JPH04282996A - Television signal transmission system and reproduction device thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmission system and a reproducing apparatus thereof which eliminate cross-color interference.

0002

[Prior Art] Conventionally, in the NTSC color television transmission system, I and Q signals are converted into color subcarrier fsc.
A color television signal that is balanced modulated and multiplexed in a frequency region that overlaps with the luminance signal is used.

0003

[Problems to be Solved by the Invention] As mentioned above, in the color television signal in the conventional NTSC system, I,
Since the Q signal is multiplexed in a frequency domain that overlaps with the luminance signal, it has been impossible to completely separate the luminance signal from the I and Q signals on the receiver side. Therefore, there is a problem in that disturbances such as cross color and cross luminance occur in the reproduced image, which deteriorates the image quality of the reproduced video.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a band-limiting means for band-limiting two color signals or I and Q signals in the horizontal and vertical directions; Compression means for compressing limited color difference signals or I and Q signals in the horizontal and vertical directions; and a color signal consisting of the color difference signals or I and Q signals compressed by the compression means in a vertical overscan region of a television signal. The structure is provided with multiplexing means for multiplexing.

In addition, the NTSC color television signal transmission system limits the bands of the two I and Q signals in the horizontal and vertical directions, compresses them, modulates them with a color subcarrier, and multiplexes them in the vertical overscan area of the NTSC signal. In a high-definition color television signal reproducing device compatible with demodulation means for demodulating the color signal; interpolation/expansion means for interpolating and expanding the color signal demodulated by the demodulation means in the horizontal and vertical directions; and a YC for separating the luminance signal Y from the color television signal after detection.
The apparatus is configured to include a separation means, a color signal derived from the interpolation/expansion means, and a matrix means for obtaining R, G, and B television signals from the luminance signal Y.

[0006]

[Operation] On the transmitting side, the color difference signal or I, Q signal is band-limited and compressed, then modulated with the color subcarrier fsc, multiplexed into the vertical overscan area of the television signal, and is a part of the television signal. Sent as . When this television signal is received on the receiving side, after detecting the video signal, the color signal multiplexed in the vertical overscan area of the video signal is separated, demodulated, interpolated and expanded, and the reproduced color is It becomes a signal. This color signal is guided to matrix means together with the luminance signal separated from the television signal, and is derived as R, G, and B signals.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. First, the transmitting side will be explained. FIG. 1 is a block diagram of an embodiment of an encoder section used on the transmitting side in the television signal transmission system of the present invention. In the figure, 2 is R (red) from input terminal 1. G(
green). NTSC encoder circuit that converts the B (blue) signal into an NTSC television signal and outputs I and Q signals; 3 is a two-dimensional low-pass filter that compresses the bands of the I and Q signals in the horizontal and vertical directions; (Hereinafter referred to as “L
PF”).

4 is a compression processing circuit for compressing the I and Q signals band-limited by the two-dimensional low-pass filter 3; 5;
is a balanced modulation circuit that balancedly modulates the I and Q signals compressed by the compression processing circuit 4 using a second subcarrier (2.1 MHz). On the other hand, 6 is the above NTSC encoder 2
The color signal from the balanced modulation circuit 5 is multiplexed into the vertical overscan area of the NTSC television signal from the NTSC system, and a television signal compatible with the NTSC color television system is sent to the output terminal T1. This is the vertical overscan multiplex circuit to be derived.

FIG. 4 illustrates the vertical overscan area used in this embodiment. An overscan area is an area where a video signal other than the effective screen exists but does not actually appear on the display.
The vertical overscan areas are located at the top and bottom of the screen indicated by diagonal lines in the figure. In this embodiment, a color signal, which will be described later, is inserted into this overscan area instead of the conventionally multiplexed video signal.

The encoder section of this embodiment has the above-mentioned configuration, and its operation will be explained next. RG input to input terminal 1 from a television camera (not shown), etc.
The B signal is guided to the NTSC encoder circuit 2, and the NTSC
The signal is converted into an NTSC television signal by a C encoder circuit 2 and guided to a vertical overscan multiplexing circuit 6, and the I and Q signals are separated and guided to a two-dimensional LPF 3. 2
In dimension LPF3, the resolution of the human eye's color information is
Taking advantage of the lower resolution of luminance information,
The above I and Q signals are band-limited. The horizontal frequency bands of the I and Q signals in this state are as shown in FIG. 3(a).

[0011] I and Q band-limited by the above two-dimensional LPF 3
The signals are supplied to the compression processing circuit 4, which uses a buffer memory (not shown) or the like to thin out the information, rearrange it, and compress the color difference signal. In this case, pixels are thinned out by 3/4 per line to 1/1
By setting the number of pixels to 4, the time is compressed to 1/4 in the horizontal direction. As a result, the horizontal frequency band becomes as shown in FIG. 3(b). In addition, one time-compressed line is horizontally
Rearrange the lines so that the time for one line is as expected. Further, by thinning out 3 out of every 4 lines, the time is also compressed by 1/4 in the vertical direction. Even if the color signal information is thinned out in this way, there is no problem because the human eye is originally not as sensitive to color as it is to brightness.

The compressed I and Q signals are sent to a balanced modulation circuit 5.
and the balanced modulation circuit 5 converts the second subcarrier (2.
1 MHz), resulting in a color signal with horizontal frequency characteristics as shown in FIG. 3(c). This color signal is supplied to the vertical overscan multiplexing circuit 6,
The multiplexing circuit 6 multiplexes the NTSC television signal into the vertical overscan area, and outputs N from the output terminal T1.
It is output as a television signal compatible with the TSC system.

