JPH04222191A - Luminance signal/chrominance signal separator circuit - Google Patents

Abstract

PURPOSE:To improve the oblique resolution of a luminance signal and to improve total picture quality in respect to the respective cases of a moving image and a quasi-moving image which has a few amount of motion a band pass filter 10 to vary a passing band corresponding to the moving amount of the picture when separating a luminance signal Y at the luminance signal/ chrominance signal. CONSTITUTION:The band pass filter 10 required for separating the luminance signal Y is made into a motion adaptive type to vary the passing band of the above-mentioned band pass filter 10 corresponding to the amount of a moving signal 14 of the picture while inserting the band pass filter 10 to a chrominance signal path for separating the luminance signal Y at the output of a synthesizing part 8 for a chrominance signal Cf outputted from a frame interdigital filter 7 in the case of a still picture and a chrominance signal Cl outputted from a line interdigital filter 4 in the case of the moving image.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] Motion-adaptive luminance signal Y in video signal processing circuits of video-related equipment such as color television receivers
and a chromaticity signal C separation circuit.

0002

2. Description of the Related Art FIG. 5 shows a conventional motion adaptive luminance signal/chromaticity signal separation circuit. When separating the input video signal 13 into a luminance signal Y and a chromaticity signal C, a frame comb filter 7 output signal corresponding to a still image and a line comb filter 4 output signal corresponding to a moving image are detected by detecting the movement of the image. By adaptively changing the mixing ratio with signals and compositing them according to the amount of image movement, deterioration in image quality due to cross color, dot interference, etc. is improved. Utilizing the fact that the chromaticity signal component of the video signal 13 is inverted in phase for each line and for each frame, the frame comb filter 7 outputs a chromaticity signal Cf by performing subtraction processing between frames, The 2H line comb filter 4 outputs an output signal 18 obtained by adding and subtracting between a total of three upper and lower lines including a predetermined line through a bandpass filter 10 as a chromaticity signal Cl. A motion detection circuit 9 detects the chromaticity signal Cf and the chromaticity signal Cl.
A synthesis section 8 mixes the motion signals 14 of the output images according to the amount thereof, and outputs a chromaticity signal 15 output from the synthesis section 8 as a chromaticity signal C via a bandpass filter 11. On the other hand, for the luminance signal Y, a subtracter 12 subtracts the chromaticity signal 15 output from the combining section 8 from the video signal 16 (luminance signal + chromaticity signal).

The frame comb filter 7 for outputting the chromaticity signal, which is selected for still images, can perform ideal Y/C separation because the image frame correlation is large, so a bandpass filter is not required on the output side. Since the frame correlation of the image is small at the time of imaging, Y/C separation is performed by the 2H line comb filter 4, so in this case, a bandpass filter 10 is required to limit only the color signal band. 2
When the chromaticity signal 18 output from the H-line comb filter 4 is subtracted from the video signal and the luminance signal Y is separated, n×fH/2 components (luminance diagonal component of the signal)
However, by passing the chromaticity signal 18 output from the 2H line comb filter 4 through the bandpass filter 10 and making the comb filter work only in the chromaticity signal band, low luminance in the low frequency region can be removed. Guarantees diagonal resolution of the area. (n: odd number, fH: horizontal scanning frequency). However, since the passband of the bandpass filter 10 is fixed, the resolution of the low luminance range cannot be sufficiently guaranteed for the amount of image movement. That is, there is no problem in completely still images and completely moving images, but in semi-moving images with intermediate movement, the bandpass filter band is not optimal, so that sufficient brightness resolution cannot be obtained.

0004

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned conventional example, and it is an object of the present invention to change the band of a bandpass filter, which was fixed, depending on the amount of image movement when obtaining a luminance signal Y from a video signal. By using a motion-adaptive band-pass filter that switches between the two, the objective is to improve the diagonal resolution of brightness even for moving images and intermediate moving images, and to improve the overall image quality.

[0005]

[Means for Solving the Problems] The present invention provides a bandpass filter that is necessary when separating the luminance signal Y of a luminance signal/chromaticity signal separation circuit, and separates the chromaticity signal for a still image from the color signal for a moving image. By inserting the luminance signal Y output from the chromaticity signal combining unit into the chromaticity signal path for separation, it is possible to improve the deterioration of diagonal resolution in the low luminance range during semi-moving images (intermediate motion), and By using a motion-adaptive band-pass filter in which the pass band of the band-pass filter is switched according to the amount of image movement, the diagonal resolution of the low luminance range is improved according to the movement of the image.

[0006]

[Operation] As shown in FIG. 1, the synthesis unit 8 combines the frame comb filter 7 output signal Cf for a still image and the 2H line comb filter 4 output signal Cl for a moving image, and a motion signal is generated according to the movement of the image. 14, a bandpass filter 10 that switches the pass band according to the motion signal 14, and a subtracter 12 that separates and outputs the luminance signal Y. Frame comb filter 7 output signal Cf and 2H according to 14
It outputs the chromaticity signal 15 mixed with the line comb filter 4 output signal Cl, and outputs the chromaticity signal C via the chromaticity signal output bandpass filter 11, while the luminance signal Y
is obtained by subtracter 12 processing which subtracts from video signal 16 chromaticity signal 17 output from bandpass filter 10 whose band is switched according to motion signal 14 .

