FI68140B - SYSTEM FOR OWNING AVAILABLE - Google Patents

Description

681 40 Color Image Signal Conversion System

This invention relates generally to color information conversion systems, and more particularly to encoding, trans-encoding and decoding systems for use in the transmission, storage and retrieval of color image information, and in particular to color image information. A signal conversion system comprising a source of a combined color image signal comprising signals representing the luminance of the color image and signals representing the chromaticity of the color image, a first comb filter device for generating a chrominance output signal under the influence of the combined image signal, and a second comb filter device for generating a combined image signal luminance output signal.

In many different systems regarding the use of image information, it is often desired that the color (i.e.

20 hue and saturation) of the relevant pixels would be transported and / or stored in addition to the basic information on the brightness of the relevant pixels. The provision of such additional color information is the main object of the present invention, the invention which will be described below in connection with one type of image information system, namely a video disc system (image recording disc). It should be noted, however, that the principles of the present invention are applicable to other types of image information systems, e.g., video recorders, CATV (cable television, common antenna) systems, picturephone systems, and the like.

U.S. Patent Application No. 126,772, March 22, 1971,

Jon K. Clemens, "Information Records and Recording / Plau-35 back Systems Therefor," discloses video disc recording and presentation 68140 (playback) systems in variable capacitance form. In the arrangement described therein, the information groove includes geometric changes in the bottom of the spiral groove in the plate, the surface of which is formed by a conductive material thinly covered with a dielectric (insulating) material. Changes in the capacitance formed by the electrodes, the conductive electrode in the groove plotter, and the conductive material of the plate occur when the plate is rotated on a rotating plate plate? capacitance changes are known to retrieve (display) stored information. In one particularly successful form used as a trace bottom information trace in the practice of the Clemens invention, the recessed areas extending across the groove base vary with unreduced areas at a frequency of variation that varies with the amplitude of the video signals to be recorded. The shape of the recorded signal is thus a carrier that is frequency modulated according to the video signals. In a preferred manner for storing information on a master video disc, an electron beam intensity modulated according to FM carrier signals impinges on a photosensitive material at the bottom of the master disc groove, so that subsequent development leaves the desired embossed shape at the bottom of the groove.

When it is desired to provide color image reproducibility of information stored on a video disc, one obvious way is to frequency modulate the image carrier with a complete color television signal in a familiar NTSC format (used in color television broadcasts e.g. in the USA and Japan). In the NTSC format, color information is added to the brightness video signal using a color subcarrier (at 3.579545 MHz, hereinafter referred to as the 3.58 MHz carrier for simplicity), which is effectively phase modulated according to hue and amplitude modulated relative to saturation. The color subcarrier signal represents the sum of the 3.58 MHz subcarrier in the first phase 35 being amplitude modulated by the first color difference signal and the 3.58 MHz subcarrier of the second phase, quadrature with the first phase, being amplitude modulated by the second color difference signal.

68140

When the unmodified NTSC mhoto is used for signals used for frequency modulation of the carrier in the video disc system described above, several difficulties are encountered. Certain practical limitations in the recording-5 process regarding the maximum instantaneous frequency that can be easily recorded result in limitations in the frequency-offset range associated with image carrier modulation. The relatively high frequency location of the color subcarrier and its sidebands in the NTSC format thus causes a relatively low modulation frequency-to-frequency offset ratio, which tends to reduce the signal-to-noise ratio achievable for color signals. Another difficult problem is the development of unwanted separation frequencies when using an unmodified NTSC format in which the frequency position-ti of the color information is high (at high frequencies).

To understand the dilemma caused by the above separation frequencies, it should be noted that the difficulty associated with storing the described FM carrier signal at the bottom of the disc groove is the tendency of the baseband signal to track the recorded FM carrier signal. A illustrative case for such tracking is the tendency for the average depth of the groove to vary slightly with respect to the small distance between the grooves, i. in relation to the instantaneous stored frequency, in addition to which there is a capacitor variation component which, when shown, is known and which varies according to the baseband video signal used to frequency modulate the image carrier.

Thus, when baseband signals tend to occur in signals recovered from disc playback, separation frequency jitter may occur between baseband signals and FM signals. When the unmodified NTSC format places the color subcarrier and its sidebands at the upper end of the baseband, the presence of color signals may result in interfering separation frequencies that fall within the user FM demodulator throughput band unless the upper frequency range in which the FM signal is located In view of the above-mentioned practical limitations regarding the highest instantaneous frequency that can be conveniently stored, the location of the picture carrier offset range significantly higher than the frequency band occupied by the base signal in unmodified NTSC format 5 is not readily available in said resolution frequency resolution.

However, a satisfactory and easy to implement solution to said jitter problems (as well as to said signal-to-noise ratio problem) is obtained by applying the principles of the present invention to color signal storage and retrieval systems. According to these principles, a modulated color subcarrier (which may be, for example, the general form used in an NTSC system) is not placed at the top of the video band 15 of a luminance signal, as in an NTSC system, but is instead "buried" (embedded) in the video band, i. the color carrier frequency is selected to be significantly lower than the subcarrier frequency of the NTSC system at 3.58 MHz, the descriptive choice for the invention is around 1.53 MHz, the color carrier side-20 bands extend to -500 kHz with both sides (e.g. to 3 MHz).

