JPS62185494A - Separating device for luminance signal and chrominance signal - Google Patents

Abstract

PURPOSE:To correctly separate a luminance signal and a chrominance signal from a composite color television signal by using picture element information having the strong correlation on a screen and between screens by separating the luminance signal and the chrominance signal of a remarkable picture element by using the information signal of the picture element constituting picture element groups decided by a correlation decision means. CONSTITUTION:In the picture element information signal of a sample point, the sample points S6, S7, S9, S10 of the phase of the chrominance signal are the same as a sample point S3 in phase and the sample points S1, S2, S4, S5, S8 are opposite in phase to the sample point S3. Of the picture element groups A-D, the group having the strongest correlation is discriminated, the luminance signal and the chrominance signal separated from the picture element information signal of the group are selected as an output. Namely, by using adder and subtracter circuits 16-19, and absolute value converters 20-23, the operation is carried out. Then, the operation result is inputted to a comparator circuit 48, the smallest value is detected, a switching control signal is outputted from the comparison circuit 48 to a switching circuit 49, the picture element information signal at the sample point S3 is separated into the luminance signal and the chrominance signal and outputted. In this manner, at the time of separating the luminance signal and the chrominance signal from the composite color television signal, the most suitable separation can be performed by taking the correlation in a time base direction of the luminance signal and the chrominance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a luminance signal/chrominance signal separation device for separating a luminance signal and a chrominance signal from a composite color television signal.

[Conventional technology]

The current composite color television signal, for example, the composite color television signal S of the NTSC system, is a color obtained by quadrature two-phase modulation of a luminance signal Y and two color difference signals U and V (or chrominance and Q) at a color subcarrier frequency fsc. Combined signal with signal C: s=y+c=y1U! 1R(2πfsc t)+V
m(2πfsc t) and f, Niru.

Here, assuming frame frequency fy (30H2), field frequency fv, and horizontal scanning frequency fH, f s c =
2 fH=, ;, °2 fy =2 '525 f
It becomes F.

Therefore, when a composite color television signal of the NTSC system is sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc, the sequence of the sampled signals becomes an arrangement as shown in FIG. That is, the phase of the color signal C is inverted by 180 degrees for each line, and four samples are extracted in one cycle of the color subcarrier.

In order to separate such a signal into a luminance signal Y and a color signal C,
Conventionally, a square-shaped filter as shown in FIG. 3 was used to separate the luminance signal and color signal.

In addition, the input television signal (Y-C) in Fig. 3
is the previous line signal (Y
(10C) is added in adder 2. In other words, as shown in Figure 2, the phase of the color signal is 1 between the current line and the previous line.
Since it is inverted 80 degrees, the output of adder 2 is 2Y,
The next attenuator 3 attenuates the level to 1/2 and separates the luminance signal Y. In addition, the input TV signal (Y-C
) is inverted by the inverter 4, and then added to the signal of the previous line in the adder 5, and the output becomes 2C, and the level is attenuated to 1/2 by the attenuator 6, and the color signal C is separated.

[Problem that the invention seeks to solve]

The conventional luminance signal/chrominance signal separation device as explained above uses the pixel information of the previous line on the assumption that the pixel information, which is the sampling sequence of the composite color television signal, has a strong correlation in the vertical direction. The luminance signal and chrominance signal of the current line were separated.

However, the conventional method described above only uses the correlation of pixel information on one screen, so in areas where the brightness and color of the image change rapidly, the reproduced image may deteriorate, such as color clouding or dot interference. There is a disadvantage that it occurs.

The present invention was made in view of the above-mentioned problems, and it is possible to accurately separate luminance signals and color signals from a composite color television signal by using pixel information that is highly correlated on and between screens. The present invention aims to provide a luminance signal chrominance signal separation device.

[Means for solving interlayer points]

When sampling a composite color television signal and obtaining a pixel information signal, the luminance signal/chrominance signal separation device of the present invention sets any 1[11 pixels among the pixels on the current screen as a pixel of interest, and sets the pixel of interest as the center of the pixel. The pixel of interest, 4 pixels on the previous screen that have a color signal that is in phase with the pixel of interest, 1 pixel on the previous screen that has a color signal that is opposite in phase to the pixel of interest, and 4 pixels on the current screen that have a color signal that is in phase with the pixel of interest.
A pixel group forming means for forming a plurality of pixel groups having the same number of constituent pixels using at least pixels on the previous screen from pixels, and a correlation between the pixels constituting the pixel group among the plurality of formed pixel groups is the strongest. A device comprising a correlation determining means for determining a pixel group, and a separating means for separating a luminance signal and a color signal of the pixel of interest using information signals of pixels constituting the pixel group determined by the correlation determining means. It is.

[For production]

With the above configuration, it is possible to separate the luminance signal and the color signal using pixel information that has the strongest correlation between screens.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a diagram showing a schematic configuration of a luminance signal chrominance signal separation circuit as an embodiment of the present invention.

FIG. 4 is a diagram showing a pixel group configuration for determining pixel correlation.

In Figure 1, 7 to 10 are IH-2 sample period delay circuits (where H is one horizontal line scanning period), 11 to 14 are two sample period delay circuits, and 15 are IF-2H period delay circuits (however, F is one frame period). (scanning period), 16 to 19 are addition/subtraction circuits, 20 to 23 are absolute value converters, 24 to 35 are adders, 36 to 43 are 1/4 level attenuators, 44 to 47 are subtracters, 48 is a comparison circuit, 49 is a switching circuit.

