JPH037198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color television signal conversion system, and in particular to a system that converts a normal NTSC color television signal into a high quality, high resolution three primary color image signal for display. It is.

Conventionally, when displaying an NTSC color television signal, a luminance signal and a color difference signal are separated from a composite color image signal using a frequency separation method or a single method.
The three primary color image signals were separated and demodulated using a comb wave system using a line delay line to drive a color picture tube, but the three primary color image signals formed by this conventional demodulation system were Because the resolution of the luminance signal decreases in the horizontal and vertical directions, sufficiently good image quality cannot be obtained.
There was a drawback.

An object of the present invention is to provide a color television signal conversion system that eliminates the above-mentioned conventional drawbacks and performs signal conversion on a normal NTSC color television signal to display a high-resolution, high-quality three-primary-color image signal. The goal is to provide a method.

That is, in the color television signal conversion system of the present invention, an input color television signal of 2:1 interlaced system is sequentially supplied to three field delay devices connected in cascade, so that the input color television signal of the 2:1 interlaced system is sequentially connected to three field delay devices for one field period, two field periods, and three field periods, respectively. forming three types of delayed color television signals delayed by a period of time, each having a time difference of two field periods from each other; the input color television signal; the delayed color television signal delayed by two field periods; the delayed color television signal delayed by one field period; A delayed color television signal with a delay of 3 field periods is supplied to two demodulators each using a wave generator based on field correlation to produce two sets of 2:1 interlaced three primary color image signals having a time difference of 1 field period from each other. The two sets of interlaced three primary color image signals are supplied to a scan conversion device, and the time axes are converted in units of scanning lines and combined to form a line sequential scanning three primary color image signal. It is something to do.

The invention will be explained in detail below with reference to embodiments with reference to the drawings.

First, FIG. 1 shows the basic configuration of a color television signal converter according to the present invention. In the illustrated configuration, NTSC color television signals A from input terminal 1 are sequentially connected in cascade to three
The data is sequentially delayed by one field period by the field memory of the stage, and one field period is sequentially delayed.
Three types of delayed color television signals B, C and D delayed by two and three field periods are formed. Next, the input color television signal A and the delayed color television signal C delayed by two field periods, that is, one frame period, are supplied to the NTSC demodulator 5 to generate the normal 2:1 interlaced three primary color image signals E, F, G. Delayed color television signals B and D are demodulated into NTSC and delayed color television signals B and D are delayed by one field period and three field periods, respectively, and have a time difference of two field periods, or one frame period, between them.
The signal is supplied to a system demodulation section 6 and demodulated into three primary color image signals H, I, and J in the same normal 2:1 interlaced system. Therefore, in the NTSC demodulators 5 and 6, the luminance signal and color signal from the composite color television signal are separated without using the conventional frequency separation method using a bandpass waver. This is done using a so-called comb-shaped filter that takes advantage of the periodicity of the image signal and consists of successive passbands that have their center frequencies at the harmonics of the scanning frequency.Moreover, the image represented by the color television signal is stationary. Sometimes a so-called frame period comb filter is used, with the center frequency of the passband located at a harmonic of the frame frequency;
When there is movement in the above-mentioned image, a so-called line-period comb filter having a center frequency in a position passband of a harmonic of the line frequency is used.

Next, two sets of interlace type three primary color image signals E, F, G and H, I, J obtained from the NTSC type demodulation units 5 and 6 and having a time difference of one field period from each other are supplied to a scan conversion unit 7, As will be described later, the three primary color image signals K, L, M of the line sequential scanning method, that is, the number of scanning lines is 525.
Converts to three primary color image signals at 60 frames per second,
The three primary color image signals K, L, and M are supplied to the color display unit 8 to display a color image using a line sequential scanning method.