The exact frequency of the subcarrier is selected to be a fraction of the line frequency (preferably 25 f / n, where n is a small integer greater than one) later than the multiple of the line frequency (f „) associated with n video signals. A particularly preferred offset selection is half the line frequency (f „/ 2), although other choices may be appropriate in special circumstances 30 (e.g. when the PAL format is selected for the subcarrier, a quarter of the line frequency f„ / 4 is offset n is suitable). The descriptive subcarrier frequency selection that includes fH / 2 paging is —fR (or approximately 1,534,091 Hz when the line frequency corresponds to the U.S. standard for color television-35 transmissions, i.e., 15,734.26 Hz).

In order to avoid interfering crosstalk effects, the luminance signal is comb-filtered over the frequency band in which the subcarrier and its side bands must be divided, i. an efficient set of wavelengths must be developed for the frequency spectrum of the luminance signal into which the subcarrier components can be "buried." In addition, it is desirable that the modulated subcarrier signal (chrominance signal) is also comb-filtered (in a manner complementary to that used to filter the luminance signal) to effectively limit the chrominance signal to components that hit the wavelengths (gaps) in the comb-filtered luminance signal. When a half-line frequency offset is selected, the characteristic curve of the appropriate comb filter for use in preparing wavebands in the spectrum of luminance signals is one with repetitive peaks at line frequency multiples and repeating zeros at 15 line frequency half-odd multiples; the characteristic curve of the appropriate comb filter with the chrominance signal is complementary to the above (repetitive peaks at odd multiples of half the line frequency and repetitive zeros at multiples of 20 of the line frequency).

When the subcarrier is located at approximately 1.53 MHz, a reasonable bandwidth can be obtained for the color sidebands (e.g., two sides of the -500 kHz subcarrier frequency f) and

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however, retains a reasonably wide band (e.g., 0-1 MHz) at the lower end of the 25 signal spectrum occupied by luminance signal components alone. In the region of the latter frequency band, the luminance signal is kept free of signal component losses.

When the luminance signals and the chrominance signals, prepared as described above, are combined, a combined signal is formed which can be stored in the above-mentioned disc recording system and then recovered substantially avoiding the above-mentioned wobbling problems and with reasonable certainty of achieving a satisfactory signal-to-noise ratio. By using appropriate comb filter equipment in the video disc reproducing apparatus, the 6 681 40 chrominance and luminance signal components occupying a shared band (e.g., approximately 1-2 MHz) can be accurately separated from each other in a suitable running current circuitry.

Subsequent use of the components of the chrominance signals to provide color information for image reproduction of the false color effects due to the midband luminance components is substantially avoided due to the judicious use of the comb filter technique described.

Also, when luminance signal components are used to input brightness information for image reproduction, false dot patterns due to the brightness effects of the midband chrominance signal components are substantially avoided due to the judicious use of the comb filter technique described. The present invention thus provides a system in which color information can be transferred and / or stored and retrieved by dividing the center band region with luminance signal components, substantially without erroneous color or brightness effects. The achievement is particularly significant given (a) that, in typical image views, the 20 luminance components are likely to be more energy-containing in the midband region than in the upper band region where the standard NTSC format places the Krominance signal, resulting in a difficult problem of luminance crosstalk. the middleband division of the connection; and (b) the dot pattern associated with the display of subcarrier components at midband frequencies is significantly coarser and thus more visible than the dot pattern associated with the representation of subcarrier components at high frequencies used in the normal band NansC format. The color image signal conversion system of the present invention is thus characterized by producing luminance signals comprising a first portion representing coarse pixels located in the first frequency band and a second portion representing medium fine pixels located at 7,681,40 seconds. in the upper frequency band, and a third portion representing fine image portions located in the upper, third frequency band in the second band; that the second luminance signal portion includes medium-fine image portions that include only a first set of regularly spaced spectral points extending over the second frequency band, said portion lacking medium-fine picture sub-components that strike the second set of regular-spaced spectral points that interleave the first; -10 with that set; that the chrominance signals from said source share a second frequency band with a second luminance signal portion, wherein the chrominance signal comprises, in said common second band, chrominance signal components placed only in a second set of spectral points, and the chrominance signal is absent from the chrominance signal; which fall into the first set of spectral points; that the first comb filter device comprises circuits forming a plurality of zeros correlated to a first set of 20 spectral points to generate said chrominance output signal without crosstalk from the medium fine image portions of the second luminance signal portion; and that the second comb filter device includes circuits forming a plurality of zeros correlated to the second set of spectral 25 points to generate said luminance output signal, including first, second and third portions in the first, second and third frequency bands, the second portion not crosstalking said chromaticity signal.

When the color image information to be stored is available in a "raw" uncoded form, the principles of the present invention can be applied directly to the encoding apparatus as opposed to "recoding" the apparatus, e.g., by directly changing the information in color separation format (such as 35 sets of simultaneous red, green, and blue base color signals). ) to the desired "buried" subcarrier format (without intervening in NTSC encoded format).

