JPS59198100A - Color and intensity separating and treating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method for converting the color signal and luminance signal of a composite video signal into a
This invention relates to a color/luminance separation processing device.

(Prior art and its problems) In the NTSC system, a composite video signal includes a color signal component and a luminance signal component, and these are separated at intervals of 1/2 of the horizontal frequency to prevent interference due to mutual beats, crosstalk, etc. Frequency interpolation is performed. This composite video signal is generally separated into color information and luminance information using a notch filter or a comb filter.

FIG. 1 shows a conventional bandpass/bandstop/notch filter used to perform color/luminance separation. A bandpass filter (BPF) (2) receives the composite video signal and passes signals around the color subcarrier of approximately 3.58 MHz. The output of this bandpass filter (2) is applied to a subtracter (6) and subtracted from the composite video signal that has been subjected to multiple phase adjustment by the phase equalizer (4). In this way, a color signal and a luminance signal are output to output terminals C and L, respectively. However, with this configuration, the color signal and the luminance signal cannot be completely separated. This is because not only the color signal but also the luminance signal near the color subcarrier passes through the filter (2).

This high-frequency luminance signal component included in the color information becomes color noise and causes cross-color interference. Furthermore, since the luminance information includes color signal components, dot interference occurs and image quality deteriorates. Furthermore, the resolution decreases due to the lack of a high frequency region of the luminance signal.

The conventional comb-shaped filter shown in FIG. 2 allows color and luminance separation to be performed without causing cross-color interference or dot interference. In the NTSC system, as described above, the chrominance signal component and the luminance signal component are frequency-interpolated, and two vertically adjacent scanning lines (the frequency of the chrominance subcarrier is an odd multiple of 1/2 of the horizontal scanning frequency). ) have color subcarriers that are equal in magnitude but differ in phase by 180° (in the case of the same color). A comb filter utilizes this characteristic. Referring to FIG. 2, the composite video signal input to the input terminal IN is transmitted through a delay line (8), a subtracter α0, and an adder (A).
is applied to The delay line (8) delays the input video signal by one scanning line, that is, about 635 μs. By subtracting this delayed video signal from the non-delayed video signal and canceling its luminance signal component, a comb-shaped F-wave color signal is output from output terminal C. Similarly, by adding the delayed video signal to the non-delayed video signal and canceling out the color signal components thereof, a comb-shaped F-wave luminance signal is output. This comb-shaped filter constitutes a comb-shaped luminance filter and a comb-shaped color filter, each having a signal path for complete color/luminance separation. In such a comb-shaped filter, high-frequency luminance signal components can also pass through the luminance filter signal path, improving resolution.

Color is determined by two independent variables. In the vector representation conventionally used to define color in television signals, color is defined by magnitude (saturation or intensity) and phase (hue) relative to the burst. In order for two colors represented by color information to be the same, they must have equal magnitude and relative phase. In this specification,'
The term "color signal level" shall mean both hue and saturation.

A conventional comb filter outputs a color signal that is the average of the color signal levels of two adjacent scanning lines.

Therefore, a color is generated at the averaged color signal level, which is intermediate between the color signal levels of each of the two adjacent scanning lines. That is, a color represented by the vector sum of vectors representing the color of the defining scanning line is generated. Therefore, if these two color signal levels are significantly different, this average color level is
It does not necessarily accurately represent the color of the scan line to be demodulated. The outputs C and L can be used for either an input signal delayed by one scanning line (IH) or an undelayed input signal. That is, outputs C and L can be used as outputs that are temporally equivalent to IH delayed outputs or non-delayed outputs.

FIG. 3 shows a conventional comb filter using three scan lines delayed by one scan line. Parts that are equivalent to those in FIG. 2 are given the same reference numerals. For the sake of explanation, these three scanning lines will be referred to as OH, IH, and 2H, respectively. Here °H”
indicates the delay time for one television scanning line, and the number before H'' indicates the number of delayed scanning lines.

Therefore, "OH'" represents no delay (actually a reference point from which to determine other delays), and "IH" and "2H" represent one and two scan lines for the husband's "OH" output. represents Ill at the time of delay. In FIG. 3, the composite video signal input to the input terminal INF is distributed to three paths.

