JPS6132681A - Signal processing circuit - Google Patents

Abstract

PURPOSE:To obtain a natural image even if a subject to be imaged moves, not by using only a signal before one field when varying into scanning signal successively, but by using an average value between a signal before one field and a signal after one field in a case that the scanning rectification is performed against TV signal making interlace scanning. CONSTITUTION:A standard is placed on output signal Xn of a line memory 3. For example, a signal Xn-262 before one field, signal Xn+263 after one field and signal Xn+1 after one line are obtd. and an average value Xa is obtd. by the first adding circuit 5 and the first 1/2 coefficient circuit 6. An average value Xb between signal Xn and signal Xn is obtd. by the second adding circuit 7 and the second 1/2 coefficient circuit 8, and the mixed ratio between the rectifying signal Xa within the field and the rectifying signal Xb within the field is changed according to the degree of movement of the subject to be imaged. Thus, the rectifying signal Xn, n+1 in accordance with the extent of the movement can be obtained, time axis is compressed to 1/2 by time compression circuits 13, 14, and switch 15 switched over by each one scanning line after time compression.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a signal processing circuit for television signals, and in particular to a signal processing circuit that performs scanning line interpolation on interlace scanning signals and converts them into progressive scanning signals. The present invention relates to a signal processing circuit.

[Background of the invention]

For example, Japanese Patent Application Laid-Open No. 58-11 discloses a method of interpolating the scanning lines of a television signal that performs interlaced scanning on the receiving side, converting the signal pressure of progressive scanning, and displaying the signal.
As shown in Japanese Patent No. 7788, there is known a system in which the movement of the subject is detected by calculating an inter-frame difference signal K, and the inter-field interpolation and intra-field interpolation are switched based on this movement K.

This method mainly performs inter-field interpolation if the degree of movement is small, and mainly performs intra-field interpolation if the degree of movement is large, thereby producing a still image.

Although it is possible to obtain an image with little deterioration for any video, the signal obtained by inter-field interpolation and the signal obtained by intra-field interpolation are at different positions on the time axis, so K, the motion When the degree changed, the image sometimes became unnatural.

The method of scanning line interpolation in this conventional example can be expressed, for example, as shown in FIG. In other words, in order to obtain an interpolated scanning line signal of In addition, if the degree of movement is large, use the average value of the signal Xn and the signal , and the ratio of intra-field interpolation and field-related interpolation in scanning line interpolation is controlled based on the value of this movement.

According to this method, the signals obtained by inter-field interpolation and the signals obtained between fields are at different positions on the time axis, resulting in an unnatural image if the degree of movement of the subject changes. has been mentioned before. In other words, when trying to obtain an interpolated scanning line signal in the (to) field 5 as shown in Fig. 2, the signal obtained only by interfield interpolation will be at the (M-1)th on the time axis as shown in b. ) field, whereas the signal obtained only between the inner fields is located at the (M)th field on the time axis, as shown by a.

Depending on the degree of movement of the subject, it becomes busy when moving on the time axis, as indicated by the arrows in the figure.

Furthermore, the movement detected by this method is not the movement at the exact position K of the scanning line to be interpolated, but only the movement K at a position one scanning line away during sequential scanning. Therefore, when only one part of the screen is moving, deterioration occurs near the boundary.

[Purpose of the invention]

The purpose of the present invention is to perform scanning line interpolation on a television signal that performs interlaced scanning and convert it into a progressive scanning signal, so that an image without unnaturalness can be obtained even when the subject moves. It's about putting pressure on people to be able to do it.

[Summary of the invention]

In order to achieve the above object, the present invention does not use only the signal one field before when performing interfield interpolation, but uses the average value of the signal one field before and the signal one field after. .

That is, in the present invention, interpolated scanning line signals are obtained as shown in FIG. When performing interfield interpolation to obtain interpolated scanning line signals Xn, n+1, the signal
The average value of n-2s2 and signal Xn+263 is used, and the average value of signal Xn and signal Xn+t is used when inter-field transition is performed. Then, the signal Xn-2sz and the signal Xn+2
63 is used to detect the movement of the subject by taking the difference between the two, and the ratio of inter-field interpolation and intra-field interpolation is controlled based on this movement value.

