JPH06141287A - Television signal processing circuit - Google Patents

Abstract

PURPOSE:To reduce the interference in a current receiver by eliminating the effect due to a DC offset of auxiliary signal multiplexed on upper and lower non-picture parts of the letter box system. CONSTITUTION:A main signal of the letter box system is outputted via a frame synthesis circuit 2, a vertical low pass filter 4, a 4 3 scanning line converter 11, an adder 12, an interlace scanning conversion circuit 13, and a switch 17. When a vertical high frequency component is extracted by an adder 5 to prepare an auxiliary signal multiplexed on upper and lower non-picture parts, a transmission auxiliary signal transmitting actually is defined as the difference signal between the frames in the main signal with high correlation with the auxiliary signal and the signal of difference of the pertinent auxiliary signal. The transmission auxiliary signal is generated by using a system comprising an inter-field difference circuit 110, a horizontal vertical low pass filter 111, and a subtractor 112 and by using a system comprising a vertical low pass filter 6, a horizontal vertical low pass filter 7, a 4 3 scanning line converter 8, a subtractor 112, a 3 2 scanning line converter 14, a time compression circuit 15, a rearrangement circuit 16 and a switch 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal processing circuit in a horizontal encoder television broadcast transmitting side encoder and receiving side decoder compatible with existing receivers.

[0002]

2. Description of the Related Art Television signals are obtained by scanning a screen. For example, in the NTSC system, the effective scanning line is 480
One screen is composed of [book / frame].

When an image is taken by a horizontally long screen camera having an aspect ratio of 16: 9 and displayed on a display having an aspect ratio of 4: 3, the circularity cannot be maintained and a circular object becomes a vertically long ellipse. In other words, the compatibility of the current receiver for landscape screen broadcasting cannot be obtained as it is. In order to display a circle as a circle on a display having an aspect ratio of 4: 3 without losing the horizontally long screen, it is necessary to perform compression processing to 3/4 in the vertical direction. In this way, the encoding method for displaying the camera signal of the horizontally long screen on the current receiver with the aspect ratio of 4: 3 while maintaining the roundness is accompanied by the non-image part at the top and bottom of the display (the black bars are at the top and bottom of the screen, The image is displayed in the center), which is called the letterbox method. In the letterbox method, if the effective scanning line number of the original image is 480 [lines / frame], the scanning line number is converted to 360 [lines / frame] to vertically compress it to 3/4 and to output 120 This is a process of setting [book / frame] as a non-image portion. On the other hand, if the letter-box type signal is displayed as it is on the display having the same horizontal aspect ratio of 16: 9 as that of the camera, a circular object becomes a horizontal elliptical shape. Therefore, in order to decode the signal transmitted as a signal compatible with the current receiver to the original horizontal screen, it is necessary to perform vertical 4/3 expansion processing and convert it to 480 [lines / frame]. become. In the letterbox method, the transmitting side performs vertical compression to transmit a 360 [lines / frame] signal, and the receiving side performs vertical decompression, but in this state it is theoretically 360 [lines / screen height] or more. The vertical resolution of is not available. Therefore, of the approximately 480 [line / frame] effective scanning lines of the NTSC system, 360 [line / frame] is used as the letterbox main screen,
The remaining 120 [lines / frames] in the upper and lower parts of the screen are used as a multiplex region of the auxiliary signal for improving the vertical resolution.

However, when the current receiver receives the above letterbox signal, the signals multiplexed on the upper and lower parts of the screen are displayed as they are, and they are detected as a kind of interference. That is, it becomes a serious problem in compatibility with the current receiver.

The original auxiliary signal of the letterbox system is intended to improve the vertical resolution, but it can be considered separately for a moving image and a still image. 3 for still images
Although it is a vertical high frequency component of 60 [lines / screen height] or more, the energy of this component is usually extremely small in many natural images, and it is difficult to detect the image quality difference due to the presence or absence of this component in terms of visual characteristics. However, in the case of moving images, the auxiliary signal has a very important meaning for resolution, and in many natural images, the energy of this component is usually extremely large. Therefore, the interference with the current receiver due to the signals multiplexed in the upper and lower non-image parts of the letterbox system is not a serious problem in a still image, and becomes a serious problem in a moving image.

[0006]

As described above, the signals multiplexed in the upper and lower non-picture parts of the letterbox system appear as interference when received by the current receiver. Therefore, the object of the present invention is to reduce interference with the current receiver in the letterbox system and provide a highly compatible means.

[0007]

According to the present invention, (A1)
On the transmitting side, the inter-field difference signal of the main screen signal is obtained,
After being converted into a difference signal between the original auxiliary signal to be transmitted and the field difference signal, it is multiplexed and transmitted as an auxiliary signal to the upper and lower portions of the screen. On the other hand, on the receiving side, the inter-field difference signal of the main screen signal is obtained, and the above-mentioned inter-field difference signal is added to the auxiliary signal multiplexed and transmitted in the upper and lower parts of the screen to reproduce the original auxiliary signal to be transmitted, and letterbox Performs signal decoding.

Further, in the present invention, (B1) on the transmitting side, the main screen signal is frame-synthesized, the vertical high-frequency signal is separated from the frame synthetic signal, and converted into a difference signal between the original auxiliary signal and the vertical high-frequency signal. After that, it is multiplexed and transmitted to the upper and lower parts of the screen as an auxiliary signal. On the other hand, on the receiving side, the main screen signal is frame-synthesized to obtain a vertical high frequency signal, and the vertical high frequency signal is added to the auxiliary signal multiplexed in the upper and lower parts of the screen to reproduce the original auxiliary signal to be transmitted. , Decode the letterbox signal.

[0009]

By the above means, the original auxiliary signal of the (A2) letterbox system is intended to improve the vertical resolution, but it can be considered separately for a moving image and a still image. In the case of a still image, the vertical high frequency component is 360 [lines / screen height] or more, but in many natural images, the energy of this component is usually extremely small, and there is also a difference in image quality due to the presence or absence of this component in terms of visual characteristics. Hard to detect. However, in the case of moving images, the auxiliary signal has a very important meaning for resolution, and in many natural images, the energy of this component is usually extremely large. Therefore, the interference with the current receiver due to the signals multiplexed in the upper and lower non-image parts of the letterbox system does not cause much problems in still images, but becomes a serious problem in moving images. In the present invention, the difference signal between the original auxiliary signal and the field difference signal between the main screen signal is regarded as a multiple auxiliary signal and transmitted. As described above, the original auxiliary signal is often generated during a moving image and has a very high correlation with the inter-field difference signal of the main screen signal. Therefore, since the transmission auxiliary signal is defined as the difference signal between the highly correlated signals, its energy becomes extremely low, and interference with the existing receiver is significantly reduced.

On the other hand, on the receiving side, after obtaining the inter-field difference signal from the main signal, the transmission auxiliary signal is added to obtain the original auxiliary signal. If the transmitting side and the receiving side use the same means for obtaining the inter-field difference signal from the main signal, the receiving side reproduces the same original auxiliary signal as the transmitting side, thereby achieving vertical resolution improvement in the letterbox system.

(B2) In the present invention, the difference signal between the original auxiliary signal and the vertical high-frequency component obtained by frame-synthesizing the main picture signal is regarded as a multiple auxiliary signal and transmitted. As described above, the original auxiliary signal often occurs during moving images. This auxiliary signal has a very high correlation with the component folded back to the vertical high-frequency component due to the interlaced structure when the main screen signal is frame-synthesized. Therefore, since the transmission auxiliary signal is defined as the difference signal between highly correlated signals,
Its energy is extremely low, and interference with current receivers is significantly reduced.