That is, one of them is sent directly to the adder αQ without delay, and the other two are sent to the delay line (
8) and (1).The OH signal is added to the 2H signal in phase with the adder α and the stirrup, and this output is applied to the divider (I
The signal is halved by F9 and the average of the OH (g signal and the 2H signal is taken.) By processing the average of the OH signal and the 2H signal and the IH multiplied signal as in the comb filter shown in Fig. A color/luminance separation is achieved, this color output signal representing the color information of the IH delay output of the delay line (8).

In this comb-shaped filter, the color information of the three scanning lines is related to each other (@
(similar to the above), the color error is smaller than that using two scanning lines as shown in FIG. In particular, vertical color and brightness delays are reduced. However, both OH signal and 2H signal are IH
There is a problem in that the color error becomes even larger when the multiplied signals are significantly different.

(Object of the Invention) An object of the present invention is to provide a color/luminance separation processing device that performs color/luminance separation with minimum error.

Another object of the present invention is to provide a color/luminance separation processing device that minimizes errors by switching between a comb filter and a notch filter. - (Summary of the Invention) The present invention provides means for outputting a plurality of scanning line signals delayed by one scanning line, and a means for outputting at least one pair of the plurality of scanning line signals to cancel the color subcarrier signal. computing means for processing the signal; comparison means for comparing the output of the computing means with a predetermined level; and filter means operable in a first mode as a notch filter and a second mode as a comb filter of at least one type. and a control means for selecting a filter mode of the filter means in accordance with the output of the comparison means.

A color/luminance separation device according to an embodiment of the present invention uses one or more types of comb filters and one notch filter, and the filter mode is selected based on a similarity relationship between a plurality of consecutive scan lines. . The three bandpass filters are OH and I, respectively.
I(, 2H scan line signal received.

The outputs of these bandpass filters are input to an adder and a subtracter, between OH and IH, between IH and 2H, and between OH and 2H.
The color signals are canceled between H. The outputs of the adder and subtracter are compared with a predetermined level in a comparator, and the degree of vertical color similarity determines whether a comb filter is suitable. Based on the information from this comparator, the color
The luminance separation processor is controlled to minimize errors by switching to the optimal filter mode.

(Example) Referring to FIG. 4, the composite video signal is transmitted through the non-delayed path,
The signal is input to a delay means including a scan line delay path and a two scan line delay path (OH, IH) as described above.

and 2H are output. These outputs are passed through bandpass filters (A), (C), (A) and color
It is input to the luminance separation means (c). This means (c) consists of a notch filter as shown in FIG. 1, and elements constituting a comb filter as shown in FIGS. 2 and 3 together with the delay means. The operating mode of the separating means (c) (notch and two scan line comb type or three scan line comb type) can be selected by a logic signal. Filter@, (to).

(a) blocks low frequency information and 3.58f of color subcarrier
' Frequency around 1iHz and higher if possible between adders.

0■ and the subtractor 0→.

Now, consider the adder (g) that receives the outputs of the bandpass filters (a) and (c). The adder (G) is
Comparator 00, threshold image generator (to) and filter (40
The color correlation (color similarity) between the OH output and the LH output is checked. The outputs of filters (A) and (C) are mostly color information and do not include low frequency luminance information.

Since the phase of the color subcarrier is inverted every l scanning lines, when the outputs of filters (a) and (c) are added to the vertically related signals of two adjacent scanning lines, both When the signals are similar in the vertical direction, the output of the adder (G) becomes approximately O. This output is a quantity that has sign and magnitude, but only this magnitude is needed now. A small output indicates that the color similarity in the vertical direction is large between the OH'' output and the IH output, and conversely, a small output indicates that the color similarity in the vertical direction is small.

This output of the adder (30) is input to one input terminal of the comparator OQ. A threshold value is inputted from the threshold image generator (to) to the other input terminal of the comparator o4. Although the threshold value is fixed, it can also be made variable. Comparison is made when the magnitude of the signal input from the adder is greater than the threshold set by the threshold image generator (b).