By doing this, it is possible to match the positions on the time axis of the signal obtained by inter-field interpolation and the signal obtained between the inner fields, and also the movement at the position of the scanning line to be interpolated. It becomes possible to detect the object itself.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. A television signal subjected to interlaced scanning inputted from an input terminal 1 is inputted to two cascade-connected field memories 2.4 and line memories 3 each having a capacity of 262H. With this configuration, the output signal Xn of the line memory 3
With reference to the signal Xn-262, 1 field before
A signal Xn+zss after the field and a signal Xn+1 after one line can be obtained. The average value Xa of the signal Xn-262 and the signal Xn+2ea is added to the first adding circuit 5 and the first
is determined by the coefficient circuit 6. Further, the average value xb of the signal Xn and the signal Xi
is determined by the ten coefficient circuit 8. The inter-field interpolation signal Xa and the intra-field interpolation signal xb obtained by applying pressure in this way
The mixing ratio is changed depending on the degree of movement of the secret object. Therefore, first, the signal Xfi-262 and the signal Xn+2ss are input to the motion coefficient calculating circuit 12 to calculate the motion coefficient K. The value of K is, for example, signal) (fi-262 and signal
If the difference from n+zss is small, it approaches l, and if the difference is large, it approaches 0, and so on.

A specific example of this motion coefficient calculation circuit 12 is, for example,
See No. 8-130685. The subtraction circuit 9, the multiplication circuit 10, and the addition circuit 11 generate the signal Xa and the signal XbK.
Then, the following equation is calculated to calculate the water pressure, and the multiplier circuit Xb+K (X
a-Xb) = K-Xa+ (1-K) Xb
If the multiplier of lo is used as a motion coefficient, an interpolation signal Xn, 1-H corresponding to the degree of motion can be obtained. The signals Xn, 'n+1 and the signal Xn thus obtained are sent to the time compression circuit 13.
, 14, and by switching the switch 15 for each scan line after time compression, it is possible to convert an interlace scanned television signal into a sequential scan signal.

According to this embodiment, the positions on the time axis of the interpolated scanning line signal obtained by interfield interpolation and the interpolated scanning line signal obtained by intrafield interpolation can be aligned.

Next, consider color television signals.

Considering a luminance signal and two color difference signals in a color television signal, human visual characteristics for the color difference signal are inferior to those for the brightness signal pressure, so for the color difference signal, adjacent scanning lines in the same field are Created only from signals. In other words, even if only the inner and outer portions of the field are processed, the deterioration of the image will hardly be noticeable. If K is used as described above, a frame memory for color difference signals and an interfield interpolation circuit are not required, so the configuration of the signal processing circuit can be extremely simplified.

By the way, considering a color television signal in which a luminance signal and two color difference signals are frequency multiplexed, in order to avoid incomplete color signal separation due to subject movement, If the movement is small, it is necessary to mainly perform inter-frame color signal separation, and if the movement is large, it is necessary to perform intra-field color signal separation. (Please see Japanese Patent Application Laid-Open No. 117788/1988 for information on inter-frame color signal separation.) Here, the frame memory used for the inter-frame color signal separation circuit is shared with the field memory for the field memory used for the inter-field interpolation circuit. It is not possible. This is because the field memory of the interfield interpolation circuit must record either a luminance signal or a color difference signal, whereas the frame memory must record a signal in which the luminance signal and color difference signal are frequency multiplexed. It is. This results in an increase in memory capacity.

Here, if the luminance signal and the two color difference signals are time-base multiplexed, the above problem will not occur. The field memory for two fields used for field interpolation can be shared with the frame memory used for motion detection, as shown in FIG.

Further, a circuit for separating the time-compressed and time-axis multiplexed luminance signal and color difference signal and then time-expanding them back to their original state can be realized using a line memory for at most several lines.

For example, a signal in which both a luminance signal and two color difference signals are time-axis multiplexed during one horizontal scanning period is
If you want to input to the circuit shown in the figure, first separate circuit 1
Each signal separated by 8 is time-expanded by a first expansion circuit 19 that time-expands the luminance signal, and second and third expansion circuits 20 and 21 that time-expands the two color difference signals, respectively. An interpolated scanning line signal can be obtained by inputting the signal into a circuit such as that shown in FIG.

In addition, in the case of a signal in which one of the two color difference signals is switched for each scanning line and multiplexed with the luminance signal on the time axis, the color difference signal that is not being sent must also be interpolated for each scan. There is. Therefore, even if only interfield interpolation is shown in the case of a still image, it is not possible to obtain an interpolated scanning line signal for both of the two color difference signals. As mentioned earlier, humans have poor visual characteristics when it comes to color difference signals. For these reasons, for color difference signals, it is sufficient to obtain interpolated scanning line signals only by intra-field interpolation.

