Robert Boschgmbh

Bts Broadcast Television Systems Gmbh

Robert Bosch Fernsehanlagen G.m.b.h.

Gerhard Illetschko

Jurgen Heitmann

Dieter Poetsch

Hans-Peter Maly

Hans-Peter Richter

Reiner Noske

Horst Peth

Color television signals obtained by scanning a still picture are converted into digital video signals and stored in video frame memory for delaying the signals. Undelayed and delayed digital video signals are added together to produce a luminance signal in which the color carrier is suppressed. A circuit for detecting a change of picture provides a start signal after which the first frame of a still picture is stored and is then recycled until there is another picture change. To reduce the effect of recycling, the continuously supplied picture signal is modified by a factor of 1-k, and the recycled picture is modified by the factor k, wherein k varies between 0 and 1 (or 100%) and is a gradually rising function whose rise time extends over a multiplicity, for example 2-4, video frame periods.

Still picture decoder for color television signals having a phase

The correction factor applied to a delayed television signal in a television noise reduction system and the complement of that factor applied to the undelayed television signal from which the delayed television signal is derived after averaging with the weighted delayed signal of an earlier of the preceding television frames, are modified in accordance with whether the source of the origninal television signals is or is not repeating at least one field of the television frames before going on to the next. The variation of the correction factor can also be made to depend on the number of repetitions of each frame. In an automatic system, operating in connection with a film scanner capable of scanning a motion picture film at different speeds (frames per second) to produce television signals in accordance with either the American or European television standard, the correction factor is set at the value 1 whenever a film frame is scanned for more than two half-frame television fields. For this purpose, a signal change from one state to another as soon as one full television frame has been provided by scanning a film frame. At the same time that the correction factor is set at the value 1, the writing-in of television signals into the store which produces the delayed television signal is blocked, so that the previously written-in signal, representing the same frame, is used, and the accumulation of correlated noise in the output signal is prevented.

Televison noise reduction system for a signal source having variable

An improved movement detector (8) for a television noise reduction system interposes a recursive filter (12) between the absolute value circuit (9) which signalizes the magnitude difference between delayed and undelayed television signals and the function generator (11) which forms the correction factor k which controls the degree of noise reduction. Especially for filtering changes in the vertical direction and the recursive filter involves a considerable saving in equipment.

System for reduction of noise in a television signal

The amount of noise reduction of a television signal produced by averaging corresponding pixels from one frame to the next is reduced by a correction factor when motion in the picture is detected. In order to prevent very active motion from disturbing detection of the noise level, a noise level measurement signal is subjected to a hold of its value in a time briefly preceding a highly active motion in the picture until a time shortly after the end of such highly active motion. The motion signal is processed so as to provide such a hold only when motion is highly active in the picture, and that signal is prolonged in a further circuit so that it will have a duration long enough to cover build-up of that motion and its trailing off, when the noise measurement signal is delayed by about half of the prolongation, so that the noise measurement level that is held corresponds to the noise level prior to the buildup of the motion which shortly thereafter becomes highly active. The noise value thus held controls the size of the correction factor (k) produced by the presence of the motion signal.

System for reducing noise in a television signal

In a system for noise reduction in a television signal utilizing a full frame picture store to enable averaging of corresponding signals of successful frames for noise reduction and having also a motion detector, the signal representing motion is passed through a combination of a low-pass filter and a threshold circuit of which, respectively, the cut-off frequency and the threshold value are controllable as a function of the noise amplitude. As a result, at low noise content of the input signal, no disturbing loss of sharpness of moving edges occurs, whereas at higher noise amplitudes, although noise reduction is at the cost of some loss of edge sharpness, the annoying effects of having noise reduction controlled by the noise itself, are avoided.

Noise reduction system for television signals

A method and apparatus for representing the amplitude curve of a selected portion of a video signal upon the picture screen of a video display device, at least the selected portion being in digital form and not requiring conversion to analog form prior to such representation. This is achieved by using the line structure of the line raster produced on the picture screen of the video display device as a digital-analog converter. The range of possible digital values for the individual picture elements of the selected line of the video signal are allocated as reference values to respective lines of the line raster, and during each line period of the line raster the digital values of the elements are compared in succession with the appertaining reference value. When during any line period of the line raster the compared values agree the picture screen is momentarily brightened, so that each picture element of the selected line is represented on the screen with a vertical displacement determined by its digital value, so that an amplitude curve similar to an oscillogram is produced having a horizontal time axis. In a further embodiment of the invention, arranged to display the amplitude curve of selected picture elements each taken from a respective line of the video signal, the reference values are allocated to respective columns of the line raster of the display device. The result is the production of an oscillogram on the picture screen having a vertical time axis.

Representing a video signal upon the picture screen of a video display

Correction signals for aperture correction of video signals are generated in such a way that the peak values of the correction signal produced in an aperture corrector which are dependent upon the frequency of the video signal to be corrected are maintained constant.

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Darmstadt, Germany

Gerhard Illetschko