681 40 e According to an embodiment of such a direct coding apparatus, conventional matrix equipment can be used to derive a luminance signal (Y) and a pair of color difference signals (e.g., BY and RY) to form a series of 5 primary color signals (R, G and B; obtained e.g. scanner). The chrominance signal is generated by modulating the first phase of unmodulated oscillations at the desired buried subcarrier frequency with one color difference signal, modulating the second phase of these oscillations (quadrature with the first phase) with the second color difference signal, and summing the modulator outputs. The chrominance signal thus generated is comb-filtered to discard components that fall at multiples of the line frequency. The luminance signal output of the matrix-15 equipment is high-pass filtered to discard frequencies that fall in the non-divisible subband. The output of the high-pass filter is comb-filtered to discard components that fall at multiples of 20 times half the line frequency. The outputs of the two comb filters are combined by summing the uncombed low-band luminance signal components (obtained by low-pass filtering the luminance signal output of the matrix apparatus) to form a combined signal in the desired buried subcarrier form.

According to another embodiment of such a direct coding apparatus, the order in which the comb filtering and the high-pass filtering for the luminance components are performed can be reversed, i. the full-band snow-30 nance signal can be properly comb-filtered and the comb-filter output can be routed to an input in an over-pass filter that rejects frequencies in a non-divisible subband. In such an arrangement (as in the second described recoding apparatus embodiment), the uncombed lower band luminance signal components that must be combined with the combed luminance and chrominance signal components to form the desired combined signal output can be conveniently derived from the luminance comb filter. As will be explained in more detail below, the use of delayed low-band luminance signal components (as opposed to using the delayed-5 tower low-band luminance signal components) in generating a combined signal can provide certain playback (display) benefits when a particular policy is filtered in the display hardware.

When reproducing (displaying "playing") a video-10 disc recording of color image information encoded by the buried carrier format described above, the manner in which the recovered information is to be processed differs depending on the nature of the display device. For example, when the display apparatus itself includes image display devices, direct decoding of the chrominance signal modulated at the buried subcarrier frequency (after separation by an appropriate comb filter) may be appropriate. However, when the display apparatus does not include an image display device but is intended to form an accessory for use as an example with a separate color television receiver, we believe it is desirable that the display apparatus include a transcoding apparatus designed to convert information buried in the buried subcarrier format to the receiver is designed to handle (eg change to NTSC encoded format),

In an embodiment of the display equipment transcoding apparatus illustrating the principles of the present invention, the combined signal obtained from the disk is passed to a Kro-30 minoss comb filter whose passbands are interrupted at odd multiples of the line frequency halves and zeros at multiples of the line frequency. Mixing the comb filter output with unmodulated oscillations at the appropriate frequency 10,681 40 (e.g., approximately 5.11 MHz, which is the sum of the typical buried subcarrier frequency of 1.53 MHz and the NTSC subcarrier frequency of 3.58 MHz) is used to transmit the separated Kro-minansignal signal for which the chrominance signal processing circuit of the receiver 5 is designed. The Luminans pig filter (where the passbands are centered at line frequency multiples and zeros at odd half-odd multiples of the line frequency) is also sensitive to the recovered combined signal, but is suitably modified to allow access to the output without combing components that hit the undivided. The output of the luminance comb filter is combined with the transmitted chrominance signal to form a new combined signal suitable for processing by the receiver. As in the recoding apparatus of the recorder described above, the lurainance and chrominance comb filters may share the same 1H delay line apparatus.

Problems may occur in the video disc presentation environment when implementing the desired processing of the recovered signals due to undesired frequency variations in the recovered signals. This means that for many reasons, including disc disc rotation speed variations, disc distortion, inaccurate disc centering, etc., there may be undesired relative speed variations between the needle 25 and the disc groove, which can result in erroneous variations in the recovered signal frequencies. Thus, for example, the color subcarrier sideband frequencies in the recovered combined signal may "vibrate" around their otherwise expected location in the frequency spectrum, and similar vibration causes a shift in the component frequency locations of the luminance signal.

According to an optional aspect of the present invention, the operation of the transcoding apparatus (or encoding apparatus) of the presentation device can be made less sensitive to such unwanted vibration by using a comb filter shape including two 1H delay lines; the shape of the two 1H delay wires can provide a comb-specific curve with wider discard slots than can be obtained with the single 1H delay wire shape, and correspondingly, more accurate luminance-chrominance separation (e.g., less luminance chrominance crosstalk) can be obtained with a certain 5 component color grade.

In another way of solving a vibration problem, a reproduction apparatus of the presentation device is formed, in which the mixing of the recovered buried subcarrier combined signal (or a part thereof) with local vibrations 10 precedes comb filtering. However, the source of local oscillations has substantially the same oscillation as the recovered signal components (e.g., by reacting the local oscillation source with frequency variations that suffer from the chromaticity signal accompanying the chrominance signal of the buried subcarrier 15). The mixing product with such local vibrations is substantially vibration-free and the comb filtration of this product can be carried out without crosstalk independently of the original vibration.

