JPH05145948A - Chrominance signal interpolating circuit - Google Patents

Abstract

PURPOSE:To execute a visually satisfactory interpolating operation even in the case of high-speed search by executing control to select the output of an LPF in normal reproduction and to select the output of a replacing means in the high-speed search. CONSTITUTION:A switch 30 is changed over so as to select the output from an LPF 28 in the case of the normal reproduction and to select the output from a replacing means 29 in the case of the high-speed search. In this case, the operation of the LPF 28 similar to the well-known conventional example. On the other hand, the replacing means 29 is operated to output recorded scan lines as they are and to replace unrecorded scan lines with scan lines preceding to the recorded scan lines. Since a Pr signal to be interpolated is calculated only by the signal of the preceding scan line with this operation, an interpolating operation is executed in a certain specified field and even when there is any motion, the interpolating operation is not affected. In the case of a signal Pb, it is interpolated according to the method similar to the Pr signal as well. Thus, the visually satisfactory interpolating operation can be executed even in the case of the high-speed search.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal interpolating circuit for recording color difference signals in the form of line-sequential color signals and interpolating the line-sequential color signals during reproduction and obtaining a video signal output. ..

[0002]

2. Description of the Related Art In a video signal recording / reproducing apparatus (hereinafter referred to as VTR), in order to realize high image quality by avoiding image quality deterioration due to interference between a color difference signal and a luminance signal of a video signal during recording and reproduction, There is one that converts a color difference signal and a luminance signal into a time division multiplex signal (hereinafter, referred to as a TCI signal) and records and reproduces. At this time, since the signal bandwidths (corresponding to the horizontal resolution) of the two color difference signals Pr and Pb are less than half of the luminance signal Y, the vertical resolutions of the Pr and Pb signals are halved, that is, for each scanning line. In some cases, the band of the recording signal is reduced by alternately selecting the Pr and Pb signals (line sequential processing).

When line-sequential processing of color difference signals is performed, the vertical spatial frequency (corresponding to the sampling frequency, hereinafter referred to as fs) corresponding to the interval between scanning lines becomes 1/2, so fs / Since vertical spatial frequency components exceeding 4 are folded back, it is necessary to limit the vertical band of the color difference signals to fs / 4 in advance. When the TCI signal subjected to such band limitation and line-sequential processing is reproduced, the total number of scanning lines of Pr and Pb signals is halved, so an operation for obtaining a signal corresponding to an unrecorded scanning line is performed. That is, it is necessary to perform interpolation. The vertical spatial frequency components of the reproduced Pr and Pb signals subjected to the line-sequential processing have a spectrum having a period of 1/2 of fs (see FIG. 1).
3 (d)), the sampling point sequence at this time is shown in FIG.
It becomes like (a). Here, the sampling frequency is doubled, and the hatched portion in FIG. 13D is a component generated by line-sequential processing. Therefore, by removing this portion, an interpolated signal can be obtained. First, zero sampling points are added between each sampling point to double the sampling frequency (see FIG. 13B). Even with this, the spectrum does not change. If a low-pass digital filter shown in FIG. 13 (e) is used to remove the shaded components, a sampling point sequence (see FIG. 13 (c)) having the spectrum shown in FIG. 13 (f), that is, interpolation The obtained signal is obtained. It is desirable that the characteristics of the filter be close to those of the ideal low pass filter shown in FIG.

