JPH05244569A - Letter box system television signal generator - Google Patents

Abstract

PURPOSE:To obtain the generator at a low cost by converting a received signal into a signal serial of specific interlace scanning and generating a signal corresponding to a wide pattern arranged in the middle of a screen. CONSTITUTION:A picture signal series VHD of interlace scanning whose aspect ratio is 16:9, whose scanning line number is 1125 at 30 frames/sec obtained from an HDTV image pickup system 1 is sampled by an A/D converter 2 and converted into a digital signal series. A scanning line conversion circuit 3 applies 3:1 scanning line thinning to the signal series with 1080 valid picture element scanning lines to generate a signal series VN of interlace scanning whose valid picture element scanning line number is 360 at 30 frames/sec. Then an encode circuit 4 applies prescribed signal processing required for the configuration of the television signal, a D/A converter 5 is used to convert the digital signal into an analog signal being a television signal Vs of a desired letter box system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a letterbox type television signal generator for preserving compatibility with the current television system and widening the screen, and more particularly to an image signal of HDTV wide aspect ratio. The present invention relates to a generator suitable for generating a letterbox type television signal as a source.

[0002]

2. Description of the Related Art The letterbox system is one of the systems for widening the screen while maintaining compatibility with the current television system. In this system, a television signal is formed by cutting the upper and lower parts of the screen of the current television system (aspect ratio 4: 3) and arranging a wide image with an aspect ratio 16: 9 in the center of the screen.

For wide images with an aspect ratio of 16: 9 used in this system, the current television system (the number of scanning lines is 525 lines,
Interlaced scanning, aspect ratio 4: 3, progressive scanning method (525 scanning lines, progressive scanning, aspect ratio 4: 3)
Or 16: 9), HDTV system (1125 scanning lines,
It is considered to use an image obtained by various imaging modes such as interlaced scanning and aspect ratio 16: 9) as a signal source.

[0004]

Conventionally, in the generation of a letterbox type television signal using an HDTV image as a signal source, first, there are 1125 scanning lines, 30 frames / sec, and a signal sequence of interlaced scanning. Is converted into a signal series of 525 scanning lines, 60 frames / sec, and progressive scanning by a scan conversion process. Then, scanning line number conversion processing (conversion from 480 effective pixel scanning lines to 360 lines) is performed on this signal sequence, and conversion from sequential to interlaced scanning is performed by scanning line thinning processing, and the center of the screen is displayed. A signal sequence corresponding to a wide screen arranged in the section is generated. For this reason, it is necessary to perform complicated signal processing many times, and high processing accuracy processing is required in order to avoid image quality deterioration due to signal processing. Therefore, there are problems that the device becomes complicated and large-scaled, and the cost becomes extremely high.

It is an object of the present invention to provide an apparatus which can generate a letterbox type television signal using an HDTV type image as a signal source by simple signal processing and can be realized at an extremely low cost.

[0006]

In order to achieve the above object, the present invention uses 1125 scanning lines and 30 frames / frame.
Second, the number of scanning lines is converted to 360 scanning lines by performing the scanning line number conversion processing on the HDTV system signal series of interlaced scanning.
The signal is converted into a signal sequence of 0 frame / sec, interlaced scanning, and a signal corresponding to a wide screen arranged at the center of the screen is generated.

Further, in the present invention, high image quality and high definition are achieved by multiplexing the signal of the field line pair, superimposing the high definition signal on the gap between the frequency bands of the television signal at the center of the screen and the upper and lower parts of the screen. To be realized.

[0008]

According to the present invention, a wide image of 360 effective pixel scanning lines arranged in the central portion of the screen is supported by the scanning line number conversion processing for the HDTV system signal sequence by thinning out the scanning lines 3: 1. Generate a signal sequence. 2 and 3 show the outline of this scanning line number conversion processing.

In the signal series of 1125 scanning lines obtained by the HDTV type image pickup system, as shown in FIG. 2, the present invention regards the signals of 1080 scanning lines as the signals of effective pixel scanning lines. Then, scanning line number conversion processing is performed on the signal series of the effective pixel scanning lines by thinning out the scanning line number of 3: 1 to perform effective pixel scanning arranged in the main area of the central portion of the screen in the letterbox method. Number of lines 3
A signal sequence corresponding to 60 (1080/3) wide images is generated.

