JPS5911312B2 - Color television luminance signal chromaticity signal separation device - Google Patents

Description

[Detailed description of the invention] (Technical field)! 0 The present invention relates to a color television luminance signal and chromaticity signal separation device that separates luminance signal components and chromaticity signal components from a color television composite signal with extremely good characteristics.

(Prior art) For example, in a color television signal of the NTSC system, a color television composite signal in which a chromaticity signal is obtained by orthogonal two-phase modulation of a subcarrier signal and multiplexed into a luminance signal is used to generate a luminance signal and a chromaticity signal. Conventionally, when separating into signal components, the horizontal frequency and the subcarrier signal frequency of the color television composite signal ro have been separated by utilizing the fact that they have a frequency interleaf relationship with each other.

In other words, by taking advantage of the fact that the phase of the subcarrier becomes opposite at a position one line apart, the subcarrier is canceled by adding the two signals, and only the luminance signal component is obtained. If the difference is taken, the luminance signal is canceled and the chromatic subcarrier components (chromaticity signals) become in phase and can be separated. However, conventional separation assumes that the signals are equal at positions one line apart, that is, that vertical correlation exists for the two lines, and this generally does not hold, so only incomplete separation can be achieved for general images. In addition, a device shown in FIG. 1 was considered as a luminance signal and chromaticity signal separation device that eliminated the above-mentioned drawbacks, but it was difficult to suppress the noise of the input color television composite signal.

FIG. 1 will be explained below. In FIG. 1, reference numeral 1 indicates an input color television composite signal (hereinafter referred to as "input NTSC composite signal").

), 2 is an analog-to-digital converter, 3 is a synchronization signal separator that separates the synchronization signal from the input NTSC composite signal, and 4 is a burst lock oscillator, which separates the color burst in the input NTSC composite signal from the synchronization signal separator 3. A continuous wave is extracted by the burst gate pulse generated from the color burst signal and is phase-locked to this color burst signal, and is usually selected as an integral multiple (for example, 4 times) of the subcarrier.
5 is a timing generator that generates various clock pulses and control pulses necessary for controlling the device from the clock frequency and horizontal frequency pulses from the burst lock oscillator and the vertical synchronization pulse from the synchronization signal separator 3. do.

6 is a serial-to-parallel converter, 7 is a one-frame memory for storing one frame of digital input NTSC composite signal, 8 is a parallel-to-serial converter, 9 is an addition circuit, 10 is a subtraction circuit, 13
, 14 are digital-to-analog converters.

The input NTSC composite signal digitized by the analog-to-digital converter 2 is converted into parallel data by the serial-parallel converter 6 so that the input high-speed serial data pulse is compatible with the writing speed of the next one frame memory 7. One frame is written into the memory 7. Data in one frame memory 7 is read out in the order in which it was written.

This read parallel data is transferred to the parallel to serial converter 81fC.
The data is then converted back to serial data. In this case, the time difference between the output of the analog-to-digital converter 2 and the output of the parallel-to-serial converter 8 corresponds to one frame of the telepicture. The timing generator 5 reads out this one frame difference. By the way, there is generally a relationship between the subcarrier frequency FsO and the horizontal frequency FH of the NT'SC composite signal.

This corresponds to 227.5 subcarriers in one horizontal scanning period, so in one frame, 227.5 x 525 = 119
It becomes 437.5. That is, N
The subcarrier signals of the TSC composite signal are reversed in phase.
If the input NTSC signal is a stationary signal, then
Since these two signals separated by one frame are originally the same image, the luminance signal has exactly the same amplitude and the same phase as the NTSC signal, whereas the chromaticity subcarrier signal has the same amplitude and inverted polarity. Therefore, the digital input NTSC composite signal via the analog-to-digital converter and the digital input N via the parallel-to-serial converter 8
Data temporally separated by VCl frames from the TSC composite signal is input to an addition circuit 9 and a subtraction circuit 10.

In the output of the adder circuit 9, the chromaticity subcarrier component is canceled, and only the luminance signal component 11 is obtained with double the amplitude. If this is shifted by one bit (multiplyed by 1/2) and an analog signal is extracted by the digital-to-analog converter 13, a signal in which only the luminance signal is selected can be obtained. On the other hand, if the subtracter 10 takes the difference between the one-frame difference signals (the digital input NTSC composite signal from the analog-to-digital converter 8 and the data from the parallel-serial converter 8, which is temporally separated from the signal by one frame), It is clear that the luminance signal is canceled and only the chroma signal component 12 is obtained. The output of the subtracter 10 is sent to the digital-to-analog converter 1.
4, an analog chromaticity signal is obtained. In this way, in the case of still images, it is possible to completely separate the luminance signal and chromaticity signal from the input composite television signal.

However, it was not possible to suppress the noise of the input NTSC signal.

(Objective of the Invention) The present invention provides a luminance signal and chromaticity signal separation device that eliminates these drawbacks.

(Structure and Embodiments of the Invention) Next, embodiments of the present invention will be described with reference to FIG. This is a chromaticity signal separation device.

6, 7, 8, 9, and 10 are the same as those described in connection with FIG.

20 is a digital input NTSC decomposed signal obtained from an analog-to-digital converter (not shown); 21 is a one-line shift register; 22 is a second addition circuit; 23
24 and 25 are the magnitudes of the signals, respectively, to the second reduced journey (
1-K), the first and second multipliers multiply by K (K is in the range O<K<1), and 26 is a third adder circuit that adds the respective outputs of the first and second multipliers. , 27 is a motion detection circuit, 2
8 and 29 are first and second switching circuits, and 30 is a fourth addition circuit.

