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WO2004025852A1 - Transmission d'images numeriques au format analogique - Google Patents

Transmission d'images numeriques au format analogique Download PDF

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Publication number
WO2004025852A1
WO2004025852A1 PCT/US2002/028684 US0228684W WO2004025852A1 WO 2004025852 A1 WO2004025852 A1 WO 2004025852A1 US 0228684 W US0228684 W US 0228684W WO 2004025852 A1 WO2004025852 A1 WO 2004025852A1
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terms
resolution
low
chrominance
luminance
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George H. Nickel
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University of California Berkeley
University of California San Diego UCSD
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University of California Berkeley
University of California San Diego UCSD
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Priority to AU2002333533A priority Critical patent/AU2002333533A1/en
Priority to PCT/US2002/028684 priority patent/WO2004025852A1/fr
Publication of WO2004025852A1 publication Critical patent/WO2004025852A1/fr
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/007—Systems with supplementary picture signal insertion during a portion of the active part of a television signal, e.g. during top and bottom lines in a HDTV letter-box system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/24—High-definition television systems
    • H04N11/30—High-definition television systems with transmission of the extra information by means of quadrature modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/12—Systems in which the television signal is transmitted via one channel or a plurality of parallel channels, the bandwidth of each channel being less than the bandwidth of the television signal
    • H04N7/127—Systems in which different parts of the picture signal frequency band are individually processed, e.g. suppressed, transposed

Definitions

  • the present invention relates generally to high definition color television (HDTV), and, more particularly, to HDTV that is compatible with existing television receivers using various national analog formats.
  • the compression system is the Joint Photographies Experts Group (JPEG) system (or its moving picture variation, MPEG), which is used in conventional computers for picture compression.
  • JPEG Joint Photographies Experts Group
  • MPEG moving picture variation
  • HDTV systems are modern digital computers that use information theoretic methods to transmit and receive the digitized image data efficiently (see Reference 2 for the Discrete Cosine Transform (DCT)-based standard, References 3 and 4 for information-theoretic methods).
  • DCT transformations also exploit features of the human visual response to minimize the number of bits required for transmission of color images, which are perceived with nearly the same quality as the original image.
  • the visual features that are used include persistence of vision, spatial resolution of different color components, and the contrast threshold limits needed to distinguish brightness variations at different spatial wavelengths.
  • the most efficiently encoded signals reach the highest entropy rate attainable; that is, they resemble gaussian random noise.
  • the HDTV receiver samples the waveform digitally, corrects for errors, inverts the entropy coding and mathematical transformations, and displays the resulting image. If such signals were presented to a television receiver with a NTSC, PAL, or SECAM format, they would appear as "snow". (Reference 5 gives an excellent overview of NTSC and HDTV systems.)
  • the present invention uses an alternate scheme to compress the luminance and chrominance data. Only high resolution details are compressed digitally, as described above for HDTVs; the remaining low resolution details are transmitted in the appropriate analog format. Analog receivers lose very little picture quality since the finer details are not discernible to the human eye in an analog TV. To be fully compatible with the respective analog format, additional “bookkeeping" information is added, such as a color burst to synchronize the reception of the color data and the synchronization pulses that trigger line sweeps. There is also some “dead time" when the electron beam is moving back to start a new line. However, there is increased compression when digital data is separated into two or more components, which partially offsets these channel capacity losses. The result is that a single channel can be used to transmit the combined signal with little loss in HDTV picture detail.
  • an NTSC receiver in the exemplary process herein, about half the extra digital information containing the finer details are seen in "letterbox" bounding lines that may be displayed above and below the wider format picture produced under the HDTV format.
  • the letterbox lines are not black, but rather a rather uniform gray since they are replaced every 60 th of a second.
  • the other half is sent in the vestigial video sideband that is not currently used by NTSC transmitters.
  • conventional NTSC transmitters can be readily modified to use the vestigial sideband.
  • the NTSC receivers will not use this data at all since it is sent in quadrature with the carrier wave for the video signal and is not processed by simple amplitude modulation detectors.
  • the new HDTV receivers can be readily modified to accept the combined signal since only a software change is needed to accept the combined data.
  • the low resolution data sent in NTSC format is converted to digital form and combined with the finer detail data to form the complete image that is displayed by the HDTV receiver.
  • the present invention includes a method for HDTV and analog compatible image processing.
  • Luminance and chrominance image data of a scene to be transmitted is obtained.