On the other hand, on the receiving side, the main signal is frame-synthesized to generate a vertical high frequency signal, and the transmission auxiliary signal is added to obtain the original auxiliary signal. If the transmitting side and the receiving side use the same means for obtaining the vertical high frequency signal from the main signal, the receiving side reproduces the same original auxiliary signal as the transmitting side, thereby achieving letterbox type vertical resolution improvement.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(1) FIG. 1 is a first embodiment and shows a processing block diagram of a letterbox type encoder for inputting interlaced scanning signals. Further, for the purpose of explaining the operation, the two-dimensional spectra of the vertical spatial frequency fv and the temporal spatial frequency ft concerning the signal of each node of the embodiment are shown in FIGS. 5 and 6.

In FIG. 1, the number of effective scanning lines having the spectrum shown in FIG. 5 (1a) at the input terminal 1 is 480 [lines / frame], the frame frequency is 30 [Hz] (field frequency 60 [Hz]), and the ratio is 2: 1. The interlaced scanning signal is input. The signals in the shaded areas A and B in FIG. 5 (1a) are characteristic of interlaced scanning. The vertical high-frequency component and the temporal high-frequency component are overlapped due to the interlacing of the interlaced scans and cannot be distinguished in terms of signals. For example, in a picture having a vertical high frequency component in a still image, a flicker called interline flicker, that is, a temporal high frequency component occurs as aliasing. Further, even if the pattern has only the vertical low-frequency component, when the pattern moves, it appears in the vertical high-frequency region as a turn. Figure 5 (1a) for interlaced scanning
The areas A and B have the same information and cannot be distinguished.

The frame synthesizing circuit 2 synthesizes the first and second fields to obtain the spectrum shown in FIG. 5 (1b). That is, it is converted into a progressive scanning signal having a frame frequency of 30 [Hz]. Interlaced scanning → sequential scanning conversion between the same frame frequency is easily realized by alternately rearranging the scanning line signals in the first field and the scanning line signals in the second field using the buffer memory and outputting them as the same frame signal. it can. The output of the frame synthesis circuit 2 is input to the vertical low pass filter (V-LPF) 4 and band-limited to the spectrum shown in FIG. 5 (1c). Further, it is converted into 360 [book / frame] by the 4 → 3 scanning line converter 11, and FIG.
The spectrum is (1d).

The input / output signal of the V-LPF 4 is input to the subtractor 5 and the difference is calculated to obtain the spectrum of FIG. 5 (1g).
This signal has an important meaning as information representing the motion in a moving image.

The output of the subtractor 5 is a vertical frequency shift (V-
The shift circuit 6 converts the spectrum into that shown in FIG. In the vertical frequency shift circuit 6, the vertical frequency shift can be easily realized by inverting the polarity for each scanning line. next,
The horizontal / vertical low pass filter (HV-LPF) 7 limits the band horizontally / vertically. As will be described later, this signal is finally multiplexed and transmitted to the upper and lower non-image area, but this area has a transmission capacity of 120 [lines / frame] which is 1/3 of the main screen 360 [lines / frame]. Not not. Therefore, the amount of information has to be reduced to 1/3, and components having a low visual contribution are deleted in advance. For this reason
HV-LPF7 is inserted. An example of this characteristic is shown in FIG.

The output of the HV-LPF 7 is input to the 4 → 3 scanning line converter 8. 360 by 4 → 3 scanning line converter 8
It is converted into a progressive scanning signal of [book / frame] and converted into the spectrum of FIG. 6 (2a) by the vertical frequency shift circuit 9.

The output of the HV-LPF 7 is passed through the 4 → 3 scanning line converter 8 to the system of the V-shift circuit 9 and the subtracter 1.
It is input to two systems of the 12, 3 → 2 converter 14. One system is to improve the resolution of the moving image when the main signal is reproduced by the current receiver, and the other system is used to reproduce the original signal.

The 4 → 3 converter 8 receives an input signal of 360 [lines / line
Frame] progressive scanning signal. The 3 → 2 converter 14 converts the input signal into a progressive scanning signal of 240 [lines / frame].

By the 4 → 3 scanning line converter 8, 360 [lines /
The signal converted into the progressive scanning signal of [frame] is converted into the spectrum of FIG. 6 (2a) by the vertical frequency shift (V-shift) circuit 9. The output of the vertical frequency shift circuit 9 is multiplied by K (K = 0 to 1) in the multiplier 10. K is given by the output of the motion detection circuit 3, and is defined as K = 0 for a still image and K = 1 for a moving image. Therefore, when the signal having the spectrum of FIG. 9 (2a) is a moving image, it is added by the adder 12 to the signal having the spectrum of FIG. 5 (1d) which is the output of the 4 → 3 scanning line converter 11, and FIG. ) Becomes a signal with a spectrum.

The output of the adder 12 is a progressive scanning signal having a frame frequency of 30 [Hz] of 360 [lines / frame],
It is input to the progressive scan-> interlaced scan conversion circuit 13 and the inter-field difference circuit 110.

The progressive scan → interlaced scan conversion circuit 13
The input signal is converted into a 2: 1 interlaced scanning signal having a frame frequency of 30 [Hz] (field frequency of 60 [Hz]). Similar to the frame synthesizing circuit 2 described above, the sequential scanning → interlaced scanning conversion between the same frame frequencies uses the buffer memory to alternately output the scanning line signals in the frame for each scanning line as the first field signal and the second field signal. This can be easily achieved. Sequential scanning → interlaced scanning converter 1
The output spectrum of No. 3 is shown in FIG. 5 (1f), and the information indicating the motion of the moving image is stored in the interlaced scanning signal of 360 [lines / frame] as shown by the shaded area, and the current reception of the letterbox method is performed. Compatibility with the machine is ensured.

The output of the adder 12 is input to the inter-field difference circuit 110, and the inter-field difference signal is obtained from this circuit. Detailed operation of the inter-field difference circuit 19 will be described later. The output of the inter-field difference circuit 110 passes through the HV-LPF 111 and has the same band as the horizontal / vertical band of the original auxiliary signal. Therefore, HV-LPF
111 has the same characteristics as the HV-LPF 7.
The difference calculation between the output of the 4 → 3 conversion circuit 8 and the output of the HV-LPF 111 is performed by the subtractor 112.
The output of 12 is 240 by the 3 → 2 scanning line converter 14.
It is converted into a progressive scanning signal of [book / frame]. 3 → 2
The output of the scanning line converter 14 is 240 [lines / frame], which is time-compressed to 1/3 and 2/3 for each scanning line, and is 120 [lines / frame] interlaced scanning format by the data rearrangement circuit 16. It is converted into a signal and becomes a screen upper and lower part multiplexed signal. The switch 17 selects and switches between the main screen signal and the upper and lower screen signals, and the letterbox type 480
[Book / frame] The interlaced scanning signal is output from the output terminal 18.

(2) FIG. 2 shows a second embodiment and is a processing block diagram of a letterbox type encoder for inputting an interlaced scanning signal and a progressive scanning signal. The parts having the same functions as those in the first embodiment are designated by the same reference numerals as those in FIG.

When the system mode is switched, the switches 31, 32, 33, 34 switch the processing mode between the interlaced scanning signal input and the sequential scanning signal input. Switches 31, 32, 3 shown in the figure
The states of 3 and 34 indicate modes at the time of inputting a progressive scanning signal.

First, the operation at the time of progressive scanning input will be described.
The switches 31, 32, 33, 34 are all closed to the progressive scan input mode side. 480 effective scanning lines at the input end 20
[Book / frame], frame frequency 60 [Hz], and progressive scanning signal are input.

