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| Motion-adaptive interpolation method for motion video signal and device for implementing the same |
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| Equalizer for the correction of digital signals |
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| Adjacent channel interference canceller with means for minimizing intersymbol interference |
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| Phase adjustment circuit |
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Method and apparatus for video signal interpolation and progressive scan conversion
| Details |
Inventors: Correa, Carlos; Stolte, John;
Assignee: Deutsche Thomson-Brandt GmbH (Villingen-Schwenningen, DE)
Primary Examiner: Groody; James J.
Assistant Examiner: Burgess; Glenton B.
Attorney, Agent or Firm: Tripoli; Joseph S., Emanuel; Peter M., Coalter; Richard G.
A video input signal is vertically interpolated and applied along with a field delayed and a field advanced video signal to respective inputs of a first median filter the output of which is applied along with a line delayed and a line advanced signal to respective inputs of a second median filter to provide an interpolated video output signal. The resultant double median filtered signal and a field delayed signal are applied via respective time compressors to a multiplex switch to provide an output signal of progressive scan form and in which every other line thereof is interpolated by double median filtering. |
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DETAILED DESCRIPTION FIG.
1 shows scanned pixels in the vertical-temporal (v, t) plane.
The small circles mark the pixels of the interlace input signal, for example 625/50/2:1 (i.
e.
, 625 lines per frame, 50 fields per second, two to one line interlace).
The large circles mark the pixels of the progressive output signal, for example 625/50/1:1.
A first field belongs to time t=0 ms and a second field belongs to time t=20 ms.
Pixels P.
sub.
2A and P.
sub.
2B in FIG.
2 represent the pixels of the progressive output signal which are to be determined in each case.
The luminance and chrominance value of pixel P.
sub.
2B is obtained by means of two median filterings from the corresponding values of the two vertically adjacent pixels (P.
sub.
2, P.
sub.
3) and the two temporally adjacent pixels (P.
sub.
1, P.
sub.
4) of the interlace input signal.
The value of pixel P.
sub.
2A is transferred unchanged from pixel P.
sub.
2.
The value for P.
sub.
2B is determined in accordance with the following formula: P.
sub.
2B =median {P.
sub.
2, P.
sub.
3, median [P.
sub.
1, (P.
sub.
2 +P.
sub.
3)/2, P.
sub.
4 [}.
With a static image content (P.
sub.
1 =P.
sub.
4), the value for P.
sub.
2B is initially equal to P.
sub.
1 or, respectively, P.
sub.
4 due to the first temporal median filtering.
Although the second vertical median filtering suppresses the theoretically highest vertical frequency which can be transmitted in the frame (frame lines alternately white-black-white), this image content does not occur in practice and would also lead to strong interline flickering in the case of a normal interlace display.
It is much more important that vertical image signal amplitude steps are reproduced with full sharpness and that at the same time, nevertheless, no 25 Hz interline flickering occurs on horizontal edges.
With a dynamic image content, the temporal resolution is slightly reduced by the first median filtering.
However, should the value for P.
sub.
2B initially determined deviate too much from the vertically adjacent image content, it is automatically corrected by the second median filtering (post test)
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Image Analysis 