  • the image data is quantized and digitally encoded to form digital image data in HDTV transmission format having low-resolution terms and high-resolution terms.
  • the low-resolution digital image data terms are transformed to a voltage signal corresponding to analog color subcarrier modulation with added retrace blanking and color bursts to form an analog video signal.
  • the analog video signal and the high-resolution digital image data terms are then transmitted in a composite analog video transmission.
  • the analog video signal is processed directly to display the scene.
  • the analog video signal is processed to invert the color subcarrier modulation to recover the low-resolution terms, where the recovered low-resolution terms are combined with the high-resolution terms to reconstruct the scene in a high definition format.
  • FIGURE 1 is an overview flow diagram of a HDTV/NTSC compatible system using only a single NTSC channel bandwidth.
  • FIGURE 2 is a matrix for low-resolution luminance transformation for pixel blocks.
  • FIGURE 3 is a matrix for low-resolution in-phase chrominance transformation for odd columns of macroblocks.
  • FIGURE 4 is a matrix for low-resolution in-phase chrominance transformation for even columns of macroblocks.
  • FIGURE 5 are matrices for low-resolution quadrature chrominance transformations for odd (upper) and even (lower) macroblock scans.
  • FIGURE 6 schematically depicts the spatial distribution for each luminance and chrominance component for the transformation of low resolution DCT coefficients.
  • FIGURE 7 is a flow diagram showing an exemplary process in accordance with the present invention.
  • FIGURE 8 is a flow diagram more particularly showing reconstruction of the HDTV data.
  • FIGURE 9 is the digital subcarrier modulation matrix.
  • DETAILED DESCRIPTION The following detailed description applies specifically to the NTSC format as an example of the invention. The methodology applies to other conventional analog formats, such as PAL and SECAM, by modification of parameters. Throughout the following description, the basis for choosing the values of parameters is described, thus indicating how the concept would be applied to other conventional analog formats.
  • digital information is imbedded within the selected analog format so that both HDTV and analog signals are accommodated within the bandwidth of a single channel.
  • the set of conventional HDTV quantized coefficients is partitioned into low-resolution and high-resolution components.
  • the numbers of low-resolution coefficients for the luminance and chrominance components to form an analog forma- compatible signal are chosen according to the bandwidths available in the analog format.
  • the low-resolution components are linearly transformed back to the image space as a viewable image, and are not quantized or entropy-coded.
  • the inefficiency that might be expected from this lack of entropy coding is small because: (1 ) there are relatively few coefficients in the low-resolution component; (2) the entropy of the low- resolution coefficients is high for most images so that entropy compression causes only a small decrease; (3) the entropy of the high-resolution component is very low for most images; and (4) an inequality associated with the entropy of partitioned data sets implies a reduction in the number of bits required when low and high resolution data are separated (see Reference 4) .
  • the high-resolution components are digitally encoded and transmitted in other portions of the signal, such as in "letterbox" lines bounding a higher aspect ratio image or the unused vestigial sideband arising from the amplitude modulated video signal.
  • FIG. 1 presents an overview of the process of the present invention as applied to a NTSC format.
  • An image is captured 10 and conventionally processed 12 as a HDTV signal.
  • the HDTV signal is separated into high resolution components 14 and low resolution components 16.
  • the high resolution conventional HDTV components are directly used to modulate 18 portions of the NTSC signal that will not be processed for the NTSC image.
  • a transformation is applied 22 to the low resolution conventional HDTV quantized coefficients to generate the NTSC-compatible signal.
  • the NTSC signal is transmitted 24 to both NTSC and HDTV receivers.
  • the low resolution components in the NTSC compatible signal directly form the image on a NTSC receiver.
  • a HDTV receiver In a HDTV receiver, according to the present invention, software digitally samples the NTSC waveform and inverts the added transformation to recover 28 the low resolution digital data.
  • the high resolution digital data is recovered 26 directly from the modulated portions of the NTSC signal.
  • the low resolution components are then processed with the high- resolution digital data and displayed 32 in the normal HDTV mode. No hardware modifications are required to create the high-definition image.
  • the effects of these transformations result in a single 6 MHz channel to transmit an image that is directly viewable on NTSC receivers and invertible to an HDTV image with only a 20%-30% decrease in the image quality delivered by an HDTV receiver.
  • an image of 1280 by 720 pixels was chosen, with a frame rate of 60 Hz (actually 59.94 Hz). Other rates could be accommodated with interpolation.
