JPH04238483A - Television signal converter - Google Patents

Abstract

PURPOSE:To prevent production of noise due to malfunction of a movement detection circuit by controlling the operating mode of the movement detection circuit in response to a signal representing the movement of a picture in control signals multiplexed onto a MUSE signal. CONSTITUTION:A mixer circuit 107 mixes a signal subject to frame addition by an inter-frame Y/C separator circuit 106 and a signal directly outputted from an A/D converter 120 based on a movement signal fed from a movement detection circuit 105. For example, when a movement information signal outputted from a MUSE-NTSC converter represents a full still picture mode, the separator circuit 106 outputs only the frame addition processing signal. Thus, the movement detection mode of the circuit 105 is controlled in response to a signal representing the movement of a picture in control signals multiplexed onto the MUSE signal to avoid improper movement detection, then production of noise due to malfunction of the circuit 105 in a still picture especially.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is based on MUSE (Muli
ple Sub-Nyqist Sampling
Encoding) method and EDTV (Extend
The present invention relates to a television signal conversion device that is effective in associating signals such as ed Definition TV).

0002

2. Description of the Related Art A MUSE-NTSC converter has been developed that converts a MUSE system signal into an NTSC system signal. However, when converting the MUSE signal to a signal of another system, it is conceivable that not only conversion to the generally widespread MTSC system but also an EDTV system signal is required. FIG. 3 shows an example of a configuration in which a MUSE-NTSC converter and an EDTV system processing device are combined.

[0003] A MUSE signal is supplied to an input terminal 101 and input to a MUSE-NTSC converter 102 . The S-terminal brightness signal Sy can be obtained from the MUSE-NTSC converter 102. Also, MUSE-N
The TSC converter 102 performs interfield interpolation processing on the MUSE signal to convert the number of scanning lines.
It is also possible to obtain five 1:1 signals (non-interlaced signals) [luminance signal Y, color difference signals (RY), (B-Y)]. The S-terminal luminance signal Sy (525 2:1 interlaced signals) is input to the luminance color separation (Y/C separation) device 104. The Y/C separation device 104 includes a motion detection circuit 451, an interframe Y/C separation circuit 106, and a mixing circuit 107, and the S terminal luminance signal output from the MUSE-NTSC converter 102 is converted into an A/D
digitized by the converter 120 and motion detection circuit 451;
The signal is input to an interframe Y/C separation circuit 106 and a mixing circuit 107. In the first place (in EDTV usage state), the interframe Y/C separation circuit 106 forcibly performs luminance/chrominance signal separation using interframe correlation when a standard signal is input. Since the S terminal luminance signal Sy is input, this signal is processed between frames, and the M
The characteristic 15 Hz flicker component of the output signal of the USE-NTSC converter 102 is removed.

[0004] In this system, during EDTV signal processing, the inter-frame Y/
The C separation circuit 106 is the MUSE-NTSC converter 1
When used in combination with 02, it is used to remove the unique 15Hz flicker component contained in the output of this converter.

[0005] However, this signal processing is effective only for still images, and is accompanied by deterioration in image quality for moving images. Therefore, as a countermeasure, the motion of the image is detected by the motion detection circuit 451, and the output signal from the interframe Y/C separation circuit 106 and the S terminal luminance signal Sy output from the MUSE-NTSC converter 102 are determined according to the degree of motion. and are mixed in a mixing circuit 107. The motion detection signal from motion detection circuit 451 is for controlling the mixing ratio.

FIG. 4 shows a specific configuration example of the motion detection circuit 451. The digital video signal from the A/D converter 120 is supplied to a frame memory 402 and subtracters 403 and 407. The output of frame memory 402 is further supplied to frame memory 404. Subtractor 403 obtains the difference between the input and output of frame memory 402 (interframe difference signal), and supplies this to low-pass filter 405 . The low-frequency output of 405 is input to an absolute value circuit 409. The subtracter 407 calculates the difference between the input of the frame memory 402 and the output of the frame memory 404 (difference signal between two frames).
is determined and supplied to the absolute value circuit 408. The output of the absolute value circuit 408 is supplied to the maximum value detection circuit 411 and is also supplied to the maximum value detection circuit 411 via the frame memory 410 after being delayed by one frame. Furthermore, the output signal from the maximum value detection circuit 411 and the absolute value circuit 40
The output signal from 9 is also supplied to an absolute value detection circuit 412.

The motion detection signal is normally obtained as an interframe difference signal, but in the case of a MUSE signal, for example, it is used together with a difference signal between two frames. Furthermore, the difference signal between two frames is delayed by one frame and used to compensate for the missing moving part of the image one frame before. The maximum value detection circuit 412 detects the maximum one of the three detection signals and outputs it to the output terminal 413.

