JPH01269391A - Video signal processing circuit - Google Patents

Abstract

PURPOSE:To accurately take out a motion signal being promptly moved when a chrominance signal does not exist, to narrow the band of an LPF and to completely eliminate the chrominance signal when the chrominance signal is intense by detecting the level of a chrominance signal, and making variable the band of the LPF to fetch a luminance differential signal from a one frame differential signal. CONSTITUTION:An input signal 101 is a video signal in an NTSC system, and digitized by an A/D converter. A DELTAY signal to be a frame differential luminance signal and the double chrominance signal (the added chrominance signals at the present frame and the following frame) are produced as the output of a subtracter 103 to detect the differential signal between the both edges delayed by one frame, the chrominance signal is eliminated by the LPF, and only the DELTAY signal is fetched. LPFs 104, 105 and 106 are the filters in the narrower band than the LPF connected to the same band or the preceding band, and coefficient multipliers 107, 108 and 109 gain-control the output of the LPFs 104, 105 and 106 by the output of a coefficient generating circuit 113. The chrominance signal is separated by an inter-line YC separator circuit 111, made into an absolute value by an absolute value circuit 112, and the gain of the coefficient multiplier is controlled by the size of the output.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to digital signal processing of video signals from TVs, VTRs, etc., and in particular to processing of motion signals when performing three-dimensional signal processing using a frame memory or the like. The present invention relates to a motion detection circuit for motion detection.

[Conventional technology]

Conventionally, a circuit as shown in FIG. 2 has been used as a circuit for detecting this type of motion signal. Hereinafter, the conventional technology will be explained using FIG. 2.

The input signal 201 is an NTSC video signal in which a luminance signal and a color signal are mixed in an interleaved relationship.
It is digitized with a D converter.

The frame memory 202 is a memory that delays the input signal by one frame.

A subtracter 203 detects the difference between both ends of the frame memory, that is, a frame difference signal.

The output signal output from the subtracter 203 is as follows.

Input signal - Frame delay signal = (Y++CI) (Y2 C2) = (Y=Y
2) +(C,+02) =ΔY+(C1+02) ΔY times signal This is a frame difference signal of the target luminance signal, and nothing is output for a completely still image.

On the other hand, CI102 is a color signal, which is always output even if the image is completely still.

Therefore, in order to extract the ΔY-times signal, which is the frame luminance difference signal for this purpose, the LPF 204 is used to extract it, and an output signal 205 is produced.

[Problem to be solved by the invention]

” In the conventional motion detection circuit with two series, △ with only L P F
Since the Y-fold signal color signal was separated, it was impossible to completely separate these two types of signals.

This is because when the hue of a color signal changes significantly or when a color signal with a fast rise (color signal created using computer graphics, etc.) is input, the band of the waveform with a peak at 3.58 MHz widens greatly and reaches lower frequencies. It's spreading. On the other hand, the frame luminance difference signal ΔY signal, which is a luminance motion signal, is not output in a still image. However, for moving images, the band of this signal widens and may extend to nearly 3 MHz.

Therefore, in order to extract this expanded ΔY-fold signal, the LP
If only F is used, it is difficult to completely remove the color signal with a wide band. For example, in FIG. 3, the ΔY signal 301 and the color signal 302 overlap, and this cannot be extracted using the LPF band characteristic 303.

This has the drawback that when the color signal is strong, the band widens, resulting in the detection of an erroneous motion signal even though it is a still image.

[Means to solve the problem]

The video signal processing circuit of the present invention includes a frame memory that delays an input signal by one frame, a subtracter that detects a difference between the input signal and the frame memory, and a motion signal and color of the frame difference detected by the subtracter. a plurality of LPFs for removing color signals from signals; and a plurality of coefficient units capable of controlling each output of the plurality of LPFs from the outside;
an adder that adds the outputs of the coefficient multiplier; an inter-line YC separation circuit that extracts only color components from the input signal; an absolute value circuit that takes the absolute value of this output; and a coefficient of the coefficient multiplier that is controlled by this output. and a coefficient generation circuit.

As described above, the present invention has a circuit that adaptively changes the band of the LPF according to the color signal situation to detect the ΔY-fold signal, thereby completely detecting the ΔY-fold signal without being interfered with by the color signal. It can be separated and output.

〔Example〕

FIG. 1 is a block diagram of one embodiment of the present invention.