A VTR having such a structure is disclosed in Technical Report Vol. 13, No. 55, pp. 1
~ 6, "Small cassette high definition VTR" UNHI "
The development of. FIG. 14 shows the VTR as described above.
3 is a block diagram showing the configuration of FIG. Here, 1 is a Y / G input terminal to which a Y signal or G signal is input, 2 is a Pr / R input terminal to which a Pr signal or R signal is input, and 3 is Pb.
Pb / B input terminal to which signal or B signal is input, 4 is a matrix circuit for converting to Y, Pr and Pb signals when G, R and B signals are input, and also A / D converting, 5 is Pr , A TCI encoder for line-sequentially processing the Pb signal and time-division-multiplexing with the Y signal to create a TCI signal; 6 is a shuffling means for rearranging the TCI signal so that it can be sequentially distributed to each track in units of one line; Channel dividing means for dividing the TCI signal rearranged in a predetermined order into two channels, 8 is a T of each channel
An FM modulator that performs D / A conversion of the CI signal to perform FM modulation,
Reference numeral 9 is a recording amplifier for amplifying an FM signal, 10 is a recording head, 11 is a tape, 12 is a reproducing head, 13 is a reproducing amplifier for amplifying an FM signal reproduced by the reproducing head 12, 14 is an FM demodulator, and 15 is an FM. Channel combining means for A / D-converting demodulated 2-channel TCI signals to combine them into 1 channel, and 16 is shuffled T
De-shuffling means for rearranging the CI signal in the original order, 17 a TCI decoder for restoring the TCI signal to Y, Pr, Pb signals, 18 Pr, P subjected to line-sequential processing
A color signal interpolating circuit for restoring the b signal, 19 is Y, Pr, P
An inverse matrix circuit for converting the b signal into G, B and R signals and D / A converting it, 20 is a Y / G output terminal for outputting the Y signal or G signal, and 21 is Pr / for outputting the Pr signal or the R signal. An R output terminal 22 is a Pb / B output terminal for outputting a Pb signal or a B signal.

FIG. 15 is a diagram showing the structure of the color signal interpolation circuit 18. In the conventional example, as the LPF for band limiting in the vertical direction, the LPF having the configuration shown in FIG. 15 is used and the coefficient of each multiplier is 1/2 times. Here, 23 is the TCI decoder 17
P to which the Pr signal or Pb signal processed by is input
r / Pb input terminal, 24 for Pr signal or Pb signal 1
1H delay line delayed by H (H is one horizontal scanning line period), 25
Is an adder, 26 is a multiplier for multiplying the Pr signal or Pb signal by a constant, and 27 is a Pr / Pb output terminal for outputting the restored Pr signal or Pb signal. It is assumed that this circuit is provided for each of the Pr signal and the Pb signal.

Next, the operation will be described. The input Y, Pr, Pb signals or G, R, B signals are converted into Y, Pr, Pb signals by the matrix circuit 4 and then converted into digital signals. The Pr and Pb signals are input to a low pass filter (hereinafter referred to as LPF) as shown in FIG. 15 in order to limit the band in the vertical direction. In addition,
As described above, each coefficient of the multiplier is 1/2 of the value shown in FIG. Band-limited Pr, Pb
The signals are alternately selected every other line (line sequential processing). The Y signal and the line-sequentially processed Pr / Pb signal are time-axis-compressed and time-division multiplexed into a signal of one line,
A TCI signal as shown in FIG. 16 is created. In the shuffling means, with the TCI signal in one field as one line, the upper part of the screen is arranged on the lower end side of the tape and the lower part of the screen is arranged on the upper end side of the tape in each track.
Sort sequentially. In the channel dividing means 7, the shuffling-processed recording TCI signal is divided into two lines for each line.
The recording TCI signal is divided into two channels, the recording TCI signal is doubled on the time axis, and a synchronization signal, a burst, etc. are added, and D /
A-convert and output. Each channel is FM-modulated by the FM modulator 8 and recorded on the tape 11 by the recording head 10. The recording track pattern at this time is shown in FIG. Here, each number indicates a scan line number.

The FM signal reproduced by the reproducing head 12 is FM-demodulated by the FM demodulator 14 and converted into a digital signal (see FIG. 18A), and the channel synthesizing means 15 is used.
To combine into one channel (see FIG. 18B).
In the de-shuffling means 16, the channel synthesizing means 15
The reproduction TCI signal from is generated in the field memory according to the scanning line number indicated by the reproduction TCI signal, the writing address is generated and written, and the read address is sequentially generated in the scanning line number order to read the original TCI signal. Rearranged in the order of scanning lines (FIG. 18 (c))
reference). The reproduced TCI signal is returned on the time axis by the TCI decoder 17 and divided into Y, Pr, and Pb signals.
Zeros are inserted into the thinned scanning lines of the Pb signal and output (see FIG. 18D). The Pr and Pb signals interpolate the scanning lines thinned by the color signal interpolation circuit 18. This Y, Pr,
After the Pb signal is D / A converted, the inverse matrix circuit 19
Convert to G, B, R signals and output, or Y, P
The r and Pb signals are output as they are.