As described above, in the interlaced scanning, as shown in FIG.
The signal areas indicated by the shaded areas A and B in (1a) cannot be distinguished, and the vertical high-frequency component and the temporal high-frequency component are overlapped by the interlacing of the interlaced scans, so that the signals cannot be distinguished. However, in the case of progressive scanning, FIG. 9 (2b)
It has the spectral structure shown in Fig. 3, and it is possible to clearly distinguish the vertical high-frequency component and the temporal high-frequency component without the aliasing like interlaced scanning. The adder 22 and the subtracter 23 respectively calculate the sum and difference of the input / output signals of the 1/60 second delay unit 21, and the 1/2 coefficient units 24 and 25 multiply it by 1/2. 1/2
The outputs of the coefficient units 24 and 25 are the sum average and the difference average between the frames, and the temporal low frequency component and the temporal high frequency component are output, respectively. The outputs of the 1/2 coefficient units 24 and 25 are frame-decimated by switches 26 and 27, respectively, to obtain 480
It is converted into a progressive scanning signal having [book / frame] and a frame frequency of 30 [Hz]. Although these two signals are half the input frame frequency, they are defined by the sum difference and there is no loss of information from the input.

The spectra of the output signals of the switches 26 and 27 are shown in FIGS. 9 (2c) and 9 (2d). The output signal of the switch 26 passes through the switch 31 and the V-LPF 4 and the subtracter 5
Entered in. The output of the subtractor 5 has the spectrum of FIG. 5 (1g), but in this case, it clearly means the vertical high-frequency component of the input. This signal becomes the spectrum of FIG. 5 (1h) in the vertical frequency shift circuit 6, and the HV-LPF 7 horizontally
The vertical band is limited and supplied to the multiplier 43.

The multiplier 43 outputs the output K of the motion detection circuit 28.
It is controlled by a value obtained by calculating 1−K by the subtracter 41 from (K = 0 to 1). That is, the output of the vertical frequency shift circuit 7, which is a component of the temporal low band and the vertical high band, is sent to the 4 → 3 scanning line converter 140 through the adder 42 and the switch 34 when the image is still.

On the other hand, the output of the switch 27, which is a temporal high frequency component, is converted into the spectrum of FIG. 5 (1h) by the temporal frequency shift circuit 46, and the HV-LPF 40 having the same characteristics as the HV-LPF 6 performs horizontal and vertical band limitation. It is received and input to the multiplier 44, and is converted to 360 [lines / frame] by the 4 → 3 scanning line number converter 8 through the switch 33. The output of the 4 → 3 scanning line number converter 8 is
The vertical frequency conversion circuit 9 converts the spectrum of FIG. 9 (2 a) and inputs the spectrum to the multiplier 10. The output of the motion detection circuit 28 is supplied to the multiplier 10 through the switch 32, and K = 1 is given when the image is a moving image. Therefore, the temporal high frequency component which is the motion information is output from the multiplier 10 during the motion, and the temporal low frequency component is 4 by the adder 12.
→ Added to the signal converted into 360 [lines / frame] by the 3-scan line number converter 11.

The output of the adder 12 is a progressive scan-> interlace scan converter 13 and a sequential scan-> interlace scan converter circuit 13 outputs a frame frequency of 30 [Hz] (field frequency 6
0 [Hz]) is converted into a 2: 1 interlaced scanning signal.

Further, HV-L which is a temporal high frequency component
The output of the PF 40 passes through the multiplier 44 and is added to the adder 42. The multiplier 43 has a gain of 1 for a still image and a gain of 0 for a moving image. On the other hand, the multiplier 44 has a gain of 0 for a still image and a gain of 1 for a moving image. This is the motion detection signal K
Is directly supplied to the multiplier 44, while the multiplier 4
3 is calculated by the subtracter 41 and given as 1-K. The output of the adder 42 is input to the 4 → 3 scanning line number converter 140 through the switch 34.

On the other hand, the output of the adder 12 is also input to the field difference circuit 110. The output of the inter-field difference circuit 110 passes through the HV-LPF 111 and has the same band as the horizontal / vertical band of the original auxiliary signal. Therefore, HV-
The LPF 111 has the same characteristics as the HV-LPF 7. Output of 4 → 3 scanning line converter 8 and HV-LPF111
After being subtracted by the subtractor 112, the 3 → 2 converter 14 converts the difference into the 240 [lines / frame] progressive scanning signal. In other words, the output of the 4 → 3 scanning line number converter 140 is subjected to difference calculation by the subtractor 48 with the signal converted from the output of the adder 12 into the interfield difference signal by the interfield differencer 19, and 3 → 2. It is converted into a 240 [book / frame] signal by the converter 14. This signal is the time compression circuit 1
5. The data rearrangement circuit 10 produces a screen upper / lower screen upper / lower part multiplexed signal.

The switch 17 switches between the main screen signal and the screen upper and lower signals, and a letterbox type 480
[Book / frame] The interlaced scanning signal is output from the output terminal 18. Next, the operation at the time of interlaced scanning input will be described. All the switches 31, 32, 33, 34 are switched to the interlaced scanning input mode side (the opposite of the illustrated state).

The number of effective scanning lines having the spectrum shown in FIG. 5 (1a) at the input terminal 1 is 480 [lines / frame], the frame frequency is 30 [Hz] (the field frequency is 60 [H]).
z]) 2: 1 interlaced scanning signal is input. If all the switches 31, 32, 33 and 34 are closed to the interlaced scanning input mode side, the same operation is performed with the same components as those in the first embodiment. Therefore, detailed description is omitted.

The following can be said according to the encoders of the first and second embodiments described above. That is, the original auxiliary signal is often generated during a moving image and has a very high correlation with the inter-field difference signal of the main screen signal. Therefore, since the transmission auxiliary signal is defined as the difference signal between the highly correlated signals (calculation in the subtractor 112), its energy becomes extremely low, and interference with the existing receiver is significantly reduced.

(3) FIG. 3 shows a third embodiment, which is a processing block diagram of a decoder which receives the letterbox-encoded signal in the first or second embodiment and outputs the interlaced scanning signal. is there.

The encode signal is input to the input terminal 50. The switch 51 switches the main screen signal to the frame synthesis circuit 52.
To the rearrangement circuit 53. The main screen signal is set to 360 by the frame synthesis circuit 52.
Interlaced scanning of [book / frame] is converted to progressive scan of 360 [book / frame] with a frame frequency of 30 [Hz], and the spectrum of FIG. 5 (1e) is obtained. The signals multiplexed on the upper and lower portions of the screen are reproduced by the rearrangement circuit 53 and the time expansion circuit 54 into the same output signals of the 3 → 2 scanning line converter 14 described in the first and second embodiments. The output of the time extension circuit 54 is input to the 2 → 3 scan line converter 55. The 2 → 3 scanning line converter 55 converts the input signal into sequential scanning with a frame frequency of 30 [Hz] at 360 [lines / frame] and supplies the same to the adder 66.

On the other hand, the output of the frame synthesizing circuit 52 is also input to the field difference minute circuit 120, and the field difference signal is obtained from this circuit. Inter-field difference circuit 1
20 uses the same characteristics as the inter-field difference circuit 110 on the transmitting side described in the first and second embodiments. The output of the inter-field difference circuit 120 is input to the HV-LPF 121. The HV-LPF 121 is the transmission-side HV-LPF 111.
Set to the same characteristics as. The output of the HV-LPF 121 is input to the adder 122 together with the output of the 2 → 3 scanning line converter 55. Therefore, the adder 122 reproduces the original letter-box type auxiliary signal generated on the transmission side.

