JPS61125298A - Luminance signal and color signal of television signal processing system - Google Patents

Abstract

PURPOSE:To perform the separation of Y (luminance signal) and C (color signal) for both a still image and moving image without deterioration in picture quality by multiplexing Y-C split mode information, which was found from luminance signal spectrum, with a television signal at sending side, and by performing the Y-C split based on this mode information at receiving side. CONSTITUTION:The spectrum of the luminance signal Y is found at the sending side by a time space filter. Using the cascade connection of a time direction filter 3, vertical direction filter 4 and horizontal direction filter 5 (high-pass filter 1), and an output signal obtained from a horizontal filter 6 (high-pass filter 2), a mode discriminant circuit 7 determines the Y-C split mode of the receiving side. If the discriminant mode is interfield Y-C, a switch 1 selects the signal, from which the luminance signal component superimposing the color signal component is removed, by the time space filter 2. In addition, an adder 10 multiplexes it with Y-C split mode information. With the mode information multiplexed with the television signal, the receiving side determines the Y-C split mode information in a mode control circuit 11, and selects the signal corresponding the mode in a switch 12.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a luminance signal (hereinafter abbreviated as YC signal) processing method for a television signal, and particularly relates to a VC processing method that does not have crosstalk with luminance signal Y and chrominance signal C. This invention relates to signal processing suitable for multiplexing and YC separation.

[Background of the invention]

Current television signals are in the form of a composite signal in which a luminance signal Y and a color signal C are superimposed.

On the image receiving side, signal processing for YC separation is required to separate the luminance signal Y and color signal C from the composite signal. At this time, cross color, in which a luminance signal component is extracted as a color signal component, and cross luminance, in which a color signal component is extracted as a luminance signal component, occur, causing image quality deterioration.

As a method for reducing image quality deterioration due to YC separation, there is, for example, motion adaptive YC separation. In this method, VC separation between frames is used for still images, and Y within the field is used for moving images.
Parameters of signal processing for YC separation, such as C separation, are switched in response to the movement of the image. however,
Since detection of motion for switching parameters is performed using a signal in which a luminance signal and a color signal are superimposed, there is a limit to motion detection.

For this reason, an image that is originally moving may be mistakenly determined to be stationary. As a result, there is a problem in that inappropriate YC separation signal processing is performed, resulting in image quality deterioration.

[Purpose of the invention]

An object of the present invention is to provide a signal processing method that performs YC separation on either still images or moving images without deteriorating image quality.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention uses YC to
The mode of separation is determined, a signal indicating this mode is multiplexed and transmitted together with the television signal, and YC separation is performed on the receiving side using the transmitted mode signal.

[Embodiments of the invention]

In order to facilitate understanding of the configuration and operation of the embodiment, first, the principle of the present invention will be described in detail.

In the current television signal, a color signal C is superimposed on a luminance signal Y, and this can be expressed in terms of three-dimensional frequencies of time, vertical, and horizontal as shown in FIG.

Color No. 16 C is the area shown by the dotted line in the figure (a) in the two-dimensional frequency domain of temporal frequency f and vertical frequency ν, and the area shown by the dotted line in the figure (a) in the two-dimensional frequency domain of horizontal frequency μ and vertical frequency ν (
It exists in the area indicated by the dotted line in b).

In the present invention, the YC separation mode is determined on the image transmission side according to the signal spectrum of the luminance signal Y.

As shown in FIG. 2(a), when the signal spectrum of the luminance signal Y is below the horizontal frequency μ of 2 MHz, the components with the horizontal frequency above 2 MHz are filtered through a band-pass filter (
The color signal C can be obtained without crosstalk by extracting the color signal C (having the characteristic shown by Fl). Therefore, when the signal spectrum of the luminance signal Y is as shown in FIG.
characteristics).

On the other hand, when the signal spectrum of the luminance signal Y is as shown in FIG. 2(b), it is possible to separate the color signal C using the yc total separation characteristic F2) between lines. Therefore, in such a case, the YC separation mode on the image receiving side is determined to be line-to-line YC separation.

