JPH04101588A - Television signal transmitter-receiver - Google Patents

Abstract

PURPOSE:To correctly decode at all times a signal with an inverted phase in two frames in the case of a still picture by separating/controlling multiplexed signals according not only to the motion of the frame but to the judgement result of the motion of a frame which is located two frames before. CONSTITUTION:For example, when frames 5 to 8 are considered to be still pictures, '+M' is multiplexed to frames 5 and 6, and '-M' is multiplexed to frames 7 and 8. At this time, since frame 3 which is two frames before the frame 5 is an animation, 1 is made to stand for the coefficient (k) of a coefficient multiplier 45, and when a signal S2 of the frame 3 is subtracted from the signal S2+M of the frame 5, a multiplex signal 'M' of the frame 5 can be obtained. Next, in terms of the frame 7, the frame 5 which is two frames before the frame 7 is a still picture, so the coefficient (k) of the coefficient multiplier 45 is 1/2. The signal S2+M of the frame 5 is subtracted from a frame signal S2-M, and as a result, '-2M' is supplied to the coefficient multiplier 45 and multiplied by 1/2. Thus, multiplex signals can be separated under any condition.

Description

[Detailed Description of the Invention] (Object of the Invention) [Industrial Application Field] This invention is applicable to, for example, a 4.2MHz luminance signal (Y signal).
The present invention relates to a television signal transmitting/receiving device that transmits a television signal by expanding the band to 6 MHz.

[Prior Art] With the spread of large-screen displays, there is a desire for further improvement in image quality in television broadcasting.

One way to improve image quality is to increase the resolution of the Y signal, and this is because the current Y signal band is 4.
2 MHz, but this band is intended to be expanded to 6 MHz for transmission.

In other words, in contrast to the conventional Y signal with a band of 0 to 4.2 MHz, a Y signal with a band of 0 to 6 MHz is transmitted, and 4.2 to 6 MHz is transmitted only for still images.
The Hz luminance signal YH times the signal is transmitted. This is based on the fact that, as a characteristic of human vision, sensitivity is lower for moving images than for still images, and it is assumed that there is less need to transmit YH times the signal for moving images. Based on ideas.

An example of means for transmitting only YH multiplied signal still images will be described below.

FIG. 3 shows the configuration of an encoder that generates such a television signal.
The Y signal of ~6 MHz is supplied to a low pass filter (LPF) 12 with a pass frequency band of 4.2 MHz. This low-pass filter 12 passes only the Y signal of 0 to 4.2 MHz, outputs a band-limited Y signal, and supplies it to the adder circuit 13 .

Further, the band-limited Y signal from this low-pass filter 12 is supplied to a subtraction circuit 14, which subtracts the Y signal of 0 to 4.2 MHz from the input signal of 0 to 6 MHz.
A Y signal (YH signal) of 4.2-6 MHz is output from this subtraction circuit 14. The output from this subtraction circuit 14 is supplied to a multiplier 15, where it is modulated at 16/7 fsc (8.2 MHz), the phase of which is inverted every two frames. This modulated signal is passed through a low-pass filter 16 at 4.2F.
The band is limited to vIHz, and the output from this low-pass filter 16 is shifted in signal frequency by YH times,
It is considered to be a signal in the band of 2.2 to 4,000 MHz. However, the polarity of this signal is inverted in two frames.

The output signal from the low-pass filter 16 is input to the adder circuit 13 via the switch circuit 17 and multiplexed with the 0-4.2 MHz Y signal from the low-pass filter 12. This multiplexed signal is output from the output terminal 18, and the signal from the output terminal 18 is encoded into an NTSC signal and transmitted.

The switch circuit 17 is controlled by a motion detection signal, and is turned on when a still image is displayed and turned off when a moving image is displayed. Then, only in the case of a still image, the adding circuit 13 selects Y.

Multiplexing of signals is performed.

The means for detecting image movement is configured as follows.

The signal input to the input terminal 11 is input to a low-pass filter 19 limited to 2.0 MHz, and is
Bandwidth is limited to the following. Motion is detected using this 0 to 2 MHz signal, and this motion detection is performed in the same way in the decoder. In other words, the signal input to the decoder, which is 2 MHz or higher, is multiplexed by YH, but the signal input to the encoder is not multiplexed by YH, so the signal input to the encoder is not multiplexed by YH. Since the decoder and encoder do not use the same signal, a signal of 0 to 2 MHz is used for this motion detection.