FIG. 2 shows an example of the detailed configuration of a color television signal converter according to the present invention having the basic configuration as described above. In the configuration shown in the second figure, circuit portions 5, 6, and 7 shown surrounded by dotted lines correspond to the blocks 5, 6, and 7 in the basic configuration shown in the first figure, respectively, and operate in exactly the same manner. That is, the NTSC color television signal A from the input terminal 1 is sequentially delayed by one field period by three stages of one-field memories 2, 3, and 4 connected in series, and is delayed by one field period and two fields, respectively. This results in delayed color television signals B, C and D that are delayed by three field periods and three field periods. Of these, the color television signal C delayed by two field periods is inputted to the color television signal A.
At the same time, the input color television signal A is guided to the frame difference signal detection section 10 to detect the mutual magnetic difference signal, and if the interframe difference signal level is below a predetermined threshold, the input color television signal A shows no change in image between frames. It is determined that the signal is a still image signal, and the changeover switch is turned on.
Drive SW1 to switch and connect the common contact a to contact b, and input the input color television signal A delayed for 1H period via the 1H memory 9 to the adder ADD.
1 and leads to the subtractor SUB1. 1H memory 11 is added to the adder ADD1 and subtracter SUB1.
A 2-field delayed color television signal C further delayed by 1H period is also supplied via the input color television signal A for addition and subtraction with the input color television signal A. Therefore, adder ADD1 outputs an addition between signals having a time difference of one frame period.
The output signal exhibits comb filter characteristics as shown in Figure 3a, with the center frequency of the passband at a frame frequency of 30 Hz and an integer multiple thereof, and the subtraction between the same input signals. The output signal of the subtractor SUB1, which is the output, has a frame frequency of 30 Hz and a center frequency of the stop band at an integral multiple thereof, and as shown in Figure 3b, it has a frequency opposite to that shown in Figure 3a. Exhibits comb filter characteristics. Therefore, the output signal of the adder ADD1 is mainly the luminance signal component that has a strong correlation between frames in the composite color television signal, and the output signal of the subtracter SUB1 is the luminance signal component that has a strong correlation between frames. chrominance signal components in which the phase of the chrominance subcarrier is inverted are mainly obtained. Next, a subtracter exhibiting the comb filter characteristics shown in FIG.
The output signal of SUB 1 is supplied to a conventional low frequency filter 15 that passes mainly the brightness signal components in the middle and low ranges among the entire frequency band of the composite color television signal, and suppresses the high frequencies in which the carrier color signal components are multiplexed. ,
The wave output signal exhibits comb filter characteristics as shown in FIG. 3c. When this wave output signal is led to the adder ADD2 and the addition output signal of the adder ADD1 mentioned above is supplied to the delay memory 51 having the same signal delay amount as the low-pass filter 15 and added to the delayed signal, The middle and low range of the comb filter characteristic shown in Figure 3a will be interpolated, so the addition output signal of the adder ADD2 will be a comb filter with a flat middle and low range as shown in Figure 3d. Therefore, as the addition output signal, only the luminance signal component in the NTSC color television signal is extracted in both the horizontal and vertical spatial frequency ranges without deterioration due to deletion of signal components. Further, the wave output signal of the low frequency filter 15 exhibiting the comb filter characteristic shown in FIG. Subtractor SUB led through
When subtracted from the subtracted output signal of 1, the mid-low range part of the comb filter characteristic shown in FIG. 3b is canceled out by the comb filter characteristic shown in FIG. Since it exhibits the comb-type filter characteristic only in the high frequency range as shown in e, only the carrier color signal component in the NTSC composite color television signal is used as the subtracted output signal. Extracted without deterioration due to deletion.

Adder ADD2 and subtracter as described above
The luminance signal component and carrier chrominance signal component obtained from SUB2 are guided to a normal chrominance signal demodulator 17 including a matrix circuit and demodulated, and both I and Q signals are obtained and matrixed with the luminance signal. It is converted into interlaced three primary color image signals E, F, and G.

On the other hand, delayed color television signals B and D are delayed by one field period and three field periods, respectively, with respect to the input NTSC interlaced signal, and have a time difference of two field periods, that is, one field period, between the input color television signals. Exactly the same configuration as described above for signal A and 2 field period delayed color television signal C, i.e. 1H memory 18,
19, adder ADD4, ADD5, subtractor SUB3,
SUB4, low frequency converter 20, delay memory 21,
52 and the color signal demodulation section 22,
Interlaced three primary color image signals H, I, J which are subjected to the same signal processing as described above and delayed by one field period with respect to the interlaced three primary color image signals E, F, G obtained from the aforementioned color signal demodulator 17. Convert to

The circuit configuration of each set that performs the above signal processing corresponds to the NTSC demodulators 5 and 6 in the basic configuration shown in the first diagram, as described above, as shown in the figure.

Next, two sets of interlaced three primary color image signals E, F, G and H, I, J having a time difference of one field period from each other obtained as described above are used.
is led to the scan conversion unit 7, and as described later, the time axis is converted in units of scanning lines for each primary color, and the combinations are appropriately changed to produce high-quality three primary color image signals K, Convert to L and M.

