Motion-adaptive interpolation method for video signal and device for implementing the same

Claim 2

A motion-adaptive interpolation method for a motion video signal, comprising the steps of detecting an integral number n of motion vectors of a moving object as units of a certain number of picture elements from two successive frames of the motion video signal; computing a smaller number m of representative motion vectors representative of motion of the moving object by using the said n motion vector; modifying the or each representative vector in such a manner that the variation of the representative motion vector at a present frame period with respect to the representative motion vector at a previous frame period is limited to a predetermined range; and increasing the number of the frames per unit of time by using the modified representative motion vector(s).

Claim 3

A method according to claim 1, characterised in that the modification is effected by executing a comparative judgement of the representative motion vector at the present frame period with the representative motion vector at the previous frame period; and selectively adding to the representative motion vector at the present frame period, or subtracting therefrom a certain constant.

Claim 4

A method according to claim 1 or 2, characterised in that the' representative motion vectors are computed by computing a frequency distribution of the said n motion vectors and evaluating the m representative motion vectors from the frequency distribution of the n number of motion vectors.

Claim 5

A method according to claim 3, characterised in that the frequency distribution is computed by computing a first frequency distribution of the said n motion vectors at a present frame period; computing a second frequency distribution of the said n motion vectors at a previous frame period; and computing a third frequency distribution as a linear combination of the first and second frequency distributions with respect to each component, and in that the representative vectors are evaluated from the third frequency- distribution.

Claim 8

A device according to claim 5, characterised in that the second function of the motion estimation means (16) comprises executing a comparative judgement of the representative motion vector at the present frame period with the representative motion vector at the previous frame period.

Claim 9

A device according to claim 5 or 6, characterised in that the first function of the motion estimation means (16) comprises computing a frequency distribution of the original motion vectors from the motion vector detector means (15), and evaluating the representative motion vector from the frequency distribution of the original motion vectors.

Claim 10

A device according to claim 7, characterised in that the frequency distribution computation comprises computing a first frequency distribution of the motion vectors at a present frame period, computing a second frequency distribution of the motion vectors at a previous frame period, and computing a third frequency distribution as a linear combination of the first and second frequency distributions with respect to each component, and in that the representative motion vector is evaluated from the third frequency distribution of the original motion vectors.

Claim 11

A device according to claim 7, characterised in that the motion estimation means (16) comprises a control signal generator (20) responsive to information indicative of frame number incremental rate to produce information indicative of a coefficient for motion-adaptive interpoltion and timing information for read and write signals; a motion vector memory (21) accessible in accordance with the timing information; a comparator (22) operative to compare the original motion vector with a previous motion vector read from the motion vector memory to produce the compared result as a correction vector; adder means (24) operative to add the correction vector to a motion vector from said motion vector memory means which is delayed by a predetermined time to produce a resultant output; frequency distribution computation means (32A) operative to evaluate an occurrence frequency distribution of each resultant output from the adder means; a second comparator (34A) operative to detect the highest occurrence frequency motion vector from the evaluated occurrence frequency distribution, thereby to provide the representative motion vector; absolute value computation means (31A) for computing the absolute value of the original motion vector to produce moving area information; a moving area memory (35A) accessible in accordance with the timing information to store the moving area information from the computation means therein; a vector memory (49) for storing the representative motion vector from the second comparator to read it therefrom in accordance with the logical state of the moving area information; and correlation means (26) operative to correlate the representative motion vector read from the vector memory with the information indicative of the coefficient for motion-adaptive interpolation to produce the motion vector for motion-adaptive interpolation.

Claim 12

A device according to claim 7, characterised in that the motion estimation means (16) comprises a control signal generator (30) responsive to information indicative of frame incremental rate to produce information indicative of a coefficient for motion-adaptive interpolation and timing information for read and write signals; absolute value computation means (31B) for computing the absolute value of the original motion vector to produce moving area information; a moving area memory (35B) accessible in accordance with the timing information from the control signal generator to produce the moving area information stored therein; frequency distribution computation means (32B) operative to compute an occurrence frequency distribution of each of the original motion vectors in accordance with the timing information from the control signal generator and to apply a correction operation to the computed occurrence frequency distribution to perform a linear combination of both said frequency distributions, thus producing a corrected occurrence frequency distribution; a comparator (34B) operative to detect the highest occurrence frequency motion vector from the corrected occurrence frequency distribution from the occurrence frequency computation means, thereby to provide the representative motion vector; a multiplier means (36) operative to multiply the representative motion vector by the moving area information; and correlation means (37) operative to correlate the representative motion vector read from the vector memory means with the information indicative of the coefficient for motion-adaptive interpolation to produce the motion vector for motion-adaptive interpolation.

Claim 13

A device according to claim 7, characterised in that the motion estimation means (16) comprises a control signal generator (40) responsive to the information indicative of frame number incremental rate to produce information indicative of a coefficient for motion-adaptive interpolation and timing information; absolute value computation means (41) for computing the absolute value of the original motion vector to produce moving area information; a moving area memory (42) accessible in accordance with the timing information from the control signal generator to produce the moving area information stored therein; frequency distribution computation means (43) operative to compute an occurrence frequency distribution of each of the original motion vectors in accordance with the timing information from the control signal generator; a first comparator (44) operative to detect the highest occurrence frequency motion vector from the occurrence frequency distribution, thereby to provide the representative motion vector; a memory (45) for storing the representative motion vector; a second comparator (46) operative to compare the representative motion vector from the first comparator with a previous representative motion vector from the memory to produce the result as a correction vector with a magnitude having a predetermined upper limit; adder means (48) for adding the corrected vector from the second comparator to the previous representative motion vector which has been delayed to produce the added result as a motion vector for interpolation; a vector memory (49) for storing the motion vector for interpolation to output it when the moving area binary information is in one state; and correlation means (50) operative to correlate the representative motion vector read from the vector memory with the information indicative of coefficient for motion-adaptive interpolation to produce the motion vector for motion-adaptive interpolation.

Claim 14

A device according to. claim 9, 10 or 11, characterised in that the absolute value computation means (31A, 31B or 41) comprises a norm computation circuit for computing the norm of the original motion vector to produce moving area information of binary nature depending upon the magnitude of the normed motion vector.