The output of the comparator OQ changes state from a low logic level "0" to a high logic level "1". Since there is no filtering effect in the comparator OQ, an output is generated every time the magnitude of the input exceeds the threshold. Threshold Image Generator 0→ determines the degree of vertical similarity required for signals to be considered similar. In this example, the inputs to the comparator (to) are filters (a), (h) ) Nodame has a center frequency near or above the color subcarrier, so the output of the comparator GQ generally changes state at the speed of the subcarrier or faster. Since it cannot be distinguished on the screen, it is neither necessary nor desirable to detect it.The output of the comparator OQ is passed through a low pass filter (LP).
F)00 and extracts the essential envelope information from this output.

Adder 02 has associated comparator (6), thresholdless generator ■
, along with the low-pass filter (9), perform the same operations as the adder, comparator (g), threshold image generator (b), and low-pass filter (10) described above.The only difference is that the adder 0■ receives input from the band pass filters (C) and (C), and checks the vertical color correlation between the IH ratio output and the 2H output of the delay means.

The subtractor (3Φ and associated comparator 0Q, threshold generator flash, and low-pass filter 4) indicates that the subtractor (b) receives the OH and 2H signals from the bandpass filters (a) and (c). Except for the adder (G).

It works almost the same as 02. Since the color subcarriers of the OH and 2H outputs are in phase with the luminance information, if the color in the direction perpendicular to these scanning lines is a (JJ), the difference between the two signals will be approximately 0. Similarly, a small difference signal means that the color similarity in the vertical direction is large, and a large difference signal means that the color similarity is small.

Subtractor e3. ) The process from the output to the output of the low-pass communication filter 62 is the same as in the case of the adder (g) and zero.

In order to explain the outputs of filters 140), I, and (g), they will be referred to as A, B, and C, respectively. Output A, B showing color similarity
.

C are supplied to a logic controller and controller Q generates logic outputs in response. As described above, the color/luminance separation means (c) includes a notch filter, a comb filter using two scanning line signals, and a comb filter using three scanning line signals. The means (c) selects a notch filter or a comb filter using an appropriate number of scan lines depending on the logic output from the controller.

The 2H signal may be removed. In that case, the color/luminance separation means uses a notch filter and two scanning line signals to
a comb filter that generates an H output signal.

Next, mode selection of the color/luminance separation means (c) will be explained with reference to FIGS. 5 and 6. FIG. 5 shows the output of the delay means. An example of three levels of color subcarriers corresponding to three scan line signals of OH, IH, and 2H is shown. The level here refers to a color level, and each level is determined by size and relative phase. The vertical scale of the graphs in FIGS. 5A-H may be arbitrary to represent different colors. Here, it is assumed that digital signals (logical signals) A, B, and C become "high # (logical 1)" when the difference between the two levels is greater than one scale on the graph in FIG.
, B, and C correspond to the level differences between OH and IH, OH and 2H, and IH and 2H, respectively. ) Also, the reference alphabetic characters A to H in FIG. 5 correspond to A to H in the left column of FIG. OH, IH
, 2'i@ signals, the color signal outputs generated by comb filtering, It or notch filtering of two or all of the signals coincide with the IH ratio output time. It is used to determine (and thus also spatially consistent) color signals.

In FIG. 5A, since the three levels are approximately equal, the logical values of the digital signals A, B, and C become (000). Therefore, the color/luminance separation means (c) outputs an OH signal.

A comb filter is selected to process the IH, 2) (scan line signal). This comb filter produces a color output close to the actual level of the IH multiplied signal. In FIG. Therefore, the logical value is (001).In this case, the average of the levels of the OH and IH multiplied signals is higher than the average of the intermediate level of the OH and 2H signals and the IH multiplied signal level, which is the actual IH multiplied signal level. Therefore, in this case, it is not a comb filter that processes 3 scanning lines (O
A comb filter that processes H and IH signals is selected. In FIG. 5 and 9, since the signal B is 1 high, the logical value ' is (0
10). In this case, a comb filter (any pair of OI (and IH or 1H and 2H) is selected) that processes 6 scanning line signals.Furthermore, in this case, the intermediate level of the OH and 2H signals is the IH multiplied signal. A comb filter that processes the 0H2IH and 2H signals may be used because the actual level is close to the actual level. They are selected in the same way.