The concept of the scanning line number conversion processing is shown in FIG. First, with respect to the signal sequence of the first field of the HDTV system, a 3: 1 scanning line thinning operation for generating a signal of one scanning line based on the three scanning lines a, b and c is performed. , A signal sequence corresponding to the first field of the main part area is generated. On the other hand, with respect to the signal sequence of the second field of the HDTV system, the operation of generating the signal of one scanning line based on the three scanning lines a, b, and c is performed, and A signal sequence corresponding to two fields is generated. And
As is clear from the figure, a signal sequence of the main part region that satisfies the interlace relationship is generated.

As described above, according to the present invention, it is possible to generate a signal sequence in the main part region of the letterbox system by an extremely simple scanning line number conversion process, and it is possible to realize a television signal generation device at low cost.

Further, according to the present invention, a television signal is formed by multiplexing a color signal component and a high definition signal by a signal component of a field line pair. For this reason, it becomes possible for the receiver side to completely separate and extract these multiple signals, and it is possible to realize high image quality and high definition of the reproduced image.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A basic block configuration of an embodiment of the present invention will be described with reference to FIG. Aspect ratio 16: 9 obtained from the HDTV imaging system 1, 1125 scanning lines, 30 frames / second, image signal series VHD of interlaced scanning (for example, three primary color R, G, B signals or luminance, color difference Cw, C
The N signal, etc.) is sampled by the A / D converter 2 and converted into a digital signal sequence.

In the scanning line number converting circuit 3, as shown in FIGS. 2 and 3, the scanning line thinning operation of 3: 1 is performed on the signal series of 1080 effective pixel scanning lines to obtain the effective pixel scanning lines. A signal series VN in the form of interlaced scanning of several 360 lines, 30 frames / second is generated.

The encoder circuit 4 performs predetermined signal processing necessary for the construction of a television signal, for example, conversion into luminance, color difference I and Q signals, frequency band limitation, and color subcarrier fs.
generation and multiplexing of a color signal C by quadrature amplitude modulation of c,
Adds a sync signal. And the D / A converter 5
Is converted into an analog signal to generate a desired letterbox type television signal Vs.

Next, the structure of each block portion in this embodiment will be described in detail with reference to an embodiment. In the following embodiments, the case where the signal sequence VHD is the three primary colors R, G, B will be described as an example.

FIG. 4 shows an embodiment of the scanning line number conversion circuit 3. The coefficient weighting circuit 7 weights the input signals R (G, B) and the signal delayed by one line period by the 1H delay circuit 6 by the coefficients k ₁ , k ₂ , and k ₃ and adds them. To generate a signal S ₄ .

An example of the characteristic of this coefficient weighting circuit is shown in FIG. In the figure (a), when the LPF characteristic is provided in the vertical direction in order to reduce the aliasing distortion caused by the scanning line number conversion processing, the figure (b) shows a simple 3: 1 scanning line thinning operation. Indicate the case. The hardware (b) is simple, but the characteristic (a) is preferable from the viewpoint of compatibility with visual characteristics.

In the memory circuit 9, the WT as shown in FIG.
(Write) operation, RD (read) operation,
A scan line number conversion process is realized by a scan line thinning operation of 3: 1. That is, the memory circuit 9 signals Li + ₁ of every three line periods of _{S 4, Li + 4, Li} + 7, ... signal component of the scanning line (corresponding to the main unit signal letterbox method shown in FIG. 3) is written Be done. On the other hand, from the memory circuit 9, the RD operation is continuously performed in the period corresponding to the main part area of the letter box system, and Li + ₁ , Li + ₄ , L
i + _7, and outputs a signal component of ... scan line as a signal S _5. Various signals necessary for the operation of the memory circuit 9 are generated by the memory control circuit 10.

In the masking processing circuit 11, a masking signal MSK of a specific component (for example, black, gray, etc.) is applied to the scanning lines in the upper and lower mask part areas of the letterbox system.
The operation of replacing the signal is carried out to generate a signal sequence RN (GN, BN) compatible with the letterbox method.