The output of the adder 122 is input to the vertical frequency shift circuit 56 and the 3 → 4 scanning line converter 60. The input signal of the vertical frequency shift circuit 56 is shown in FIG. 6 (2a).
Is converted into the spectrum of and input to the multiplier 57. The output K of the motion detection circuit 64 is supplied to the other input terminal of the multiplier 57, and K = 1 is output when the image is a moving image. Therefore, in the case of a moving image, the output of the vertical frequency shift circuit 56 is the multiplier 57.
The vertical / temporal folding component included in the interlaced scan of 360 [lines / frame] is added to the subtractor 58 through the above, and the spectrum of FIG. 5 (1d) is obtained. 360 has been cleaned up by removing the folding components.
The progressive scanning signal having a frame frequency of 30 [Hz] at [lines / frame] is converted to a progressive scanning signal having a frame frequency of 30 [Hz] at 480 [lines / frame] by the 3 → 4 scanning line converter 59, as shown in FIG. The spectrum of 1c) is obtained and sent to the adder 62. Further, the 3 → 4 scanning line converter 60 allows the frame frequency 30 [H] at 480 [lines / frame].
The signal converted into the progressive scanning signal of [z] becomes the spectrum of FIG. 5 (1g) by the vertical frequency shift circuit 61,
It is sent to the adder 62. Therefore, 3 →
Output of 4-scan line converter 59 and vertical frequency shift circuit 61
Output is added to obtain the spectrum of FIG. 5 (1b).
The output of the adder 62 is a progressive scanning signal with a frame frequency of 30 [Hz] of 480 [lines / frame].
It is converted into a 2: 1 interlace scanning signal of [Hz] (field frequency 60 [Hz]). As described in the first embodiment, the sequential scanning → interlaced scanning conversion between the same frame frequencies uses the buffer memory to alternately output the scanning line signals in the frame for each scanning line as the first field signal and the second field signal. It can be easily realized.

(4) FIG. 4 shows a fourth embodiment, which is a processing block diagram of a decoder which receives the letterbox-encoded signal in the first or second embodiment and outputs a progressive scanning signal. . The same functional parts as those in the embodiment of FIG. 3 are designated by the same reference numerals.

The encode signal is input to the input terminal 50. The switch 51 switches the main screen signal to the frame synthesis circuit 52.
To the rearrangement circuit 53. The main screen signal is set to 360 by the frame synthesis circuit 52.
Interlaced scanning of [book / frame] is converted to progressive scan of a frame frequency of 30 [Hz] of 360 [book / frame], and the spectrum of FIG. 5 (1e) is obtained. The signals multiplexed on the upper and lower parts of the screen are reproduced by the rearrangement circuit 53 and the time expansion circuit 54 into the same output signals of the 3 → 2 scanning line converter 14 described in the first and second embodiments. The output of the time extension circuit 54 is supplied to the 2 → 3 scan line converter 55. The 2 → 3 scanning line converter 55 outputs the input signal to the 360
The [book / frame] is converted into a progressive scan with a frame frequency of 30 [Hz] and supplied to the adder 66.

On the other hand, the output of the frame synthesizing circuit 52 is also input to the field difference circuit 120 and an inter-field difference signal is obtained. The output of the inter-field difference circuit 121 is H
It is input to the V-LPF 121. The HV-LPF 121 has the same characteristics as the HV-LPF 111 on the transmission side.
The output of the HV-LPF 121 is input to the adder 122 together with the output of the 2 → 3 converter 55. The inter-field difference circuit 120 uses the same characteristics as the inter-field difference circuit 110 on the transmitting side described in the first and second embodiments. Therefore, the original letter-box type auxiliary signal generated on the transmission side is reproduced at the output of the adder 122.

The output of the adder 122 is supplied to the vertical frequency shift circuit 56 and the 3 → 4 scanning line converter 60. The output of the adder 122 is progressive scanning at a frame frequency of 30 [Hz] at 360 [lines / frame], is converted into the spectrum of FIG. 9 (2a) by the vertical frequency shift circuit 56, and is input to the multiplier 57. . The output K of the motion detection circuit 64 is supplied to the other input terminal of the multiplier 57, and K = 1 when the image is a moving image.
Is output. Therefore, in the case of a moving image, the output of the vertical frequency shift circuit 56 is added to the subtractor 58 through the multiplier 57, and the vertical / temporal folding component included in the interlaced scanning of 360 [lines / frame] is removed. Figure 5
The spectrum is (1d). The progressive scanning signal with a frame frequency of 30 [Hz] at 360 [lines / frame] that has been cleaned by removing the aliasing component has a frame frequency of 30 [Hz] at 480 [lines / frame] by the 3 → 4 scanning line converter 59. Is converted into a progressive scanning signal, and the adder 77,
It is input to 78. This progressive scanning signal has the spectrum shown in FIG. 5 (1c).

In addition, the 3 → 4 scanning line converter 60 causes 48
The signal converted into a progressive scanning signal having a frame frequency of 30 [Hz] at 0 [lines / frame] is supplied to the vertical frequency shift circuit 61 and the multiplier 72-1, and the polarity inverting circuit 7 is also provided.
6 and is supplied to the multiplier 72-2. The signal having the spectrum shown in FIG. 5 (1g) by the vertical frequency shift circuit 61 is sent to the multipliers 73-1 and 73-2. The output K of the motion detection circuit 64 is supplied to the multipliers 72-1 and 72-2, converted into 1-K by the subtractor 74, and supplied to the multipliers 73-1 and 73-2. K = for movies
Becomes 1, and the multipliers 72-1 and 72-2 are made conductive,
The multipliers 73-1 and 73-2 are turned off. The reverse is true for still images. The outputs of the multipliers 72-1 and 73-1 are added by the adder 75-1 to obtain the multipliers 72-2 and 73-1.
The output of −2 is added by the adder 75-2. Adder 75
The outputs of -1 and 75-2 are input to adders 77 and 78. The output of the 3 → 4 scanning line converter 59 is also added by the adder 7.
7 and 78 are input. The output of the adder 77 is time-compressed to 1/2 by the time compression circuit 80 and connected to the switch 82. The output of the adder 78 is delayed by 1/60 seconds by the delay circuit 79, time-compressed to 1/2 by the time compression circuit 81, and supplied to the switch 82. The switch 82 switches every 1/60 second, and the output terminal 83 outputs a sequential scanning signal at a frame frequency of 60 [Hz] at 480 [lines / frame].

Regarding the signal in the case of the moving image of the 3 → 4 scanning line converter 60 described above, the same frame signal is output for 1/60 seconds by a series of operations of the polarity reversing circuit 76, the delay circuit 79 and the switch 83. This is repeated with the polarity reversed at intervals, and the temporal frequency shift is performed, resulting in the spectrum of FIG. 9 (2g). Also, 3 →
Output of 4-scan line converter 59 and vertical frequency shift circuit 61
The same frame signal is repeatedly output at 1/60 second intervals.

