JPS6363295A - Constitution method for television signal - Google Patents

Abstract

PURPOSE:To ideally separate signals Y and C in terms of a still picture, to minimize the deterioration of horizontal and vertical resolutions in terms of a moving picture and to suppress a cross fault by previously decreasing horizontal and vertical frequency components around a moving picture (about 15 Hz) and a color difference signal out of an original luminance signal and then carrying out NTSC encoding together with the color difference signal. CONSTITUTION:Since vertical and horizontal band-pass filters 12a and 12b have the same characteristics as those of vertical and horizontal band-pass filters 14 and 15, the output of the horizontal band-pass filter 12b is the signal Y in a signal C (color difference) area at vertical and horizontal frequencies. An adder 12c subtracts said output from the original luminance signal and supplies it to a mixer 11. In accordance with the size of the signal Y (original component of cross color) lying in the signal C area, its component is derived as a suppressed signal. A wide band color difference signal I is directly inputted to a mixer 22 or through a vertical low-pass filter 21. The output of a move detection circuit 17, using the output of a time band-pass filter 13 as an input, shows a change in the level of the signal Y. The output of the circuit 17 controls the mixing ratio of a source l signal from the mixer 22 to a band-limited signal I at a vertical frequency. A narrow band color difference signal(Q) is inputted to a vertical band processing circuit 23, and an NTSC encoder 18 horizontally limits the bands of signals Y, I and Q at 4.2, 1.5 and 0.5 mHz, respectively, and encodes them to an NTSC signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for configuring television signals, and particularly to standard (NTSC, etc.) color television signals.

This is a signal configuration method suitable for separating the luminance (hereinafter referred to as Y) and chrominance (hereinafter referred to as C) signals of the color difference signal.

(Prior Art) In NTSC color television, only the horizontal frequency is band-limited. That is, Y and the two color differences I and Q
The signals are 4.2 MHz and 1.5 MHz, respectively.
.

Bandwidth limited to 0.5 MHz. This situation is shown in FIG. 2 in the entire horizontal and vertical frequency domain. The vertical frequency band (cycle per height) is
In the illustration, the toilet compartments Y and C are each shown as 12'4.

Eight. is the color subcarrier frequency.

In recent years, comb-type filters using one-line or two-line delay circuits and arithmetic circuits have enabled horizontal
A technique has been developed to improve the horizontal resolution of the Y signal by creating characteristics indicated by y and c in the vertical frequency domain and separating the Y and C signals. However, Y in Figures 2 and 3,
As is clear from comparing the area C, cross disturbances (cross color, cross luminance) remain.

On the other hand, recently, a technology has been developed to improve image quality by controlling the YC separation operation using still images and moving images. For still images, time domain (interframe) YC separation is performed using an image memory such as a frame memory, that is, YC separation is performed using correlation between frames. For moving images, conventional horizontal and vertical domain (intra-field) YC separation is performed, that is, YC separation is performed using the correlation between lines within the field. FIG. 4 shows the time-vertical frequency domain. In the case of a still image, as shown in Fig. 4(a)K, Y
and C are in the regions shown by the broken lines at the OHz and 15 Hz positions, respectively, so by performing YC separation between frames, horizontal and vertical resolutions are not impaired and there is no cross disturbance. However, with regard to moving images, cross-failures remain, as shown in FIG. 4(b).

(Problems to be Solved by the Invention) As described above, in the case of conventional color television signals, when YC separation is performed on a moving image, a cross failure always occurs, causing an appearance of noise on the screen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for configuring a television signal that does not cause cross interference not only when separating YC of still images but also when separating YC of moving images.

[Structure of the Invention] (Means for Solving the Problem) In this invention, when the luminance signal satisfies the following conditions, the components of ■ and ■ are subtracted from the original luminance signal in advance, After that, NTSC encoding is performed together with the color difference signals.

■Video (with components around 15Hz).

(2) Contains horizontal and vertical frequency components near color difference signals (near fse, near 525/4 cph) during NTSC encoding.

