A process for digitizing closed books without having to open them, printed documents or manuscripts, bound or in batches, without having to separate them, by means of an imaging system of a three-dimensional object by Terahertz waves comprising a step of acquisition by an THz acquisition subsystem of a set of low-resolution three-dimensional images {A uvw} representative of said object, said 3D low-resolution images being obtained by application of translation shifts in three orthogonal dimensions according to which the object and the THz acquisition subsystem are relatively shifted relative to each other, and the amplitude of said relative shift (M X, M Y, M Z) in each of these three dimensions is equal to the ratio of the spatial resolution (rA x, rA y, rA z) of said THz acquisition subsystem by a super-resolution factor (FSR; FSR X, FSR Y, FSR Z), a step of three-dimensional super-resolution processing, capable of generating a super-resolved 3D image I SR from a linear combination of said 3D low-resolution images and a step of image-restoration capable of generating a restored super-resolved 3D image J SR from deconvolution by a point spread function of said super-resolved 3D image I SR, said linear combination of said 3D images being determined by the following equation: I S R i + a, j + b, k + c = 1 F S R X * F S R Y * F S R Z ∑ u = 0 a ∑ v = 0 b ∑ w = 0 c A u v w p, q, r + ∑ u = a + 1 F S R X − 1 ∑ v = 0 b ∑ w = 0 c A u v w p − 1, q, r + ∑ u = 0 a ∑ v = b + 1 F S R Y − 1 ∑ w = 0 c A u v w p, q − 1, r + ∑ u = a + 1 F S R X − 1 ∑ v = b + 1 F S R Y − 1 ∑ w = 0 c A u v w p − 1, q − 1, r ∑ u = 0 a ∑ v = 0 b ∑ w = c + 1 F S R Z − 1 A u v w p, q, r − 1 + ∑ u = a + 1 F R S X − 1 ∑ v = 0 b ∑ w = c + 1 F R S Z − 1 A u v w p − 1, q, r − 1 + ∑ u = 0 a ∑ v = b + 1 F S R Y − 1 ∑ w = c + 1 F S R Z − 1 A u v w p, q − 1, r − 1 + ∑ u = a + 1 F S R X − 1 ∑ v = b + 1 F S R Y − 1 ∑ w = c + 1 F S R Z − 1 A u v w p − 1, q − 1, r − 1 where: I SR designates the super-resolved image of dimension N X, N Y, Nz; FSR X, FSR Y, FSR Z designate the factors of super-resolution according to X, Y and Z in a orthonormal marker (O; X, Y, Z), whereof the values are natural whole numbers greater than or equal to 1; I SR (i+a, j+b, k+c) designates the voxel of the image I SR located at the coordinate i+a of the dimension X, the coordinate j+b of the dimension Y and the coordinate k+c of the dimension Z of the matrix I SR, with i a multiple of FSR X such as 0 ≤ i < N X, j a multiple of FSR Y such as 0 ≤ j < N Y, k a multiple of FSR Z such as 0 ≤ k < N Z, and with a, b, c whole variables such that they take their values in the set 0, 1, 2,..., FSR X -1 (respectively FSRy-1, FSR Z -1); {A uvw, with 0 ≤ u < FSR X; 0 ≤v< FSR Y 0 ≤w< FSR Z} is the set of 3D low-resolution images, where u, v, w represent the index of the position of the image in respectively the dimensions X, Y and Z; A uvw (p, q, r) designates the voxel of the image A uvw located at the coordinate p of the dimension X, the coordinate q of the dimension Y and the coordinate r of the dimension Z of the matrix A uvw, with p = i F S R X; q = j F S R Y; r = k F S R Z. I SR designates the super-resolved image of dimension N X, N Y, Nz; FSR X, FSR Y, FSR Z designate the factors of super-resolution according to X, Y and Z in a orthonormal marker (O; X, Y, Z), whereof the values are natural whole numbers greater than or equal to 1; I SR (i+a, j+b, k+c) designates the voxel of the image I SR located at the coordinate i+a of the dimension X, the coordinate j+b of the dimension Y and the coordinate k+c of the dimension Z of the matrix I SR, with i a multiple of FSR X such as 0 ≤ i < N X, j a multiple of FSR Y such as 0 ≤ j < N Y, k a multiple of FSR Z such as 0 ≤ k < N Z, and with a, b, c whole variables such that they take their values in the set 0, 1, 2,..., FSR X -1 (respectively FSRy-1, FSR Z -1); {A uvw, with 0 ≤ u < FSR X; 0 ≤v< FSR Y 0 ≤w< FSR Z} is the set of 3D low-resolution images, where u, v, w represent the index of the position of the image in respectively the dimensions X, Y and Z; A uvw (p, q, r) designates the voxel of the image A uvw located at the coordinate p of the dimension X, the coordinate q of the dimension Y and the coordinate r of the dimension Z of the matrix A uvw, with p = i F S R X; q = j F S R Y; r = k F S R Z.