Circuit arrangement for improving the quality of a video signal by adding a filtered video signal to a delayed video signal and by using a coring stage for suppressing low level signal components

#The invention relates to a circuit arrangement for improving the quality of video signals read out from a storage medium by isolating a radio-frequency component, which is conditioned in a signal processing branch parallel to the main signal branch by using a coring stage for suppressing signal components with signal values lying below a first threshold value and which is added to the delayed video signal of the main signal branch.

#It is known that the picture quality of conventional VHS and S-VHS recorders is inferior to that of normal video signals. This applies in particular with regard to picture details which are of significance in particular in the luminance signals.

#It is known that the picture quality can be improved by establishing a correlation between neighboring signal values (pixels). In principle, this involves conditioning a radio-frequency component of the video signal, for example, of the luminance signal, in a signal processing branch parallel to the main signal branch by limiting and weighting, and then adding it again to the delayed video signal in the main signal branch. One method known to accomplish picture quality enhancement is to divide the luminance signal over two parallel processing branches, a low-pass filter being arranged in one processing branch and a band-pass filter for radio-frequency signal components being arranged in the other processing branch. The band-pass filter is followed downstream by an amplifier and a threshold stage, by which the radio-frequency signal components which are allowed through by the band-pass filter of which the amplitudes below the threshold switching are suppressed. The signal is "decored" of the low amplitude values (coring technique), as a result of which a noise reduction is attained. The signal components of the two processing branches are combined again by addition.

#The features of the present invention are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures in which like reference numerals identify like elements, and wherein:

#FIG. 1 shows a block diagram for explaining the use of the signal improvement according to the invention;

#FIG. 2 shows a signal improvement circuit arrangement for a luminance signal; and

#FIG. 1 shows diagrammatically and in a dashed-line representation a recording part 1 of a video recorder, by which video signals are applied in the known way by a recording head 2 onto a video tape 3.

#The recorder video signals can be picked up from the tape by a playback head 4 and processed in a Y/C processing stage 5 and divided into a luminance signal Y and at least one chrominance signal C. In accordance with the invention, luminance signal Y passes to a picture improving stage 6 and is subsequently fed together with the unprocessed chrominance signal C to an adder 6 for the forming of a customary composite video signal, which can be reproduced by a customary television receiver.

#FIG. 2 shows an exemplary embodiment of a picture improving stage 6 for a luminance signal Y.sub.1 (t). The luminance signal passes both into a main signal branch 11 and into a parallel signal processing branch 12. In the main signal branch 11, the luminance signal Y.sub.1 (t) is delayed essentially by a delay circuit 13.