(Function) With the above method, ideal YC separation can be performed for still images using conventional inter-frame YC separation. For moving images, since all components that cause cross disturbances are removed in advance when intra-field YC separation is performed, it is possible to minimize the deterioration of horizontal and vertical resolution and suppress the occurrence of cross disturbances.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a system according to one embodiment of the present invention. 4
．． The luminance signal band-limited to 2 MHz is passed through a mixer 11, a horizontal/vertical low-pass filter 12, and a time-band filter 1.
3 is input.

Time band filter 13Fi, two 1-frame delay circuits, 3-tap Rals with coefficient < 1.1.1)
It is an ed Cos type transversal filter, and 1
It has a peak at 5 [Hz]. This time band filter 13
The output of is the Y motion signal, which is passed through the vertical bandpass filter 14
is input to the motion detection circuit 17.

The vertical bandpass filter 14 uses two line delay circuits,
Rais with 3 tags whose coefficient is (-left, -!-1-!-)
It is an ed Cog type transpersal filter, and 1
- It has a peak at [c p h ]. The output of this vertical bandpass filter 14 will represent the Y signal in the C signal domain in time and vertical frequency. This signal is then input to the horizontal band filter 15.

R of 3 taps using 2 taps and coefficient of (-4'2' 4)
It is an a1sed Cos type transnomous filter and has a peak at fsc [Hz]. The output of this horizontal bandpass filter 15 is the Y signal in the C signal domain in time, vertical and horizontal frequency, i.e.
C is a component that always generates cross color even if it is separated. (Hereinafter, this component will be referred to as the cross color source component).

The cross-color source components are input to a motion detection circuit 16 consisting of a known absolute value circuit and a nonlinear circuit.

The output of this circuit indicates the absolute amount of the cross color source component, and is input to the control terminal of mixer 1 to control the mixing ratio of the original luminance signal and the output signal of horizontal and vertical low pass filter 12. used for

The horizontal/vertical low-pass filter 12 is a vertical bandpass filter 12a.
, horizontal band filter 12b1 and adder 12c. Vertical band filter 12a1 Horizontal band filter 12
bTd has the same characteristics as the vertical band filter 14 and the horizontal band filter 15, respectively. Therefore, the output of the horizontal bandpass filter 12b is a Y signal in the C signal region in vertical and horizontal frequencies, and in the adder 12c,
This Y signal will be subtracted from the original luminance signal.

The output of the adder 12c is then supplied to the mixer 11.

As a result of the above, the luminance signal obtained from the mixer 11 has a Y signal (
If a cross color source component exists, the component of that signal region is derived as a suppressed signal according to its thickness, and is input to the NTSC encoder 18.

Next, the C signal processing system will be explained.

The broadband chrominance (I) signal is input to vertical band processing circuit 20 . The I signal input to the vertical band processing circuit 20 is
The signal is input to a mixer 22 and a vertical low-pass filter 21. The vertical low-pass filter 21 uses two line delay circuits ft and is a 3-tap Ra1sed Co with a coefficient of (4'2'4).
Using two s-type transparsal filter 2-line delay circuits, 3-tap Ra1s with a coefficient of (4'2"4)
This is a series connection of ed Cos type transparsal filters. The output of this vertical low-pass filter 21 is
The signal is input to the mixer 22.

The motion detection circuit 17 which receives the output of the time band filter 13 as its input has the same configuration as the motion detection circuit 16 described above, and its output indicates the motion of the Y signal as a level change.

The output of the motion detection circuit 17 is supplied to the control terminal of the mixer 22 to control the mixing ratio of the original I signal and the vertical frequency band-limited signal. In the case of video, the proportion of band-limited engineering signals increases. The output of the mixer 22 is N
The signal is supplied to the TSC encoder 18.

The narrowband color difference signal is input to the vertical band processing circuit 23 . The configuration of this vertical band processing circuit 23 is the same as that of the vertical band processing circuit 20 described above, and its output is NTSC.
The signal is input to the encoder 18.