FIG. 7 shows a concrete configuration example of the inter-field differencers 19 and 65. For the sake of explanation, FIG. 8 shows a vertical-time spatial structure of the scanning lines. A progressive scan signal having a frame frequency of 30 Hz is introduced to the input terminal 179 of the inter-field differencer, which is shown in FIG. However, on the transmission side, the signal is finally converted into the interlaced scanning signal shown in FIG. On the receiving side, as shown in FIG.
Is a signal obtained by combining the interlaced scanning signals.
In FIG. 8A, the first field signal is indicated by a white circle and the second field signal is indicated by a black circle. Therefore, the signal at the input end 179 is a sequential scanning signal having a frame frequency of 30 Hz, but as shown in FIG. 8B, the first and second signals are provided for each scanning line.
It corresponds to the field signal. The signal of the input terminal 179 is switched by the switch 180 for each scanning line. One output end of the switch 180 has an interpolation filter (IPF) 18
1 and the subtractor 189, and the other output terminal of the switch 180 is connected to the IPF 182 and the subtractor 190. IP
In F181, the adder 185 performs a sum operation on the input and output of the 1H delay unit 183, and the coefficient unit 187 multiplies by 1/2. IPF18
The output of 1 is represented by the white triangle in FIG. IPF18
In the case of 2, the input and output of the 1H delay unit 1843 are summed by the adder 186, and the coefficient unit 188 makes 1/2. The output of the IPF 182 is represented by the black triangle in FIG. Subtractor 18
9 and 190, the white circle and the second signal which are the original signals of the first field
A switch 191 alternates between a differential signal with a black triangle, which is a signal interpolated from the field, and a differential signal with a white triangle, which is a signal interpolated from the first field, and a black circle, which is the original signal of the second field. Output terminal 19
3 to the signal shown in FIG.

As described above, according to the present invention, on the transmitting side, the inter-field difference signal of the main screen signal is obtained, converted into the difference signal between the original auxiliary signal to be transmitted and the field difference signal, and then used as the auxiliary signal. Multiplex transmission to the top and bottom of the screen.

On the receiving side, the inter-field difference signal of the main screen signal is obtained, the above-mentioned inter-field difference signal is added to the auxiliary signal multiplexed and transmitted at the upper and lower parts of the screen to reproduce the original auxiliary signal to be transmitted, and the letterbox signal is sent. Decode.

The original auxiliary signal of the letterbox system is intended to improve the vertical resolution, but it can be considered separately for a moving image and a still image. 3 for still images
Although it is a vertical high frequency component of 60 [lines / screen height] or more, the energy of this component is usually extremely small in many natural images, and it is difficult to detect the image quality difference due to the presence or absence of this component in terms of visual characteristics. However, in the case of moving images, the auxiliary signal has a very important meaning for resolution, and in many natural images, the energy of this component is usually extremely large. Therefore, the interference with the current receiver due to the signals multiplexed in the upper and lower non-image parts of the letterbox system does not cause much problems in still images, but becomes a serious problem in moving images. Therefore, in the present invention, the difference signal between the original auxiliary signal and the inter-field difference signal of the main screen signal is regarded as a multiple auxiliary signal and transmitted. As described above, the original auxiliary signal is often generated during a moving image and has a very high correlation with the inter-field difference signal of the main screen signal. Therefore, since the transmission auxiliary signal is defined as the difference signal between the highly correlated signals, its energy becomes extremely low, and interference with the existing receiver is significantly reduced.

On the other hand, on the receiving side, after obtaining the inter-field difference signal from the main signal, the transmission auxiliary signal is added to obtain the original auxiliary signal. If the transmitting side and the receiving side use the same means for obtaining the inter-field difference signal from the main signal, the receiving side reproduces the same original auxiliary signal as the transmitting side, thereby achieving vertical resolution improvement in the letterbox system.

(5) FIG. 9 is a fifth embodiment of the present invention and is a block diagram of a letterbox type encoder corresponding to input of interlaced scanning signals and progressive scanning signals. The letterbox type encoder corresponding to the interlaced scanning signal and the progressive scanning signal input is also described in FIG. 2, but in the case of this embodiment, the means for creating the multiple auxiliary signal is different from the embodiment of FIG. The motion adaptive processing system is different. Other functions are the same as those of the previous embodiment, but the reference numerals of the blocks are newly added and described.

This system includes switches 208, 220,
The processing mode is switched between sequential scanning signal input and interlaced scanning signal input by 313. Also, for the purpose of explanation of the operation, FIG. 12 and FIG.
3 shows a two-dimensional spectrum diagram of the vertical spatial frequency fv and the temporal spatial frequency ft.

First, the case where an interlaced scanning signal is input will be described. 480 effective scanning lines at the input end 300
A 2: 1 interlace scanning signal of [book / frame] and frame frequency 30 [Hz] (field frequency 60 [Hz]) is input. The signals in the shaded areas A and B in FIG. 12A are characteristic of interlaced scanning. The vertical high-frequency component and the temporal high-frequency component overlap due to the interlacing of the interlaced scans, and are indistinguishable in terms of signal. For example, in a picture having a vertical high frequency component in a still image, a flicker called interline flicker, that is, a temporal high frequency component occurs as aliasing. Further, even if the pattern has only the vertical low-frequency component, when the pattern moves, it appears in the vertical high-frequency region as a turn. Figure 12 for interlaced scanning
The areas A and B in (a) have the same information and cannot be distinguished. The frame synthesizing circuit 201 synthesizes the first and second fields to obtain the spectrum shown in FIG. That is, it is converted into a progressive scanning signal having a frame frequency of 30 [Hz]. Interlaced scanning → sequential scanning conversion between the same frame frequency is easily realized by alternately rearranging the scanning line signals in the first field and the scanning line signals in the second field using the buffer memory and outputting them as the same frame signal. it can. The output signal of the frame synthesis circuit 201 is input from the switch 208 to the V-LPF 7209, and
The spectrum is band-limited to the spectrum shown in (c). Further 4 →
It is converted into 360 [lines / frame] by the 3-scan line conversion circuit 210, and the spectrum shown in FIG. The output of the 4 → 3 scanning line conversion circuit 210 is the 3 → 4 scanning line conversion circuit 211.
12C, the signal of the spectrum shown in FIG. 12C is returned, and the subtracter 217 subtracts the signal from the output signal of the frame synthesizing circuit 301 to obtain the spectrum of FIG. 12E.

The signal which is once converted from 4 → 3 scanning lines is again converted to 3 →
What is subtracted after the conversion of 4 scanning lines is the signal of the spectrum of FIG.
This is done so that the connection of the bands becomes smooth when the signals of the spectrum of (c) are added. This signal has an important meaning as information representing the motion in a moving image. The output of the subtractor 217 is converted by the vertical frequency shift circuit 218 into the spectrum shown in FIG. In the vertical frequency shift circuit 218, the vertical frequency shift can be easily realized by inverting the polarity for each scanning line. Next, H
Bandwidth is limited in the horizontal and vertical directions by the V-LPF 219.
This signal is finally multiplexed and transmitted to the upper and lower non-image areas as will be described later, but the area has a transmission capacity of 120 [lines / frame] which is 1/3 of the main screen 360 [lines / frame]. Absent. Therefore, the amount of information has to be reduced to 1/3, and components having a low visual contribution are deleted in advance. For this reason, HV-LPF219 is inserted. An example of this characteristic is shown in FIG.

The output of the HV-LPF 219 is supplied to the 4 → 3 scanning line conversion circuit 306, which converts it into a progressive scanning signal of 360 [lines / frame].

The output of the HV-LPF 219 is output from the 4 → 2 scanning line conversion circuit 211, 2 → 3 via the switch 220.
The scanning line conversion circuit 223 converts it into a sequential scanning signal of 360 [lines / frame], the vertical frequency shift circuit 224 shifts it to a band as shown in FIG. 12C, and then the adder 213 performs 4 → 3 scanning. It is added to the output of the line conversion circuit 210.