[0008]Returning to FIG. 3, explanation will be given. Y/C separation device 1
The output signal from 04 is input to the next stage motion adaptive progressive scan converter 108. Motion adaptive progressive scan conversion device 10
8, the interlaced signal is converted into a 525-line 1:1 signal (non-interlaced signal). in this case,
In still images, inter-frame signal processing is performed, so 30
Hz flicker components are removed. This signal is input to the next stage low frequency replacement circuit 112. Low frequency replacement circuit 112
is a subtracter 109, a low-pass filter 110, an adder 1
11. The subtracter 109 has MUS
The luminance signal (525
1:1) is supplied via switch 113. The switch 113 is the MUSE-NTSC converter 10
Opening/closing is controlled by the mode signal output from 2, and is turned on in the simple MUSE signal processing mode. Subtractor 10
9, the signal output from the motion resistance progressive scan converter 108 is subtracted from the progressive scan luminance signal from the MUSE-NTSC converter 102, and the output is passed through the low-pass filter 1.
10 to an adder 111.

[0009] Low-pass filter 110 has a cutoff frequency of about 3 MHz. By adding the output of the low-pass filter 110 and the signal output from the motion adaptive progressive scan converter 108, the horizontal low frequency component of the output of the motion adaptive progressive scan converter 108 is converted to MUSE-N with high vertical resolution.
It will be replaced by the luminance signal Y from the TSC converter 102. In this way, the low frequency replacement circuit 112
Since there is no flicker of the 15 Hz component in the 4 MHz or lower component of the E signal, this is used. The luminance signal from the low frequency replacement circuit 112 is input to the matrix circuit 114.

A mode signal is also input to the matrix circuit 114, and when this mode signal indicates the MUSE signal processing mode, the MUSE-NTSC converter 1
It is controlled so that the (RY) and (B-Y) signals from 02 are introduced. These (RY) and (B-Y) signals are non-interlaced signals. Matrix circuit 114 uses the input signal to obtain R, G, and B signals.

FIG. 5 shows the MUSE-NTSC converter 1.
02 is shown. A MUSE signal is supplied to an input terminal 501, and is supplied to an A/D converter 503 via an 8.1 MHz band low-pass filter 502. This signal is converted to 16.2MH by A/D converter 503.
It is digitized by the clock rate of z. The output of the A/D converter 503 is input to a simple MUSE processing circuit 504 and a timing circuit 507. Scanning line converter 505
is supplied with a timing signal from a timing circuit 507, and a process of converting a 1125-line 2:1 interlaced signal into a 525-line 1:1 non-interlaced signal is performed here. The luminance signals Y, (RY), and (B-Y) that have been subjected to scanning line conversion are distributed to an interlace system and a non-interlace system, respectively. In the interlace system, the output signal from the scanning line conversion processing circuit 505 is supplied to the interlace conversion processing circuit 506, where it is converted into a 525-line 2:1 interlaced signal. Interlace-converted luminance signal Y,
(RY) and (B-Y) signals are each sent to the D/A converter 5.
After being converted into analog signals at 08, 509, and 510, the signals are supplied to low-pass filters 511, 512, and 513. The outputs of the low-pass filters 512 and 513 are supplied to a quadrature modulator 514 and modulated into a 3.58 MHz carrier color signal, and then supplied to a synchronization burst adding circuit 516 and an adder 515.

The adder 515 combines the chrominance signal and the luminance signal and supplies the combined signal to a synchronization burst adding circuit 516 . A synchronization burst adding circuit 516 creates an NTSC composite video signal by adding a synchronization signal and a burst signal to the output signal obtained from the adder 515 and outputs it to an output terminal 519. Also, the output terminal 517 has a low-pass filter 5.
An S-terminal luminance signal Sy can be obtained by adding a synchronization signal to the output signal from the quadrature modulator 514, and an S-terminal chrominance signal Sc can be obtained by adding a burst signal to the output signal from the quadrature modulator 514 at the output terminal 518. .

In the non-interlaced system, the luminance signals Y, (R-Y), obtained by the scanning line conversion processing circuit 505 are
(B-Y) signals are sent to D/A converters 520 and 521, respectively.
, 522, and each analog signal passes through low-pass filters 523, 524, 525 to output terminals 526, 5.
27 and 528, respectively, as non-interlaced signals.