Next, the basic construction of an embodiment of the encoding circuit 4 is shown in FIG.

The YIQ conversion circuit 12 converts the signal series VN into Yw, Iw and Qw signals corresponding to the luminance and color difference I and Q signals of the current television system by a predetermined matrix operation.

The preprocessing circuit 13 performs signal processing corresponding to various signals described later and processing such as frequency band limitation by a filter to generate a luminance signal Y and color difference signals I and Q.

In the color modulation circuit 14, the current television system (N
TSC system), color difference I and Q signals are converted to color subcarrier fs
Quadrature amplitude modulation is performed by c to generate a color signal C. Then, the adder circuit 15 adds the color signal C to the luminance signal to generate a composite type signal similar to the current television system.

The process circuit 16 carries out operations such as blanking processing in the horizontal and vertical blanking periods, addition of sync signals and burst signals, aperture correction, etc. to generate a desired television signal.

Table 1 shows the relationship between various signals and signal processing in the preprocessing circuit 13.

[0027]

[Table 1]

The ED1 does not perform signal processing for high image quality and high definition, and configures a television signal in a form similar to the current television system.

The ED 2 constitutes a television signal by multiplexing the signal of a pair of field lines and realizes complete separation of the multiplexed signal without crosstalk on the side of the receiver to achieve high image quality. Further, the ED3 further configures a television signal in a form in which horizontal high frequency components are further multiplexed as a high definition signal,
High definition is also realized.

The preprocessing circuit 1 for these signals will be described below.
The configuration of No. 3 will be described. First, FIG. 8 shows an embodiment corresponding to the ED1. The one-dimensional signal spectrum of this signal is shown in FIG.

The signal Yw has a cutoff frequency fc of 4.
The LPF circuit 17 having a low-pass filter characteristic of 2 MHz limits the band to generate the luminance signal Y.

The signal Iw is band-limited by the LPF circuit 18 having a low-pass filter characteristic of fc of 1.5 MHz to generate a color difference signal I.

On the other hand, the LPF circuit 19 has an fc of 0.5 MH.
The band of the signal Qw is limited by the characteristic of z, and the color difference signal Q
To generate.

Next, an embodiment corresponding to ED2 is shown in FIG.
0, this one-dimensional signal spectrum is shown in FIG. In this signal, the luminance mid-range component Ym (2 MHz or more), the color difference I,
The components of the Q signal are formed in the form of field line pairs whose period is one frame described below.

One of the signals Yw and Iw, Qw are input to the field line pair generation circuit 20. In this circuit, as shown in FIG. 12, the scanning line a of the first field
(B) and a scanning line c (d) of the second field separated by 263 line periods form a field line pair,
The same signal component is assigned to these scanning lines. This field line pair is
That is, one frame is formed as a cycle.

FIG. 13 shows a configuration example of this circuit. In this example, the average value of the signals of these scanning lines is assigned to the scanning lines forming the field line pair as a signal component.

Signal S ₆ and 263 line delay circuit 2
The signal S ₆ D (corresponding to the signals on the scanning lines a and c shown in FIG. 12) delayed by 263 line periods in 5 is output by the averaging circuit 26 as the signal S ₇ which is the average value of the two signals. In the switch circuit 27 selects S ₇ for each field period by a selection signal SL, and a signal S ₇ D 263 line delay circuit 25 alternately outputs a signal S _8. Then, to the scanning lines forming the field line pair, the average value of the signals of both scanning lines is assigned as the same component.

The output signals of the field line pair generation circuit 20 are the LPF circuits 18, 19 and the BPF circuit 21.
Then, a predetermined band limitation is carried out to generate the mid-luminance component Ym of the form of the field line pair and the color difference I and Q signals.

On the other hand, the signal whose time delay associated with the processing of the field line pair is adjusted by the delay circuit 22 is the LPF.
The circuit 23 extracts the component of 2 MHz or less as the luminance low frequency component YL. Then, the adder circuit 24 adds the signal Ym to generate a luminance signal Y.

