1. A computer-implemented motion estimation method for processing images intended to be inserted, between a preceding original image and a following original image, into a sequence of images, each of the images being divided into a plurality of pixel blocks, and a motion vector being associated with each of the pixel blocks of a processed image, the method comprising, for a current block of an image being processed, steps of: selecting spatial motion vectors associated with respective pixel blocks of the image being processed and temporal motion vectors associated with respective pixel blocks of a preceding processed image; generating, by a processing device, candidate motion vectors from the motion vectors that were selected; electing one motion vector from among the candidate motion vectors that were generated; and storing information associating the one motion vector that was elected with the current pixel block, wherein the selecting step comprises the sub-steps of: determining a set of temporal motion vectors; and only selecting some temporal motion vectors from the set of temporal motion vectors based on the respective orientations of the temporal motion vectors of the set, and a specified number Q of candidate motion vectors is selected by a process comprising the steps of: generating a specified number X of candidate vectors from spatial motion vectors, X being less than the number of candidate motion vectors remaining to be selected with respect to the current pixel block; generating candidate vectors from temporal motion vectors that satisfy a selection criterion based on the respective orientations of the temporal motion vectors as long as the number of candidate motion vectors already generated is less than or equal to Q; if the number of generated candidate motion vectors is less than Q after the steps of generating the specified number X of candidate vectors from spatial motion vectors and generating candidate vectors from temporal motion vectors that satisfy the selection criterion, repeating the step of generating the specified number X of candidate vectors from spatial motion vectors; if the number of generated candidate motion vectors is less than Q after repeating the step of generating the specified number X of candidate vectors from spatial motion vectors, repeating the step of generating candidate vectors from temporal motion vectors that satisfy the selection criterion; and repeating the previous two repeating steps in succession until the number of generated candidate motion vectors is equal to Q.