An illustrative embodiment of a display device transcoder using the principles of the present invention, which includes a latter jitter correction solution, is an arrangement in which the entire buried carrier combined signal recovered during playback is mixed with local vibration in a modulator. The nominal frequency of the Pai-25 expensive oscillations (e.g., approximately 5.11 MHz) corresponds to the sum of the nominal buried subcarrier frequency (e.g., 1.53 MHz) and the subcarrier frequency (e.g., 3.58 MHz) desired for receiver operation, but is corresponding to the vibration from which the recovered signal components suffer. The modulator output is passed through a suppressed sideband filter to an input in a chrominance comb filter (i.e., a filter with multiple passbands centered on odd multiples of half the line frequency and zeros on the multiples of the line frequency). The suppressed sideband filter restricts the comb filter input primarily to the modulation separation frequency products 12 6 ε 1 4 o (i.e., the lower sideband of the primary modulated local oscillation frequency) although

Appropriate bandpass filtering from the comb filter output provides a chrominance signal for the frequency band (e.g., 3.58 MHz to 500 kHz) desired to be provided to the receiver. Subtracting this chrominance signal from the uncombed version of the modulo-10 output output provides an output that is substantially free of chrominance signal components; when the two 1H delay lines form the spent comb filter, the uncombed input to the reducer is taken from the junction between the parts of the pair of 1H delay lines in the cascade. The output of the reducer is fed to the envelope detector; the detector output is low pass filtered and summed together with the separated chrominance signal to form a new combined signal desired for use in the receiver.

A number of additional embodiments of a display device recoding arrangement are also possible, including modifications to the illustrative embodiments described above, as described below.

According to other optional features of the present invention, the same delay line apparatus used for comb filtering may be connected to additional circuits for controlling the point distortion correction of the luminance signal.

It will be readily apparent to one skilled in the art from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

Figures 1a and 2a show coding apparatus according to the principles of the present invention, which are suitable for accepting a series of color signals and providing an encoded signal output in buried-carrier format for video disc recording purposes.

Fig. 1b is a block diagram illustrating apparatus for performing a transcoding operation that complements the operation performed with the apparatus of Fig. 1a using additional principles of the invention, the apparatus being suitable for use in a video reproducer to transcode signals from a buried carrier format to a general NTSC encoded signal.

Fig. 2b shows a modification of the apparatus of Fig. Ib, which includes a vertical point distortion correction operation.

Figures 3, 4, 5 and 6 show other embodiments of the present invention suitable for re-operating the apparatus shown in Figure Ib in a reproducing apparatus.

Fig. Ib illustrates such apparatus for post-use of a composite signal 15 generated by the apparatus of Fig. 1a and represents, for example, transcoding apparatus that may be used in a video disc player that responds to and converts a buried-carrier composite signal recovered from a video disc during playback. signals to an NTSC encoded format suitable for transmission to a color television receiver.

In the apparatus of Figure Ib, a buried-carrier combined input signal (obtained, for example, from a video disc reproducing apparatus) is passed through an amplifier 25 60 to the input point T of the comb filter apparatus 70. An example is the comb filter apparatus 70 (in this example, as in the following examples of repeater apparatus) of the type shown using two 1H delay lines (71, 72) in a cascade; as already mentioned above, this type of comb filter offers special advantages over the type with one 1H delay line in terms of the shape of the drop-offs in the comb-like frequency response, which makes it possible to accurately separate the luminance and chrominance signal components from the difficult to maintain in the environment of a video disc player, as already mentioned above). It should be noted, however, that a simple 1H delay line version of each 681 40 14 example may alternatively be used, especially where appropriate frequency correction techniques can be used to alleviate instability problems or, for example, in other operating environments where component frequency stability is not inherently a difficult problem.

In order to obtain a comb filter characteristic curve of the above-mentioned chrominance comb filter type 10 (i.e., passbands for half-frequency odd multiples of the line frequency and zeros for multiples of the line frequency 74), To the sum of 15 input signals (i.e., signal output from delay line 72). The summing of the input and output signals is performed by a combiner 73; the input and output signal portions must be properly amplitude weighted relative to the center signal to provide the desired cancellation of components that are multiples of the line frequency and have a weighting ratio of 1: 2 in the described arrangement. Thus, it must be assumed that the connector 73 includes suitable attenuators. to provide an output corresponding to the sum of the half-amplitude input signal and the 25 half-amplitude output signal, the output of the subtractor 74 occurs at the filter output point Tb and is passed to a bandpass filter 81 with a bandwidth sidebands of the subcarrier signal (eg f ± 500 kHz). The output of the filter 81 thus corresponds to a chrominance signal buried in the center band of the combined input signal substantially excluding the low band and center band 35 signal output components, and this selected chrominance signal is shifted up in the frequency range 83 to the frequency band desired for the output signal. Illustratively, the latter operates at a frequency f + f (e.g. 3.58 MHz + 1.53 MHz = 5.11 MHz), so that the modulation difference frequency products fall in a band centered at the desired output subcarrier frequency f (e.g., the NTSC subcarrier frequency). 3.58 MHz). A bandpass filter 87 having a passband of a suitable width (e.g., f ί 500 kHz) and centered at f is coupled to the output of modulator 83 and selectively transmits the desired difference frequency modulation products.

