Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-07-24
1993-05-04
Peng, John K.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358141, 358 11, H04N 701, H04N 704, H04N 1120
Patent
active
052086682
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns a television transmission system compatible with current television standards having a 4:3 aspect ratio, including an encoder and a decoder. Such a transmission system is described, for example, in German patent DE 3840054.
BACKGROUND OF THE INVENTION
For improved television transmission systems, it has been shown to be desirable, particularly in view of the preference of the general public, to increase the aspect ratio of a television receiver from 4:3, as found in present standard receivers, to 16:9 (i.e., the recommended aspect ratio of future HDTV standards) or 5:3 without losing compatibility with existing television standards (PAL, NTSC, SECAM). To achieve this, it is suggested in German patent DE 3840054 to separate, at the transmitter, every fourth line of the picture signal, and to spatially compress or interpolate the remaining lines in the correct spatial position. The separated lines are added, directly or in scrambled form, into vacated spatial areas created by the spatial compression along upper and lower edges of the picture. The resulting picture signal is then transmitted in coded form. The original picture signal with a 16:9 or 5:3 aspect ratio is reconstructed from a received decoded picture signal. Specifically, the separated lines (i.e., every fourth line) disposed in the upper and lower picture edge areas are, after descrambling, inserted among the remaining spatially decompressed (expanded) lines in the correct line sequence. Upon reproducing the received signal by a current (state-of-the-art) 4:3 aspect ratio television receiver, the scrambled lines added along the upper and lower picture edge areas are reproduced as quasi-noise bands (bars) which can be disturbing to a viewer.
It is an object of the invention to develop a system of the aforementioned type such that, upon reproduction of the picture signal by a conventional 4:3 television receiver, the upper and lower edge areas of the picture appear as essentially consistent picture areas.
SUMMARY OF THE INVENTION
A compatible wide aspect ratio television signal in accordance with the principles of the present invention is representative of an image containing vacated spatial areas along upper and lower edges of an image defined by lines remaining after lines are separated from groups of successive lines within an image scanning interval. The separated lines are inserted into the vacated spatial areas. A first carrier is modulated with non-active portions of the separated lines, and with the remaining lines. A second carrier is modulated with time expanded active image portions of the separated lines, and is disposed in an upper portion of the television signal frequency spectrum so as to be suppressed in a standard aspect ratio receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram of television signal transmitter apparatus including a system according to the invention.
FIG. 2 shows a block diagram of a television signal receiver including a system according to the invention.
FIG. 3 shows a conventional 8 MHz television channel occupied by two picture signal bands and audio carriers located therebetween in accordance with the television system of FIGS. 1 and 2.
FIG. 4 depicts expansion at the transmitter and compression at the receiver of the active regions of separated television lines which are transmitted in the right-hand picture signal partial band of FIG. 3.
In the transmitter arrangement of FIG. 1, a television picture source 10 (e.g., a camera) scans using an enlarged picture aspect ratio of 16:9 (or 5:3). In this example, the picture signals from source 10 correspond to conventional picture signals except for the altered aspect ratio. In accordance with the PAL standard, every television picture comprises 575 active lines.
The output signal from source 10, either an RGB or a YUV signal (indicated by the 3-way line), is applied to a picture signal processing stage 151 which separates one line from every group of four (or five) successive lines of th
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Schmidt et al., Transmission of Two NTSC Color Television Signals Over a Single Satellite Transponder Via Time-Frequency Multiplexing, IEEE Transactions on Communications, Nov. 1983, pp. 1257-1266.
Weckenbrock et al., ACTV: Advanced Compatible Television, Fernseh und Kino-Technik, vol. 42, Jul. 1988, pp. 305-311, and translation filed Jul. 24, 1992.
Dinsel Siegfried
Habermann Werner
Herrmann Eric P.
Kurdyla Ronald H.
Peng John K.
Telefunken
Tripoli Joseph S.
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