Next, the operation of the color signal interpolation circuit 18 will be described with reference to FIG.
It will be described with reference to FIG. As described above, the reproduced signal is FM-demodulated, then channel-synthesized (see FIG. 19A) and de-shuffled (FIG. 19).
(See (b)), TCI decoding is performed. Here, although the luminance signal and the color signal are shown to have the same time width in FIGS. 19A and 19B, the time width is actually as shown in FIG. As described above, the principle of the interpolation operation of the color difference signals subjected to the line-sequential process is explained. Among the Pr signals from the TCI decoder 17, the signal corresponding to the scanning line which is not recorded by the line-sequential process is set to 0 (see FIG. 19
(See (c) of FIG. 1), which is sequentially input to the LPF as shown in FIG.
9 (d), (e), (f) and (g)).
The input Pr signal and the Pr signal delayed by 6H are added, and (-
2/32) multiplied signal, 2H delayed Pr signal and 4H delayed Pr signal are added, (18/32) multiplied signal and 3H delayed Pr signal multiplied by 1 And are added to remove the frequency component generated by the line-sequential processing, and the interpolated Pr signal is obtained (FIG. 19).
(See (h)). Further, the interpolated Pr signal can be obtained by performing the same operation for the Pb signal as for the Pr signal.

[0009]

A VT having such a configuration
When a high-speed search is performed with R, the shuffling process causes the upper part of the screen of the video signal of one field to appear on the lower end side of the tape.
FIG. 20A shows how the reproducing head scans the tape 11 arranged at the lower end of the screen on the upper end side of the tape. The reproduced ch. The video signal of A is shown in FIG. In addition, ch. A and ch. Since there is a difference in azimuth in B, ch. The track recorded by the head of B is ch. It cannot be reproduced with the A head. Thus, at the time of high-speed search, one head scan will scan over several tracks,
The scanning line number of the video signal reproduced at that time is shown in FIG.
It shows in (c). This signal is rearranged by the de-shuffling means 16 as shown in FIG. 20 (d) in the same procedure as in the normal reproduction to form a video signal for one field. When the processing at the time of high-speed search is performed by the above-described method, as shown in FIG. 20D, a video signal for almost one field is formed although there are scanning lines missing from the video signal over several fields. A sufficiently identifiable search image is obtained.

However, since the conventional color signal interpolating circuit is configured to obtain a scanning line to be interpolated from seven consecutive scanning lines in the same field, the field to which the seven scanning lines belong during high speed search. However, since the scanning lines to be interpolated are obtained from such signals, the interpolated color signal is blurred in time, and a good interpolated color signal cannot be obtained.

The present invention has been made to solve the above problems, and two line-difference signals are line-sequentially processed and recorded, and two color-difference signals are interpolated to obtain two color-difference signals. It is an object of the present invention to obtain a color signal interpolation circuit capable of visually performing a good interpolation operation even in a high speed search in a VTR.

[0012]

A color signal interpolating circuit according to the present invention replaces an LPF which passes at least a frequency of fs / 4 or less and a signal of a scanning line which is interpolated with a signal of a scanning line which is close on the time axis. The replacement means and the output of the LPF and the output of the replacement means are selected according to the reproduction speed.

Further, the signal of the scanning line for interpolating the replacing means is replaced with the signal of the scanning line immediately before the scanning line or immediately after the scanning line, or the signals of the scanning lines before and after the scanning line.

[0014]

In the present invention, the output of the LPF is selected during normal reproduction, and the output of the replacing means is selected during high-speed search, so that the above-described temporal blurring does not occur visually and is good. To obtain various color signals.

[0015]

EXAMPLES Example 1. FIG. 1 is a block diagram showing the configuration of a color signal interpolation circuit according to an embodiment of the present invention. Where 28
Is an LPF and is the color signal interpolating circuit 18 (see FIG.
5)), and 29 is a replacement means for replacing the signal of the scanning line to be interpolated with the signal of the scanning line close on the time axis,
Reference numeral 30 is a switch for selecting which of the output of the LPF 28 and the output of the replacing means 29 is output according to the reproduction speed. The color signal interpolating circuit shown in FIG. 1 is provided for each of the Pr signal and the Pb signal.

