Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1989-02-23
1990-09-18
Britton, Howard W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358160, H04N 322
Patent
active
049582291
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method for the area enlargement of a television picture.
Background of the Invention
When transmitting films, whose format has a height-breadth ratio different from that of a television screen, il may be desirable to enlarge the displayed picture, thus making use of the full screen format. It also may be desirable to display several scenes of a television transmission in a larger format.
The picture can be stretched or expanded by increasing the vertical and horizontal scanning amplitudes. It will be recognized that the horizontal deflection circuitry consumes the greatest energy in a receiver and imposes the greatest strain on the modular elements. A further increase in the horizontal scanning amplitude would further increase the energy consumption and the load on the modular elements.
Therefore, it is an object of this invention to provide a method for the area enlargement of a television picture, which renders it possible to stretch the television picture in the horizontal direction while maintaining the horizontal deflection.
Summary of the Invention
In this invention expansion of the picture in the horizontal direction is achieved by a stretching in time rather than by a geometrical stretching. This occurs by reproducing only those sections of the scanning line that are to be displayed and by suppressing the other ones. Thus, the contents of the picture can be distributed over the full horizontal width while maintaining the horizontal deflection. A further advantage of this method lies in the fact that by this stretching in time no loss in brightness occurs and no problems in picture geometry arise demanding special remedial measures. Furthermore, it is possible to select particular areas of the television picture for the enlargement.
Apparatus to perform the invention includes a memory circuit for storing at least a portion of a scanning line to be expanded and a control circuit for establishing periods that video information is to be written-to and read-from the memory circuit.
By storing the picture information of a scanning line or at least of the area of the scanning line that is to be displayed, a time-independent access to this picture information is provided. Correspondingly, a stretching in time in the horizontal direction can be achieved, if the picture information of the area of the scanning line is read-out in such a way that it is evenly distributed over a line filling the total screen format.
It is especially suitable to provide for two read-write memories (3,4), whose data-input units (8, 9) are connected to an incoming picture signalling line (1) and whose data-output units (10, 11) are connected by a reversing switch (5) to an outgoing picture signalling line (6). These read-write memories are alternately activated in the modes "write" and "read". This means, that one read-write memory is in the mode "read" and the other in the mode "write" and subsequently the former read-write memory is in the mode "write" and the latter in the mode "read".
Further developments and an advantageous design of the invention result from the claims, the description, and the drawings that illustrate an example of construction of the object of the invention.
Brief Description of the Drawings
FIG. 1 is a waveform diagram illustrating the transmission, storage, and reading procedures for the stretching of a television picture in the horizontal direction corresponding to a realization of the method according to the invention.
FIG. 2 is a block diagram of a circuit arrangement for the stretching of a television picture in the horizontal direction according to an example of application of the invention.
FIG. 3a is a pictorial diagram for illustrating the display procedures in the stretching of a televion picture in the vertical direction according to a further development of the method according to the invention.
FIG. 3b is a waveform diagram useful in explaining vertical expansion of the picture by means of altering the vertical deflection drive signal.
FIG. 4 is a block di
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Guillon Jean-Claude
Rufray Jean-Claude
Britton Howard W.
Deutsche Thomson-Brandt GmbH
Hayes James B.
Herrmann Eric P.
Juo James
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