JPS623580A - Picture signal converter - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a reproducing picture in an object having a motion and to obtain a high definition and good quality picture by forming an interpolation signal with weighting and combining the outputs of the first - the third interpolating means corresponding to the motion of the picture. CONSTITUTION:An output signal X32 from an A/D converter 3 and an output X12 from a 262H delay circuit 20 are inputted to a subtraction circuit 32 and by the circuit 32, the difference between the signal X12 and the signal X32 that is delayed by one frame from the signal X12 is calculated and is inputted to a motion detecting circuit 33. At the motion detecting circuit 33, a control signal is outputted detecting the motion of the object between two continuous frames based upon an input signal. The control signal from the motion detecting circuit 33 switches an alteration switch 31 to the output side of an adder 28 when the volume of the motion is smaller, and to that of an adder 26 when it is larger and at the same time, controls the coefficients of the coefficient circuits 29 and 30 corresponding to the motion of the object. Thereby, it is possible to obtain the optimum interpolation signal corresponding to the volume of the motion of the object and to convert the picture signal having a low resolution to a high definition signal, the picture quality of which is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conversion device for image signals such as television signals.

[Prior Art] Current NTSC television signals are interlaced scanned by field signals of 282.5 scanning lines every 1 field, that is, every 1/60 seconds.
! One frame signal of 525 trees is formed, but for example, a high-definition signal is used to double the scanning lines of the current television signal and display such a television signal on a high-definition monitor. Conversion circuits are known.

FIG. 1 shows the basic configuration of a conventional high-definition signal conversion processing circuit.

As shown in FIG. 1, a television signal (analog signal) 1 supplied to an input terminal 1 is filtered at high frequencies by a low-pass filter 2, converted to a digital signal by an A/D converter 3, and converted into a digital signal by an A/D converter 3. 1 is input to the time axis compression circuit 5 and also to the field memory 4. The signal from the field memory 4 is input to a second time axis compression circuit 8.

The output of the field memory 4 is the signal of the previous field, which in the case of a 2:1 interlaced operation scheme traces the middle of the scan line of the current field. This kind of A/D
The time axes of the current field signal from the converter 3 and the previous field signal from the field memory 4 are compressed to 1/2 by the time axes compression circuits 5 and 6, respectively, and then scanned after the time axes are compressed via the changeover switch 7. By switching the switch 7 every line period and taking out the signals from both circuits 5 and 6, the signal obtained by doubling the scanning line is operated at twice the sampling frequency of the A/D converter 3 mentioned above. The analog-converted signal from this D/A converter 8 is passed through a low-pass filter 8 having a cutoff frequency twice that of the low-pass filter 2 described above. , a high-definition analog television signal with doubled scanning lines is obtained at the output terminal 10.

The basic block diagram shown in FIG. 2 is an application of the basic configuration of KA-KARU to a composite color television system.

In FIG. 2, the composite color television signal input to the input terminal 11 is separated into a luminance signal Y and a chrominance signal C by a Y/C separation circuit 12. It is demodulated into color difference signals, for example, I and Q signals. The luminance signal Y undergoes high-definition (scanning!! doubling) processing by the signal conversion processing circuit 14 having the configuration shown in FIG.

The color difference signals I and Q are also processed in the same way as the luminance signal Y described above in the signal conversion processing circuit 15, and then the color difference signals I and Q are processed in the matrix circuit 18, which is input together with the luminance signal after the high-definition processing from the circuit 14. Converted to primary colors R, G, B M,
It is displayed on a high-definition color monitor 17.

In this scanning line doubling conversion processing method, as shown in FIG. 3, the previous field (i.e. 1-1
) is used as an interpolation signal as it is at the corresponding position X'. On the other hand, for example, as shown in FIG. 3, a signal having an average value of scanning lines A and B above and below the image position X to be interpolated can be used as the interpolation signal for the position X.

As described above, various methods have been proposed in which the scanning line signal of the previous field or the scanning line signal of the current field is selected and used as an interpolation signal. The basic idea behind these proposals is to use the signal from the previous field as an interpolation signal for static images with little movement, and to form an interpolation signal from the operation signal in the current field for images with large movement. It is in.

[Problems to be Solved by the Invention] However, in the prior art as described above, when the display screen is based on information that does not move much, a high-definition and high-quality image can be obtained, but the display screen is When based on information with large movements, there is a drawback that images with satisfactory image quality cannot always be obtained.

[Means for Solving the Problems] Accordingly, it is an object of the present invention to prevent deterioration of a reproduced image caused by a moving subject, and for this purpose, it is an object of the present invention to provide a first field that forms an interpolated signal from a signal within a first field. a second interpolation means for forming an interpolation signal from a signal of a field before or after the first field; a third interpolation means for forming an interpolation signal by a combination of a signal of a previous field and a signal of a subsequent field; The interpolation means 1 includes a control means for weighting and combining the outputs of the first, second, and third interpolation means to form an interpolation signal in accordance with the movement of the image.

[Example 1] Hereinafter, the present invention will be specifically explained in detail with reference to the drawings of the embodiment.

FIG. 4 shows an embodiment of the image signal conversion device according to the present invention. In FIG. 4, the same parts as in the conventional example are designated by the same numbers.

As shown in FIG. 4, an analog signal is input from an input terminal 1 to an A/D converter 3 via a low-pass filter 2.
/D converted. The signal from the A/D converter 3 is 26
The signal is input to a 2B (horizontal period) delay ([1elay) circuit 18 , from which the signal is further input to an IH delay circuit 18 , and from this delay circuit 19 to a 282H delay circuit 20 .