Moreover, the luminance signal Y is changed over a period of time as shown in FIG. 2(c).
When existing in the vertical two-dimensional frequency domain, the color signal C can be separated by inter-frame YC separation (characteristic F3). Therefore, the mode of YC separation on the image receiving side is determined to be inter-frame Yc separation.

Furthermore, as shown in FIG. 3(a), if there is a region where the signal spectrum of the luminance signal Y overlaps with the color signal C in any of the temporal, vertical, and horizontal regions,
As shown in the same figure (b), the crosstalk component with the color signal C is removed from the luminance signal Y by band limiting, and the Yc separation on the receiving side is changed to the mode of inter-field Yc separation (characteristic F4). stipulate.

The Yc separation mode information obtained from the luminance signal spectrum on the image sending side is multiplexed onto the television signal, and on the receiving side, by performing Yc separation using this mode information,
Separation of luminance signals and color signals without cross color or cross luminance can be realized.

FIG. 4 shows the configuration of an embodiment on the image sending side when implementing the present invention. The spectrum of the luminance signal Y is obtained using a spatio-temporal filter. That is, the temporal direction filter (VBPF-1) 3, the vertical direction filter (VBPF-1)
-1) Cascade connection of 4 and horizontal filter (bypass filter 1) 5, and horizontal filter (
The output signal obtained from the bypass filter 2) 6 is input to the mode determination circuit 7.

FIGS. 5(a), (b), and (c) show the filter 3,
A characteristic diagram of filter 4 and filters 5 and 6 is shown.

The shaded area indicates the passband.

FIG. 6 is a diagram showing the operation when mode determination is made based on the output of each of the above-mentioned filters. The mode of Yc separation on the receiving side is determined based on the output signals of the filters, and when the determination mode is inter-field Yc, the signal from which the luminance signal component that overlaps with the color signal component is removed by the spatio-temporal filter 2 is selected by the switch 1. do.

On the other hand, the color difference signals I and Q are amplitude-modulated by a color printing carrier wave in a modulation circuit 8 to generate a color signal C. Then, it is superimposed on the luminance signal Y in the adder circuit 9. Furthermore, the addition circuit 10 adds YC
Multiplexes separation mode information.

This mode information is multiplexed, for example, during the vertical blanking period of the television signal.

FIG. 7 shows a configuration diagram of an embodiment of the image receiving side.

The mode control circuit 11 determines the YC separation mode based on the mode information multiplexed on the television signal, and switches the switch 1.
2 select the signal corresponding to the mode.

That is, in the interframe YC separation mode, a signal with a frame delay of 13 is selected, in the interfield YC separation mode, a signal with a field delay of 14, in the interline YC separation mode, a signal with a line delay of 15, and in the separation using a bandpass filter, a signal of zero is selected. do. A subtraction circuit 16 takes the difference from the television signal, and a bandpass filter 17 extracts components in the color signal band to form a color signal C. And subtraction circuit 1
At step 8, the color signal C is subtracted from the television signal to reproduce the luminance signal Y.

〔Effect of the invention〕

According to the present invention, since the crosstalk-free YC separation mode can be determined based on the signal spectrum in the time, vertical, and horizontal three-dimensional frequency domains of the luminance signal on the image sending side, the receiving side uses this mode information to It is possible to achieve YC separation with extremely low color and cross-luminance.
There is no image quality disturbance caused by separation, and this has an extremely large effect on improving image quality.

[Brief explanation of the drawing]

Figure 1 shows the three-dimensional frequency of the current television signal. Figure 6 is a characteristic diagram of the filter used in the configuration of Figure 4. Figure 6 is an explanatory diagram of the operation of the determination circuit used in the configuration of Figure 4. .

Claims (1)

[Claims] 1. The television signal transmitting side determines the luminance signal/chrominance signal separation mode from the luminance signal, multiplexes the signal indicating this mode into the television signal and transmits it, and the receiving side selects the multiplexed mode. A method for processing luminance signals and chrominance signals of television signals, which is characterized in that luminance signals and chrominance signals are separated according to the signals shown.