The aspect of the above-mentioned scan conversion will be explained with respect to the interlaced primary color image signals E and H, which are red image signals, for example.
and H are delay memories 23 and 3, respectively.
3 to accurately adjust the time difference between them to one field period, and then to the common contact a of the changeover switch SW6 and the changeover contact c of the changeover switch SW3. In addition, the changeover switch
SW3, together with other changeover switches SW4 and SW5, drives switching by the frame difference signal detection circuit 10, and when the image of the input color television signal is a still image with no movement, the interframe difference signal level is set to below the threshold value. Depending on the corresponding detection output signal, the switching contact c is switched and connected to the common contact a. Therefore, if the input color television signal is a still image as described above, the interlaced red image signal H with a one-field delay is
3 to the changeover switch SW8. Therefore, the 1H memories 29 and 30 connected to the changeover switch SW6 and its changeover contacts b and c, respectively, and the 1H memories 31 and 32 connected to the changeover switch SW8 and its changeover contacts b and c, respectively, are illustrated for only the red image signal. The changeover switch SW7, which connects the 1H memories 29, 30, 31, and 32 to the changeover contacts a, b, c, and d, respectively, operates at the timing described later in FIG. Line-sequential scanning high-quality three primary color image signals are formed from two sets of interlaced three primary color image signals having a time difference of one field period, which are supplied to the scan conversion circuit shown enclosed by , and are displayed on a display device 8. In the above explanation, only the red image signal has been described, but it goes without saying that the same scan conversion is performed on the other two primary color image signals, that is, the green image signal and the blue image signal.

Next, a changeover switch is operated which scan-converts the interlaced red image signals E and H described above to form a line-sequential scanning red image signal K.
SW6, SW8 and SW7 and 1H memory 29,
To explain the operation of 30, 31 and 32 with reference to FIG. 4, the input red image signals E and H are based on the standard television system of 2:1 interlace, 525 lines, 60 fields per second, and 30 frames scanning system. Of these, the input red image signal E is subjected to signal processing in units of scanning lines, and the image signals for one line are sequentially switched by the changeover switch SW6 and written to the one-line memories 29 and 30. When writing, the image signal for one line previously written is read from the other one-line memory at twice the writing speed, and is alternately supplied to switching contacts a and b of the switching switch SW7. Further, the input red image signal H is also subjected to signal processing similar to that described above using the changeover switch SW8 and the 1-line memories 31 and 32.
Image signals corresponding to one line read out alternately at high speed from 2 are alternately supplied to switching contacts c and d of a switching switch SW7, respectively. Since there is a time difference of exactly one field period between the interlaced red image signals E and H, for example, if one red image signal E is an odd field and the line is Number 1,
When processing the image signals for each line of 2, 3, etc., the other red image signal H becomes an even field, and the line number 26 is processed as shown in the figure.
Image signals for each line of 3, 264, 265, . . . are processed. Furthermore, by doubling the scanning speed and arranging the image signals of these odd and even fields sequentially and alternately from the beginning of each field, the same image as when interlaced was scanned line-sequentially at 60 frames per second. An equal line sequential scanning red image signal is obtained, and such arrangement conversion of the odd and even field image signals is performed by the changeover switch SW7, as shown in the bottom row of FIG. 4.

Next, we will explain the operation of the signal processing apparatus having the configuration shown in the second figure when the input color television signal A represents a moving image. Since the threshold is exceeded, the common contact a of the changeover switch SW1 is connected to the changeover contact c, and therefore the common contact a of the changeover switch SW2, under the control of the detection output signal of the frame difference signal detection section 10. As a result, the adder ADD1 and subtracter SUB1 connected to the common contact a of the changeover switch SW1 are supplied with the switching output signal of the changeover switch SW2, and the color television signal C delayed by two field periods is supplied to the 1H memory 11.
It will be supplied via. As described later, the switching output signal of the changeover switch SW2 is the color television signal E delayed by 2 field periods, or its 1H delay to 2H delay.
Since the signal is a delayed signal, in the case of the above-mentioned still image, the adder ADD1, the subtracter SUB1, the low frequency filter 15, and the delay memory 16, which constitute a so-called frame period comb filter, are used as a so-called line period comb filter. Therefore, although image quality may deteriorate due to loss of signal components due to the use of a line-period comb filter, , it is possible to avoid significant image quality deterioration due to image blur caused by image movement.