  • a complete high-definition image is transmitted in each NTSC half-frame.
  • a doubling of the image quality of a single frame in bits/pixel can be obtained by using 30 Hz frame rates.
  • the NTSC frame rate and video bandwidth translate to about 521 independent symbols per scan line, where a "symbol" is a digit in the numerical base used by a video channel.
  • base 2 binary system
  • there are only two different symbols, 0 and 1 but digital transactions do not have to be in binary.
  • the horizontal retrace blanking occupies 41 of these symbols, and the color burst another 24, leaving 456 symbols for the video information.
  • luminance data are divided into 8x8 arrays of pixels, and the two chrominance components are each formed from 16x16 arrays of pixels where each chrominance value is an average of a corresponding 2x2 array of pixels.
  • the resulting 8x8 arrays of chrominance components are "macroblocks".
  • Y luminance data
  • I,Q chrominance data
  • Each block is an array of 64 bytes of pixel brightness values in an 8x8 array, which are transformed into a corresponding array of DCT coefficients in accordance with the JPEG Standard (Reference 2 and Appendix C).
  • the blocks and macroblocks are processed in horizontal raster scan order, beginning at the upper left corner of the image.
  • Each DCT coefficient matrix is reshaped into a one-dimensional array using the "zigzag" pattern of the JPEG standard.
  • the amount of information that can be transmitted in the NTSC format is determined by the number of bits of data that can be used to represent each symbol. Broadcast signals are assumed to have a signal-to-noise ratio (S/N) corresponding to 3 bits/symbol (above the loss of 0.4 bits/symbol that is due to the restriction to 75% of the signal range).
  • S/N signal-to-noise ratio
  • the NTSC format permits 456 symbols per scan line.
  • the present invention uses 3 low resolution symbols to represent each block on each scan line. However, the full block array is 160 blocks per line across the width of the image, requiring 480 symbols per line.
  • the 1 st , 2 nd , 3 rd and 5 th luminance ⁇ coefficients, the first 6 ⁇ coefficients, and the 1 st and 3 rd ⁇ coefficients from the one-dimensional DCT coefficient arrays are transformed back to the corresponding image space coefficients Y * , I * , and Q * , with the transformation matrices shown in Figures 2-5.
  • a set of (x,y) coordinate patterns is established for the luminance (Y*) and each chrominance component (I* and Q*).
  • An exemplary pattern is shown in Figure 6. The coordinates are measured from an origin at the upper left corner of each block or macroblock, with x increasing to the right and y increasing in the downward direction. The lower right corner has coordinates
  • Figure 6 illustrates the pattern of points at an odd half-frame, for eight adjacent blocks (two macroblocks), the basic symmetry element of this transformation.
  • Each luminance block is traversed by two lines. The "slant" of a line across each block or macroblock is ignored.
  • the block y-coordinate values are 1/8 and 5/8 for odd NTSC half-frames, and 3/8 and 7/8 for even half- frames.
  • Each macroblock is traversed by four line scans in a HDTV frame. The four y-coordinates are thus 1/16, 5/16, 9/16 and 13/16 for odd half-frames, and 3/16,7/16, 11/16 and 15/16 for even half-frames.
  • the x-coordinates of the Y-components are centered at % and %, and those of the Q-chrominance are at VT. and staggered in alternate macroblocks.
  • the l-values are also staggered in alternate macroblocks, with two x-coordinates at 1/6 and 5/6 in one, and one at ⁇ A in the other. In this way, a uniform spacing of each set of coefficients is achieved, and the transformation matrices ( Figures 2-5) describing brightness values in terms of DCT coefficients are invertible.
  • the coefficients of the basis function transforms e.g., DCT transform, of the (Y,I,Q) components are computed 44; i.e., sequential 8x8 blocks of (Y, I, Q) are converted to basis function coefficients ( ⁇ , ⁇ , ⁇ ).
  • the preferred basis function is the DCT transform, which will be exemplified herein. This should not be considered a limitation of the present invention except as specifically recited in the claims. In accordance with present HDTV methods, these coefficients are then quantized.
  • RGB to YIQ is preferable when interfacing with the NTSC standard.
  • low-resolution terms in the transformation of each luminance/chrominance component are linearly transformed 46 back to (Y*, I*,Q*) image space.
