Sub-nyquist sampling encoder and decoder

Claim 2

A sub-Nyquist sampling encoder comprising: means (6; 19; 41) for thinning out pixels from a sampled video data signal in accordance with a prede­termined rule; a plurality of interpolation means (7, 8; 24, 25; 42, 43) for interpolating a pixel thinned out by said thin-out means by using non-thinned-out pixels adjacent to the thinned-out pixel; selection means (9, 10, 11; 26, 27, 28; 44, 45, 46) for comparing a sampled value of said thinned-out pixel with a plurality of interpolation values produced from said plurality of interpolation means and selecting one of said plurality of interpolation means; coding means (12; 29; 49) responsive to an output signal of said selection means to produce a coded word for interpolation means indicating which interpola­tion means is selected by said selection means; and superimposition means (13; 30; 50) for super­imposing said coded word for interpolation means obtained from said coding means on a non-thinned-out pixel.

Claim 3

A sub-Nyquist sampling encoder according to Claim 1 wherein said plurality of interpolation means comprise a horizontal low-pass filter (24) and a vertical low-pass filter (25).

Claim 4

A sub-Nyquist sampling encoder according to Claim 1 wherein said superimposition means changes the value of the pixel to be superimposed in such a manner that the interpolation error is not increased by super­imposing said coded word for interpolation means on said pixel.

Claim 5

A sub-Nyquist sampling encoder according to Claim 1 wherein said superimposition means does not effect the superimposition of said coded word for interpolation means when the value of the pixel to be interpolated falls within the filter pass band common to all of said inter­polation means.

Claim 6

A sub-Nyquist sampling encoder according to Claim 4 wherein said superimposition means does not effect the superimposition of said coded word for interpolation means when the difference between the plurality of interpolation values is less than a predetermined value.

Claim 7

A sub-Nyquist sampling encoder according to Claim 1 wherein said superimposition means superimposes said coded word for interpolation means on the least significant bit of a non-thinned-out pixel.

Claim 8

A sub-Nyquist sampling encoder according to Claim 6 wherein said superimposition means effects the superimposition in such a manner that said coded word for interpolation means is represented by information as to whether the least significant bits of values of two non-thinned-out pixels are equal to each other.

Claim 9

A sub-Nyquist sampling encoder according to Claim 1 wherein said superimposition means superimposes said coded word for interpolation means on a non-thinned-­out pixel adjacent to the interpolated pixel.

Claim 10

A sub-Nyquist sampling encoder according to Claim 1 further comprising pre-filtering means (40) for cutting off the skewed frequency component of the video signal in advance of the extraction of interpolation values.

Claim 11

A sub-Nyquist sampling encoder according to Claim 9 wherein said pre-filtering means comprises a skewed frequency component pass filter (51, 52) for producing an output signal representative of the product of horizontal high-pass filtering (52) and vertical high-pass filtering (51) and a subtracter (53) for subtracting said product signal from the original video signal so as to cut off said skewed frequency component.

Claim 12

A sub-Nyquist sampling encoder and decoder comprising: an encoder including means (6; 19; 41) for thinning out pixels from an sampled video data signal in accordance with a predetermined rule, a plurality of interpolation means (7, 8; 24, 25; 42, 43) for interpolat­ing a pixel thinned out by said thin-out means by using non-thinned-out pixels adjacent to the thinned-out pixel, selection means (9, 10, 11; 26, 27, 28; 44, 45, 46) for comparing a sampled value of said thinned-out pixel with a plurality of interpolation values produced from said plurality of interpolation means and selecting one of said plurality of interpolation means, coding means (12; 29; 49) responsive to an output signal of said selection means to produce a coded word for interpolation means indicating which interpolation means is selected by said selection means, and superimposition means (13; 30; 50) for super­imposing said coded word for interpolation means obtained from said coding means on a non-thinned-out pixel; and a decoder, responsive to information transmitted from said encoder, including a plurality of interpolation means (14, 15; 34, 35) having the same characteristics as those of corresponding plural interpolation means of said encoder, separation means (16; 36) for separating said coded word for interpolation means from the non-thinned-­out pixel, and insertion means (17, 18; 37, 39) for responding to said coded word for interpolation means produced from said separation means to select one of said corresponding plural interpolation means and inserting an interpolation value obtained from the selected interpola­tion means into a position between non-thinned-out pixels.

Claim 13

A sub-Nyquist sampling encoder and decoder comprising: an encoder including means (6; 19; 41) for thinning out pixels from an sampled video data signal in accordance with a predetermined rule, a plurality of interpolation means (7, 8; 24, 25; 42, 43) for interpolat­ing a pixel thinned out by said thin-out means by using non-thinned-out pixels adjacent to the thinned-out pixel, selection means (9, 10, 11; 26, 27, 28; 44, 45, 46) for comparing a sampled value of said thinned-out pixel with a plurality of interpolation values produced from said plurality of interpolation means and selecting one of said plurality of interpolation means, coding means (12; 29; 49) responsive to an output signal of said selection means to produce a coded word for interpolation means indicating which interpolation means is selected by said selection means, and superimposition means (13; 30; 50) for super­imposing said coded word for interpolation means obtained from said coding means on a non-thinned-out pixel; and a decoder, responsive to information transmitted from said encoder, including a plurality of interpolation means (14, 15; 34, 35) having the same characteristics as those of corresponding plural interpolation means of said encoder, separation means (16; 36) for separating said coded word for interpolation means from the non-thinned-­out pixel, and insertion means (17, 18; 37, 39) for responding to said coded word for interpolation means produced from said separation means to select one of said corresponding plural interpolation means and inserting an interpolation value obtained from the selected interpola­tion means into a position between non-thinned-out pixels.