According to the above example, MUSE-NTSC
The converter outputs 525 sequential scanning signals each of a luminance signal and two color difference signals, and in the EDTV circuit, the S terminal and 5
A path is provided that receives both of the 25 sequential scanning signals and leads the S terminal luminance signal to the three-dimensional Y/C separation circuit. Then, frame addition processing is performed on the still image portion of the luminance signal, and after motion-adaptive progressive scanning conversion is performed on this signal, the horizontal low-frequency components of the 525 progressive scanning inputs and the horizontal low-frequency components of the motion-adaptive progressive scanning conversion output are combined. component is replaced. As a result, it is possible to reduce the 15Hz flicker in the high spatial resolution part that remained in the MUSE-NTSC converter, and by using the signal from the MUSE-NTSC converter before interlace conversion as the horizontal low frequency component. , the vertical resolution can be improved even in moving images.

[0015]

[Problem to be solved by the invention] As mentioned above, MU
High-definition output signal of SE-NTSC converter (ED
By supplying the signal to the TV (TV) circuit, it is possible to eliminate flicker and improve vertical resolution, but this alone cannot eliminate noise caused by folding, which is unique to the MUSE method. As mentioned above, the MUSE signal has 4
Contains no aliasing components below MHz. When this signal is converted into an NTSC signal by a MUSE-NTSC converter, the signal does not include folding up to approximately 1.4 MHz. This is a value converted by the number of scanning lines and the aspect ratio of the screen.

By the way, the low-pass filter 405 in FIG.
has a cut-off frequency of about 2 MHz. However, as mentioned earlier, the output signal from the MUSE-NTSC converter does not include aliasing components up to 1.4 MHz, so the low-pass filter 4
The output signal from 05 will even include aliasing components. For example, when the image is a still image, the motion detection circuit malfunctions due to the aliasing component, and it is determined that there is movement even though it is a still image, and that area is subjected to motion processing. In other words, the input signal does not pass through the interframe Y/C separation circuit 106 shown in FIG. 3 and is not subjected to addition processing between frames, so the 15 Hz aliasing component cannot be removed. Furthermore, when there is a scene change where the picture changes completely between frames, it is affected by the picture between the two frames, so for example, even if there is no movement between the previous frame and the previous frame, it is determined that there has been movement. There are problems such as folding appearing on the entire screen.

As mentioned above, the MUS is connected to the EDTV system circuit.
When the output signal from the E-NTSC converter is input and processed. Due to the aliasing component included in the MUSE signal, high image quality performance cannot be fully exploited.

Therefore, the present invention provides an EDTV system circuit with M
When the output signal from the USE-NTSC converter is input, the motion information included in the MUSE signal is used to perform processing according to the movement of the screen, suppressing deterioration of image quality due to aliasing components included in the MUSE signal, and An object of the present invention is to provide a television signal conversion device that can improve image quality.

[0019]

[Means for Solving the Problems] The present invention provides a method for converting a television signal having a different number of scanning lines from that of the current television system into a band compressed television signal by performing offset subsampling between frames. a first means for interpolating subsamples within a field and converting the number of scanning lines to the same number as the number of scanning lines of the current television system; and delaying the output signal of the first means by one frame. a delay means, a second means for reproducing the motion information signal multiplexed during the blanking period of the band-compressed television signal, and a third means for detecting a moving part of the image from the output of the first means. means for adding an input to the delay means and an output from the delay means; mixing the input to the delay means and the output from the addition means in accordance with a motion detection signal from the motion detection means; and a fourth means for outputting the motion information, and the third means is configured to be controlled by the motion information obtained from the second means.

[0020]

[Operation] By the above means, MU is added to the EDTV system circuit.
The output of the SE-NTSC converter (525 lines interlaced) is supplied, and in order to perform interframe addition processing, 15Hz flicker components are removed for still images, and interframe addition is performed according to the motion control information multiplexed on the MUSE signal. Since the processing is performed, it is possible to prevent malfunctions occurring in the motion detection circuit in the EDTV system circuit due to the aliasing component included in the MUSE signal.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. Parts common to those in FIG. 3 are given the same reference numerals as in the same figure. The difference from the device in FIG. 3 is the MSUE-NTSC converter 1.
The motion information from 02 is sent to Y/C via switch 103.
This is applied to the motion detection circuit 105 of the separation device 104. Here, the switch 103 is MUSE-NTSC
On/off control is performed by a mode signal output from converter 102. The switch 103 is turned on in the MUSE signal processing mode, and transfers the motion information output from the MUSE-NTSC converter 102 to the Y/C separation device 10.
Supply to 4. The other parts are the same as the configuration shown in FIG. 3, and the functions are also the same. Note that the mode signal from the MUSE-NTSC converter 102 is output from the timing circuit 507 as explained in FIG.