FIG. 6 shows, as an embodiment thereof, a circuit configuration according to the present invention when processing a color television B signal. In the figure, input terminals 25, 26 and 27 are connected to output terminals 22, 23 and 24 in FIG. 5, respectively. The scanning line interpolation circuit 28 for the luminance signal input to the first input terminal 25 has the same configuration as the circuit shown in FIG. The scanning line interpolation circuit for the first color difference signal inputted to the second input terminal 26 and the scanning line interpolation circuit for the second color difference signal inputted to the third input terminal 27 are exactly the same. Since any configuration may be used, the scanning line interpolation circuit for the first color difference signal will be explained. Input signal Cn of line memory 29
+1 and the output signal Cn are input to the adder circuit 31 to obtain interpolated signals Cn and n+1. This signal Cn, n+
1 and the signal Cn into sound by the time compression circuits 33 and 34, and by switching the switch 37 for each scanning line after the time compression, sequential scanning is performed starting from the TV Jimin signal that is performing interlaced scanning. signal.

According to this embodiment, the configuration of the scanning line interpolation circuit for color difference signals can be extremely simplified.

In this embodiment, the color difference signal output is 1
Since it is preceded by a field period K, color shift may occur. In order to avoid this, the color difference signal may be delayed by one field period in advance on the transmitting side.

If no processing is being performed on the transmitting side, field memories with a capacity of 262H may be added after the input terminals 26 and 27 in this embodiment.

〔Effect of the invention〕

According to the present invention, the signal obtained by inter-field interpolation and the signal obtained by intra-field interpolation can be placed at the same position on the time axis, so even if the degree of movement of the subject changes, there will be no degradation due to movement K. It is possible to convert an interlaced scanning signal to a progressive scanning signal without causing any interference.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining a conventional example of the scanning line interpolation method;
3 is a diagram illustrating the principle of scanning line interpolation according to the present invention, and FIG. 4 is a diagram illustrating an embodiment according to the present invention.
Figure 5 is a diagram showing the time expansion circuit, Figure 6 is the 8AIC of the present invention.
FIG. 3 is a diagram showing another embodiment according to the present invention. 1, 17, 25, 26, 27...input terminals,
16, 22, 23. 24, 39, 40, 41...output terminal, 2, 4
... Field memory, 3, 29, 30... Line memory, 5, 7, 11゜31, 32... Adder, 6, 8... Coefficient circuit, 10... Multiplier, 9・・・
・Subtractor, 12...Motion coefficient calculation circuit, 13゜14
, 33, 34, 35, 36... time compression circuit,
15, 37. 38... Switch, 18... Separation circuit, 19, 20
．． 21... Time expansion circuit, 28... Scanning line interpolation circuit for brightness signal.

Claims (1)

[Claims] 1. In a signal processing method for inputting a television signal performing interlaced scanning and converting it into a progressive scanning signal, a first field memory that delays the input signal by one field period; a second field memory for further delaying the output of the field memory by one field period; and a first scanning line interpolation circuit that obtains a first interpolated scanning line signal from the average value of the output signal of the second field memory and the average value of the output signal of the second field memory; and a second scanning line interpolation circuit that obtains two interpolated scanning line signals, and the mixing ratio of the first interpolated scanning line signal and the second interpolated scanning line signal is determined depending on the degree of movement of the subject. and mixing means for changing the signal processing circuit. 2. The input signal of the first field memory and the second field memory
The mixing means has a motion detection circuit that determines the degree of movement of the subject from the output signal of the field memory of the field memory, and the mixing means detects the first interpolated scanning line signal and the second interpolated scanning line signal based on the output of the motion detection circuit. The signal processing circuit according to claim 1, characterized in that the ratio of scanning line signals is changed. 3. The signal according to claim 1, wherein a color television signal is input as the television signal, and the first and second interpolated scanning line signals are obtained at least for the luminance signal. processing circuit. 4. The signal processing circuit according to claim 3, wherein only the second interpolated scanning line signal is obtained for the color difference signal in the color television signal. 5. The television signal is a color television signal in which both a luminance signal and two color difference signals are time-axis multiplexed during one horizontal scanning period, and at least the luminance signal is subjected to first and second interpolation. The signal processing circuit according to claim 1, wherein the signal processing circuit obtains a scanning line signal. 6. The signal processing circuit according to claim 5, wherein a second interpolated scanning signal is obtained for the color difference signal. 7. The signal processing circuit according to claim 6, wherein the color difference signal in the television signal is delayed by one field from the luminance signal on the transmitting side.