Method for reconstructing a colour image acquired by a photosensitive sensor of size H × W, covered with a mosaic, of size H × W, of P filters of different colours making up a base pattern of size h × w such that h < H and w < W, said base pattern of the mosaic of filters being repeated so as to cover the mosaic of filters without overlap between the base patterns, said method being carried out by computer and being characterized in that it comprises at least the following steps: • a first preliminary step of constructing a demosaicing matrix D starting from a simulation using a first database of N images I i,i ∈ [1,..., N], with P colour components, called reference images, for producing a second database of N images J i, i ∈ [1,..., N] simulating images produced originating from the sensor, after acquisition by said sensor of the images of the first database, said reference images I i and images produced J i being represented respectively in the form of matrices of HW /( hw) vectors y 1, x 1 such that: - the components of y 1 are the P components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the reference image I i, - the components of x 1 are the components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the image produced J i, with n h > h and n w > w; • a second step of reconstructing a colour image producing the product of the demosaicing matrix D with a matrix representation of a mosaic image originating from the sensor after acquisition of the colour image by said sensor, said product of the demosaicing matrix D with the matrix representation of the mosaic image using an interpolation of the colour of each pixel of the mosaic image as a function of a neighbourhood, of size n h × n w pixels, of a base pattern of size h × w, corresponding to the base pattern of the mosaic of filters. • a first preliminary step of constructing a demosaicing matrix D starting from a simulation using a first database of N images I i,i ∈ [1,..., N], with P colour components, called reference images, for producing a second database of N images J i, i ∈ [1,..., N] simulating images produced originating from the sensor, after acquisition by said sensor of the images of the first database, said reference images I i and images produced J i being represented respectively in the form of matrices of HW /( hw) vectors y 1, x 1 such that: - the components of y 1 are the P components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the reference image I i, - the components of x 1 are the components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the image produced J i, with n h > h and n w > w; - the components of y 1 are the P components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the reference image I i, - the components of x 1 are the components of a reduced neighbourhood of size n h × n w of one of the HW /( hw) base patterns applied to the image produced J i, with n h > h and n w > w; • a second step of reconstructing a colour image producing the product of the demosaicing matrix D with a matrix representation of a mosaic image originating from the sensor after acquisition of the colour image by said sensor, said product of the demosaicing matrix D with the matrix representation of the mosaic image using an interpolation of the colour of each pixel of the mosaic image as a function of a neighbourhood, of size n h × n w pixels, of a base pattern of size h × w, corresponding to the base pattern of the mosaic of filters.