Once in the 4 → 2 scanning line conversion circuit 221, 24
After being converted to a signal of 0 [lines / frame], the 2 → 3 scanning line conversion circuit 223 converts it to a progressive scanning signal of 360 [lines / frame] because this component (current reception This is because the component has the same band as the reproduced signal of the multiplex signal when removing the component for improving the resolution) (when restoring the letterbox type signal to the original).

The output of the adder 212 and the output of the 4 → 3 scanning line conversion circuit 210 are input to the mixer circuit 213, and the coefficients are switched and mixed according to the motion signal generated by the motion detection circuit 225 and output. . At this time, the output of the 4 → 3 scanning line conversion circuit 210 is output as it is for a still image, and the output of the adder 212 is output as it is for a moving image. The output of the mixer circuit 213 is input to the interlaced scanning conversion circuit 214 and converted into an interlaced scanning signal having an effective scanning line 360 [lines / frame] and a frame frequency of 30 [Hz] (field frequency of 60 [Hz]).

Here, the output of the mixer circuit 213 is input to the vertical high pass filter (V-HPF) 321,
The components of the spectrum shown in FIG. 12 (h) are extracted.
The output of the V-HPF 321 is the vertical frequency shift circuit 322.
Is converted into the spectrum of FIG. The output of the vertical frequency shift circuit 322 is a horizontal low pass filter (H-
LPF) 323, and becomes the same band as the horizontal and vertical bands of the original auxiliary signal. Therefore, the output of the H-LPF 323 is set to a signal having the same characteristics as the output of the HV-LPF 219.

Output of 4 → 3 scanning line conversion circuit 306 and H-
After subtracting the output of the LPF 323 by the subtractor 309, the output of the subtractor 309 and the 4 → 3 scanning line conversion circuit 306
Is output to the mixer circuit 312. Then, according to the motion signal generated by the motion detection circuit 225, the respective coefficients are switched and mixed and output. At this time, the output of the 4 → 3 scanning line conversion circuit 306 is output as it is for a still image, and the output of the subtractor 309 is output as it is for a moving image.

The output of the mixer circuit 312 is the switch 31.
3 through 2 and input to the 3 → 2 scanning line conversion circuit 314
It is converted into a progressive scanning signal of 0 [lines / frame]. 3 →
The output of the 2-scan line conversion circuit 314 is 240 [lines / frame], and the time compression circuit 315 outputs 1/3, 2 for each scan line.
The data is time-compressed to / 3 and is converted by the data rearrangement circuit 316 into a 120 [lines / frame] interlaced scanning format signal to become a screen upper / lower portion multiplexed signal.

The switch 215 selects and switches between the main screen signal and the screen upper and lower part signals, and the letter box type 4 is selected.
80 [books / frames] Interlaced scanning signal and output end 2
It is output from 16. Next, the operation at the time of progressive scanning input will be described.

The input terminal 200 has 480 effective scanning lines [line / line
Frame] and a frame frequency of 60 [Hz]. As described above, in the interlaced scanning, as shown in FIG.
The signal areas shown by the shaded areas A and B in 2 (a) cannot be distinguished, and the vertical high-frequency component and the temporal high-frequency component are overlapped by the interlacing of the interlaced scans, so that the signals cannot be distinguished. However, in the case of progressive scanning, FIG.
It is possible to limit the band to the spectrum as shown in, and it is possible to clearly distinguish the vertical high frequency component and the temporal high frequency component without the aliasing like the interlaced scanning. The sum and difference of the input / output signals of the 1/60 second delay unit 201 are added to the adder 20 respectively.
2, calculated by the subtractor 203, and 1/2 coefficient units 204, 20
5 times 1/2. The outputs of the 1/2 coefficient units 204 and 205 are the sum average and the difference average between frames, respectively, and are output as a temporal low frequency component and a temporal high frequency component, respectively. The outputs of the 1/2 coefficient units 204 and 205 are 60 [H
The z] → 30 [Hz] conversion circuits 205 and 207 thin the frames to convert them into progressive scanning signals of 480 [lines / frame] and a frame frequency of 30 [Hz]. Although these two signals are half the input frame frequency, they are defined by the sum difference and there is no loss of information from the input. 6
The spectra of the outputs of the 0 [Hz] → 30 [Hz] conversion circuits 206 and 207 are shown in FIGS. 13B and 13C. The output signal of the switch 208 is the V-LPF 209 and the subtractor 217.
Entered in. The output of the V-LPF 7209 is input to the 4 → 3 scanning line conversion circuit 210, converted into a sequential signal of 360 [lines / frame], and input to the adder 212. The output of the subtractor 217 has the spectrum shown in FIG. 13D, but in this case, it clearly means the vertical high-frequency component of the input. This signal has the spectrum of FIG. 13 (e) in the vertical frequency shift circuit 218 and is band-limited in the horizontal / vertical directions by the HV-LPF 219, and 360 by the 4 → 3 scanning line conversion circuit 306.
Converted to a [book / frame] sequential signal.

The output of the 60 [Hz] → 30 [Hz] conversion circuit 207 is shifted by the temporal shift (T-shift) circuit 302 to the temporal low-frequency signal shown in FIG. , 304.
The HV-LPF 303 is band-limited to the spectrum shown in FIG. The output of the HV-LPF 303 is once converted into a sequential signal of 240 [lines / frame] by the 4 → 2 scanning line conversion circuit 221 through the switch 220, and then 2
→ The 3 scanning line conversion circuit 223 converts the signal into a sequential signal of 360 [lines / frame], and further the vertical frequency shift circuit 22
4 is converted into a signal having the spectrum shown in FIG.
It is input to the adder 212.

Adder 212 and 4 → 3 scanning line conversion circuit 21
The output of 0 is input to the mixer circuit 213. The mixer circuit 213 switches and mixes respective coefficients according to the motion signal generated by the motion detection circuit 225, and outputs the mixed and mixed coefficients.

From the output of the mixer circuit 213, V-HP
In F321, the components of the spectrum shown in FIG. 13 (j) are extracted. The output of the V-HPF 321 is converted to the spectrum shown in FIG. 13 (k) by the vertical frequency shift circuit 322, and then limited to the same band as that of FIG. 13 (g) by the H-LPF 323.

Here, the output of the temporal shift circuit 302 input to the HV-LPF 304 is as shown in FIG.
The spectrum is band-limited to the spectrum shown in (4) and is converted into a sequential signal of 360 [lines / frame] by the 4 → 3 scanning line conversion circuit 305. The outputs of the H-LPF 323 and the 4 → 3 scanning line conversion circuit 305 are input to the subtractor 308. 4 →
The output of the 3-scan line conversion circuit 306 and the output of the subtractor 308 are input to the mixer circuit 311 and the respective coefficients are switched and mixed according to the motion signal and output. here,
The outputs of the 4 → 3 scanning line conversion circuit 305 and the H-LPF 323 are both temporal high frequency components at the time of moving image,
It can be seen that the signals are highly correlated. Therefore, 2
The signal level can be reduced by subtracting two signals.

The output of the mixer circuit 311 is the switch 31.
3 is input to the 3 → 2 scanning line conversion circuit 314, and 24
It is converted into a progressive scanning signal of 0 [lines / frame]. 3 →
The output of the 2-scan line conversion circuit 314 is 240 [lines / frame], and the time compression circuit 315 outputs 1/3, 2 // for each scan line.
The time is compressed to 3 and the data rearrangement circuit 316 outputs 1
It is converted into a signal of an interlace scanning format of 20 [lines / frame] and becomes a screen upper and lower part multiplexed signal. Switch 215
Thus, the main screen signal and the screen upper and lower part signals are switched and selected, and a letter box type 480 [lines / frame] interlaced scanning signal is output from the output terminal 216.