[0007]

[Example] 4 in FIG. 1 is a 1H line delay circuit 1, 2 and an adder 3 which input a video signal 13 (luminance signal + chromaticity signal).
A 2H line comb filter 7 outputs a chromaticity signal Cl for a moving image, and 7 outputs a chromaticity signal Cf for a still image, which is composed of a frame memory 5 and a subtracter 6, which input the 1H delayed video signal 16. A frame comb filter to be output; 9 is a motion detection circuit that outputs a motion signal 14 according to the movement of the image; 8 is a chromaticity signal Cf for a still image and a chromaticity signal Cf for a moving image according to the motion signal 14 of the motion detection circuit 9; The chromaticity signal Cl
10 is a motion adaptive bandpass filter that switches the passband of the chromaticity signal 15 according to the amount of the motion signal 14, 11 is a bandpass filter for the chromaticity signal C, and 12 is a 1H delayed video signal. This is a subtracter that subtracts the chromaticity signal 17 output from the band pass filter 10 from 16 (luminance signal + chromaticity signal) and outputs a luminance signal Y.

FIG. 2 shows a circuit diagram of the motion adaptive bandpass filter 10 shown in FIG. 22 is a decoder that outputs a control signal 26 according to the amount of the motion signal 14 output from the motion detection circuit 9; 21a, 2;
1b is a bandpass filter 20a by the same control signal 26.
, 20b, 20c. Here, the passband W1, W
2. W3 band pass filters 20a, 20b, 20
By adaptively switching c depending on the amount of image movement, the diagonal resolution of luminance that is lost when the luminance signal Y is separated is guaranteed. FIG. 4 shows the passband W depending on the amount of image motion signal 14.
1, W2, W3 bandpass filters 20a, 2
Selector 21b that combines bandpass filters 20a, 20b, 20c characteristics (a), (b), (c) and 2H comb filter 4 characteristics (d) when switching between 0b and 20c Output chromaticity signal 17 Comprehensive characteristics (e), (f),
(g) is shown.

For example, if the movement of the image is small, the image shown in FIG.
As shown in (a), the band (W
1) by widening Y/ by frame comb filter 7.
By C separation, the broadband chromaticity signal 17 shown in FIG. 4(e) is separated from the video signal 16 by the subtracter 12, and a luminance signal Y is obtained. If the movement of the image is large, narrow the band (W3) of the bandpass filter 20c as shown in Fig. 4(c).
By Y/C separation using the line comb filter 4, the narrow band chromaticity signal 17 shown in FIG. 4(g) is separated from the video signal 16 to obtain a luminance signal Y with little deterioration in diagonal resolution in the low luminance range. Also, for quasi-video (intermediate motion), Fig. 4(b
) as shown in FIG.
In addition to separating the common band chromaticity signal 17 of f), the bandpass filter 10 is used to separate the luminance signal Y of the synthesis section 8 output.
Since the circuit is configured to be inserted into the chromaticity signal path for separation, the n×fH/2 component corresponding to the luminance signal in the low frequency region in the frequency spectrum distribution of the video signal leaking from the frame comb filter 7 during quasi-video and improve the diagonal resolution of low brightness range. (n: odd number, fH: horizontal scanning frequency). That is, in the case of a still image, the chromaticity signal 17 is separated by the frame comb filter 7 and the broadband bandpass filter 20a to ensure resolution over the entire band for both the luminance signal Y and the chromaticity signal C, and in the case of a moving image, the line comb filter Filter 4 and narrowband bandpass filters 20b and 20c
By separating the color signal 17, diagonal resolution in the low luminance range is ensured.

0010

As described above, the present invention provides a bandpass filter that is necessary when separating the luminance signal Y of the luminance signal/chromaticity signal separation circuit, and which separates the chromaticity signal in a still image and the color in a moving image. The luminance signal Y output from the combining unit with the chromaticity signal is inserted into the chromaticity signal path for separating the luminance signal Y to improve the deterioration of diagonal resolution in the low luminance range during quasi-moving images (intermediate motion), and also to A motion-adaptive band-pass filter that switches the passband of the filter according to the amount of motion in the image, and improves the overall image quality by improving the diagonal resolution of luminance even for moving images and intermediate moving images. I can do it.

[0011]

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a motion-adaptive luminance signal/chromaticity signal separation circuit.

FIG. 2 is a block diagram of the bandpass filter circuit of FIG. 1;

FIG. 3 is a band characteristic diagram of a bandpass filter for explaining FIGS. 1 and 2;

FIG. 4 is a band characteristic diagram of a motion signal of a bandpass filter and a line comb filter for explaining FIGS. 1 and 2;

FIG. 5 is a block diagram of a conventional luminance signal/chromaticity signal separation circuit.

[Explanation of symbols]

1 1H delay circuit 4 Line comb filter 5 Frame memory 7 Frame comb filter 8 Chromaticity signal synthesis unit 9 Motion detection circuit 10 Motion adaptive bandpass filter 20a Bandpass filter 21a Selector 22 Decoder

Claims (3)

[Claims] 1. A motion-adaptive luminance signal and chromaticity signal separation circuit that adaptively switches between a frame comb filter and a line comb filter according to the movement of an image in a signal processing circuit of a color television receiver or the like. A luminance signal/chromaticity signal separation circuit characterized in that the bandwidth of a bandpass filter to be inserted is varied according to the amount of movement of an image. 2. The bandpass filter is characterized by comprising a still image bandpass filter, a quasi-moving image bandpass filter, and a moving image bandpass filter, and is switched to any one of the filters based on a motion detection signal. The luminance signal/chromaticity signal separation circuit according to claim 1. 3. After combining the chromaticity signal output from the frame comb filter and the chromaticity signal output from the line comb filter according to the amount of image movement, the chromaticity signal path of the luminance signal separation subtractor 2. The luminance signal/chromaticity signal separation circuit according to claim 1, further comprising an adaptive bandpass filter.