The output signal from this low-pass filter 19 is input to a subtracter 21 after being delayed by 1/30 seconds in a delay circuit 20.

A signal from the low-pass filter 19 is also input to the subtracter 21, and the signal is subtracted from the output from the low-pass filter 19. Therefore, the subtracter 21 outputs a difference signal between one frame. When this signal is large, it is regarded as a moving image, and when it is small, it is regarded as a still image.

The non-linear circuit 22 performs this determination process, and the output from this circuit 22 is used as a motion detection signal.
In the case of a moving image, the output of this circuit 22 is "1", and in the case of a still image, the output of this circuit 22 is "0".

Here, YH-fold signal multiplexing is multiplexed by inverting the phase in two frames, and in order to separate this with a decoder, Y,
The signals must be multiplexed. Therefore,
The motion detection signal from the nonlinear circuit 22 is supplied to a 1/3o second delay circuit 23 and also to a maximum value circuit 24. In this maximum value circuit 24, the nonlinear circuit 2
The magnitude of the two outputs and the output 1/30 seconds earlier, that is, one frame earlier, is determined, and the larger signal is output. That is, 2 of the maximum value circuit 24
Only when both inputs are rOJ indicating a still image,
The output from the maximum value circuit 24 becomes "0" indicating a still image,
This continues for two or more frames and is used as a motion detection signal indicating that the image is a still image. When at least one of the two inputs of the maximum value circuit 24 is "1" indicating a moving image, the d signal of the maximum value circuit 24 comes to indicate a moving image.

The motion detection signal from the maximum value circuit 24 controls the switch circuit 17, and only when the still image continues for two or more frames, the switch circuit 17 is turned on, and YH times the signal is multiplexed. .

A signal output from such an encoder is supplied to a decoder shown in FIG. That is, a luminance signal Y of 0 to 4.2 MHz multiplexed with a high frequency signal YH is supplied to the input terminal 31. This input signal is serially supplied to 1/30 second delay circuits 32 and 33, and is further supplied to a subtracter 3.
4 and 35, 2.0 MHz low-pass filters 36 in parallel. First, the delay circuit 32 delays the input signal by one frame. This signal is further delayed by one frame in the delay circuit 33, and is supplied to the subtracter 34, where it is subtracted from the signal input to the input terminal 31. do.

This subtracter 34 performs subtraction with the signal of two frames before, and obtains a multiplexed signal with the phase inverted in two frames.

The primary signal is S and the multiplexed signal is M. Since multiplexing is performed only in still images, let us consider the case of still images. Since the multiplexed image is a still image, the main signal two frames before is S.

In this case, since the multiplexed signal is inverted between two frames, it becomes "-M". Therefore, the current signal is (S+M)
Therefore, the signal two frames before becomes (SM). If this difference is calculated, it will be (S + M) -' (SM) -2M, and only the multiplexed signal will be obtained, which will be the output of the subtracter 34.

In this state, the value is doubled, so the coefficient multiplier 36 multiplies it by 1/2 to obtain the correct multiplexed signal M.

The output signal from the coefficient multiplier 3B can be obtained as a multiplexed signal only when the image is a still image, and the switch circuit 37 allows it to be extracted only when the image is a still image. That is, in the case of a moving image, this switch circuit 37 is turned off so that the signal from the coefficient multiplier 36 is not output, and in the case of a still image, this switch circuit 37 is turned on and outputted. The output signal from this switch circuit 37 is then supplied to a subtracter 35 and a multiplier 38.

In the subtracter 35, the multiplexed signal is subtracted from the input signal, so that the subtracter 35 outputs either the high frequency luminance signal YH or the unmultiplexed O~4.2MHz signal.
A Y signal is output.

Such an operation occurs in the case of a still image; in the case of a moving image, since the switch circuit 37 is in an off state, the signal input to the input terminal 31 is output from the subtracter 35 as it is.

However, in the case of such a moving image, the YH signal is not multiplexed on the human input signal, so a Y signal of 0 to 4.2 MHz is output from the subtracter 35.