FIG. 2 specifically shows the motion detection circuit 105 described above. Portions common to the circuit shown in FIG. 4 are given the same reference numerals. The difference from the circuit shown in FIG. 4 is that switches 206 and 207 are provided between the absolute value circuit 408 and the maximum value detection circuit 414, and between the absolute value circuit 409 and the maximum value detection circuit 412, respectively. be. The switches 206 and 207 are controlled by control signals 204 and 205 from the motion information discrimination circuit 203, and the motion information discrimination circuit 203 receives the output (motion information) from the switch 103 shown in FIG. signals) are supplied.

[0024] From MUSE-NTSC converter to terminal 2
The motion information signal supplied through 02 is a 3-bit signal indicating the movement of the screen among the control signals multiplexed with the MUSE signal, and is a 3-bit signal that indicates screen movement. This indicates the degree of movement. The motion information discrimination circuit 203 uses control signals 204 and 207 to turn on switches 206 and 207, respectively, when the motion information signal indicates the normal mode, and turns on the switch 206 when the motion information signal indicates the still image mode. , controls the switch 207 to turn off. Due to this effect, in normal mode, 2
A motion detection signal based on an inter-frame difference signal and a 1-frame difference signal is obtained; in quasi-still image mode, a motion detection signal using only a 2-frame difference signal is obtained; and when a scene change is indicated, a 1-frame difference signal is obtained. only is input to the maximum value detection circuit 412. In the complete still image mode, the two-frame difference signal and the one-frame difference signal are not output, so no motion detection operation is actually performed.

Referring back to FIG. 1, the explanation will be given below. The mixing circuit 107 is
The signal subjected to frame addition processing by the interframe Y/C separation circuit 106 and the signal directly output from the A/D converter 120 are mixed based on the motion signal supplied from the motion detection circuit 105 described above. For example, MUSE-NTSC
When the motion information signal output from the converter indicates the all still image mode, only the signal subjected to frame addition processing by the interframe Y/C separation circuit 106 is output. In this way, the motion detection circuit 1 operates according to the signal indicating the movement of the image among the control signals multiplexed with the MUSE signal.
The motion detection mode of 05 is controlled to prevent inappropriate motion detection. Therefore, noise generation due to malfunction of the motion detection circuit 105 can be prevented, especially in still images. FIG. 6 shows the MUSE-NTSC converter in FIG. 1 in more detail.

The difference between this converter and the circuit shown in FIG. 5 is that a control signal decoding circuit 550 is newly added to the timing circuit 507, and a motion information signal indicating the movement of the screen is decoded from among the control signals multiplexed on the MUSE signal. It has the ability to extract. The motion information signal is derived via terminal 530 and provided to switch 103 as shown in FIG.

[0027]

As explained above, the present invention controls the operation mode of a motion detection circuit according to a signal indicating image movement among the control signals multiplexed on the MUSE signal by simple means, and Since necessary motion detection is not performed, noise generation due to malfunction of the motion detection circuit is prevented. Therefore, MUSE-N
The output of the TSC converter can be fed to an EDTV circuit to help obtain improved picture quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram specifically showing the motion detection circuit of FIG. 1;

FIG. 3 is a block diagram showing a high-definition television signal processing device that is a premise of the present invention.

FIG. 4 is a circuit diagram specifically showing the motion detection circuit of FIG. 3;

FIG. 5 is a block diagram specifically showing the MUSE-NTSC converter of FIG. 3;

FIG. 6 is a block diagram specifically showing the MUSE-NTSC converter of FIG. 1;

[Explanation of symbols]

102...MUSE-NTSC converter, 103...Switch, 104...Y/C separation device, 105...Motion detection circuit, 106...Inter-frame Y/C separation circuit, 107...Mixing circuit, 108...Motion adaptive progressive scan conversion device, 109 ...Subtractor, 110...Low pass filter, 111...Adder, 11
2...Low frequency replacement circuit, 113...Switch, 114...Matrix circuit, 203...Motion information discrimination circuit, 206, 20
7... Switch, 402, 404, 410... Frame memory, 403... Subtractor, 405... Low pass filter, 40
8, 409... Absolute value circuit, 412, 414... Maximum value detection circuit.

Claims (1)

[Claims] Claim 1: A television signal having a different number of scanning lines than the current television system is band-compressed by performing offset subsampling between frames, and the offset subsampling between frames is interpolated within the field. a first means for processing and converting the number of scanning lines to the same number as the number of scanning lines of the current television system; and reproducing the motion information signal multiplexed during the blanking period of the band-compressed television signal. a second means; a delay means for delaying the output signal of the first means by one frame; a third means for detecting a moving part of the image from the output of the first means; addition means for adding an input and an output from the delay means; and fourth means for mixing and outputting the input to the delay means and the output from the addition means according to a motion detection signal from the motion detection means. A television signal conversion device, characterized in that the third means is configured such that a motion detection mode is controlled by a motion information signal obtained from the second means.