  • the desired properties of these transformations are: that the resulting NTSC image be an accurate representation of the original image; that the relative information in the Y, I and Q values be in the proper proportion for the NTSC video bandwidths for the luminance and subcarrier signals; and that the transformations be easily invertible in the new software path for HDTV receivers. Because of the interlacing of scan lines in the NTSC format, there are separate transformations for even and odd frames.
  • the basic symmetry element of the transformation is a pair of macroblocks, with the centering of luminance and chrominance values indicated in Figure 6 for an odd frame.
  • NTSC-resolution image values are then transformed 48 to a voltage signal using pulse code modulation that corresponds to the NTSC color subcarrier modulation with added retrace blanking and color bursts.
  • An exemplary digital subcarrier modulation matrix is presented in Figure 8 for use in displaying the resulting images generated by numerical simulations. Because this matrix is large, relating 12 luminance/chrominance values to 48 voltages in 4-to-1 oversampling, it is represented in symbolic form. The first 8 rows represent the repetition of 8 luminance values as the scan line traverses the two macroblocks of the basic symmetry element.
  • the next 3 rows represent the equations for the subcarrier modulation of the 3 in-phase chrominance values (the constant 11/60 in the argument of the cosines represents a rotation of 33 degrees in the NTSC modulation system).
  • the last row, with the sine function, represents the quadrature chrominance values.
  • the symbol j in these equations represents a cumulative index running from 261 (the first point following the retrace blanking and color burst) to 2084 (the oversampling factor times the number of independent symbols per scan line allowed by the video bandwidth).
  • This matrix is only approximate, and is used to demonstrate the form of the voltage vs. time in the NTSC format. In practice, it will be necessary to modify the matrix by appropriate windowing factors to eliminate the possibility of out-of-bandwidth fourier components.
  • the number of coefficients taken for each component is chosen to be consistent with the NTSC bandwidths for Y, I and Q (8:3:1 ).
  • the remaining higher order coefficients are quantized and encoded 50 by the standard methods of data compression and error correction for HDTV digital data and modulates the NTSC signal for transmission 52 with the NTSC signal as, e.g., letterbox boundary lines or in a vestigial video sideband. Since the vestigial video sideband is not used by a NTSC receiver, the data carried by the sideband can modulate the sideband by any efficient means, such as quadrature amplitude modulation.
  • the entire 6 MHz bandwidth is processed conventionally to separate the video information and to recover the audio data.
  • the pulse amplitude modulated signal is simply processed as an analog signal.
  • the resulting 4.1 MHz video "baseband" signal can be viewed directly 56, either as would be seen on an old black-and-white receiver, or demodulated to represent the color image shown by a current NTSC receiver.
  • the NTSC baseband signal is digitally processed to invert the chrominance subcarrier modulation.
  • the NTSC signal is digitally sampled 64 to recover the luminance and chrominance components from the pulse amplitude modulated signal.
  • the resulting digital image arrays for Y, I, and Q information are processed 66 with the inverse of the transformation matrices of Figures 2-5 to recover the spatial transform coefficients.
  • the letterbox lines are digitally sampled 68, as are the vestigial sidebands 72, to recover the high resolution information. Because the video carrier was not suppressed, it is available for synchronous detection of the video sidebands. After recombining 76 the low- and high-resolution coefficients, the high-definition image is reconstructed and displayed as in conventional HDTV receivers.
  • Figure 8 more particularly depicts processing of the combined NTSC signal with both high and low resolution image data.
  • the combined signal is input 82 to a HDTV receiver where the signal is sampled 84 over the entire 6 MHz bandwidth of the video signal.
  • Data components of the video signal are digitally detected 86 to output 88 a signal in-phase with the video carrier and to output 92 a signal in quadrature with the video signal.
  • the in-phase output signal contains the low-resolution image information, which is first processed to detect 94 the luminance signal components Y and to detect 96 the chrominance signal components I, Q..
  • the chrominance signal components are further processed to separate the data 198 that is in-phase with the video subcarrier and the data Q 102 that is in quadrature with the video subcarrier.
  • the Y, I, Q components in the image lines are then inverted 104 to recover the low-resolution digital coefficients ⁇
  • the Y, I, Q components in the bounding lines are also inverted 109 to recover the
  • the high resolution image data is contained in the quadrature video signal 92.
  • the lines are then recovered 114 to directly obtain hi s h 116, hi s h 118, and h
  • the low and high resolution ⁇ , ⁇ , and ⁇ components are collated 124 and inverted 126 to recover the Y,I, and Q coefficients, respectively.