The input signal 101 is an NTSC video signal in which a luminance signal and a chrominance signal are mixed in an interleaved relationship.
It is digitized by a D converter. Frame memory 1
02 is a memory that delays the input signal by one frame. The subtracter 103 is a circuit that detects the difference between both ends of the frame memory 102, that is, a frame difference signal.

LPF104. LPF105. The LPF 106 is a filter with the same band or a narrower band than the LPF connected before. The coefficient multiplier 1.07, 108°109 is as follows:r
, PF (104, 105, 106) with the output of the coefficient generation circuit 13.

The adder 110 is a circuit that adds each output from the coefficient multipliers 107, 1.08, and 109, thereby obtaining an output signal 114 that is a luminance movement signal between frames.

The line-to-line YC separation circuit 111 separates the color signal from the video signal of input signal 1.01 using an line-to-line edge filter. The absolute value circuit 112 is a circuit that converts the color signal separated by the line-to-line 6-YC separation circuit 111 into an absolute value, and this output is used by a coefficient generation circuit 113 to generate a coefficient for controlling the gain of the output of the LPF. The coefficients of the components 107 to 109 are controlled.

The operation of this circuit will be explained with reference to FIG. ■ By outputting the difference signals at both ends of the frame delay in the subtracter 103, the output of the subtracter 103 is a ΔY times signal which is a frame difference luminance signal, and a double color signal (the current frame and the added color signal one frame later). ) is output. The color signal is removed by an LPF, and a signal multiplied by ΔY is extracted. At this time, three signals with different bands are extracted.

The first band has a wider band than fsc, such as 401.

(Note: fsc refers to 3.58 MHz) Second
has a band close to 2 MHz, such as 402.

The third band, like 403, has an extremely narrow band of IMHz.

The coefficient multiplier 107 controls the gain of the first band, the coefficient multiplier 108 controls the gain of the second band, and the coefficient multiplier 109 controls the gain of the third band.

These coefficient multipliers are controlled by the magnitude of the amplitude of the color signal.

The color signal is separated by an inter-line YC separation circuit 111, and the color signal is converted into a direct current by converting it into an absolute value.

Therefore, an LPF may be installed after the absolute value circuit 112. The gain of the coefficient multiplier is controlled by the magnitude of this output. For example, if there is no color signal at all, the band of the LPF is widened like 401. That is, the gain of the coefficient multiplier 107 is set to 1'', and the coefficient multiplier 10
8. Let the gain of 109 be II OII. On the other hand, if the color signal is strong, narrow the LPF band like 403,
Prevent color signals from being mixed in. That is, the coefficient unit 10
7,108 is set to ``0'', and the gain of the coefficient multiplier 109 is set to ``1''. The values of these coefficients are adaptively switched depending on the magnitude of the color signal. In this way, a complete motion signal without any malfunction due to color signals can be detected.

FIG. 5 is a block diagram of another embodiment of the invention. The basic circuit configuration is the same as in Figure 1, but LPF504~
506 is changed to a cascade connection or a parallel connection.

〔Effect of the invention〕

As described above, the present invention detects the level of the color signal and thereby varies the band of the LPF that extracts the luminance difference signal from the one-frame difference signal.

As a result, when there is no color signal, a fast-moving motion signal can be accurately extracted, and when the color signal is strong, the color signal can be completely removed by narrowing the band of the LPF.

As a result, motion signals can be completely detected using conventional motion detection using only one frame memory, and a huge effect is that what used to be necessary to use two frame memories can now be configured with only one frame memory. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a motion detection circuit according to the present invention, FIG. 2 is a block diagram of a conventional motion detection circuit, and FIG. 3 is a block diagram of a conventional motion detection circuit.
FIG. 4 is an LPF band characteristic diagram of the present invention, and FIG. 5 is a block diagram of another embodiment of the present invention. Agent Patent Attorney Oto Uchihara

Claims (1)

[Claims] A frame memory that delays an input signal by one frame, a subtracter that detects a difference between the input signal and the frame memory, and a color signal is detected from the motion signal and color signal of the frame difference detected by the subtracter. a plurality of low-pass filters, a plurality of coefficient multipliers capable of controlling each output of the low-pass filters from the outside, a circuit that outputs a motion signal of a frame difference by an adder that adds the outputs of the coefficient multipliers, and the input signal It is equipped with an inter-line YC separation circuit for extracting only color components, an absolute value circuit, and a coefficient generation circuit for controlling the coefficients of the plurality of coefficient units using the output of the absolute value circuit. A video signal processing circuit characterized by changing the band characteristics of a low-pass filter depending on its size.