As described above, this system supports two input signals of the interlaced scanning signal and the sequential scanning signal input, and the hardware can be shared. Further, as in the previous embodiment, the interference with the current image receiver in the upper and lower non-image parts is reduced.

(2) FIG. 10 shows the fifth embodiment, and is a processing block diagram of a decoder which receives the signal encoded by the letterbox method in the first embodiment and outputs the interlaced scanning signal.

The encode signal is input to the input terminal 400. The main screen signal is switched by the switch 401 to the frame synthesis circuit 3
0a, and the screen up / down signals are taken into the rearrangement circuit 35a. The frame synthesizing circuit 402 converts the main screen signal from the interlaced scanning of 360 [lines / frame] to the progressive scanning of 360 [lines / frame] with a frame frequency of 30 [Hz] to obtain the spectrum of FIG. 12 (d). . The signals multiplexed on the upper and lower parts of the screen are reproduced by the rearrangement circuit 415 and the time expansion circuit 416 to be the same as the output signal of the 3 → 2 scanning line converter 314 described above. The output of the time expansion circuit 416 is input to the 2 → 3 scan line converter 417. The output of the 2 → 3 scanning line converter 417 is 360 [lines /
Frame] is converted into sequential scanning with a frame frequency of 30 [Hz] and input to the adder 418.

On the other hand, the output of the frame synthesis circuit 402 is
It is input to the V-HPF 411 and becomes the vertical high frequency component of the spectrum shown in FIG. The output of the V-HPF 411 becomes a signal of the spectrum shown in FIG. 12 (g) by the vertical frequency shift circuit 412. As the V-HPF 411, one having the same characteristics as the V-HPF 321 on the transmitting side described in FIG. 9 is used. The output of the vertical frequency shift circuit 412 is H-LP.
It is input to F413 and set to the same characteristics as the H-LPF 323 on the transmission side. The output of the H-LPF 413 is input to the adder 418 together with the output of the 2 → 3 scanning line converter 417, and reproduced as the original letterbox type auxiliary signal generated on the transmission side. The output of the adder 418 is the coefficient unit 41
9 is input. In the coefficient unit 419, the motion detection circuit 42
The coefficient value is switched and output according to the motion signal generated in 5. Since the output of the coefficient unit 419 is the motion information in the temporal high range, the coefficient K = 1 is set for a moving image and K is set for a still image.
The coefficient is controlled according to the degree of movement so that = 0. The output of the coefficient multiplier 419 is the vertical frequency shift circuit 42.
At 0, the spectrum is converted into the spectrum shown in FIG. 12 (i), and the subtracter 403 subtracts the spectrum from the output of the frame synthesis circuit 402. Therefore, the vertical / temporal aliasing component included in the interlaced scanning of 360 [lines / frame] in the case of a moving image is removed to obtain the spectrum of FIG.

The frame frequency is 30 [Hz] at 360 [lines / frame] which has been cleaned by removing the aliasing component.
The progressive scanning signal of 4 is output by the 3 → 4 scanning line converter 404.
It is converted into a progressive scanning signal having a frame frequency of 30 [Hz] at 80 [lines / frame], and the spectrum shown in FIG. On the other hand, the output of the 2 → 3 scanning line converter 417 is input to the coefficient unit 421, and the coefficient value is switched and output according to the motion signal generated by the motion detection circuit 425. Since the output of the coefficient unit 421 is the vertical high-frequency component of the temporal low frequency band, the coefficient is controlled according to the degree of movement so that K = 0 for a moving image and K = 1 for a still image. The output of the coefficient unit 421 is converted into a progressive scanning signal having a frame frequency of 30 [Hz] at 480 [lines / frame] by the 3 → 4 scanning line converter 423. The output signal of the 3 → 4 scanning line converter 423 is the vertical frequency shift circuit 4
The spectrum of FIG. 12E is obtained by 24 and is sent to the adder 405. The output of the 3 → 4 scanning line converter 404 and the output of the vertical frequency shift circuit 424 are added by the adder 405, and the spectrum shown in FIG. 12B is obtained. The output of the adder 404 is a progressive scanning signal with a frame frequency of 30 [Hz] of 480 [lines / frame].
The interlaced scan conversion circuit 406 sets the frame frequency to 30.
It is converted into a 2: 1 interlace scanning signal of [Hz] (field frequency 60 [Hz]).

As described with reference to FIG. 9, in the sequential scanning → interlaced scanning conversion between the same frame frequencies, the scanning line signal in the frame is alternately changed into the first field signal and the second field signal by using the buffer memory. It can be easily realized by outputting.

(3) FIG. 11 is a sixth embodiment and is a processing block diagram of a decoder for receiving a letterbox encoded signal in the circuit of FIG. 10 and outputting a progressive scanning signal. The parts having the same functions as those in the embodiment of FIG. 10 are designated by the same reference numerals.

The encode signal is input to the input terminal 400. The switch 401 switches the main screen signal to the frame synthesis circuit 4
02, and the screen up / down signals are taken into the rearrangement circuit 415. The frame synthesizing circuit 402 converts the main screen signal from interlaced scanning of 360 [lines / frame] to progressive scanning of 360 [lines / frame] with a frame frequency of 30 [Hz], and the spectrum of FIG. 13 (d) is obtained. .
The signals multiplexed on the upper and lower parts of the screen are reproduced by the rearrangement circuit 415 and the time expansion circuit 416 to be the same as the output signal of the 3 → 2 scanning line converter 314 described in FIG. The output of the time extension circuit 416 is connected to the 2 → 3 scan line converter 417. The output of the 2 → 3 scanning line converter 417 is 360 [lines / line
Frame] is converted into sequential scanning with a frame frequency of 30 [Hz] and input to the adder 418.

On the other hand, the output of the frame synthesis circuit 402 is V
-It is input to the HPF 411 and becomes the vertical high frequency component of the spectrum shown in FIG. The output of the V-HPF 411 becomes a signal having the spectrum shown in FIG. 13 (g) in the vertical frequency shift circuit 412. As the V-HPF 411, one having the same characteristics as the V-HPF 321 on the transmitting side described in FIG. 9 is used. The output of the vertical frequency shift circuit 412 is HL
It is input to the PF 413 and set to the same characteristics as the H-LPF 303 on the transmission side. The output of the H-LPF 413 is input to the adder 418 together with the output of the 2 → 3 scanning line converter 417, and the original letterbox type auxiliary signal generated on the transmission side is reproduced.

The output of the adder 418 is input to the coefficient unit 419. The coefficient unit 419 switches and outputs the coefficient value according to the motion signal generated by the motion detection circuit 425. Since the output of the coefficient unit 419 is motion information in the temporal high range, the coefficient is controlled according to the degree of motion so that K = 1 for a moving image and K = 0 for a still image. Coefficient unit 41
The output of 9 is input to the V-LPF 432. V-LP
The output of F432 is made to have the same characteristics as the spectrum shown in FIG. This is because the temporal high-frequency component added to the main signal is 120 [T as shown in FIG. 13 (k) with respect to the compensation signal having the spectrum shown in FIG. 13 (i).
This is because the bands are the same because there is only VL / PH].

