1. A method of converting a first motion vector field into a second motion vector field by determining a first one of the motion vectors of the second motion vector field, the first motion vector field being computed, on basis of a first image and a second image of a sequence of images, for a temporal position between the first image and the second image, the method comprising: establishing a first group of un-referenced pixels in the first image, by selecting a first set of mutually connected pixels of the first image for which the first motion vector field does not comprise respective motion vectors; establishing a second group of un-referenced pixels in the second image, by selecting a second set of mutually connected pixels of the second image for which the first motion vector field does not comprise respective motion vectors; computing a match error of a candidate motion vector, which is oriented from the first group of un-referenced pixels to the second group of un-referenced pixels; and comparing the match error with a predetermined match threshold and assigning the candidate motion vector to the first one of the motion vectors of the second motion vector field if the match error is below the predetermined match threshold, wherein establishing the second group of un-referenced pixels is based on a spatial environment of the first group of un-referenced pixels and on a particular motion vector which belongs to the first motion vector field and which is located in the spatial environment of the first group of un-referenced pixels.