The comb filter apparatus 70 of the arrangement of Fig. Ib further includes a combiner 76 which summing combines a center point signal (output from delay line 71) and a weighed sum of input and output signals (i.e., 15 outputs from combiner 73) to form the aforementioned luminance comb filter format. for multiples and zeros for odd multiples of half the line frequency), the output of combiner 73 is passed to combiner 20 through high pass filter 77 in order to avoid combing the undivided lower band portion of the luminance signal spectrum. Illustratively, the high-pass filter (HPF) 77 has a similar shape to the HPF 20 in Figure 1a, using a low-pass filter (LPF) 77A for the incoming signal and combiner 77C, reducing the output of the low-pass filter to an unfiltered input signal version passed through a delay element 77B together with the LPF 77A delay). As with the HPF 29, the cutoff frequency of the HPF 77 is preferably selected to fall just below the lowest buried subcarrier sideband frequency (e.g., f ~ 1 MHz). The center signal is applied to the combiner 76 via the delay element 75 (substantially compatible with the delay of the delay element 77B).

The output of the summing combiner 76 is present at the output point Tc of the filter and includes uncombed lower band luminance signal components (which fall on the back 681 40 16 hairs under f) and combed midband and high band luminance signal components, substantially excluding the midband chromosome signal. The output of combiner 76 is passed to a delay element 82 which delays the luminance signal components for a time selected to substantially equalize the total delay of the luminance signal components with the delay of the chrominance signal components (mainly due to passage to the pin of the BPF filter 87). The luminance signal output of the delay element 82 is coupled to a frequency shifted chrominance signal output from a filter 87 by a combiner 90 to form a combined output signal suitable for processing in, for example, an NTSC encoded color receiver of the NTSC type.

In the construction of the transcoding apparatus according to Figures 1a and 1b, the 1H delay lines (31,71,72) may illustratively be of the broadband ultra-type available from Corning Glass Co., the modulators (43,83) may conveniently be of a double-balanced form, a short delay-20 element ( 15,32,42,75,77B, 82) may be a coaxial line of appropriate length and the oscillators (45,85) may be a start-stop shape suitably controlled by a line frequency signal (H) associated with the combined signal being processed.

Figure 2b illustrates how horizontal and vertical spot distortion corrections can be incorporated into the comb filtration arrangements of the present invention. In order to avoid making the presentation of the additional embodiments too complicated, the embodiments described below do not discuss the application of these point distortion correction features thereto, but will be readily apparent to one skilled in the art by ways comparable to the above embodiments, including those shown in Fig. 2b. control features.

Figure 3 illustrates a modification of the embodiment of the playback device illustrated in Figure 1b. In this variation, the bandpass filter delimits the inlet of the comb filtration apparatus into the relatively narrow centerband divided between the luminance signal components and the buried subcarrier chrominance signal components; both the lower and upper band components of the input signal bypass the filtering equipment,

In the arrangement according to Fig. 3, the combined input signal, which is in the buried subcarrier form and obtained, for example, when playing ("playing") a video disc, 10 is passed to the bandpass filter li? through the comb filtering apparatus 70 'to the input TJ, the bandpass filter 150 311 is described as using a band elimination filter 150A responsive to the combined input signal and reducing the combiner 150C to connect the output of the filter 15 150A to an unfiltered version of the connected input signal 150 (whose delay substantially coincides with the signal delay associated with filter 150A). The elimination band of filter 150A corresponds to a shared middle band of 20 (e.g., f t 500 kHz).

The comb filter apparatus 70 'uses cascaded delay lines 71 and 72, a combiner 73 to sum the input and output of the delay line correctly weighted, and a combiner 74 which reduces the connecting center signal to the output of the combiner 73. These elements form a chrominance comb filter similar to that shown in Figure Ib, the output signals of the combiner 74 appearing at the output point T 1 of the filter. The signals present at the terminal T 1 'are processed by a bandpass filter 81, a modulator 83 and a bandpass filter 87, as in Fig. 1b, to frequency shift the chrominance signal to the desired (NTSC) position for the output signal. The bandpass filter 81 may optionally be omitted, taking into account said comb limiting effect on the passband-35 emission in the filter 150,

The comb filter apparatus 70 'also includes a connector 76' for summing the center signal to the output of the combiner 73. These inputs are fed directly to the combiner 76 'as opposed to using the high pass filter 77 and the combiner 76' in the arrangement of Figure Ib. The luminance comb filter output from the adder 76 'at the filter output point T' of the filter 5 contains only midband components, due to the said limiting effect of the input bandpass filter 150. from the output of the displacement filter 150A, the output of the adder 150 supplies the luminance signal input (via the delay element 82) to the output signal combiner 90 for connection to the frequency shifted chrominance signal output 15 from the bandpass filter 87.

A particular advantage of the apparatus shown in Figure 3 is the relatively narrow band requirements (e.g., about 1 MHz bandwidth) for the comb filter apparatus 70, which may ultimately be reflected in lower costs for 1H delay-20 control elements,

Figure 4 illustrates a variation of the apparatus shown in Figure 3 that retains the aforementioned narrowband requirement while introducing frequency shifting prior to filtering to use a relatively inexpensive, commercially available and narrowband ultrasonic delay line (e.g., Amperex Type DL45 1H delay). . In the arrangement shown in Fig. 4, the combined input signal (buried subcarrier shape) is applied to the bandpass filter 150 just as in Fig. 3. However, the output of the bandpass filter 150 is mixed with oscillations at the above-mentioned subcarrier sum frequency (i.e., f + fs1) oscillator is shown to be in a double balanced form.