FIG. 2 is a block diagram showing the detailed construction of the replacing means 29. Here, 31 is a selector. In FIGS. 1 and 2, the same reference numerals as those in FIG. 15 indicate the same or corresponding parts.

Next, the operation will be described. Hereinafter, the case of interpolating the Pr signal will be described. In the same manner as in the conventional example, the Pr signal corresponding to the unrecorded scanning line is set to 0 and input to the color signal interpolation circuit 18. L during normal playback
The output from the PF 28 is replaced by the replacing means 29 during the high speed search.
The switch 30 is switched so as to select the output from. Here, the operation of the LPF 28 is similar to that of the conventional example. Next, the operation of the replacement means 29 will be described. The TCI-decoded Pr signal is input (see FIG. 3A), and 3
A signal (see FIG. 3B) combined with the delay amount of the LPF 28 is input to the a of the selector 31 by the 1H delay line 24. A signal obtained by further delaying the signal of FIG. 3B by 1H (see FIG. 3C) is input to b. In the selector 31, according to the selector control signal (see FIG. 3E), the two signals (FIGS. 3B and 3C) to FIG. 3D.
Create a signal as shown in. That is, the recorded scanning line is output as it is, and the unrecorded scanning line is replaced with the recorded scanning line immediately before it. When operated in this way, the Pr signal to be interpolated is obtained only by the signal of the immediately preceding scanning line, so that the interpolation operation is performed within a specific field, and the interpolation operation is not affected even when there is motion. Further, even in the case of the Pb signal, interpolation is performed by the same method as the Pr signal.

Example 2. Example 1. Then, the replacement means 29
Although the example in which the above is configured as shown in FIG. 2 has been described, it may be configured as in FIG. Next, the operation of the replacing means 29 will be described. The other operations are the same as those in the first embodiment. Is the same as. The TCI-decoded Pr signal is input (see FIG. 5 (a)), and 2H is generated by two 1H delay lines 24.
The delayed signal (see FIG. 5 (b))
To enter. Further, a signal (see FIG. 5C) that is delayed by 1H and is combined with the delay amount of the LPF 28 is input to b. In the selector 31, according to the selector control signal (see FIG. 5E), the two signals (FIGS. 5B and 5C) are generated.
Is. ) To generate a signal as shown in FIG. In other words, the recorded scan lines are output as they are,
The unrecorded scan line is replaced by the scan line immediately following it. Pr interpolated when operated in this way
Since the signal is obtained only by the signal of the scanning line immediately after, the interpolation operation is performed within a specific field, and even if there is a motion, the interpolation operation is not affected. Further, even in the case of the Pb signal, interpolation is performed by the same method as the Pr signal.

Further, the Pr signal is obtained in the first embodiment. The Pb signal is interpolated by the method of 2. May be used for interpolation. Further, the Pr signal is obtained in the second embodiment. The Pb signal is interpolated by the method of 1. May be used for interpolation.

Example 3. Example 1. And 2. Then P
Although the example in which the r signal and the Pb signal are separately processed has been described, the replacing means 29 may be configured as shown in FIG. 6 so as to process the Pr signal and the Pb signal together. Here, 33 is a Pr / Pb mixer that uses the TCI-decoded Pr signal and Pb signal as one signal, Pr / Pb signal, and 34 is a selector.

Next, the operation will be described. In the Pr / Pb mixer, only the recorded scan lines are selected from the TCI-decoded Pr signal and Pb signal as shown in FIG. 7A to create the Pr / Pb signal (FIG. 7B). reference). Example 1 Similarly, a signal (see FIG. 7C) obtained by combining the Pr / Pb signal with the delay amount of the LPF 28 by the three 1H delay lines 24 is input to a of the selector 34. Further, the signal delayed by 1H (see FIG. 7D) is input to b. The selector 34 alternately selects the a input or the b input of the selector 34 every 1H by the selector control signal (see FIG. 7E) to obtain the output as shown in FIG. 7F. In this way, the Pr or Pb signal is obtained in which the recorded scanning line is left as it is and the unrecorded scanning line is replaced by the scanning line immediately before it being recorded.

