JPH0352488A - Y/c separation output circuit - Google Patents

Abstract

PURPOSE:To obtain a luminance signal (Y signal) and a chrominance signal with high quality by separating a video signal into a luminance signal and a chrominance signal with an inter-line comb-line filter circuit and an inter- frame comb-line filter circuit with use of the movement adaptive system. CONSTITUTION:A movement detection circuit 133 is a circuit detecting whether or not a picture element of a current processing object is moving and, e.g. the 1 frame luminance signal difference detection system is adopted. That is, the picture elements on the same position on a CRT screen between a current frame and a just preceding frame are compared, and when the difference exceeds a prescribed value, the presence of movement is decided and when not, the absence of movement is decided. When the result of detection by the movement detection circuit 133 represents the presence of movement, a changeover circuit 134 is thrown to the position of an inter-line comb-line filter circuit 131 and when the result of detection by the movement detection circuit 133 represents the absence of movement, the changeover circuit 134 is thrown to the position of an inter-frame comb-line filter circuit 132. Thus, a high luminance and chrominance signal of a picture element is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Y/C separated output circuit used for transmitting video signals between devices.

[Prior art] The terminal connected to this type of output circuit is called the S terminal.
It outputs a video signal as two types of signals separated into a luminance signal Y and a color signal C, and is installed in, for example, a video camera, a video monitor, etc.

[Problem to be solved by the invention]

However, conventional Y/C separation circuits use a frequency separation method that takes advantage of the fact that the frequency bands of the luminance signal and color signal are different.
Most of them are line-to-line (two-dimensional)<C type filters that utilize the fact that the phase of color signals differs by 180 degrees between adjacent lines (scanning lines).

FIG. 4(a) is a diagram showing a Y/C separation circuit using a frequency separation method. A composite bi-Y signal is input to input terminal 1, and a chrominance signal is input to input terminal 1 of 3.58 MHZ. This circuit removes the color signal and outputs the luminance signal Y, and extracts and outputs the color signal C using a 3.58 MHz bandpass filter circuit 3.

FIG. 4(b) is a diagram showing a line-opening filter circuit, in which a composite video signal input manually to the k terminal 4 is delayed by LH in the 114 delay circuit 5, and a current composite video signal is shown. is subtracted by the bow arithmetic circuit 6, and the result is applied to the 3.58 MHz bandpass filter circuit 7.
A color signal C is output by passing through the color signal C, and this color signal C is subtracted from the current composite video signal in a subtraction circuit 8 to obtain a luminance signal Y.

The conventional Y/'C separation output circuit separately outputs the luminance A3 Y and the color signal C separated by the circuit as described above.

[Problem to be solved by the invention]

However, in the Y/C separation circuit mentioned above, if the frequency separation type is used, when the horizontal spatial frequency (pixel change frequency in the scanning line direction) of the luminance signal becomes high, that portion falls into the chrominance signal band. The signal mixes with the color signal, causing an interference called cross color. Conversely, when the horizontal spatial frequency of the color signal increases, it enters the high pitched portion of the luminance signal, so this color signal mixes with the luminance signal. , a disturbance called dot disturbance occurs.

On the other hand, in the line-to-line comb type filter method, when the vertical spatial frequency (vertical pixel change frequency) of the color signal increases, do-not interference occurs, and when the horizontal spatial frequency of the luminance signal increases, cross-color interference occurs. arise.

Therefore, the luminance signal and chrominance signal obtained by the conventional Y'/C separation output circuit suffer from cross color interference and dot interference, making it impossible to obtain a high quality luminance signal and chrominance signal.

The present invention has been made in view of these points, and its object is to provide a Y/C separation output circuit that can obtain high quality luminance signals and color signals.

[Means to solve the problem]

To this end, the present invention digitizes a video signal, separates it into a luminance signal ε and a chrominance signal using an interline comb filter circuit and an interframe comb filter circuit using a motion adaptive method, and converts both of the separated signals into analog signals. [Example] Hereinafter, an example of the present invention will be described. FIG. 1 is a block diagram of an IDTV (or EDTV) including a Y/C separation output circuit according to one embodiment. Input terminal 11
The composite video signal applied to the A/D conversion circuit 12 is converted into an approximately 8-bit digital signal. The sampling frequency at this time is selected to be approximately four times the color subcarrier frequency. This digital video signal is input to a Y/C separation circuit 13 using a comb filter between lines or frames using a motion adaptive method, and is separated into a luminance signal Y and a color signal C. The color signal C is then input to the color demodulation circuit 14 and demodulated into color difference signals RY and BY.