The arrangement of the components (71, 72, 73, 74 and 76 ') of the comb filter apparatus 70 "of Fig. 4 corresponds to their arrangement in Fig. 3. However, for example, the delay lines 71 and 19 681 40 72 are of the above-mentioned DL 45 shape which passes through a narrowband difference frequency modulation product (which for example, in the band 3.58 MHz t 500 kHz) substantially excluding the total frequency product of modulation. However, since the components to be connected to the comb filter 70 "have an immediate input signal, it makes sense to include appropriate means (such as a low pass or bandpass filter) in the modulator 154. summing the cheese product before passing it to the comb filter inlet 10 in pinch T ",

The separated chrominance signal components are present at the output of subtractor 74 (voltage T 1 ") at the spectral point desired for output signal operation. Selection of these components by bandpass filter 87 simply generates a chrominance signal to be applied to output signal combiner 90.

The separated luminance signal components, only from the shared band, are present at the output of the summing combiner 76 '(pin T ") but occupy the output of the wrong band 20 with respect to the output signal usage 156 The Modu-25 generator 156 is described as having a double-balanced form.

It should be noted that the arrangements of Figs. extent. If, on the other hand, the subband bypass of the delay line is avoided in the recorder, there is complete freedom to use or not to use the subband bypass in the playback device, and the result is a much less visible synchronous drop effect in both cases. It makes sense to accept the cost of a broadband delay line in a recorder if this facilitates the use of cost-saving narrowband delay lines in a consumer instrument (i.e., a playback device).

Fig. 5 illustrates a form of a reproducing apparatus recoding apparatus in which the above-mentioned reducing process is used to obtain a luminance comb filter characteristic. The comb filter apparatus 70A of Fig. 5 includes a conventional arrangement of elements 71, 72, 73 and 74 to form a chrominance comb filter output at the output of a reducing connector 74 (output terminal T), but does not include any summing connector corresponding to element 76 'in Fig. 4 / Centerpoint output. T ^, is an uncombed signal.

In use of the arrangement of Figure 5, the full band combined (complete) input signal is mixed with oscillations (f '+ f) from the oscillator 152' modulated.

5 S

25J, which in this example is not carrier equalized. One of the modulation products corresponds to a carrier at 2fs *: 2fs (e.g., approximately 10.2 MHz), with the subcarrier hitting its lower sideband at f '+ 2fs (e.g., approximately 8.7 MHz). The stubband sideband filter 30 155 generates bandpass characteristics with the carrier at the center of the top end slope.

The combed chrominance signal components surrounding the (f 1 + 2f) subcarrier frequency occur in pin-S s at T 2 and are selected by bandpass filter 157 for mixing (f 1: f) to the output from oscillator 152 's in modulator 156 *. A difference frequency product containing chrominance signals in the desired (NTSC band around f, 21 68140 is selected by a bandpass filter 87 to be applied to the output signal combiner 90,

The combed chrominance signal output from the bandpass filter 157 is also passed to a combiner 163 for reduction to be combined with an uncombed combined signal (at the uplink spectral point) obtained from the pin T via a delay element 161 (substantially compatible with the bandpass filter 157 delay). The output of the subtraction combiner 163 is passed to the curtain-10 curve detector 165, and the low pass filter 167 picks up a baseband luminance signal from the detector output that includes the combed midband components along with the uncombed lower band and high band components. The output of filter 167 is applied to combiner 90 to generate the desired 15 (NTSC format) combined output signal.

Figure 5 illustrates an arrangement that uses shifting to a relatively high frequency band so that a relatively wideband complete combined signal appears as a small relative portion of the carrier frequency.

A certain bandwidth can be more easily implemented with an ultrasonic delay line operating at a high carrier frequency because the relative variation is smaller.

Figure 5 also illustrates the apparatus of the recoding-25 of the reproducing apparatus, which includes "vibration" correction before comb filtering, which has the above-mentioned advantages over undesired frequency variations of the input-combined signal. For this purpose, the oscillator 152 'is descriptively a voltage controlled oscillator (VCO) that responds to the output of the phase detector 175. The phase detector compares the output of a reference oscillator 177 operating at frequency f (e.g., a 3.58 MHz crystal oscillator) to a synchronizing chromaticity signal-to-output from a color synchronous gate 173. The color synchronous gate 173 87) synchronizing the color synchronous part 22 6814 0 (at frequency f). The arrangement described is in the form of a phase locked loop (PLL) which tends to make the output of the modulator 154 'substantially free of "vibration" of the input signal and is also suitable for use in the arrangement of Fig. 5.

Fig. 6 shows a modification of the embodiment of Fig. 5 in which the stub band sideband filter 155 'passes an unbalanced (f' + f) carrier product from one balanced modulator 154 '(responsive to a combined input signal and VCO 152' output) and a lower sideband f , The bandpass feature of the filter 1551 places (f 1 + f) the upper end of the carrier at the midpoint of the slope so that a small portion of the upper sideband is also passed through. The% modulation of the carrier (f '+ f) implemented in the modulator 154' is considered relatively low.