In addition, the second embodiment. You may perform the same interpolation operation as. The Pr / Pb signal delayed by 2H is used by the selector 3
The Pr / Pb signal obtained by further delaying it by 1H is input to b of 4). In the selector 34, the a control signal (see FIG. 7 (e)) alternately inputs a or b every 1H.
Select an input. In this way, the Pr or Pb signal is obtained in which the recorded scanning line is left as it is and the unrecorded scanning line is replaced by the scanning line immediately after it being recorded.

Example 4. Example 1. 2. And 3. Then, an example in which different interpolation means are provided for normal reproduction and high-speed search has been described. In addition to these embodiments, the interpolation means at the time of normal reproduction used in the above embodiments, for example, the color signal as shown in FIG. 8 which shares the 1H delay line 24 of the LPF 28 and the replacement means 29 as shown in FIG. The interpolation means 18 may be configured.

Next, the operation will be described. The TCI-decoded Pr signal is input. The interpolated Pr signal obtained by calculating the Pr signal delayed by the six 1H delay lines is output to the a side of the switch 30 in the same manner as in the conventional example. On the b side of the switch 30, the first embodiment described above. Similarly, the Pr signal is delayed by 3H and 4H by the six 1H delay lines, and the Pr signal in which the scanning line interpolated by the selector 31 is replaced by the immediately preceding scanning line is output. The switch 30 selects the a side during normal reproduction and the b side during high speed search to obtain an interpolated signal.

Further, in the second embodiment. The same effect can be obtained even if the Pr signal obtained by the same interpolation operation (the scanning line to be interpolated is replaced by the scanning line immediately after) is output to the b side of the switch 30.

Example 5. Example 1. 2. 3. And 4. In the above, an example in which the LPF 28 is separately provided for each of the Pr signal and the Pb signal has been described, but the third embodiment will be described. Similarly, the LPF 28 may be configured to process the Pr signal and the Pb signal as one signal, Pr / Pb signal. For example, the color signal interpolation circuit 18 is shown in FIG. 9, and the LPF 28 is shown in FIG.
It is configured as shown in 0. The replacing means 29 is the same as that of the third embodiment. Same as the above (however, from FIG. 6, Pr / Pb
(Excluding the mixer 33).

Next, the operation will be described with reference to FIGS. 9, 10 and 11. Example 3 above. In the same manner as Pr / P
The b mixer 33 outputs one signal, P, from the Pr signal and the Pb signal.
The r / Pb signal is input to the LPF 28 and the replacement means 29. In the replacing means 29, the third embodiment described above. The same operation is performed to obtain the interpolated Pr signal and Pb signal, respectively. LP
In F28, the Pr / Pb signal is delayed by 2, 3, 4, and 6H (see FIGS. 11B, 11C, 11D, and 11E), and the input Pr / Pb signal is delayed by 6H in Pr /. Pb
Signals added together and multiplied by (-2/32) and 2H
Delayed Pr / Pb signal and 4H delayed Pr / Pb
The signals are added, and the signal obtained by multiplying (18/32) is added and input to a of the selector 36 (see FIG. 11 (f)). The Pr / Pb signal delayed by 3H is input to b of the selector 36 (see FIG. 11 (g)). The selector 36 alternately selects the a input or the b input for each 1H, and
Pr signal like 1 (h) and Pb like FIG. 11 (i)
Get the signal. In this way, the LPF 28 and the replacement means 2
The Pr signal and the Pb signal obtained in step 9 are selected and output by the switch 35 depending on whether the normal reproduction or the high speed search is performed. The same effect as can be obtained.

Example 6. Example 5. In the above, an example in which different interpolation means are provided for normal reproduction and high-speed search has been described. Similarly, the color signal interpolating means 18 may be configured as shown in FIG. 12 so that the LPF 28 and the 1H delay line 24 of the replacing means 29 are shared.