The multiplier 38 divides the signal obtained from the switch circuit 37 into 2
16/7fsc (8,2M
Hz), and this demodulated signal is band-limited by a 6 MHz low-pass filter 39. The output signal from this low-pass filter 39 is YH of 4.2 to 6 MHz.
There is a doubled signal, and this signal is added in an adder 40 with the Y signal of 0 to 4.2 MHz, which is the output from the subtracter 35, and the Y signal of 0 to 6 MHz is obtained from the adder 40. This Y signal is output from the output terminal 41.

In the case of a still image, the Y signal obtained by adding the YH times signal is output. In the case of a moving image, the input to the multiplier 38 is "0", so the output of the low-pass filter 39 is also "0". Therefore, the output from the adder 40 becomes the same Y signal as the output from the subtracter 35.

That is, the band of the Y signal output from the output terminal 41 is 0 to 6 MHz in the case of a still image, and 0 to 4.2 MHz in the case of a moving image.

Here, the switch circuit 37 is controlled by a motion detection signal. This motion detection signal is sent to a 1/30 second delay circuit 42, which is supplied with a signal from a low-pass filter 36, and a subtracter 4.
3. Non-linear circuit 44. This is obtained by a motion detection circuit consisting of a 1/30 second delay circuit 45 and a maximum value circuit 46, and this is the same configuration as shown in FIG. 3 from the low-pass filter 19 to the maximum value circuit 24. Therefore, the explanation will be omitted.

That is, in the case of a still image, if the phase is inverted and multiplexed in two frames of the YH multiplied signal and the television signal is transmitted, it is possible to increase the resolution of the luminance signal (Y) in the case of a still image.

However, correct reproduction is actually performed only when a still image continues for two or more frames, and correct reproduction is no longer performed when a moving image is converted to a still image. Therefore, in the case of an image in which a moving image and a still image are rapidly switched, the reproduced image may become corrupted, resulting in an inconvenient situation.

[Issue 8 to be solved by the invention] This invention was made in view of the above points, and in the case of a still image, the encoder inverts the phase in two frames and multiplexes the Y)l signal. This solves the problem that when trying to decode, accurate playback is performed only when a still image continues for two or more frames, and it cannot be played correctly when a video changes to a still image. An object of the present invention is to provide a television signal transmitting/receiving device that can always correctly decode a signal whose phase is inverted in two frames to operate a television receiver.

(Structure of the Invention) [Means for Solving the Problem] The television signal transmitting/receiving device according to the present invention inverts the phase in two frames in the case of a still image, multiplexes the YH signal, transmits it, and decodes it. At this time, it is determined whether the transmitted signal is a still image or a moving image, and when it is determined that it is a still image, the movement of the frame two frames before is judged instead of the movement of that frame, and the Separation of multiplexed signals is controlled accordingly.

[Function] In the television signal transmitting/receiving device configured in this manner, when the signal two frames before is determined to be a still image, the multiplexed signal of the current frame is inverted and the multiplexed signal of the two frames previous is determined to be a still image. multiplexed into the signal. Therefore, in order to separate the multiplexed signal of the current frame, it is sufficient to subtract the signal of two frames before from the signal of the current frame and multiply the signal by 1/2. In addition, if the signal two frames before is a moving image, there is no multiplexed signal in the signal two frames ago and only the main signal, and this main signal is the current frame or the main signal of the current frame if it is a still image. is the same as Therefore, if the current frame is a still image and the previous frame is a moving image, the multiplexed signal of the current frame can be separated by subtracting the signal of the previous frame from the signal of the current frame. That is, by switching the multiplexed signal separation means depending on whether the signal from two frames before is subjected to still image processing or moving image processing,
The correct multiplex signal separation operation is always performed.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a decoder, and a signal from an encoder as shown in FIG. 3 is input to an input terminal 41 of this decoder. The input signal is supplied to a 1/30 second delay circuit 42, and the output signal from this delay circuit 42 is
The signal is further supplied to a 1/30 second delay circuit 43. That is, the signal is delayed by two frames by the delay circuits 42 and 43, and the output signal from the delay circuit 43 is supplied to a subtracter 44 and subtracted from the input signal. The subtracter 44 outputs a difference signal between two frames, and this difference signal is input to the coefficient unit 45. The coefficient of this coefficient unit 45 is controlled and set by a motion detection signal, and is set to "1" in the case of a moving image, and to rl/2J in the case of a still image.