Note that the changeover switch SW2 operates as follows. That is, the switching contacts b, c, and d of the switching switch SW2 are connected to the field memory 3.
An adder adds the 2-field period delayed color television signal C from , the 1H delayed signal C ₁ obtained by introducing that signal to the 1H memory 11, and the 2H delayed signal C ₂ obtained by introducing the signal to the 1H memory 12. The signal level of the addition output signal added by ADD3 is halved by -6dB attenuator 13, and the 2H delayed signal
C ₂ respectively, and furthermore, 2 field period delay signal C, 1H delay signal C ₁ and 2H delay signal
Depending on whether the signal level of the carrier color signal component multiplexed by supplying C ₂ exceeds a predetermined threshold, each signal C to be switched is switched in the manner shown in FIG. , the average of C ₁ and C ₂ and
Switch C ₂ and use it as an output signal. Therefore, such switching of input signals to a line-period comb-type filter is difficult, for example, when only the color television signal C delayed by two field periods is used as one input signal of the line-period comb-type filter. A dot pattern based on the action of the comb-shaped filter is generated at the boundary between the colored area and the achromatic area, which significantly deteriorates the image quality. Therefore, the comb-shaped filter is This is to switch one input signal of the filter as described above to prevent the occurrence of a dot pattern at the boundary.

The luminance signal component and the carrier color signal component separated and extracted by the line-period comb filter configured and operated as described above are supplied to the color signal demodulation section 17 and demodulated in the same manner as in a normal color decoder. The interlaced three-primary color image signals E, F, and G obtained in the above-mentioned manner are supplied to the scan converter 7, and are converted into high-quality three-primary color image signals in the line-sequential scanning method in the same way as described above. are switch SW3, SW4, and switch provided for each primary color image.
SW5 is switched from switching contact o to b under the control of the frame difference signal detection unit 10,
Therefore, the three primary color image signals H, I, and J, which are delayed by one field period and have a large difference in signal level between fields, which are supplied to the switching contact c, are not supplied to the scan conversion circuit 7, and are supplied to the switching contact b for each interpolation signal. The above-mentioned interlacing method is supplied via the low-frequency wave generators 26, 27, 28 and the 1/2H memories 36, 37, 38 for forming the image signal of the other field period in pseudo 2:1 interlacing, respectively. The three primary color image signals E, F, and G are supplied to one switch SW8 in the scan conversion circuit, and the interlaced three primary color image signals E, F are supplied to the other switch SW6 via delay memories 23, 24, and 25, respectively. . In addition, when performing scan conversion in the case of such a moving image, a red image signal E delayed by 1/2H period is used instead of the 1-field delayed red image signal H shown in FIG.
Instead of the image signals for each line of lines 4, 265, . . . , the image signals for each line of line numbers 1, 2, 3, . . . are used with a delay of 1/2H period. The red image signal of the line sequential scanning method is line number 1, 1,
1 of the same line number like 2, 2, 3, 3,...
The image signal is a pseudo line-sequential scanning method in which the image signal for each line is repeated twice, but since it is a moving image, the image quality deterioration due to such pseudo line-sequential scanning is negligible. stay.

Note that the interpolation low-frequency filters 26, 27,
28, it is preferable to use a so-called transversal filter. For example, the basic configuration of the red image signal low frequency filter 26 is as shown in FIG. The output image signals are added by adder ADD6,
The signal level is restored by a 6 dB attenuator 40 before being extracted. In order to more precisely perform signal interpolation using a transversal filter having such a basic configuration, for example, as shown in FIG. 6b,
Multiple 1H memories 41, 42,..., 43, 44
Coefficient units 45, 46, 47, . . . , 4 are connected in cascade and reduce the appropriate signal level of the sequentially delayed 1H image signals obtained from each input/output terminal.
Take out via 8, 49, 50 respectively, adder
Perform addition and synthesis using ADD7. Further, the delay amounts of the delay memories 23, 24, 25 and 33, 34, 35 in the scan converter 7 in the configuration shown in the second figure are respectively
It is preferable to set the delay amount equal to 7.28.

In the example of the detailed configuration shown in the second figure, which is based on the basic configuration shown in the first figure, the three primary color image signals E, F, and G of the interlace system are combined with each other to form an image signal of the line sequential scanning system by scan conversion. Three primary color image signals H delayed by one field period to be combined,
In order to form I and J, 1 field memory 4 and 1H memory 1 constituting the NTSC demodulator 6 are used.
8, 19, adder ADD4, ADD5, subtractor SUB
3. Instead of using the SUB 4, the low-pass filter 20, the delay memory 21, and the color decoding/demodulation section 22, the three primary color image signals E, F, and G, or the three primary color image signals E, F, and G are subjected to matrix processing. By delaying the luminance signal and two types of color difference signals formed in the color signal demodulating section 17 by one field period each using three separately provided one-field memories, a three-primary color image delayed by one field period is obtained. If the signal is formed, the number of 1-field memories used will increase, but the configuration shown in FIG. 2 can be significantly simplified.

