Method and apparatus for field rate up-conversion

Claim 3

A method according to claim 1 wherein said basic coefficients are median filtered horizontally prior to said horizontal-vertical linear filtering.

Claim 4

A method according to claim 2 wherein, the step of median filtering said basic coefficients is carried out over a five-sample window.

Claim 5

A method according to claim 1 wherein said adaptive filter is applied to a luminance component only.

Claim 6

A method according to claim 1 wherein for said sums: principal differences between pixels involved in said adaptive filter are used which are calculated between each of two of these pixels, of which one is the input pixel and the other a pixel as nearly as possible opposite (minimum deviation angle) the input pixel with respect to the pixel to be interpolated (X); two differences parallel to each principal difference are used; for pixels which represent vertical displacements relative to X, the parallel differences are those to the left and right of the principal difference; for pixels which represent horizontal displacements, the parallel differences are those above and below the principal difference; and for pixels having two principal differences, the minimum of the two corresponding sums of differences is taken.

Claim 7

A method according to claim 5 wherein said basic coefficients are median filtered horizontally prior to said horizontal-vertical linear filtering.

Claim 9

A method according to claim 1, wherein for said normalization of said value for said pixel (X) to be interpolated, for each pixel a sum S of said filtered coefficients is produced and added to a fast motion indicator signal CF to produce a normalization control signal.

Claim 10

A method as recited in claim 8 wherein said fast motion indicator signal CF is selected to equal the function max{1/2*S max - S,0} where S max is a nominal maximum value of the sum of the coefficients.

Claim 11

A method as recited in claim 1 wherein for calculating said correction values (MC) a cross-shaped window of five pixels is used.

Claim 12

Apparatus for field rate upconversion using adaptive interpolation, wherein each pixel (X) value of an interpolated field (IP) is calculated using an adaptive filtering the input of which are original pixel values spatially-temporally surrounding a pixel value to be interpolated (X), said apparatus comprising: first calculation means for providing one or more sums of absolute pixel value differences from said original pixel values spatially-temporally surrounding said pixel value (X) to be interpolated; second calculation means for calculating for each of said original pixel values a basic coefficient which depends on said sums, wherein the smaller said sum, the larger the contribution of the associated Original pixel value is in said adaptive filtering; horizontal-vertical linear filter means for filtering each of said basic coefficients to form filtered coefficients; combining means for calculating the value of the pixel to be interpolated (X) from the pixel values involved in said adaptive filtering after having been multiplied in multiplier means with respective ones of said filtered coefficients; third calculation means for adjusting the value for said pixel (X) to be interpolated or of said filtered coefficients; and normalization means for adjusting the value for said pixel (X) to be interpolated or of said filtered coefficients.

Claim 13

Apparatus for field rate upconversion using adaptive interpolation, wherein each pixel (X) value of an interpolated field (IP) is calculated using an adaptive filtering the input of which are original pixel values spatially-temporally surrounding a pixel value to be interpolated (X), said apparatus comprising: first calculation means for providing one or more sums of absolute pixel value differences from said original pixel values spatially-temporally surrounding said pixel value (X) to be interpolated; second calculation means for calculating for each of said original pixel values a basic coefficient which depends on said sums, wherein the smaller said sum, the larger the contribution of the associated Original pixel value is in said adaptive filtering; horizontal-vertical linear filter means for filtering each of said basic coefficients to form filtered coefficients; combining means for calculating the value of the pixel to be interpolated (X) from the pixel values involved in said adaptive filtering after having been multiplied in multiplier means with respective ones of said filtered coefficients; third calculation means for adjusting the value for said pixel (X) to be interpolated or of said filtered coefficients; and normalization means for adjusting the value for said pixel (X) to be interpolated or of said filtered coefficients.

Claim 14

Apparatus according to claim 11 wherein median filtering means are inserted between said second calculation means and said horizontal-vertical linear filtering means for filtering said basic coefficients horizontally.

Claim 15

Apparatus according to claim 12 wherein said median filtering means includes a five-sample window.