Reference numeral 15 denotes a scanning line interpolation circuit, which interpolates the luminance signal Y between lines or fields using a motion adaptive method, and interpolates the color difference signals Ry and BY between lines. Reference numeral 16 denotes a double speed conversion circuit, which converts the horizontal scanning frequency of the current scanning line and the horizontal scanning frequency of the interpolation scanning line into a frequency that is twice the horizontal scanning frequency included in the composite shift signal inputted to the terminal 1l.

17 is a D/A converter that individually converts the luminance signal Y and color difference signals R-Y, B-Y into analog signals; and 18 is a matrix circuit that outputs RGB primary color signals.

Further, 19 indicates a Y/C separation output circuit of this embodiment, and 2
0 is a D/A converter that individually converts the luminance signal Y and the color difference signals R-Y, BY into analog signals.
While the A converter 17 handles data with a frequency eight times the sub-color carrier frequency, here it handles data with a frequency four times half that frequency. 21 is this luminance signal Y, color difference signal R-Y, 13-
This is a gongcoder that outputs a luminance signal Y, a color signal C, and a composite video signal from Y.

As shown in FIG. 3, each of the Y/C separation circuits 13 shown in FIG.
b)), an interframe comb filter 132, a motion detection circuit 133, and a switching circuit 134 shown in FIG.

The interframe comb filter 132 converts the signal input to the input terminal 13 into a frame delay circuit 1322 for one frame (
1/3 0 seconds) The delayed signal and the current input signal are subtracted by the subtraction circuit 1323, and it'c 3.58 MH
z band pass filter circuit 13241 2 to output a color signal C, and this color signal C is subtracted from the current input signal in a subtraction circuit 1325 to produce a luminance signal Y.
It is designed to output.

In other words, this interframe comb filter 132
L H of the interline comb filter circuit shown in figure (bl)
It replaces the delay circuit 5 with a frame delay circuit, and is also called a three-dimensional comb filter because it compares data with data from one frame before.

The motion detection circuit 133 is a circuit that detects whether or not the pixel currently being processed is moving, and uses, for example, a one-frame luminance signal difference detection method. This method compares pixels at the same position on the CRT screen between the current frame and the previous frame, and if the difference exceeds a predetermined value, there is movement (moving image part), otherwise there is no movement (still image part). ). When the detection result of this motion detection circuit 133 indicates that there is motion, the switching circuit 134
is switched to the inter-line comb filter circuit 131 side, and when there is no movement, the inter-frame comb filter circuit 132 is switched to the inter-line comb filter circuit 131 side.
This is to switch to .

As a result, in the past, for example, a line-to-line comb filter circuit was used regardless of the still image portion or the video portion, so cross color interference and don't interference were noticeable in the still image portion. In this case, Y/C separation is performed using a comb-type filter circuit between frames, and Y/C separation is performed using a comb-type filter circuit between lines in the video part, so cross color interference and dosoto interference are eliminated in the still image part, and the video part Then it becomes less noticeable.

In this way, in this embodiment, the Y/C separation method according to the moving image portion and the still image portion is used to output separated luminance signals and color signals through motion adaptation, so that a luminance signal with high image quality can be output. and color signals can be obtained.

In the above embodiment, the luminance signal Y and the color difference signals R-Y, BY are taken in from the main body side to the Y/C separation output circuit 19 and processed, but the luminance signal Y and color difference signals from the Y/C separation circuit l3 are It is also possible to take in the signal C as it is and process it.

In addition, the input composite video signal is first color demodulated, then A/D converted, and then Y/C separated to extract the luminance signal Y and color difference signals R-Y, B-Y.
/C separation output circuit 19.

[Effects of the Invention] As described above, according to the present invention, there is an advantage that a luminance signal and a color signal of high image quality can be output.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a part of an IDTV circuit including a Y/C separation output circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a frame opening filter circuit, and FIG. 3 is a motion adaptive Y/C separation output circuit. /
FIG. 4(a) is an overall circuit diagram of the C separation circuit, FIG. 4(a) is a circuit diagram of a frequency separation type Y/C separation circuit, and (b+ is a circuit diagram of an inter-line comb filter circuit).

Claims (2)

[Claims] (1) Digitize the video signal, separate it into a luminance signal and a chrominance signal using an interline comb filter circuit and an interframe comb filter circuit using a motion adaptive method, and convert both of the separated signals into analog output. A Y/C separated output circuit characterized by: (2) The Y/C separation output circuit according to claim 1, wherein the separation of the luminance signal and color signal using the motion adaptive method is performed within an IDTV or an EDTV.