Next, FIG. 14 shows an embodiment of the preprocessing circuit corresponding to the ED3, and FIG. 15 shows the one-dimensional signal spectrum of this signal. In this example, the luminance high frequency component Yh (4.2 MH
(z or more) is shifted to the 2 to 4 MHz band by frequency shift operation and multiplexed as the high definition signal YH '. Further, the middle luminance component Ym constitutes a television signal in the form of a field line pair having a cycle of one frame, and color difference I and Q signals and a high-definition signal having a field line pair having a cycle of two frames.

A field line pair having a period of one frame has the same structure as that shown in FIG. On the other hand, 2
A field line pair having a frame cycle is formed by the shape shown in FIG. That is, a field line pair is formed by the scanning line a (b) of the first field and the scanning line c (d) of the second field over two frames, and the average value of the signals of these scanning lines is assigned as the same component.

Field line pair generation circuits 20, 28
Then, the signal components of the field line pairs corresponding to one frame period and two frame periods are generated, respectively. Then, the LRF circuits 18 and 19 and the BPF circuit 21 limit the predetermined frequency band to generate the color difference I and Q signals and the luminance mid-range component Ym.

On the other hand, the HPF circuit 29 causes 4.2 MHz.
The luminance high frequency component Yh extracted from the above components is subjected to carrier suppression amplitude modulation operation by the subcarrier Mo (16 / 7fsc) in the frequency shift circuit 30, and its lower sideband component is extracted to be in the 2 to 4 MHz band. Shifted high-definition signal YH '
To generate. At this time, a high-definition signal can be generated in various forms by controlling the phase of the subcarrier Mo for each line cycle and each field cycle. An example thereof is shown in FIG. FIG. 11A shows the phase characteristics when arranged in the Fukinuki Holes in the first and third quadrants of the vertical / time frequency domain, which are in a conjugate relationship with the color signal. Further, FIG. 6B shows an example of arranging in the high frequency region on the vertical frequency axis by the field offset operation.

The delay circuit 31 performs delay adjustment of the time delay associated with the field line pair generation processing, and the LPF
The circuit 23 extracts the component of 2 MHz or less as the luminance low frequency component YL. Then, the addition circuit 32 adds Ym and YH 'to generate a luminance signal Y. It should be noted that it is possible to realize higher image quality and higher definition in other forms. As an example of this, FIG. 18 shows an embodiment of the preprocessing circuit 13 when the upper and lower mask portion regions are also used. In this embodiment, the television signal is configured to have a high image quality and a high definition by constructing the television signal in such a manner that the main portion area of the letterbox system is in the form of ED2 and the high definition signal is superimposed on the upper and lower mask portion areas as the auxiliary signal HS. Try to. The high-definition signal uses the horizontal high-frequency component of the luminance signal.

The luminance high frequency component Yh extracted by the HPF circuit 29 is input to the time axis conversion circuit 33, and a time axis conversion operation is performed to generate a signal Yhs which is time axis converted to a position corresponding to the upper and lower mask portion areas. ..

The modulation circuit 34 generates the auxiliary signal HS within the frequency band of the current television system by the frequency shift operation by the amplitude modulation, the time axis compression operation and the like. And
The addition circuit 35 adds the YL and Ym signals to obtain a luminance signal Y.
To generate.

The pre-processing corresponding to the ED2 in the main area can be realized with the same configuration as in FIG.

FIG. 19 shows a characteristic example of the auxiliary signal HS which can be realized in this embodiment.

FIG. 9A shows the case of the auxiliary signal HS mainly composed of the components of the horizontal luminance high range, and the horizontal frequency is 4.2 to 8M.
The luminance high frequency component of Hz (however, the vertical frequency ν is limited to the characteristic of 1/3 of the current television system) is shifted to the 0 to 4 MHz band by the frequency shift operation and multiplexed in the upper and lower mask portion regions.

FIG. 6B shows an example of the auxiliary signal HS mainly composed of horizontal and vertical high frequency components, which has a horizontal frequency of 4.2 to 5.6 MH.
The luminance high frequency component of z (however, the vertical frequency ν is the same as in the current television system, ν ₁ = 525/2 chp) is multiplexed in the upper and lower mask part areas by frequency shift and time axis 1/3 compression operation. ..