The means for detecting image movement is configured as follows.

The signal input to the input terminal 41 is input to the low-pass filter 4B limited to 2.0 MHz, and the band is limited to 2 MHz or less.

The output signal from the low-pass filter 46 is delayed by 1/30 seconds in a delay circuit 47 and then input to a subtracter 48 .

The signal from the low-pass filter 46 is also input to this subtracter 48, and the signal is subtracted from the output from this low-pass filter 46. Therefore, the subtracter 48 outputs a difference signal between one frame. When this signal is large, it is regarded as a moving image, and when it is small, it is regarded as a still image.

The non-linear circuit 49 performs this determination process, and the output from this circuit 49 is a motion detection signal.
In the case of a moving image, the output from this circuit 49 is "1", and in the case of a still image, the output from this circuit 49 is "0".

Here, YH-fold signal multiplexing is multiplexed with the phase reversed in two frames, and in the decoder, YH-fold signal multiplexing is performed only when a still image continues for two frames or more. It must be determined that there is. Therefore, the motion detection signal from the non-linear circuit 49 is supplied to a 1/30 second delay circuit 50 and also to a maximum value circuit 51. In this maximum value circuit 51, the output from the non-linear circuit 49 and It is determined whether the signal is larger or smaller than the output before 1730 seconds, that is, one frame, and the larger signal is output. That is, only when the two outputs of the maximum value circuit 51 both become "0" indicating a still image, the output from the maximum value circuit 51 becomes "0" indicating a still image, and the output from the maximum value circuit 51 becomes "0" indicating a still image. This is followed by a motion detection signal indicating that the image is a still image. When at least one of the two inputs of the maximum value circuit 51 is "1" indicating a moving image, the output of this maximum value circuit 51 comes to indicate a moving image.

The motion detection signal output from the maximum value circuit 51 is 1/3
Coefficient unit 45 via 0 second delay circuits 52 and 53 in series
is supplied to Here, the output signal from the delay circuit 53 is a motion detection signal of the signal two frames before, and therefore the coefficient unit 45 determines whether the coefficient k is "1" or rl according to the motion detection signal two frames before. /2J.

Here, the case where YH is multiplexed by inverting the phase in two frames will be explained using FIG. 2. In this figure, consecutive 1
The signal for 0 frames is being viewed, and the number shown in the circle at the top indicates the frame number, Sn indicates the main signal, and M indicates the multiplexed signal.

The movement of the image is determined by comparing it with the signal from one frame before. That is, if it is the same as the previous frame, it is determined that it is a still image, and if it is different, it is determined that it is a moving image. Therefore, in the case shown in this figure, 4 to 8 frames are still images. However, in this example, the phase is inverted and multiplexed between two frames, so it is only considered a still image when it continues for two or more frames.
Therefore, frames 5 to 8 are now considered to be still images.

In such a signal, multiplexing is performed by inverting the phase in two frames, so in frames 5 and 6, "
+M'' will be multiplexed, and -M'' will be multiplexed on the 7th and 8th frames. If you try to separate this multiplexed signal in a decoder, for example, in 7 frames, 2
Find the difference from the previous 5 frames and divide that value by 1/2
do it. That is, ((S2-M)-(S2+M))/2--M, and a signal multiplexed into 7 frames is obtained.

Further, in order to obtain the main signal S2 of 7 frames, the multiplexed signal obtained by the above equation may be subtracted from the transmitted 7 frame signals. In order to separate the 8-frame signal into the main signal and the multiplexed signal, it is sufficient to perform calculations on the 6-frame signal two frames before the 8-frame signal, as in the case of the 7-frame signal. This applies to still images; in the case of moving images, no multiplexing is performed, so the transmitted signal becomes the main signal as it is.

However, even in the case of a still image, if the 3 frames before 2 frames are considered to be a video and are not multiplexed or multiplexed, such as the 5th frame, the 5th frame cannot be decoded using the same method as the 7th frame described above. Correct decoding cannot be performed assuming that the image is a still image. In other words, if you try to separate multiplexed signals in 5 frames, it becomes ((S2 + M) - (S2))/2 - M/2,
The main signal of 5 frames is (S2 +M)-(S/2)-82+(M/2). Therefore, neither the main signal nor the multiplex signal can be correctly decoded in 5 frames. This also applies to 6 frames.