Although not shown in FIG. 2, it has a circuit for generating various clock pulses and control pulses similar to that in FIG. 1. 1
Input NTSC composite signal 2 input to line register 21
0 is accumulated for one horizontal scan, and there is a time difference between the output by human input and one horizontal scan.

The second addition circuit 22 and the second subtraction circuit 23 have inputs NT
The Sσ signal 20 and the output of the 1-line register 21 are added and subtracted to decompose the input NTSC composite signal 20 into a luminance signal and a chromaticity signal. Furthermore, the motion detection circuit 27 calculates the difference between the input NTSC composite signal 20 and the data from the one-frame memory 7 via the parallel-to-serial conversion circuit 8 for each pixel, so that this difference reaches a certain threshold. A pixel exceeding this value is considered to be a moving pixel. If the motion detection circuit 27 determines that the pixel is a moving pixel, the first and second switching circuits 28, 2
9 to select the luminance signal and chromaticity signal from the second addition circuit 22 and the second subtraction circuit 23, and if the pixel is not determined to be a moving pixel, the luminance signal and the chromaticity signal from the first addition circuit 9 and the first subtraction circuit 10 are selected. Switch to select the luminance signal and chromaticity signal. These luminance signals and chromaticity signals are sent to a fourth addition circuit 3.
0 to form a composite signal, which is supplied to the second multiplier 25. The first and second subtraction circuits 10, 23 are polarized so that their outputs (chromaticity signals) are opposite in phase to the color subcarriers of the input NTSC composite signal 20. In this way, the digital input NTSC composite signal 20 is multiplied by (1-K) by the first multiplier 24, and the third adder 30
A signal obtained by multiplying the output (digital NTSC decomposed signal) by K in the second multiplier 25 is added in the third adder circuit 26, and the noise is suppressed by utilizing the random nature of the noise. Note that the first and second multipliers 24, 2
The value of K of 5 is controlled by the output of the motion detection circuit 27. In the embodiment, the still image portion and the moving image portion of the input NTSC signal are distinguished, and the still image portion is completely separated by adding and subtracting the input NTSC signal and data separated by one frame from the input NTSC signal. A luminance signal and a chromaticity signal can be obtained, and an extremely high quality image can be obtained.

In particular, in conventional signal separation, since signals separated by one or two lines are added and subtracted, deterioration of vertical resolution cannot be avoided. On the other hand, in the embodiment, signals separated by one line are added and subtracted only for moving parts, but this does not pose a big visual problem because the sensitivity of the eye to the fineness of moving images is greater than that of still images. Note that the input NT is input to the 1-line register 21, the second addition circuit 22, and the second subtraction circuit 23 (point A in FIG. 2).
This can also be achieved by supplying the output from the resistive parallel-to-serial converter 8 that supplies the SC signal 20.

As explained above, according to the present invention, it is possible to completely separate luminance signals and chromaticity signals, especially in still images with extremely little deterioration in resolution, and it is also possible to suppress noise, thereby producing high-quality signals. Obtainable.

It is extremely useful in various image processing devices that require separation of luminance signals and chromaticity signals of still images, and its effects are significant.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram explaining an embodiment that is the premise of the present invention,
FIG. 2 is a circuit diagram illustrating an embodiment of the present invention. 1... Input NTSC composite signal, 2...
Analog-digital converter, 3... Synchronous signal separator, 4... Burst lock oscillator, 5...
...Timing generator, 6...Serial-to-parallel converter, 7...1 frame memory, 8...
・Parallel-serial converter, 9, 22, 26, 30...
Addition circuit, 10, 23... Subtraction circuit, 13, 1
4...Digital to analog converter, 20...
...Digital input NTSC decoding signal, 21...
...1 line register, 24, 25... Multiplier, 27... Motion detection circuit, 28, 29...
...Switching circuit.

Claims (1)

[Claims] 1. A first storage circuit that stores one frame of a color television signal; and a readout circuit that sequentially reads out the data stored in the first storage circuit with one frame temporally separated from the television signal. and a first adding the input television signal and the read data.
a first subtraction circuit for subtracting; and a second subtraction circuit for delaying either the input color television signal or the data from the first storage circuit by one horizontal scan.
a storage circuit, the data stored in the second storage circuit is read out after one horizontal scanning time, and the data read out from the second storage circuit and the input color television signal on the input side of the second storage circuit are read out. a second addition circuit for adding data and a second subtraction circuit for subtracting the data; a motion detection circuit that compares each pixel and detects a pixel whose difference exceeds a certain threshold; a first switching circuit that selects a luminance signal component from the first addition circuit when the pixel is not determined to be a moving pixel;
When the motion detection circuit determines that the pixel is a moving pixel, the second
a second switching circuit that selects the chromaticity signal component from the second subtraction circuit when the chromaticity signal component from the subtraction circuit is not determined to be a moving pixel; a third addition circuit that adds the luminance signal component and the chromaticity signal component obtained from the second switching circuit; and a first multiplication that multiplies the output of the third addition circuit by K (0<K<1). a second multiplier that multiplies the input color television signal by (1-K); and a second multiplier that multiplies the input color television signal by (1-K);
a fourth color television signal to a storage circuit;
1. A color television luminance signal chromaticity signal separation device, characterized in that it has an addition circuit.