Next, the operation will be described. The Pr / Pb mixer 33 creates the Pr / Pb signal from the TCI-decoded Pr signal and Pb signal. Example 5 In the same manner as above, a signal obtained by calculation from the input Pr / Pb signal and the Pr / Pb signals delayed by 2H, 4H and 6H (see FIG.
1 (see (f)) is input to the switch 30. The Pr / Pb signal delayed by 4H (see FIG. 11D) is switched 3
Enter on the other side of 0. The switch 30 selects one of the signals according to the normal reproduction or high-speed search by the selector 3
Output to b of 6. The output signal corresponds to the interpolated signal. Further, the Pr / Pb signal delayed by 3H (see FIG. 11C) is input to a of the selector 36. Note that this signal is the recorded signal. The selector 36 alternately selects the a input or the b input for each 1H to obtain the interpolated Pr signal and Pb signal.

Example 7. Example 1. 2. 3. ,
4. 5. And 6. Then, the LPF 28 is configured as a 7-tap FIR filter as shown in FIG. Other than this example, the LPF 28 may have any configuration as long as it is an LPF having a pass band of at least fs / 4.
The same effect as that of the above embodiment can be obtained.

[0031]

As described above, according to the present invention, in a VTR in which two color difference signals are line-sequentially processed and recorded, and two color difference signals are obtained by interpolating from reproduced color difference signals, a high speed search is performed. Since the signal of the scanning line to be interpolated is replaced by the signal of the scanning line close to the signal, it is possible to perform a visually excellent interpolation operation even during the high speed search.

[Brief description of drawings]

FIG. 1 is a first embodiment of the present invention. 3 is a block diagram showing a configuration of a color signal interpolation circuit according to FIG.

FIG. 2 is a block diagram showing a configuration of a replacement unit of FIG.

FIG. 3 is a diagram for explaining the operation of FIG.

FIG. 4 is a second embodiment of the present invention. It is a block diagram showing a configuration of a replacement means of.

5 is a second embodiment of the present invention. 6 is a diagram for explaining the operation of FIG.

FIG. 6 is a third embodiment of the present invention. It is a block diagram showing a configuration of a replacement means of.

FIG. 7 is a third embodiment of the present invention. 6 is a diagram for explaining the operation of FIG.

FIG. 8 is a fourth embodiment of the present invention. 3 is a block diagram showing a configuration of a color signal interpolation circuit according to FIG.

FIG. 9 is a fifth embodiment of the present invention. 3 is a block diagram showing a configuration of a color signal interpolation circuit according to FIG.

10 is a block diagram showing the configuration of the LPF of FIG.

FIG. 11 is a diagram for explaining the operation of FIG. 9.

FIG. 12 is a sixth embodiment of the present invention. 3 is a block diagram showing a configuration of a color signal interpolation circuit according to FIG.

FIG. 13 is a diagram for explaining a conventional interpolation operation of a color difference signal subjected to line-sequential processing.

FIG. 14 is a block diagram showing a configuration of a conventional VTR that performs line sequential processing.

FIG. 15 is a block diagram showing a conventional color signal interpolation circuit.

FIG. 16 is a diagram showing a TCI signal of a conventional VTR.

FIG. 17 is a diagram showing a recording track pattern of a conventional VTR.

FIG. 18 is a diagram for explaining the operation of a conventional VTR reproduction system.

FIG. 19 is a diagram for explaining the operation of a conventional color signal interpolation circuit.

FIG. 20 is a diagram for explaining the operation of a conventional VTR during high speed search.

[Explanation of symbols]

 28 LPF 29 replacement means 30 switch

Claims (2)

[Claims] 1. A video signal recording / reproducing apparatus in which two color difference signals are line-sequentially processed and recorded, and two color difference signals are obtained by interpolating from the reproduced color difference signals, which corresponds to at least an interval between scanning lines during reproduction. Vertical spatial frequency of 1
A low-pass filter that passes frequencies equal to or lower than / 4, and a replacement unit that replaces the signal of the scanning line to be interpolated with the signal of a scanning line close on the time axis, and the output of the low-pass filter and the replacement unit. The color signal interpolation circuit is characterized in that which of the output and the output is selected according to the reproduction speed. 2. A replacement unit configured to replace a signal of a scanning line to be interpolated with a signal of a scanning line immediately before the scanning line, immediately after the scanning line, or before and after the scanning line. The color signal interpolation circuit according to claim 1.