Based on this premise, the operation of the coefficient multiplier 45 will be further explained. For example, considering separating a 5-frame multiplexed signal, the following will occur. In other words, since the 3 frames 2 frames before frame 5 are moving images,
The output signal from the 1/30 second delay circuit 53 comes to indicate a moving image, and the coefficient of the coefficient multiplier 45 is set to "1". Therefore, the signal obtained by subtracting the signal of two frames before from the signal of the current frame output from the subtracter 44 is sent to the coefficient unit 44 as it is.
Output from 5. In other words, the signal of 5 frames (S2
-M), a 5-frame multiplexed signal "M" is obtained, and the coefficient unit 45 outputs the current frame multiplexed signal.

Next, if we consider the case of 2 frames before or a still image, for example 7 frames, the 57 rem 2 frames before is a still image, so the output from the 1/30 second delay circuit 53 indicates a still image. There is. Therefore, the coefficient set in the coefficient unit 45 is rl/2j. In such an example, the subtracter 44 subtracts the 5-frame signal (S2 +M) from the 7-frame signal (S2-M), and the result is "-
2M" is supplied to the coefficient multiplier 45 and multiplied by 1/2. Therefore, the output from the coefficient multiplier 45 becomes a multiplexed signal "-M" of seven frames.

Furthermore, when the current frame is a moving image, the switch circuit 54 to which the output signal from the coefficient multiplier 45 is supplied is turned off by the motion detection signal from the maximum value circuit 51, so that regardless of the output from the coefficient multiplier 45, the switch circuit 54 is turned off by the motion detection signal from the maximum value circuit 51. , the multiplexed signal is always “0”
” is set.

The multiplexed signal taken out when the switch circuit 54 is on is subtracted from the input signal by a subtracter 55 and transmitted to an adder 56 as only the main signal. The adder 5B receives the multiplexed signal from the switch circuit 54, and the multiplier 57 inverts the phase of the multiplexed signal in two frames.
The multiplexed signal demodulated at 0 to 6 MHz is supplied through a 6 MHz low-pass filter 58 and output from an output terminal 59 as a 0 to 6 MHz signal.

[Effects of the Invention] As described above, according to the television signal transmitting/receiving device according to the present invention, a circuit that delays a motion detection signal by two frames is set, and the coefficients of a coefficient multiplier are determined by the motion detection signal delayed by two frames. By switching, multiplexed signals can be separated under any conditions.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining the decoder of a television signal transmitting/receiving device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the state of multiplexed signals, and FIG. 3 is a diagram for explaining the state of multiplexed signals. FIG. 4 is a block diagram illustrating a conventional decoder. 12.1tli-o-pass filter (4,2MHz),
20.23.42.43.47.50.52.53...
・1/30 second delay circuit, 13.50...adder, 14
．． 21.44.48.55...Subtractor, 24.51...
・Maximum value circuit, 15.57...multiplier, 45...coefficient unit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] Only when the first television signal is determined to be a still image, the second television signal is multiplexed so that the phase is inverted every two frames, and the third television signal is means for generating a signal; determining whether the third television signal is a moving image or a still image; and generating a motion detection signal for determining whether the third television signal is a moving image or a still image; means for separating the first television signal and the second television signal only when the signal indicates that the signal is a still image, and the separating means is configured to separate the third television signal two frames before the third television signal. means for determining whether the signal is a moving image or a still image; means for subtracting the television signal to obtain a second television signal; and subtracting the second television signal determined by the means from the third television signal of the current frame to obtain the first television signal. a first separating means for determining and separating the first and second television signals; and when the determining means determines that the image is a still image, the third television signal of the current frame is separated two frames before the third television signal. means for obtaining a multiplexed second television signal by subtracting a third television signal from the subtracted signal and multiplying the subtracted signal by 1/2; and a second television signal obtained by this means. a second separating means for obtaining the first television signal by subtracting the current frame from the third television signal, and separating the first and second television signals. John signal transmitter/receiver.