For example, when an NTSC composite color television signal is sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc, the sampling points are as shown in FIG.

In FIG. 4, the operation of separating the luminance signal and the color signal into luminance 1 for the sample point S3 will now be described.

In FIG. 1, when NTSC composite color television signals sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc are sequentially input, the IH
-2 sample period delay circuits 7 to 10. Two sample period delay circuits 11 to 14 and an IF-2H period delay circuit 15 simultaneously extract pixel information signals of sample points 81 to Slo shown in FIG.

Incidentally, the pixel information signals at the sampling points as shown in FIG. 4 have the phases of the color signals as the sampling points Ss, S7+ Ss, S+.

is in phase with sampling point S3, and sampling point 5IIS2, 541Ss
, Ss are in an antiphase relationship with the sample point S3.

This is because, as described above, the NTSC composite color television signal is sampled at the sampling frequency fs, which is four times the color subcarrier frequency fsc.

From the pixel information signal of the sample point Sl''S+o obtained in the above manner, luminance signals and color signals are separated for each pixel group A to D shown in FIG. Color signal C is pixel group A: Y a= +(S8"S2"S7
+S3)1c a=-i-(S, +52-87-83
) Pixel group B: Yb=+ (S8”S4+3
9+83).

Cb=+ (S8"54-89-83) Pixel group C: Y c"" + (S8"Sl"S6+S3)
.

Co=+ (Sa"S+-3s-8s) Pixel group D: Y d =+ (Ss"Ss+S+.+83)
.

Since the relationship is Cd''+(Ss''5s-8+o-83), the tllllffi filter using the above relationship is applied by 1/4 level attenuators 36 to 43, adders 24 to 35, and subtractors 44 to 47. The resulting luminance signal YB
-yd N color signal ca-Cd is supplied to the switching circuit 49.

Here, in order to determine which signal to separate and output from the luminance signal and color signal separated by each separation filter as described above, the pixel groups A to D
Among them, the group with the strongest correlation is determined, and the luminance signal and color signal separated from the pixel information signal of that group are output and selected.

That is, addition/subtraction circuits 16 to 19, absolute value converters 20 to
23 is used to perform the calculations shown below.

ls8+s I-Sl-531=T c , lSs"
Ss-S+o-831=TdThe formula for calculating T and -Td shows the correlation in the vertical and horizontal directions, taking into account the correlation in the time axis direction, and if the value of each formula is large, The correlation is weak, and if it is small, the correlation is strong.

The above calculation result is input to the comparison circuit 48, which detects the smallest value among Ta-'rd, and
From the comparison circuit 48 to the switching circuit 49, Ya is outputted when a is small, Yb is outputted when Ca5Tb is small, Yc is outputted when CblTo is small, and Yd and cd are outputted when Td is small. A switching control signal is output, and the pixel information signal at the sample point S is separated into a luminance signal and a chrominance signal and output. Optimal separation can be performed taking into consideration the correlation of the luminance signal and color signal in the time axis direction.

In addition, in this embodiment, a signal sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc is used as an NTSC composite color television signal, but by changing the configuration of the pixel block, PAL It can also be applied to other 1M numbers such as methods.

〔Effect of the invention〕

As described above, the present invention provides a luminance signal/chrominance signal separation device that can accurately separate luminance signals and chrominance signals from a composite color television signal using pixel information that is highly correlated on and between screens. can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a luminance signal/chrominance separation circuit as an embodiment of the present invention. FIG. 2 is a diagram showing a series of sampled signals obtained by sampling a composite color television signal of the NTSC system using a sampling frequency fs that is four times the color subcarrier frequency fsc. FIG. 3 is a diagram showing a schematic configuration of a conventional luminance signal/chrominance signal separation comb filter. FIG. 4 is a diagram showing the relationship between the sampling points of the sampled signal in FIG. 2 and the configuration of the pixel groups of this embodiment. 7-10...IH-2 sample period delay circuit 1
1 to 14...2 sample period delay circuit 15...
...IF-2H period delay circuits 16 to 19...
-Addition/subtraction circuits 20-23...Absolute value converters 24-35...Adders 36-43...1/4 level attenuators 44-47
...Attenuator 48...Comparison circuit 49...Switching circuit

Claims (1)

[Claims] When sampling a composite color television signal to obtain a pixel information signal, any one pixel among the pixels on the current screen is set as the pixel of interest, and the color signal of the pixel of interest and the color signal in phase with the pixel of interest is centered around the pixel of interest. A pixel group having an equal number of constituent pixels using at least 4 pixels on the previous screen from 4 pixels on the previous screen with a color signal having a color signal opposite to that of the pixel of interest, and 4 pixels on the current screen. a pixel group forming means for forming a plurality of pixel group forming means, a correlation determining means for determining a pixel group having the strongest correlation among the pixels constituting the pixel group among the plurality of formed pixel groups, 1. A luminance signal/chrominance signal separation device comprising a separation means for separating a luminance signal and a chrominance signal of a pixel of interest using information signals of pixels constituting a pixel group.