In this embodiment, both I and Q signals are 0.5MH
Although a band up to Z is transmitted, it is also possible to increase the compression rate in the compression processing circuit 4 and transmit a higher band color signal. Digital multiplexing can also be performed using predictive encoding, transform encoding, or the like as an image compression technique.

Next, the receiving side will be explained. FIG. 2 is a block diagram of the television signal reproducing apparatus of this embodiment. In FIG. 2, 7 is an input terminal for receiving the television signal from the transmitting side, detecting it, and converting it to baseband, and 8 is the input terminal for the television signal supplied to the input terminal 7. This is a vertical overscan separation circuit that separates signals multiplexed in the vertical overscan area. 9 is the brightness signal Y from the television signal
10 is a balanced demodulation circuit that demodulates the signal multiplexed in the vertical overscan area separated by the vertical overscan separation circuit 8 to demodulate the I and Q signals; 11 is the balanced demodulation circuit that demodulates the I and Q signals; This is an interpolation/expansion processing circuit that interpolates and expands the I and Q signals from the balanced demodulation circuit 10 in the horizontal and vertical directions and returns them to the original I and Q signals.

Reference numeral 12 denotes a matrix circuit which derives R, G, and B signals from the luminance signal Y from the YC separation circuit 9 and the I and Q signals from the interpolation/expansion processing circuit 11 to the output terminal T2. The television signal reproducing apparatus of this embodiment has the above-mentioned configuration, and its operation will be explained next. The television signal received by the main unit from the transmitting side is detected by a detection circuit (not shown) and then converted to baseband, and the television signal converted to baseband is sent from input terminal 7 to vertical overscan. It is supplied to the separation circuit 8. The vertical overscan separation circuit 8 separates the signal multiplexed in the vertical overscan area from the received signal, and this separated signal is guided to the balanced demodulation circuit 10.
The main signal is supplied to the YC separation circuit 9. The YC separation circuit 9 separates only the luminance signal and supplies it to the matrix circuit 12. On the other hand, in the balanced demodulation circuit 10, the balanced modulated I,
The Q signal is demodulated and derived as I and Q signals. These I and Q signals are then supplied to an interpolation/expansion processing circuit 11. The interpolation/expansion processing circuit 11 interpolates and expands the input I and Q signals in the horizontal and vertical directions, returns them to the original color signals, and supplies them to the matrix circuit 12. The matrix circuit 12 generates RGB signals from the input luminance signal Y, I, and Q signals, and outputs a high-definition RGB television signal to the output terminal T2.

In this embodiment, color difference signals such as R-Y and B-Y may be used instead of the I and Q signals. Also,
The color signal of the current NTSC signal is multiplexed into the effective screen area, but this is done in consideration of compatibility with current television receivers.If such compatibility were not taken into account, the effective screen area would be multiplexed. Since it is not necessary to multiplex color signals in the area, in this case, there is almost no cross-luminance interference caused by color signals mixed into luminance signals.

[0017]

According to the present invention, since the color signal multiplexed in the overscan area is temporally separated from the luminance signal existing in the effective screen area, cross color interference caused by the luminance signal being mixed into the color signal can be avoided. The image quality of the reproduced image can be improved. Furthermore, if receivers using the color difference signal processing method according to the present invention become mainstream and there is no need to consider compatibility with current television receivers, it would be possible to reduce the number of color signals multiplexed in the effective screen area. It is also possible not to transmit the signal, and in that case, it is possible to eliminate cross-luminance interference caused by the chrominance signal being mixed into the luminance signal, and the problem of difficulty in Y/C separation can also be eliminated. Furthermore, according to the present invention, it is possible to increase the compression rate of the color signal and widen the color signal band compared to the current NTSC system, thereby improving image quality.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a block diagram of main parts on the transmitting side.

FIG. 2 is a block diagram of main parts on the receiving side, showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of the operation of the present invention.

FIG. 4 is an explanatory diagram of the operation of the present invention.

[Explanation of symbols]

3 2D LPF 4 Compression processing circuit 5 Balanced modulation circuit 6 Vertical overscan multiplex circuit 8 Vertical overscan separation circuit 9 YC separation circuit 10 Balanced demodulation circuit 11 Interpolation/expansion processing circuit 12 Matrix circuit

Claims (2)

[Claims] 1. A band limiting means for band-limiting a color difference signal or I, Q signals in the horizontal and vertical directions, and a band limiting means for band-limiting the color difference signals or I, Q signals in the horizontal and vertical directions. A television signal transmission comprising: a compression means for compressing; and a multiplexing means for multiplexing a color signal composed of a color difference signal or I and Q signals compressed by the compression means into a vertical overscan area of a television signal. method. Claim 2: Band-limiting the two I and Q signals in the horizontal and vertical directions, compressing them, and then modulating them with a color subcarrier.
In a high-definition color television signal reproducing device that is compatible with the TSC color television signal transmission system,
Separating means for separating the color signals multiplexed in the overscan area after detecting the received color television signal, demodulating means for demodulating the color signals separated by the separating means, and colors demodulated by the demodulating means. an interpolation/expansion means for interpolating and expanding a signal in the horizontal and vertical directions; a YC separation means for separating a luminance signal Y from a color television signal after detection; a color signal derived from the interpolation/expansion means; 1. A television signal reproducing device comprising matrix means for obtaining R, G, and B television signals from a luminance signal Y.