METHOD FOR SUBPIXEL VALUE INTERPOLATION
First Claim
1. A method for subpixel value interpolation to determine values for subpixels situated within a rectangular bounded region defined by four corner pixels with no intermediate pixels between the corners, the pixels and subpixels being arranged in rows and columns, the pixel and subpixel locations being representable mathematically within the rectangular bounded region using the coordinate notation K/2^{N}, L/2^{N}, K and L being positive integers having respective values between zero and 2^{N}, N being a positive integer greater than one and representing a particular degree of subpixel value interpolation, the method comprising:
 interpolating a subpixel value for a subpixel having coordinates with odd values of both K and L, according to a predetermined choice of a weighted average of the value of a nearestneighbouring pixel and the value of the subpixel situated at coordinates ½
, ½
, and a weighted average of the values of a pair of diagonallyopposed subpixels having coordinates with even values of both K and L, including zero, situated within a quadrant of the rectangular bounded region defined by corner pixels having coordinates ½
, ½ and
the nearest neighbouring pixel;
interpolating subpixel values for subpixels having coordinates with K equal to an even value and L equal zero and subpixels having coordinates with K equal to zero and L equal to an even value, used in the interpolation of the subpixels having coordinates with odd values of both K and L, using weighted sums of the values of pixels located in rows and columns respectively; and
interpolating subpixel values for subpixels having coordinates with even values of both K and L, used in the interpolation of subpixel values for the subpixels having coordinates with odd values of both K and L, using a predetermined choice of either a weighted sum of the values of subpixels having coordinates with K equal to an even value and L equal to zero and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions, or a weighted sum of the values of subpixels having coordinates with K equal to zero and L equal to an even value and the values of subpixels having corresponding coordinates in immediately adjacent bounded rectangular regions.
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Accused Products
Abstract
A method of interpolation in video coding in which an image comprising pixels arranged in rows and columns and represented by values having a specified dynamic range, the pixels in the rows residing at unit horizontal locations and the pixels in the columns residing at unit vertical locations, is interpolated to generate values for subpixels at fractional horizontal and vertical locations, the method comprising: a) when values for subpixels at half unit horizontal and unit vertical locations, and unit horizontal and half unit vertical locations are required, interpolating such values directly using weighted sums of pixels residing at unit horizontal and unit vertical locations; b) when values for subpixels at half unit horizontal and half unit vertical locations are required, interpolating such values directly using a weighted sum of values for subpixels residing at half unit horizontal and unit vertical locations calculated according to step (a); and c) when values for subpixels at quarter unit horizontal and quarter unit vertical locations are required, interpolating such values by taking the average of at least one pair of a first pair of values of a subpixel located at a half unit horizontal and unit vertical location, and a subpixel located at a unit horizontal and half unit vertical location and a second pair of values of a pixel located at a unit horizontal and unit vertical location, and a subpixel located at a half unit horizontal and half unit vertical location.
108 Citations
3 Claims

1. A method for subpixel value interpolation to determine values for subpixels situated within a rectangular bounded region defined by four corner pixels with no intermediate pixels between the corners, the pixels and subpixels being arranged in rows and columns, the pixel and subpixel locations being representable mathematically within the rectangular bounded region using the coordinate notation K/2^{N}, L/2^{N}, K and L being positive integers having respective values between zero and 2^{N}, N being a positive integer greater than one and representing a particular degree of subpixel value interpolation, the method comprising:

interpolating a subpixel value for a subpixel having coordinates with odd values of both K and L, according to a predetermined choice of a weighted average of the value of a nearestneighbouring pixel and the value of the subpixel situated at coordinates ½
, ½
, and a weighted average of the values of a pair of diagonallyopposed subpixels having coordinates with even values of both K and L, including zero, situated within a quadrant of the rectangular bounded region defined by corner pixels having coordinates ½
, ½ and
the nearest neighbouring pixel;
interpolating subpixel values for subpixels having coordinates with K equal to an even value and L equal zero and subpixels having coordinates with K equal to zero and L equal to an even value, used in the interpolation of the subpixels having coordinates with odd values of both K and L, using weighted sums of the values of pixels located in rows and columns respectively; and
interpolating subpixel values for subpixels having coordinates with even values of both K and L, used in the interpolation of subpixel values for the subpixels having coordinates with odd values of both K and L, using a predetermined choice of either a weighted sum of the values of subpixels having coordinates with K equal to an even value and L equal to zero and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions, or a weighted sum of the values of subpixels having coordinates with K equal to zero and L equal to an even value and the values of subpixels having corresponding coordinates in immediately adjacent bounded rectangular regions.


2. A method for quarter resolution subpixel value interpolation to determine values for subpixels situated within a rectangular bounded region defined by four corner pixels with no intermediate pixels between the corners, the pixels and subpixels being arranged in rows and columns, the pixel and subpixel locations being representable mathematically within the rectangular bounded region using the coordinate notation K/4, L/4, K and L being positive integers having respective values between zero and 4, the method comprising:

interpolating a subpixel value for a subpixel having coordinates with both K and L equal to 1 or 3, according to a predetermined choice of a weighted average of the value of a nearestneighbouring pixel and the value of the subpixel situated at coordinates 2/4, 2/4, and a weighted average of the values of a pair of diagonallyopposed subpixels having coordinates with both K and L equal to zero, 2 or 4, situated within a quadrant of the rectangular bounded region defined by corner pixels having coordinates 2/4, 2/4 and the nearest neighbouring pixel;
interpolating subpixel values for subpixels having coordinates with K equal to 2 and L equal zero and subpixels having coordinates with K equal to zero and L equal to 2, used in the interpolation of the subpixels having coordinates with both K and L equal to 1 or 3, using weighted sums of the values of pixels located in rows and columns respectively; and
interpolating a subpixel value for the subpixel having coordinates with both K and L equal to 2, used in the interpolation of subpixel values for the subpixels having coordinates with both K and L equal to 1 or 3, using a predetermined choice of either a weighted sum of the values of the subpixel having coordinates with K equal to 2 and L equal to zero and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions, or a weighted sum of the value of the subpixel having coordinates with K equal to zero and L equal to 2 and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions.


3. A method for eighth resolution subpixel value interpolation to determine values for subpixels situated within a rectangular bounded region defined by four corner pixels with no intermediate pixels between the corners, the pixels and subpixels being arranged in rows and columns, the pixel and subpixel locations being representable mathematically with the rectangular bounded region using the coordinate notation K/8, L/8, K and L being positive integers having respective values between zero and 8, the method comprising:

interpolating a subpixel value for a subpixel having coordinates with both K and L equal to 1, 3, 5 or 7, according to a predetermined choice of a weighted average of the value of a nearestneighbouring pixel and the value of the subpixel situated at coordinates 4/8, 4/8, and a weighted average of the values of a pair of diagonallyopposed subpixels having coordinates with both K and L equal to zero, 2, 4, 6 or 8, situated within a quadrant of the rectangular bounded region defined by corner pixels having coordinates 4/8, 4/8 and the nearest neighbouring pixel;
interpolating subpixel values for subpixels having coordinates with K equal to 2, 4 or 6 and L equal zero and subpixels having coordinates with K equal to zero and L equal to 2, 4 or 6, used in the interpolation of the subpixels having coordinates with both K and L equal to 1, 3, 5 or 7, using weighted sums of the values of pixels located in rows and columns respectively; and
interpolating subpixel values for subpixels having coordinates with both K and L equal to 2, 4 or 6, used in the interpolation of subpixel values for the subpixels having coordinates with both K and L equal to 1, 3, 5 or 7, using a predetermined choice of either a weighted sum of the values of subpixels having coordinates with K equal to 2, 4 or 6 and L equal to zero and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions or a weighted sum of the values of subpixels having coordinates with K equal to zero and L equal to 2, 4 or 6 and the values of subpixels having corresponding coordinates in immediately adjacent rectangular bounded regions.

1 Specification