JP3350322B2 - Video signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device for separating an NTSC composite video signal into a luminance signal (Y signal) and a chrominance signal (C signal).

[0002]

2. Description of the Related Art In domestic VTRs and TV receivers, NTS
A YC separation circuit is required to separate a C-system composite video signal into a luminance signal (Y signal) and a chrominance signal (C signal). In recent years, a motion-adaptive three-dimensional YC separation circuit has been mounted on VTRs and TV receivers for the purpose of improving YC separation performance. Hereinafter, the above-described conventional motion adaptive three-dimensional YC separation circuit will be described with reference to the drawings.

FIG. 2 shows a block diagram of a conventional motion adaptive three-dimensional YC separation circuit. In FIG. 2, reference numeral 21 denotes input means for a digitized NTSC composite video signal;
Reference numerals 3 and 24 denote a two-dimensional YC separation circuit, a three-dimensional YC separation circuit, and a motion detection circuit to which the input means 21 is connected.
A selector to which the outputs of the two-dimensional YC separation circuit 22 and the three-dimensional YC separation circuit 23 are connected and the output of which is switched by the output of the motion detection circuit 24; 26, an arithmetic unit; 27, a color signal output means; , A is a moving image color signal, b
Is a still color signal. FIG. 3 is a block diagram showing the configuration of the two-dimensional YC separation circuit 22 in FIG. 2. In FIG. 3, reference numeral 31 denotes input means for a digitized composite video signal, and reference numeral 32 denotes an input signal delayed by one line and output. A line memory 33 is an arithmetic unit. FIG. 4 is a block diagram showing a configuration of the three-dimensional YC separation circuit 23 in FIG. 2. In FIG. 4, reference numeral 41 denotes input means for a digitized composite video signal, and reference numeral 42 delays the input video signal by one frame. The frame memory 43 is an arithmetic unit.

First, a digitized NTSC composite video signal is input to a two-dimensional YC separation circuit 22. The two-dimensional YC separation circuit 22 utilizes the fact that the color signal is phase-inverted for each line, and as shown in FIG. 3, the current composite video signal and the composite video signal one line before output from the line memory 32 are output. The difference is calculated by the calculation device 33. The color signal obtained in this manner is used as a moving image color signal a as a two-dimensional YC
Output from the separation circuit 22.

[0005] Further, the digitized NTSC composite video signal is input to a three-dimensional YC separation circuit 23. The three-dimensional YC separation circuit 23 utilizes the fact that the color signal is inverted in phase for each frame, and as shown in FIG. 4, the current composite video signal and the composite video signal one frame before output from the frame memory 42 are output. The difference is calculated by the calculation device 43.
The color signal obtained in this way is referred to as a still color signal b.
It is output from the dimensional YC separation circuit 23.

[0006] The motion detection circuit 24 receives the composite video signal and detects the motion of the image based on the difference between the frames of the composite video signal. If the difference value between the frames is equal to or smaller than a predetermined threshold value X, it is determined to be stationary, and if it is larger than X, it is determined to be motion, and a motion detection signal is output.

The selector 25 receives the moving image color signal a, the still color signal b, and the motion detection signal, and outputs the moving image color signal a for a moving image and a moving image color signal for a still image. A still color signal b is output. The color signal obtained in this way is subtracted from the composite video signal by the arithmetic unit 26 to obtain a luminance signal.

As described above, the conventional motion adaptive three-dimensional YC
The separation circuit switches to the two-dimensional processing for the moving image portion of the video signal, thereby avoiding the adverse effects of the three-dimensional processing (for example, afterimages and dot interference) at the time of frame decorrelation.

[0009]

In the above-described motion detection circuit 24, a difference between frames is obtained. If the difference is equal to or smaller than a predetermined threshold value X, it is determined that the image is stationary. Output a motion detection signal. here,
If the set threshold value X is extremely small, the motion detection circuit 24 determines that the input composite video signal is a motion due to the influence of noise or the like even if the input composite video signal is a still image. Therefore X
The value of is set a little higher, for example, in consideration of such factors.

However, even if the input composite video signal is a moving image, the threshold is set to be slightly higher this time, so that it is determined that the image is a still image less than the threshold X, and the three-dimensional YC separation is performed. As a result, adverse effects occur at a level lower than X due to decorrelation between the preceding and succeeding frames. This adverse effect is at a level where there is almost no problem visually when the ordinary composite video signal shown in the signal waveform diagram of FIG. 5A is input, but as shown in the signal waveform diagram of FIG. A problem arises when a composite video signal having a very low color signal level, including a color burst signal, is input.

When a signal having such a very low color signal level has a difference from the previous frame equal to or smaller than the threshold value X and is determined to be a still image, and is subjected to three-dimensional YC separation and input to the monitor TV, the monitor TV Color level correction (AC
By C), the color signal having a small amplitude is corrected to a normal level. For example, if the burst signal level of the color signal output from the three-dimensional YC separation circuit is 1/4 of the normal level, the monitor TV amplifies the color signal four times. Accordingly, the level of adverse effects of the three-dimensional processing is expanded to a level that cannot be ignored. In particular, there is a problem that dot interference is noticeable at a low color signal level. An example of a case where a composite video signal having a very low color signal level, including a color burst signal, is input is a composite video signal output from a TV tuner slightly out of frequency tuning.