The output of the filter 155 'is led to the inlet point T * of the comb filter apparatus 70A'. The internal arrangement of the apparatus 70A '20 is similar to that of the comb filter 70A of Fig. 5, the conventional arrangement of the elements 71, 72, 73, 74 providing a chrominance comb filter output to the pin T1 (output from the reducing connector 74). However, z unlike the arrangement of Fig. 5, the chrominance-25 signal components in the pin TzJ hit the (NTSC) spectral point desired for output operation, so their selection by the bandpass filter 87 directly produces f a chrominance signal to be applied to the output signal combiner 90.

The uncombed combined signal (center signal) is present in the pin T 'of the apparatus 70A' and is passed through a delay element 161 (substantially compatible with the delay of the bandpass filter 87) to the combiner 163 to be reduced to be connected to the output of the bandpass filter 3587. The output of combiner 163 is passed to envelope detector 163. The low pass filtering of detector output by low pass filter 167 returns a baseband 681 40 23 alumina signal including combed midband components and uncombed subband and high band output components.

The arrangement shown in Figure 6 also includes vibration-5 correction prior to comb filtration, using elements 171, 173, 175, 177 and 152J in the PLL system, which is comparable to the arrangement shown in Figure 5. The arrangement shown in Figure 6 preferably avoids the need for a post-combing modulator 10 (1561) included in the system shown in Figure 5.

Figures 1a and 2a illustrate the application of the principles of the present invention to systems for directly encoding color image information into a buried subcarrier format.

In Fig. 1a, a typical source for uncoded color distortion information is a conventional format color film scanner 200 that provides a series of three simultaneous video signals (R, G, and B) representing the red, green, and sinusoids of the film image to be scanned, respectively. The color signals are applied to a conventional matrix-20 apparatus 210 to convert the three independent input signals into a different series of three independent signal outputs in which the signals are of the form (RY, BY and Y, where Y = 0.3 R + 0.59 G + 0.11 B) and which is suitable for use in coding.

Each of the color difference signals (R-Y, B-Y) produced by the matrix 210 is fed to the appropriate modulator 231, 233, which is a double balanced form. The corresponding phases, 0D v and 0D v (differing by 90 °) from the reference oscillations at the desired buried (embedded) subcarrier-30 frequency f '(e.g. 1.534091 MHz) are derived to the corresponding

S

modulators 231 and 233. The outputs of modulators 231 and 233 are combined by adder 235 to form a chrominance signal that is effectively phase modulated in hue and amplitude modulated in saturation. In Fig. 35, the bandwidth of each modulating color difference signal is limited to 500 kHz, and the chrominance signal occupies the frequency band f 1 ± 500 kHz.

68140 24

The chrominance signal output of the adder 235 is fed to a comb filter apparatus including a 1H delay line 241 and a connector 243, which has the function of reducing the input and output of the delay line in a reduced manner. The output of combiner 5 243 is a chrominance signal combed so that the chrominance signal components are passed at or near odd multiples of half the line frequency and the chrominance signal output is reduced. a filter 250A responsive to the Y-matrix output and a combiner 250C degressively connecting the output of the low-pass filter 250A to an unfiltered version of the Y-matrix output passed through a delay element 250B (the delay substantially coincides with the delay of the low-pass filter 250A),

The cut-off frequency (f) of the high-pass filter 205 corresponds to the cut-off frequency of the low-pass filter 250A and is suitably selected just below the lowest sideband frequency of the buried subcarrier (e.g., f = 1 MHz). The luminance signal components above the frequency f pass from the output of the connector 250C to a comb filter apparatus comprising a 1H delay line 261 and a connector 263 which together connect the input and output of the delay line 261. The output of combiner 263 is a luminance signal that lacks its subband component (O-f) and is combed above fco to let the luminance signal components at or near multiples of the line frequency and discard the luminance signal components at half the line frequency.

The combed luminance signal components at the output of combiner 263 are combined to be combined with (a) an uncombed subband component from the output of low pass filter 35A and (b) a combed chrominance signal output from combiner 270 to form the desired combined output for storage.

68140 25

In the direct coding environment illustrated by Figure 1a as an example, the use of comb filtering to form "soles" (wavelengths) can be clearly seen because the encoder does not have to perform any messy separation operations. The crosstalk of midband diagonal luminance components into color is substantially prevented by eliminating such components from the luminance signal prior to its initial incorporation into chrominance information. substantially eliminated from the chrominance signal before it is initially combined with the luminance information. Thus, each signal that divides the average 15 tan in the stored combined signal occupies only the mutually exclusive portions of this band. In the subsequent use of the recorded signal in the reproducing device, the interleaved luminance and chrominance signals can be separated by comb filtering without the risk of diagonal-type crosstalk.

When the functions of the playback device include recoding to the NTSC encoded format from the buried-carrier format exemplified herein (i.e., buried-carrier frequency 1.53 MHz, split center band 1-2 MHz; and luminans-25 bandwidth 0-3 MHz) , the following color television receiver processing operations with the recoded signals (also without using the receiver comb filter) are free of luminance crosstalk because the recoded chrominance signal is located in a band (3.08-30.08 MHz) with no luminance information of any kind.