  • the Y, I, and Q coefficients are transformed 128 to RGB space for display 138 of the original image on a HDTV screen.
  • process step 104 the NTSC-compatible transformations of the low resolution coefficients (Y*, I*, Q*) are inverted back to the ( ⁇ , ⁇ , ⁇ ) HDTV image space.
  • These inversion transformations relate voltage values of the horizontal scan lines of the NTSC format, spatially distributed as shown in Figure 6 over the luminance blocks and chrominance macroblocks.
  • the pseudoinverse of the matrix shown in Figure 8 does exist, demonstrating that digital sampling of these scan lines can recover the original luminance/chrominance values. Because the inverses of the transformations in Figures 4-7 are also well-defined, the HDTV receiver can recover the low resolution DCT coefficients from the central 180 lines of each NTSC half-frame. Numerical simulation using various images have verified: that the inversion of the low resolution NTSC image to recover the original DCT coefficients is practical; that the introduction of errors by noise in the channel is consistent with standard practice; and that the amount of information in the remaining high resolution DCT coefficients is consistent with the bandwidth available in the letterbox lines and the vestigial video sideband.
  • Bandwidths The allotted 6 MHz channel is divided into two portions, an FM-modulated audio channel 0.5 MHz wide at the high end, and an AM-modulated video channel with an unsuppressed carrier 1.25 MHz above the low end. Coding of the audio channel is not addressed in this paper. Of the 4.25 MHz in the upper sideband, approximately 4.1 MHz is usable without interfering with the audio channel. The 1.25 MHz vestigial sideband is not used in NTSC, although synchronous detection is possible using the highly stable, unsuppressed AM carrier. The main 4.1 MHz video sideband is further divided by subcarrier modulation with a suppressed carrier approximately 3.6 MHz above the AM carrier.
  • This subcarrier supports two sidebands in quadrature: the In-phase component I (1.5 MHz) and the Quadrature component Q ( 0.5 MHz). Actually, these components are "rotated" by 33° (11 ⁇ /60 in Figure 8) in NTSC for some historical reason.
  • Luminance data Y is contained in the entire 4.1 MHz sideband, as it was in the original black-and-white receivers.
  • Y, I and Q are related to R, G and B by a linear transformation.
  • Y is a nonnegative weighted sum of the color components, but I and Q can be negative.
  • Synchronous detection is made possible by including 8-11 waves of the subcarrier in each line of the scan. The precise frame rate and subcarrier frequency were chosen so that the chrominance components would be seen on old black-and-white receivers as a high spatial frequency "checkerboard" pattern.
  • Time domain partitioning A full frame of approximately 1/30 s contains 525 lines, which are interlaced into two half-frames. In the first half-frame, the lines start at the upper left and terminate at the lower right; in the next half-frame, they begin at the upper center and terminate at the lower center. A total of 21 lines are blanked during the vertical retraces, although closed-caption information is included within these lines. Each line is blanked for about 8% of its duration to allow for the horizontal retrace, and another 5% is allocated to the "color burst" (the 8-11 waves of subcarrier frequency mentioned above), used for synchronous detection. By design, there are exactly 455 half-waves of the subcarrier in one line.
  • the 4.1 MHz bandwidth allows approximately 521 independent symbols per line, of which 450-460 are available for image data.
  • Signal voltage ranges Expressed in terms of the percentage of unmodulated carrier amplitude, the signal corresponds to full brightness at 100% modulation (actually a little less to be certain to avoid overmodulation), and darkness at 25% modulation. Signals in the last 25% of the modulation range are referred to as "ultrablack", and are used to trigger retraces and blank the trace.
  • the aspect ratio of an NTSC image is 4:3 (for HDTV, a ratio of 16:9 is used).
  • the relative bandwidths for Y, I and Q correspond to ratios of 8:3:1 in the numbers of these coefficients.
  • JPEG COMPRESSION Although many compression schemes (such as wavelets) are available, the Joint Photographic Experts Method, or JPEG S-91 ,793
  • MPEG often used in satellite TV systems, is essentially an extension of JPEG that allows extra compression when successive frames either do not change or are transformations of the previous frame due to pan, tilt, and zoom.
  • the luminance image is partitioned into 8x8 blocks.
  • the pixel at image location (i,j) is represented by integer data yy, usually a byte.