An object of the present invention is to solve the above-mentioned problem and to avoid the adverse effects of the three-dimensional YC separation processing when a composite video signal having a very low color signal level including a color burst signal is input. It is assumed that.

[0013]

According to the present invention, there is provided a video signal processing apparatus comprising: a motion detection circuit for detecting a motion of a video signal; and a color detection circuit for inputting a moving image color signal and detecting a color signal level. A level detection circuit, a moving image color signal and a still color signal are input, and a color signal is selected and output based on the motion detected by the motion detection circuit and the color signal level detected by the color level detection circuit. Selection means.

According to the present invention, when the burst signal level of the composite video signal is smaller than a predetermined value,
Alternatively, when the color signal level of the composite video signal is smaller than a predetermined value, or when the burst signal level of the composite video signal is smaller than the predetermined value and the color signal level is smaller than the predetermined value, the moving image color signal is selected and the color signal is selected. By using the output, the adverse effect of the three-dimensional YC separation processing when the color level is small is avoided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a two-dimensional YC separation circuit that receives an NTSC composite video signal and performs YC separation using line correlation of the video signal.
A three-dimensional YC separation circuit for performing YC separation using the frame correlation of the video signal, a motion detection circuit for detecting the motion of the video signal, and a color signal level by inputting a moving image color signal output from the two-dimensional YC separation circuit A color level detection circuit for detecting
Select either the moving image color signal output from the two-dimensional YC separation circuit or the still color signal output from the three-dimensional YC separation circuit
Selecting means for detecting the motion detected by the motion detecting circuit.
Output signal and the color signal detected by the color level detection circuit are input.
The motion detection signal detected by the motion detection circuit
The condition that the value is equal to or more than a predetermined threshold value X and the color level detection
The color signal level detected by the output circuit is a predetermined threshold.
When any of the following conditions is satisfied:
Only when the video color signal is selected by the selection means,
In case of, control the selection means to select the still color signal
A video signal processing device provided with a logic circuit for selectively hand
Detected by the motion detection circuit by the logic circuit controlling the stage
When the output motion detection signal is equal to or greater than a predetermined threshold X,
And the color signal detected by the color level detection circuit
Any of the conditions that the level is below a predetermined threshold X
If all of the above conditions are satisfied, select the video color signal.
This has the effect of controlling the selection means.

According to a second aspect of the present invention, the color burst signal level detected by the color level detection circuit is a predetermined level.
When more than the threshold value X, a video signal processing apparatus according to claim 1, wherein the selecting means outputs a video color signal as a color signal, color as the output color level detection circuit
The Rukoto using color signal level over the burst duration, the value selection means when the predetermined value or less has an effect of selecting the video color signal.

According to a third aspect of the present invention, the color burst signal level detected by the color level detection circuit is a predetermined level.
The threshold value X or less and the color signal level is a predetermined threshold
When less than the value X, a video signal processing apparatus according to claim 1, wherein the selecting means outputs a video color signal as a color signal, the color burst signal level and color signal level as the output color level detection circuit the Rukoto used, the value selection means when the predetermined value or less has an effect of selecting the video color signal.

[0018]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a video signal processing device according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes input means of a digitized NTSC composite video signal, 11, 12, and 13 denote a two-dimensional YC separation circuit, a three-dimensional YC separation circuit, and a motion detection circuit to which input means 10 is connected. A color level detection circuit to which the output of the two-dimensional YC separation circuit 11 is connected, 15 is a motion detection circuit 1
3 is a logic circuit to which the output of the color level detection circuit 14 is connected as input, 16 is a selector for switching the output of the two-dimensional YC separation circuit 11 and the three-dimensional YC separation circuit 12 by the output of the logic circuit 15, and 17 is the input means 10. An arithmetic unit for subtracting the output of the selector 16 from the output, 18 is a color signal output means, 19 is a luminance signal output means, a is a moving image color signal, and b is a still color signal. The two-dimensional YC separation circuit 11 and the three-dimensional YC
The detailed configuration of the separation circuit 12 is the same as the configuration shown in FIGS.

The operation of the video signal processing apparatus thus configured will be described below with reference to FIG. In FIG. 1, a digitized NTSC composite video signal input from an input means 10 is first converted to a two-dimensional YC separation circuit 1.
It is input to the one- and three-dimensional YC separation circuit 12 and the motion detection circuit 13. The two-dimensional YC separation circuit 11 utilizes the fact that the phase of the color signal is inverted for each line, for example, calculates and outputs the difference between the current composite video signal and the composite video signal one line before. The color signal thus obtained is converted to a moving image color signal a.
From the two-dimensional YC separation circuit 11.

Further, the digitized NTSC composite video signal is input to a three-dimensional YC separation circuit 12. The three-dimensional YC separation circuit 12 utilizes the fact that the phase of the color signal is inverted for each frame, and calculates and outputs, for example, the difference between the current composite video signal and the composite video signal one frame before. The color signal thus obtained is output from the three-dimensional YC separation circuit 12 as a still color signal b.