If extending the cut-off frequency of the luminance signal beyond 3 MHz is used in the stored signal of the example, the apparatus of Figure 1a has the additional task of combing out the diagonal type luminance signal components in the shared upper band. It should be further noted that the direct coding apparatus shown in Figure 8 does not have 681 40 26 "internal structures" crosstalk from the upper band "diagonal" components (as found when looking at the recorder coding apparatus of the recorder) because there is no combination of luminance and chrominance information before combing.

Fig. 2a illustrates a modification of the coding apparatus shown in Fig. 1a in which luminance comb filtering (with elements 261 ', 263') precedes and does not follow high-pass filtering as filter 250. This allows the low-band 10 luminance component input to the combiner 270 to be passed through a low pass filter. with the characteristic curve of the working filter 250A) from the output of the 1H delay line. This arrangement avoids the use of a subband delay line bypass in the recorder, which is advantageous due to its previously mentioned effect on the design freedom of the reproducing device,

It should be noted that if it is desired to comb only the split center luminance signal and allow "diagonal" luminance components with frequencies above 20 to remain in the stored signal, this can be accomplished by a simple modification of the apparatus shown in Figure 2a: replacing the matched low-pass filters 280) with two matched band-stop filters, each with a block band of 25 equal to the split center band.

As explained in the aforementioned Clemens application, slower-than-real-time video disc recording technology can be used that utilizes time-scale-extended video signals. It should be noted that the coding technique of Figures 1a and 2a can be used for "slow motion" video signals as well as for "real time" video signals, given that the line frequency of "slow motion" video signals corresponds to the "real time" line frequency divided by a time scale multiplier.

Claims (6)

21 68140 A color image signal conversion system comprising a combined color image signal source, the signal 5 including color image luminance signals and color image chrominance signals, a first comb filter device for generating a chrominance output signal under the influence of the combined image signal, and a second comb filter device 10 for generating a combined image signal. generating a luminance output signal, characterized in that said combined signal source (60) produces luminance signals comprising a first portion representing coarse (coarse) image portions located in the first frequency band and a second portion representing medium fine image portions located in the second frequency band; in the upper frequency band, and a third portion representing fine image portions located in the upper, third frequency band in the second band; that the second luminance signal portion includes medium fine pixels located in only a first set of regularly spaced spectral points extending over the second frequency band, said portion lacking medium fine picture sub-components hitting the second set of regular spaced spectral points interleaved in the first set 25 with; that the chrominance signals from said source share a second frequency band with a second luminance signal portion, wherein the chrominance signal comprises, in said common second band, chrominance signal components arranged in only a second set of spectral points, and wherein the chrominance signal lacks chrominance signal components; the first set of spectral points; that the first comb filter device (70) includes circuits (71, 73, 74) forming a plurality of zeros correlated to the first set of spectral points to generate said chrominance output signal without crosstalk from the medium portions of the second luminance signal portion 28 6 8 1 40; and that the second comb filter device (70) includes circuits (71,73,76) forming a plurality of zero points correlated to the second set of spectral points to generate said luminance output signal, including first, second and third portions in the first, second and third in the frequency band, where in the second part there is no crosstalk from said color signal components. A system according to claim 1, characterized by a mixing device (152, 154) which shifts the frequency of the components of the combined signal before passing them to the first comb filter device, wherein the plurality of zeros formed by the first comb filter device differs from the first set of spectral points by said frequency shift. A system according to claim 1 or 2, characterized by a mixing device (152, 154) which transfers the components of the combined signal before passing them to the second comb filter device, wherein the plurality of zeros formed by the second comb filter device differs from the second set of spectral points by said frequency shift. A system according to any one of the preceding claims, characterized by an output signal generating device (90) responsive to the output signals of the first and second comb filter devices such that luminance and chrominance signals are transmitted from said conversion device, including comb-unfiltered luminance signals of the first frequency band. 29,681 40 1. A system for signaling, a signaling system for combining signaling and signaling, combining signaling with luminance and signaling and signaling for chrominating signaling, for combining with signaling, for which the genome has been used in chrominance signals, and in the field of signaling, in which the genome pa-10 network of the combinatorial signaling luminance signaling, the transverse signal, the signal (60) for these combinatorial signaling signals, luminance signaling coarse) bilddelar, vilka är belägna pä ett första frekvensband, och 15 en andra representerande medelfina bilddelar, vilka är belägna pä ett andra högre frekvensband, och en tredje del, representerande fina bilddelar, vilka är belägna pä en tredje frekv second; att den andra luminanssignaldelen innefattar medelfina bilddelar, 20 belägna self i en första mängd med jämna mellanrum belägna spectralställen, vilka sträcker sig över det andra frequency bandet, varvid i sagda del fattar de medelfina bild-delskomponenter, vilka belägna spektralställen, vilka ligger var-25 vade med den första mängden; the chrominance repressive signaling signal may be used to transmit the signal and the luminance signal to the luminance signal, the chrominance repressive signal to the luminance signal and the bandwidth of the signal band, fattas krominansen representerande signalkomponenter, vilka träffar spektralställenas första mängd, att den första kamfilteranordningen (70) innefattar kretsar (71,73,74), vilka bildar ett fler-35 tai nollställen, vilka ställets n relörstörn f faststast chrominance requirements, in which case they are used for commercial purposes