Therefore, A/D converter 3 and each delay circuit 18.1
From 8.20 onwards, as shown in FIG. 5(a), the scanning line signal X32 (A/D converter 3
, the scanning line signal x23 of the current field delayed by 282H (output of the delay circuit 18), and the scanning line signal x21 of the current field delayed by IHi1% from this signal. Then, a scanning line signal X12 of the previous field delayed by 282H from this signal X21 is obtained.

The output of the 262H delay circuit 1st and the output of the 1H delay circuit IS are input to the adder 21, and from this adder 21
2 coefficient circuit 22, and from there (X21+X23
)/2 signals are output.

The output of the A/D converter 3 and the output of the 282H delay circuit 20 are input to an adder 23, and from this adder 23 are input to a 172 coefficient circuit 24, from which (X12+X32)
/2 signals are output.

1/2 coefficient circuit 22 output signal (X21+X23) /
2 is input to the subtracter 25 and adder 26, and the output signal (X12.X32) of the 1/2 coefficient circuit 24
/2 is similarly input to one input terminal of the subtracter 27 and the adder 28.

The other input terminals of both subtracters 25 and 27 have 262
Hia! The output signal X12 of the extension circuit 20 is inputted, and the outputs of both subtracters 25 and 27 are inputted to adders 26 and 28 via coefficient circuits 28 and 30, respectively. Adder 26
The outputs of 8 and 28 are connected to the input end of a switch means 31 which is switched by detecting the motion of the subject as described later.

On the other hand, the output signal X32 of the A/D converter 3 and 2B
2Hia! The output X12 of the delay circuit 20 is input to a subtraction circuit 32, which calculates the difference between the signal X12 and the signal X32 delayed by one frame as shown in FIG. 5(a), and calculates the difference. The signal shown is input to the motion detection circuit 33. The motion detection circuit 33 detects the motion of the subject between two consecutive frames based on the input signal value, and outputs a control signal based on the detection result.

The control signal from the motion detection circuit 33 switches the aforementioned changeover switch 31 to the output side of the adder 28 when the motion of the subject is small, and to the output side of the adder 26 when the motion is large. The coefficients of coefficient circuits 29 and 30 are controlled in accordance with the movement as described below.

Detection of the movement of the subject in the motion detection circuit 33 is basically performed based on the difference between the two input signal values.

The motion detection circuit 33 controls the two coefficient circuits 29 and 30 and the switch 31 as follows.

i) When there is almost no movement of the image (subject), the selector switch 31 is switched to the adder 28 bias, and the coefficient of the coefficient circuit 30 at that time is controlled to be almost 0, and as a result, the switch 31 outputs the signal (X32+X12). / Outputs 2.

ii) When the image movement approaches "moderate" from "rare", the coefficient of the coefficient circuit 30 is controlled to be closer to 1 than 0, and the switch 31 is set to (X32+X12)/2 and X12
Outputs a signal with a value between .

1ii) When the image movement is "medium", the coefficient of the coefficient circuit 30 is controlled to be 1, and the switch 31 outputs X12.

ii) When the movement of the image becomes larger than the state in 1ii), the switch 31 is switched to the adder 2B@, and the coefficient of the coefficient circuit 29 at that time is controlled so that it gradually approaches 0 from 1, and the switch 31 is X12 and X21+X23 /2
Outputs a value intermediate between .

M) When the movement of the image becomes large, the coefficient of the coefficient circuit 29 is controlled to be 0, and the switch 31 outputs (X21+X23)/2.

Let's summarize more than one thing about image movement.

First, if the movement is large, the interpolated signal is obtained using the signal in the current field. If the movement is intermediate, the interpolated signal is obtained using the signal from only the previous field. Furthermore, if the movement is small, the interpolated signal is obtained using the signal from the previous field. An interpolated signal is obtained by using not only a field signal but also a post-field signal that is more spatially correlated.

This situation is shown in FIG. 5(b).

The time compression circuits 5 and 6 are the same circuits as the conventional ones,
The output from such switch 31 and 282) +1! The output from the extension circuit 20 is inputted, compressed by 1/2 time, and supplied to the switch 7. The switching output of the switch 7 is inputted to a low-pass filter 9 via a D/A converter 8, and from there is supplied to an output terminal 10 as a high-definition signal in which the scanning lines are doubled.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain an optimal interpolation signal corresponding to the magnitude of the movement of the subject, and even for image signals with low resolution, high resolution signals with improved image quality can be obtained. It can be converted into a fine signal.

[Brief explanation of drawings]

Figure 1 shows the basic configuration of a conventional high-definition conversion processing circuit, Figure 2 shows an example of applying the same circuit to a composite color television system, and Figure 3 shows the inside of the field using the same circuit. FIG. 4 is a diagram showing an embodiment of the image signal conversion device according to the present invention; FIG. , FIG. 5(b) is a diagram showing the relationship between the movement of the subject between fields and the interpolation signal. 18.20...262H delay circuit, 19...IH7 delay circuit, 21.23.28.27...Addition circuit, 25.32.
...Subtraction circuit, 22.24...L/2 coefficient circuit, 29.30...Coefficient circuit, 31...Switch, 33...Motion detection circuit. Figure 3 i-field Figure 5

Claims (1)

[Claims] A first field that forms an interpolated signal from a signal within a first field.
interpolation means for forming an interpolation signal from a signal of a field before or after the first field; a second interpolation means for forming an interpolation signal by a combination of the signal of the previous field and the signal of the subsequent field. 3. An image signal conversion device comprising: an interpolation means according to No. 3; and a control means for forming an interpolation signal by weighting and combining the outputs of the first, second, and third interpolation means according to the movement of the image.