In FIG. 5G, signals A and C are 1 high. In this case,
OH,II(,2I) Neither combination of signals can reduce the color error due to comb filter operation.

Therefore, a notch filter is selected to prevent color errors. In FIG. 5H, a synoptic filter is selected for the same reason.

Next, let us consider an initial state in which the three scanning line signals are not output from the five delay means. When the M" 1 scanning line signal is subjected to the delay means f2@, the 1st scanning line structure appears at the OH output, but no signal appears at the IH and 2H outputs. At this time, the signal t, The logical value of B and C is (110), and the color/luminance separation means (c) uses a comb filter that processes the IH and 2H signals.Therefore, the color output of the means (c) is 0.Next: When the second scan line is supplied, the first
and the second scanning line signal appears as OH and IH specific outputs, respectively;
No signal appears on the 2H output. Comparing the OH and IH double signal outputs, if the difference in both levels is small, the logical value is (011
) and if it is large, it becomes (111). Therefore, depending on this logical value, a comb filter or a notch filter is used to process the OH and IH multiplied signals. The operation after the third scanning line is supplied to the delay means θ) is as described above.

The present invention is not limited to the specific embodiments described with reference to FIGS. 4 to 6, and various modifications can be made without departing from the gist of the present invention. In particular, it should be noted that the described embodiment is a general case. In reality, the bandpass filters (a), Q→, and (c) may be part of the combination/luminance separation means (c), or may be placed before the delay means.

In this case, only one bandpass filter is required. Still, in certain cases, it is not necessary to use all of the adders, ea, and subtractors. For example, only the subtracter 04 may be used.

This case is equivalent to the case where comparator 041) IQ has a very high threshold. Furthermore, slight changes
In particular, if changes are made to the adder, 0 mute, and subtracter 04), it can also be used to process PAL signals.

For ease of understanding, although the above description describes the present invention as a color/luminance separation processing device used in a video decoder of a television receiver, in a preferred embodiment of the present invention, the color signal component is a luminance signal. It is not separated from the luminance signal component, but is inverted with respect to the luminance signal component.

, the luminance signal and color signal C thus separated (
An LC signal is output. This L-
A C signal is required. 1 frame in the NTSC television system? - Four sequential fields are required for generation.

Therefore, from the L+C signal accumulated in field 1,
-C signal (for field 3). Inverting the color signal component is functionally equivalent to separating the color signal component and the luminance signal component and then subtracting the color signal component from the luminance signal component. However, in the preferred embodiment, the chrominance and luminance signal components are not clearly separated. This separation is not necessary when performing algebraic simplifications.

In a preferred embodiment of the invention, the input video signal is a digital signal and the various operations (F-wave, delay, etc.) are performed using digital techniques.

(Effects of the present invention) According to the color/luminance separation device of the present invention, one of the colors between two scanning lines is
lffj (Since the JJ degree is detected and the notch filter and comb filter are switched accordingly, it is possible to compensate for the drawbacks of both filters and minimize color errors. Therefore, extremely high quality images can be obtained. effective.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional notch filter, Fig. 2 is a block diagram of a conventional comb filter that performs two scanning line processing, Fig. 3 is a block diagram of a conventional comb filter that performs three scanning line processing, and Fig. 4 is a block diagram of a conventional comb filter that performs three scanning line processing. The figure is a block diagram of an embodiment of the present invention.
5 and 6 are diagrams for explaining the operation of the embodiment of the present invention. In the figure, (a) indicates a delay means, +361, (421) and a decoy comparator which is a detection means, and (b) indicates a color-luminance separation means.

Claims (1)

[Claims] a delay means for outputting a plurality of scanning line signals delayed by one scanning line by dropping the composite video signal; and detecting color similarity of at least one pair of the plurality of delayed scanning line signals. a detection means; and a color/luminance separation means that selectively performs a filter operation with different characteristics depending on the output of the detection means and separates the delayed scanning line signal from the delay means into a color component and a luminance component. color/luminance separation processing device.