be obtained, making it possible to convert current television signals into high-definition, high-quality images. It can be converted and displayed as an image, and an economical high-definition television transmission system can be realized. Furthermore, in the future, if high-definition televisions are realized in which all television cameras have twice the number of scanning lines, current television programs can be converted to high-definition television signals using the method of the present invention, which is expected to have a great effect on the spread of high-definition televisions. can.

Furthermore, if a television signal made high in definition by the processing method of the present invention is used for electronic printing, any television image can be printed as a high definition image with little deterioration.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the general configuration of a television receiver in which the scanning lines of the input television signal are doubled;
The figure is a block diagram for explaining the principle of the time axis conversion circuit 2 in Fig. 1 and a diagram showing the relationship of scanning lines in the field for explaining its operation. FIG. 4 is a diagram showing the relationship between scanning lines in three fields of a television signal, and is a circuit diagram of an embodiment of means for obtaining an interpolated signal, which is a main part of a signal processing circuit of a television receiver according to the present invention. 20...Motion coefficient circuit, 21.22...Multiplication circuit. 23... Countable circuit, 24.25... Time axis conversion circuit. No.! figure

Claims (1)

[Claims] 1. In a television receiver that obtains a reproduced image by setting the number of scanning lines to twice the number of scanning lines of the input television signal using an input television signal and an interpolation signal obtained from the input television signal, the number of lines between frames of the input television signal is A television receiver characterized in that a motion coefficient of a subject is determined from a difference signal, and the interpolation signal is controlled based on this motion coefficient.