The output of the V-LPF 432 is converted into the spectrum shown in FIG. 13 (d) by the vertical frequency shift circuit 420, and subtracted from the output of the frame synthesizing circuit 402 by the subtractor 403. Therefore, 360 [book / frame] for moving images
The vertical / temporal folding components included in the interlaced scanning of are removed. The signal from which the aliasing component has been removed is input to the 3 → 4 scanning line converter 404 and converted into a progressive scanning signal with a frame frequency of 30 [Hz] at 480 [lines / frame]. The output of the 3 → 4 scanning line converter 404 is converted by the double speed conversion circuit 431 into a progressive scanning signal having a frame frequency of 30 [Hz] and a frame frequency of 60 [Hz]. Further, the output of the coefficient unit 419 is changed from the frame frequency 30 [Hz] to the frame frequency 6 by the double speed conversion circuit 433.
It is converted into a progressive scanning signal of 0 [Hz]. The outputs of the double speed conversion circuits 433 and 431 are input to the adder 434 and the subtractor 435, respectively. The outputs of the adder 434 and the subtractor 435 are input to the switch 436, switched every 1/60 [sec], and output. As a result,
The progressive scanning signal output in the moving image mode having the spectrum shown in (l) is reproduced.

The output of the 2 → 3 scanning line converter 417 is input to the coefficient unit 421, and the coefficient value is switched and output according to the motion signal. Here, the output of the coefficient unit 421 is a vertical high frequency signal of the temporal low frequency range, so K =
The coefficient is controlled in accordance with the degree of movement so that 0 is set and K = 1 when the image is a still image. The output of the coefficient unit 421 is converted into a progressive scanning signal with a frame frequency of 30 [Hz] at 480 [lines / frame] by the 3 → 4 scanning line converter 423, and the vertical frequency shift circuit 424 converts the spectrum of FIG. Converted to a signal. The output of the vertical frequency shift circuit 424 is output by the double speed conversion circuit 437 to the frame frequency 30.
[Hz] is converted into a progressive scanning signal having a frame frequency of 60 [Hz]. Double speed conversion circuit 437 and switch 436
Is output to the adder 438. The output of the adder 438 reproduces the signal having the spectrum shown in FIG.

As described above, in this system, the transmitting side obtains the temporal high frequency signal of the main screen signal at the time of moving image,
After being converted to a difference signal between the original auxiliary signal to be transmitted and the temporal high frequency signal, the signal is multiplexed and transmitted to the upper and lower portions of the screen as a transmission auxiliary signal.

On the receiving side, the temporal high frequency signal of the main screen signal is obtained at the time of moving image, and the temporary high frequency signal is added to the transmission auxiliary signal multiplexed and transmitted at the upper and lower parts of the screen to reproduce the original auxiliary signal to be transmitted, It is decoding the letterbox signal.

The original auxiliary signal of the letterbox system is intended to improve the vertical resolution, but it can be considered separately for moving images and still images. 3 for still images
Although it is a vertical high frequency component of 60 [lines / screen height] or more, the energy of this component is usually extremely small in many natural images, and it is difficult to detect the image quality difference due to the presence or absence of this component in terms of visual characteristics. However, in the case of moving images, the auxiliary signal has a very important meaning for resolution, and in many natural images, the energy of this component is usually extremely large. Therefore, the interference with the current receiver due to the signals multiplexed in the upper and lower non-image parts of the letterbox system does not cause much problems in still images, but becomes a serious problem in moving images. In the present invention, the difference signal between the original auxiliary signal and the temporal high frequency signal of the main screen signal is regarded as a multiple auxiliary signal and transmitted. As described above, the original auxiliary signal is often generated during a moving image and has a very high correlation with the temporal high frequency signal of the main screen signal. Therefore, since the transmission auxiliary signal is defined as the difference signal between the highly correlated signals, its energy becomes extremely low, and interference with the existing receiver is significantly reduced.
On the other hand, on the receiving side, after obtaining the temporal high frequency signal from the main signal, the transmission auxiliary signal is added to obtain the original auxiliary signal.
The means for obtaining the temporal high frequency signal from the main signal is
If the same one is used for both the receiving side and the receiving side, the same original auxiliary signal as the transmitting side is reproduced, and the vertical resolution improvement of the letterbox system is achieved.

[0087]

As described above, according to the present invention,
In the letterbox method, the DC offset that inevitably occurs on the receiving side is removed, that is, when the signal multiplexed to the upper and lower non-image parts of the letterbox method is reproduced on the receiving side, the effect of the DC offset is removed. It is possible to reduce interference in the receiver.

[Brief description of drawings]

FIG. 1 is a diagram showing an interlaced scanning signal input encoder that is a first embodiment of the present invention.

FIG. 2 is a second embodiment of the present invention in which interlaced scanning
The figure which shows the encoder for which a progressive scanning signal input is shared.

FIG. 3 is a diagram showing an interlaced scan output decoder according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a progressive scan output decoder according to a fourth embodiment of the present invention.

FIG. 5 is a view of the vertical / temporal spatial frequency domain or the horizontal / vertical spatial frequency domain for explaining the operation of the present invention.
The figure which shows a three-dimensional spectrum.

FIG. 6 is a diagram showing a two-dimensional spectrum in the vertical / temporal spatial frequency domain or in the horizontal / vertical spatial frequency domain for explaining the operation of the present invention.

FIG. 7 is a diagram showing a specific configuration of an inter-field difference circuit shown in the first to fourth embodiments.

FIG. 8 is a diagram for explaining the operation of the inter-field difference circuit of FIG. 7.

FIG. 9 is a fourth embodiment of the present invention in which interlaced scanning /
The figure which shows the encoder for which a progressive scanning signal input is shared.

FIG. 10 is a diagram showing an interlaced scan output decoder that is a fifth embodiment of the present invention.

FIG. 11 is a diagram showing a progressive scan output decoder according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a two-dimensional spectrum in the vertical / temporal spatial frequency domain or in the horizontal / vertical spatial frequency domain of interlaced scan input for explaining the operation of the fifth and sixth embodiments.

FIG. 13 is a diagram showing a vertical / temporal spatial frequency domain or horizontal / vertical spatial frequency domain two-dimensional spectrum of progressive scanning input for explaining the operation of the fifth and sixth embodiments.

[Explanation of symbols]

2 ... Frame synthesizing circuit, 4 ... Vertical low-pass filter, 5
... Subtractor, 6 ... Vertical low-pass filter, 7 ... Horizontal / vertical low-pass filter, 8, 11 ... 4 to 3 scanning line converter, 9
... vertical frequency shift circuit, 10 ... multiplier, 12 ... adder, 13 ... interlaced scan conversion circuit, 14 ... 3 to 2 scan line converter, 15 ... time compression circuit, 16 ... rearrangement circuit, 1
7 ... Switch, 110 ... Inter-field difference circuit, 111
… Horizontal and vertical low pass filters.

Claims (4)

[Claims] 1. A television signal processing circuit that multiplex-transmits an auxiliary signal to a main signal, comprising means for generating an inter-field difference signal from the main signal and means for calculating a difference between the inter-field difference signal and the auxiliary signal. A television signal processing circuit characterized by transmitting the difference calculation output as an auxiliary signal. 2. A television processing circuit for receiving the above-mentioned signal, having means for generating an inter-field difference signal from a main signal, and having means for performing a sum operation with this inter-field difference signal and an auxiliary signal to be transmitted. The television signal processing circuit according to claim 1, which reproduces a signal. 3. A television signal processing circuit that multiplex-transmits an auxiliary signal to a main signal, comprising means for generating a temporal high frequency signal from the main signal and means for calculating a difference between the temporal high frequency signal and the auxiliary signal. A television signal processing circuit characterized by transmitting the difference calculation output as an auxiliary signal. 4. A television processing circuit for receiving the above signal, having means for generating a temporal high frequency signal from a main signal, and having means for performing a sum operation with this temporal high frequency signal and an auxiliary signal to be transmitted. The television signal processing circuit according to claim 3, which reproduces a signal.