The motion detecting circuit 13 receives the composite video signal and detects the motion of the image based on the difference between frames of the composite video signal. If the difference value between the frames is equal to or smaller than a predetermined threshold value X, a motion detection signal having a value of 0 (stationary) is output if it is larger than X, and a motion detection signal having a value of 1 (motion) is output.

The color level detection circuit 14 receives the moving picture color signal a and receives the moving picture color signal in a line corresponding to the burst signal while the level of the moving picture color signal during a burst signal period is equal to or less than a predetermined value. When the value is less than a predetermined value,
Otherwise, 0 is output as a color level detection signal.

The motion detection signal and the color level detection signal are input to the logic circuit 15, and 1 is output as a selection signal if either of the two signals is 1, and 0 is output if both are 0.

The selector 16 receives a still color signal, a moving image color signal, and a selection signal, and selects a still color signal when the value of the selection signal is 0 and a moving image color signal when the value of the selection signal is 1 as a color signal. Output.

Further, the arithmetic unit 17 receives the composite video signal and the color signal output from the selector, calculates the difference between the two, and outputs the result as a luminance signal.

As described above, according to the present embodiment, the level of the moving image color signal in the burst period is equal to or less than the predetermined value and the level of the moving image color signal of the line is set to the predetermined value. When the following is detected, the selector 16 switches to the moving image color signal a, thereby avoiding the above-described problem of performing the three-dimensional YC separation when the level of the color signal including the burst signal is small.

In this embodiment, the color level detection circuit 14
Is the color of the moving image color signal a. For example, when the level of the moving image color signal in the burst signal period is equal to or lower than a predetermined value and the level of the moving image color signal of the line is equal to or lower than the predetermined value, the color is 1; Although it is assumed that the video signal is output as the level detection signal, simply input the moving image color signal a and output, for example, 1 as the color level detection signal when the level of the moving image color signal in the burst signal period is equal to or less than a predetermined value, and output 0 otherwise. Alternatively, when the moving image color signal a is input and its level is equal to or lower than a predetermined value, 1 may be output as a color level detection signal otherwise, and 0 may be output.

[0029]

As described above, according to the present invention, a two-dimensional YC separation circuit for performing YC separation using the line correlation of a video signal and a YC separation circuit for performing YC separation using the frame correlation of the video signal 3 By providing a two-dimensional YC separation circuit, a motion detection circuit that detects the motion of the video signal, and a color level detection circuit that receives a moving image color signal output from the two-dimensional YC separation circuit and detects a color signal level. When the color signal level is smaller than the predetermined value, it is possible to prevent the adverse effect of the three-dimensional YC separation from being enlarged on the monitor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video signal processing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional motion adaptive three-dimensional YC separation circuit.

FIG. 3 is a block diagram of a two-dimensional YC separation circuit.

FIG. 4 is a block diagram of a three-dimensional YC separation circuit.

FIG. 5 is a signal waveform diagram of a composite video signal.

[Explanation of symbols]

10,21,31,41 Digitized NTSC
Input means for composite video signal 11, 22 2D YC separation circuit 12, 23 3D YC separation circuit 13, 24 Motion detection circuit 14 Color level detection circuit 15 Logic circuit 16, 25 Selector 17, 26, 33, 43 Arithmetic unit 18 , 27 color signal output means 19, 28 luminance signal output means 32 line memory 42 frame memory a video color signal b still color signal

Continuation of the front page (56) References JP-A-2-58492 (JP, A) JP-A-6-327030 (JP, A) JP-A-6-105332 (JP, A) JP-A-4-123680 (JP) , U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04N 9/78

Claims (3)

(57) [Claims] 1. A two-dimensional YC separation circuit that receives an NTSC composite video signal and performs YC separation using line correlation of the video signal, and three-dimensional YC separation that performs YC separation using frame correlation of the video signal. Circuit, a motion detection circuit for detecting a motion of a video signal, a color level detection circuit for receiving a moving image color signal output from a two-dimensional YC separation circuit and detecting a color signal level, and an output from the two-dimensional YC separation circuit. What that video color signal and the still color signal outputted from the three-dimensional YC separation circuit
Selection means for selecting one of the
Motion detection signal and detected by the color level detection circuit
Motion detected by the motion detection circuit when a color signal is input
A condition that the detection signal is equal to or greater than a predetermined threshold X;
The color signal level detected by the color level detection circuit is predetermined
Condition is not greater than the threshold value X of
Only when the video signal stands, the video signal is selected by the selection means.
Otherwise, select to select a still color signal.
A video signal processing device provided with a logic circuit for controlling selection means . 2. A detected by the color level detection circuit Kara
-When the burst signal level is below a predetermined threshold X ,
2. The video signal processing device according to claim 1, wherein the selection unit outputs the moving image color signal as a color signal. 3. A color burst signal level detected by the color level detection circuit is equal to or less than a predetermined threshold X, or
2. The video signal processing device according to claim 1 , wherein when the color signal level is equal to or less than a predetermined threshold value X, the selection means outputs the moving image color signal as a color signal.