Method for coding an image signal comprising motion information, by selection of a motion vector from a set of at least three candidate vectors, for at least one current block of a current image to be coded, comprising a step of determination of an optimal selection subset, comprising some of said candidate vectors, a step of selection of said motion vector ( p) from the vectors of said optimal selection subset, and a step of insertion, into said signal, of information designating the motion vector selected from the vectors of said optimal selection subset, characterized in that said determination step comprises the following substeps: - comparison of at least two first candidate vectors, delivering information on proximity between said first candidate vectors, that can take a first value indicating that said first candidate vectors are identical or close according to a predetermined criterion, and a second value indicating that said first candidate vectors are not identical or close according to said predetermined criterion, the implementation of said predetermined criterion belonging to the group comprising equality between said first candidate vectors and the comparison of the difference between said first candidate vectors with a first predetermined threshold, the position in space and/or in time of said first candidate vectors being pre-identified, - if said proximity information takes said first value, construction of said optimal selection subset with one of said first candidate vectors or a vector of amplitude corresponding to an average of the amplitudes of said at least two first candidate vectors and at least one second candidate vector, distinct from said first candidate vectors; - if said proximity information takes said second value, construction of said optimal selection subset with said first candidate vectors. - comparison of at least two first candidate vectors, delivering information on proximity between said first candidate vectors, that can take a first value indicating that said first candidate vectors are identical or close according to a predetermined criterion, and a second value indicating that said first candidate vectors are not identical or close according to said predetermined criterion, the implementation of said predetermined criterion belonging to the group comprising equality between said first candidate vectors and the comparison of the difference between said first candidate vectors with a first predetermined threshold, the position in space and/or in time of said first candidate vectors being pre-identified, - if said proximity information takes said first value, construction of said optimal selection subset with one of said first candidate vectors or a vector of amplitude corresponding to an average of the amplitudes of said at least two first candidate vectors and at least one second candidate vector, distinct from said first candidate vectors; - if said proximity information takes said second value, construction of said optimal selection subset with said first candidate vectors. - if said proximity information takes said first value, construction of said optimal selection subset with one of said first candidate vectors or a vector of amplitude corresponding to an average of the amplitudes of said at least two first candidate vectors and at least one second candidate vector, distinct from said first candidate vectors; - if said proximity information takes said second value, construction of said optimal selection subset with said first candidate vectors.