In this embodiment, in addition to the auxiliary signal having the characteristic shown in FIG. 19, significant information of various characteristics (for example, horizontal color difference high-frequency component, vertical color difference high-frequency component, etc.) is used as the auxiliary signal. can do. Further, the signals in the main area can be composed of ED1 and ED3.

In the above embodiments, the image signal series VHD of the HDTV image pickup system has been described by taking the three primary color R, G, B signals as an example. It can be realized with a similar configuration.

Although the signal processing has been described by taking the case of digital processing as an example, it can also be realized by signal processing in which digital and analog are mixed.

[0054]

According to the present invention, a letter box type television signal for realizing high image quality and high definition by simple signal processing is generated based on an image signal sequence obtained from an HDTV type image pickup system. Therefore, the generator can be provided at an extremely low cost.

In the description of the embodiment, an example in which the luminance high frequency component is multiplexed as a high-definition signal with respect to the signal of the ED3 has been shown, but the invention is not necessarily limited to this. It is possible to multiplex components and the like as a high-definition signal.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment according to a basic block configuration of the present invention.

FIG. 2 is an explanatory diagram of letterbox television signal generation according to the present invention.

FIG. 3 is an explanatory diagram of scanning line number conversion by a 3: 1 scanning line thinning operation.

FIG. 4 is a block diagram of an embodiment of a scanning line number conversion circuit.

FIG. 5 is a characteristic example diagram of a coefficient weighting circuit used for this.

FIG. 6 is an operation explanatory diagram of this memory circuit.

FIG. 7 is a block diagram of an encoding circuit.

FIG. 8 is an explanatory diagram of an example of a preprocessing unit for the ED1.

FIG. 9 is a one-dimensional signal spectrum diagram thereof.

FIG. 10 is a block diagram of an embodiment of a preprocessing unit for the ED2.

FIG. 11 is a one-dimensional signal spectrum diagram thereof.

FIG. 12 is an explanatory diagram of a configuration of a field line pair.

FIG. 13 is a block diagram of an embodiment of a field line pair generation circuit.

FIG. 14 is a block diagram of an example of a preprocessing unit for the ED3.

FIG. 15 is a one-dimensional signal spectrum diagram thereof.

FIG. 16 is an explanatory diagram of the field line pair.

FIG. 17 is a phase characteristic diagram of subcarrier Mo.

FIG. 18 is a block diagram of a preprocessing unit according to another embodiment of the present invention.

FIG. 19 is a characteristic diagram of an auxiliary signal used for this.

[Description of Codes] 1 ... HDTV image pickup system, 2 ... A / D converter, 3 ... Scan line number conversion circuit, 4 ... Encoding circuit, 5 ... D / A converter.

Claims (4)

[Claims] 1. An aspect ratio of 16: 9 obtained from an HDTV image pickup system, a number of scanning lines of 1125, and a signal series of interlaced scanning, 1080 of effective pixel scanning lines is 3: 1.
By converting the number of scanning lines by the scanning line thinning operation, a signal sequence of 360 effective pixel scanning lines and interlaced scanning is generated, and a television signal in the main part area of the letterbox system is configured by this signal sequence. Characteristic letterbox television signal generator. 2. The letterbox system according to claim 1, wherein, in the television signal of the main part region of the letterbox system, the signal components of the luminance middle range component Ym and the color signal C are formed in the form of field line pairs. Television signal generator. 3. The high-definition signal according to claim 1, wherein the luminance signal component or chrominance signal component in the horizontal high frequency range is field offset multiplexed or Fukinuki Hole multiplexed in the frequency band of the current television system. Frequency-multiplexed letterbox television signal generator. 4. A frequency shift operation for a luminance signal component or a color difference signal component in a horizontal high range according to claim 1 or 2,
A letterbox television signal generator that generates an auxiliary signal within the frequency band of the current television system by time axis compression and multiplexes it in the upper and lower maskbox regions of the letterbox system.