Sub-pixel accurate motion vector estimation and motion-compensated interpolation

A method of generating an intermediate image using sub-pixel accurate motion vectors having vector components that may have non-integer values, from first and second images having a given mutual temporal distance, the intermediate image being at a fractional distance from said first image, said fractional distance being a fraction of said given mutual temporal distance, the method comprising the steps:

• deriving first and second vectors from said sub-pixel accurate motion vectors;
• and
• generating said intermediate image by combining first positions in said first image shifted over said first vectors and second positions in said second image shifted over said second vectors;
• characterized in that said deriving step comprises the steps:
• multiplying said vector components of said sub-pixel accurate motion vectors by said fraction to obtain fractional vector components;
• rounding said fractional vector components to obtain vector components of said first vectors, said first vectors having only integer vector components;
• and
• subtracting said first vector from said candidate vector to obtain said second vector, whereby said second vectors has vector components that, depending on said candidate vector and said fraction, may have non-integer values.

A device for estimating sub-pixel accurate motion vectors between first and second images having a given mutual temporal distance, the sub-pixel accurate motion vectors being intended for use in an interpolation or prediction of an image at a fractional distance from said first image, said fractional distance being a fraction of said given mutual temporal distance, the device comprising:

• means for generating a candidate vector having vector components that may have non-integer values;
• means for deriving first and second vectors from said candidate vector;
• and
• means for evaluating said candidate vector to determine said sub-pixel accurate motion vectors by comparing a first position in said first image shifted over said first vector to a second position in said second image shifted over said second vector;
• characterized in that said deriving means comprises:
• means for multiplying said vector components of said candidate vector by said fraction to obtain fractional vector components;
• means for rounding said fractional vector components to obtain vector components of said first vector, said first vector having only integer vector components;
• and
• means for subtracting said first vector from said candidate vector to obtain said second vector, whereby said second vector has vector components that, depending on said candidate vector and said fraction, may have non-integer values.

A device for generating an intermediate image using sub-pixel accurate motion vectors having vector components that may have non-integer values, from first and second images having a given mutual temporal distance, the intermediate image being at a fractional distance from said first image, said fractional distance being a fraction of said given mutual temporal distance, the device comprising:

• means for deriving first and second vectors from said sub-pixel accurate motion vectors;
• and
• means for generating said intermediate image by combining first positions in said first image shifted over said first vectors and second positions in said second image shifted over said second vectors;
• characterized in that said deriving means comprises:
• means for multiplying said vector components of said sub-pixel accurate motion vectors by said fraction to obtain fractional vector components;
• means for rounding said fractional vector components to obtain vector components of said first vectors, said first vectors having only integer vector components;
• and
• means for subtracting said first vector from said candidate vector to obtain said second vector, whereby said second vectors has vector components that, depending on said candidate vector and said fraction, may have non-integer values.