As is clear from the above description, according to the present invention, when converting a normal NTSC color television signal into a line-sequential scanning three-primary color image signal to display a high-quality color image, For still images, a comb filter with a frame period is used to separate the luminance signal component and the carrier color signal component from the composite color television signal, so it has high resolution and does not cause image deterioration due to cross color. , high-quality color images can be reproduced and displayed, and for moving images, the color image signal is converted by switching the above-mentioned frame period comb filter to a period comb filter according to the result of image motion detection. Since the demodulation is performed, it is possible to reproduce and display high-quality color moving images without blurring the moving parts of the images. Furthermore, since the interlaced color image signal is converted into a high-speed line sequential scanning color image signal for reproduction and display, interline flicker does not occur and there is no deterioration in the spatial frequency characteristics inherent to the interlaced method. It is possible to stably obtain a high-quality color image with no distortion, and it is possible to display a color image with significantly superior image quality compared to the conventional technology.

In the signal conversion method of the present invention, a field memory is used in order to obtain the above-mentioned remarkable effects, but the field memory is used in common for the configuration of the field periodic comb filter and for converting the scanning method. Therefore, the number of field memories used can be kept to the minimum necessary for this type of signal conversion.

In addition, according to the signal conversion method of the present invention, without any changes to the standard NTSC color television signal specifications, only by adding a field memory and a minimum signal processing circuit for playback display, it is possible to Since it is possible to reproduce and display a color image with a much better image quality than that of the present invention, it is possible to significantly improve the received image quality of the current sub-standard color television broadcasting.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the basic configuration of a color television signal converter according to the present invention, FIG. 2 is a block diagram showing an example of its detailed configuration, and FIGS. 3 a to 3 are the same. 4 is a timing chart showing the timing of the operation of each part, FIG. 5 is a diagram showing an example of the conversion input signal switching operation, and FIG. 6a is a characteristic curve diagram showing the filtering characteristics of each part. and b are block diagrams showing an example of the basic configuration and detailed configuration of the signal interpolation low-frequency filter, respectively. 1... Input terminal, 2, 3, 4... 1 field memory, 5, 6... NTSC demodulation section, 7... Scan conversion section, 8... Color display section, 9, 1
1, 12, 18, 19, 29, 30, 31, 32
...1H memory, 10...frame difference signal detection section,
13...attenuator, 14...vertical signal detection section,
15, 20, 26, 27, 28...low frequency device,
16, 21, 23, 24, 25, 33, 34, 3
5, 51, 52...Delay memory, 17, 22...
...Color signal demodulation section, 36, 37, 38...1/2H memory, ADD1 to ADD7...Adder, SUB1 to
SUB4...Subtractor, SW1-SW8...Switch switch, 39, 41, 42, 43, 44...1H
Memory, 40... Attenuator, 45, 46, 47, 4
8, 49, 50...Coefficient unit.

Claims (1)

[Claims] 1. Three types of 2:1 interlaced input color television signals are sequentially supplied to three field delay devices connected in cascade and delayed by 1 field period, 2 field periods, and 3 field periods, respectively. said input color television signal and said delayed color television signal of said two field period delay, said delayed color television signal of said one field period delay and said three field period delay, each having a time difference of two field periods from each other; The delayed color television signal is supplied to two demodulators each using a filter based on frame correlation to generate two sets of 2:1 signals having a time difference of one field period from each other.
Forms an interlaced three primary color image signal, supplies these two sets of interlaced three primary color image signals to a scan conversion device, converts the time axis in units of scanning lines and combines them to form a line sequential scanning three primary color image signal. A color television signal conversion method characterized by: 2. The demodulation device also uses a filter based on line correlation and includes a motion detection device, and the demodulation device uses a filter based on the line correlation and includes a motion detection device, and the demodulation device uses a filter based on the line correlation according to the presence or absence of image movement caused by the input color television signal detected by the motion detection device. Claim 1, characterized in that a filter and a filter based on the frame correlation are selectively used.
The color television signal conversion method described in . 3. The scan conversion device includes a signal selection device controlled by the motion detection device, and when there is movement in the image based on the input color television signal, only one of the two sets of interlaced three primary color image signals is selected. 3. The color television signal conversion method according to claim 2, wherein the line sequential scanning method three primary color image signals are formed by converting the time axis in units of scanning lines.