A method for regenerating the background of digital images of a video stream produced by a fixed camera and including a plurality of time-sequential frames, wherein each frame includes pixels of a respective unit image, the method comprising steps of: - setting a background image associated with the unit image in a memory, - cutting the unit image of the video stream into blocks b(i, j, t) of at least one pixel, and - cutting the background image into corresponding blocks Bo(i, j, t) having the same size and the same coordinates (i, j) as those of the blocks of the unit images, the method characterized in that it further includes steps of: - selecting given blocks b(i, j, t) of an unit image at a time (t), b(i, j, t-a) of said unit image at a preceding time (t-a), Bo(i, j, t) of the background image at a time (t), and Bo(i, j, t-a) of said background image at a preceding time (t-a), - calculating a space correlation Corr_spat_mes_b_Bo(i:i±x*δi, j:j±y*δj, t:t) between block b(i, j, t) and at least one block Bo(i±x*δi, j±y*δj, t), and - calculating a space correlation Corr_spat_mes_Bo(i:i±x*δi, j:j±y*δj, t-a:t) between block Bo(i, j, t-a) and at least one block Bo(i±x*δi, j±y*δj, t), where δ represents a change, (i±δi, j±δj) are the coordinates of a block adjacent to a block having the coordinates (i, j), and x and y are integers, the method further comprising steps of: - calculating a time correlation (Corr_temp_mes_b) between block b(i, j, t) and block b(i, j, t-a), and - calculating a time correlation (Corr_temp_mes_Bo) between block Bo(i, j, t) and Block Bo(i, j, t-a), where the correlations are calculated based on luminance and/or chrominance values of the pixels of the respective blocks; and the method further comprising steps of: - calculating a first value Sum1 associated to block Bo(i, j, t), as a function of the time correlation and the space correlation weighted by a parameter λ(t) depending on time, such that: Sum 1 = Corr _ temp _ mes _ b i, j, t + λ t * Corr _ spat _ mes _ b _ Bo i: i ± x * δi, j: j ± y * δj, t: t, and - calculating a second value Sum2 associated to Block Bo(i, j, t-a) as a function of the time correlation and the space correlation weighted by the parameter λ(t), such that: Sum 2 = Corr _ temp _ mes _ Bo i, j, t + λ t * Corr _ spat _ mes _ Bo i: i ± x * δi, j: j ± y * δj, t-a: t, wherein the value of the block Bo(i, j, t) is updated replacing block Bo(i, j, t) by either block b(i, j, t) or Bo (i, j, t-a), based on the minimum value of both first and second values Sum1 and Sum2, respectively. - setting a background image associated with the unit image in a memory, - cutting the unit image of the video stream into blocks b(i, j, t) of at least one pixel, and - cutting the background image into corresponding blocks Bo(i, j, t) having the same size and the same coordinates (i, j) as those of the blocks of the unit images, - selecting given blocks b(i, j, t) of an unit image at a time (t), b(i, j, t-a) of said unit image at a preceding time (t-a), Bo(i, j, t) of the background image at a time (t), and Bo(i, j, t-a) of said background image at a preceding time (t-a), - calculating a space correlation Corr_spat_mes_b_Bo(i:i±x*δi, j:j±y*δj, t:t) between block b(i, j, t) and at least one block Bo(i±x*δi, j±y*δj, t), and - calculating a space correlation Corr_spat_mes_Bo(i:i±x*δi, j:j±y*δj, t-a:t) between block Bo(i, j, t-a) and at least one block Bo(i±x*δi, j±y*δj, t), - calculating a time correlation (Corr_temp_mes_b) between block b(i, j, t) and block b(i, j, t-a), and - calculating a time correlation (Corr_temp_mes_Bo) between block Bo(i, j, t) and Block Bo(i, j, t-a), - calculating a first value Sum1 associated to block Bo(i, j, t), as a function of the time correlation and the space correlation weighted by a parameter λ(t) depending on time, such that: Sum 1 = Corr _ temp _ mes _ b i, j, t + λ t * Corr _ spat _ mes _ b _ Bo i: i ± x * δi, j: j ± y * δj, t: t, and - calculating a second value Sum2 associated to Block Bo(i, j, t-a) as a function of the time correlation and the space correlation weighted by the parameter λ(t), such that: Sum 2 = Corr _ temp _ mes _ Bo i, j, t + λ t * Corr _ spat _ mes _ Bo i: i ± x * δi, j: j ± y * δj, t-a: t, wherein the value of the block Bo(i, j, t) is updated replacing block Bo(i, j, t) by either block b(i, j, t) or Bo (i, j, t-a), based on the minimum value of both first and second values Sum1 and Sum2, respectively.