The N'rSC encoder 18 horizontally limits the Y, I, and C signals to 4.2MH311, 5MIH2, 0, and 58■z, respectively, and encodes them into ■sci.

The NTSC signal encoded as described above has the following advantages when decoded by a receiver.

First, when the Y signal is a still image, in most cases the C signal is also a still image, and by performing interframe processing, an image with the maximum horizontal and vertical resolution of the NTSC system is reproduced without cross interference. can. When the Y signal is a still image and the C signal is a moving image (although such cases are rare), there is no significant image deterioration even if interframe processing or intrafield processing is performed within the receiver. In order to eliminate this drawback, the C signal may be subjected to the same processing as the Y signal.

Next, when the Y signal is a moving image, in most cases the C signal is also a moving image, and intra-field YC separation is performed within the receiver. However, at this time, since the cross source component that causes the cross interference is removed in advance, the cross image can be reproduced with minimum horizontal and vertical band limitations without causing the cross interference. If the Y@ signal is a moving image and the C signal is a still image (although such cases are rare), in this case, intra-field YC separation is normally performed in the receiver, so there is no particular deterioration in image quality.

FIG. 5 shows another embodiment of the invention.

This embodiment makes effective use of the vertical band filter 14 and horizontal band filter 15 shown in FIG. That is, the adder 12c in the horizontal/vertical low-pass filter 12 in FIG. 1 is left in place, and the output of the horizontal band filter 15 is subtracted from the original luminance signal. By simplifying in this way, unnecessary signals are mixed into the pixels around the moving part, but the amplitude is small and it is originally a component of a detailed picture with a high vertical frequency component, so it is not automatically displayed on the screen. There are no words to stand on. The other parts are the same as the embodiment shown in FIG.
The same reference numerals as in the figure are given and the explanation is omitted.

FIG. 6 shows yet another embodiment. This embodiment is an example in which the motion detection circuit 16 and mixer 1 of the embodiment shown in FIG. 5 are omitted, and the output of the adder 12c is directly supplied to the NTSC encoder 18. In the previous example,
Although it was possible to nonlinearly process the motion signal to change the mixing ratio of the # motion signal and the moving image signal, this processing is not performed in this embodiment. However, even in this configuration, since the motion Y signal within the C signal area is subtracted, the effect can be sufficiently obtained.

FIG. 7 shows yet another embodiment. In this embodiment, the motion detection circuit 17 in FIG. 6 is further omitted, and C
In this example, the signal is passed through vertical bandpass filters 27 and 2J' and supplied to the NTSC encoder 22. The vertical resolution of the C signal is -6 dB,
This is because there is no particular problem in terms of subjective evaluation even if the amount is reduced (for Shiomi CPH).

[Effects of the Invention] As described above, the present invention can provide a method of configuring a television signal that does not cause the i-cross disturbance not only when separating YC of still images but also when separating YC of moving images.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a configuration according to an embodiment of the present invention, Fig. 2 is a spectrum distribution diagram of a luminance signal and a color difference signal, Fig. 3 is a spectrum distribution diagram in intra-field YC separation, and Fig. 4 is a time diagram. The brightness signal and color difference signal in the vertical plane 4
The tractram distribution diagram, FIG. 5, FIG. 6, and FIG. 7 are configuration explanatory diagrams according to other embodiments of the present invention, respectively. 11.22... Mixer, 12... Horizontal/vertical low pass filter, 13... Time band filter, 14... Vertical band filter, 15... Horizontal band filter, 16.17
...Motion detection circuit, 18...NTSC encoder,
20...Vertical band processing circuit. Applicant's agent Patent attorney Suzue Take Hikoki

Claims (1)

[Claims] At least 15 Hz in the horizontal and vertical frequency domain of the color difference signal
When a cross signal component, which is a nearby motion component, exists in the original luminance signal, at least the cross signal component is subtracted from the original luminance signal, and the luminance signal and color difference signal obtained thereby are used to perform the standard method. A method of configuring a television signal, the method comprising encoding the signal into a television signal.