  • the resulting coefficients c m n contain all the information of the y 's, but their values tend to be largest for smaller values of m and n, at least for conventional "smooth" images.
  • the dc component, c_o is non-negative and generally larger in magnitude than the others, which can be either positive or negative. Their absolute values decrease approximately monotonically if they are arranged in the "zig-zag" order
  • Quantization of these coefficients based on the ability of the human visual system to detect spatial modes of different contrast and color makes the transformation noninvertible, or lossy, but can lead to a sparse sequence of small integers that is effectively encoded with very few bits. Quantization is based on the observation that a certain threshold of contrast change is necessary for human observers to detect differences in brightness for these patterns. The level of change needed for perceptible difference is greater with patterns with more stripes. These levels are expressed as an array of "quantization" values, which are used to break up the range of each transformation coefficient into a finite number of perceptible ranges. Once quantization has been performed, the transformation is no longer invertible, but the number of bits necessary to define the image has been reduced by a large factor. Quantization is the man reason for the huge compression obtained by DCT-based coding.
  • the dc component can be difference-encoded, entering only its difference from some prediction. This prediction could be complicated, or as simple as the previous dc value.
  • this sequence of symbols can be entropy encoded by substituting variable length symbols, the shorter ones denoting more frequently encountered values ("Huffman coding").
  • the encoded string is interpreted, requantified, and inverse transformed to produce a suitable approximation of the original image. Chrominance values are treated similarly, except that the reduced resolution of the human eye for color makes it possible to average I and Q over 2x2 squares without noticeable effect.
  • the information for both of the color components takes only half as many bits as the luminance information. For most images, the number of bits needed for a color image is about equal to the number of pixels.
  • APPENDIX C DCT TRANSFORMATION: The transformation from image space to transform coefficients is presented for reference.
  • a compact expression of the transformation uses a similarity transformation of a block of brightness values of each luminance or chrominance component:
  • T the transpose of T
  • ⁇ the 8x8 matrix of transform coefficients
  • Y a block of luminance values
  • the subscripts are the row r and column c offsets from the (r,c) value at the upper left comer of the block.
  • the unitary transformation matrix T is formed from only 8 (signed) values:

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  • Compression Or Coding Systems Of Tv Signals (AREA)
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Abstract

La communication d'images compatibles TVHD (12) et au format analogique (figure 1) se fait dans une seule largeur de bande de canal analogique. A partir de données de luminance et de chrominance (10) d'images d'une scène à transmettre, les données d'image sont quantifiées et codées numériquement pour former des images numériques dans un format de transmission TVHD comportant des termes basse résolution (16) et haute résolution (14). Les termes basse résolution (16) de données d'image numérique sont transformés en un signal de tension correspondant à une modulation de sous-porteuse couleur analogique avec suppression de rafraîchissement et train d'ondes pour former un signal vidéo au format analogique (22, 28). Ce signal vidéo au format analogique et les termes de données d'image numérique haute résolution sont alors transmis en mode de transmission vidéo analogique (24) composite (24, 26).
PCT/US2002/028684 2002-09-10 2002-09-10 Transmission d'images numeriques au format analogique Ceased WO2004025852A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4870489A (en) * 1987-07-23 1989-09-26 Ducret Robert P NTSC compatible HDTV transmission system
US5053857A (en) * 1988-07-28 1991-10-01 British Broadcasting Corporation Television signals
US5589993A (en) * 1993-02-23 1996-12-31 Matsushita Electric Corporation Of America Digital high definition television video recorder with trick-play features
US5841480A (en) * 1989-09-07 1998-11-24 Advanced Television Technology Center Film to video format converter using least significant look-up table
US20020024998A1 (en) * 2000-08-25 2002-02-28 Cooper J. Carl System and method for enabling compatibility between digital and analog television systems

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4870489A (en) * 1987-07-23 1989-09-26 Ducret Robert P NTSC compatible HDTV transmission system
US5053857A (en) * 1988-07-28 1991-10-01 British Broadcasting Corporation Television signals
US5841480A (en) * 1989-09-07 1998-11-24 Advanced Television Technology Center Film to video format converter using least significant look-up table
US5589993A (en) * 1993-02-23 1996-12-31 Matsushita Electric Corporation Of America Digital high definition television video recorder with trick-play features
US20020024998A1 (en) * 2000-08-25 2002-02-28 Cooper J. Carl System and method for enabling compatibility between digital and analog television systems

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