An imaging method for producing an image of a region inside a medium, wherein said method is implemented by a processing unit connected to an array of transducers in relation with said medium, and said method comprising the following steps: (a) a transmission step (101; 201) in which a first plurality of waves are transmitted inside the medium by the transducers, (b) a reception step (102; 202) in which a set of data is acquired by said transducers in response to the waves, the method being characterized in that: (c) a beamforming step (103; 203) in which the set of data is processed by a second plurality of beamforming processes for providing beamformed pixel values ( U n (x,z)) of at least a portion of the image, each beamforming process using a transmit weighting vector ( W Tn) in the calculus of the beamformed pixel values, and (d) a combining step (104; 204) in which the beamformed pixel values of said second plurality are combined together to provide a pixel value ( I(x,z)) of a pixel inside the image, and wherein the transmit weighting vectors (W Tn) are different and orthogonal one to an other one, a transmit weighting vector of index i being orthogonal to a transmit weighting vector of index j, index i being different of index j, and ∑ l = 1 L W Ti l. W Tj l = 0, L being the number of components of the transmit weighting vectors ( W Tn), wherein the transmit weighting vectors ( W Tn) are applied during the beamforming step (c), and - during the beamforming step (c), the beamforming process is a synthetic beamforming in which the beamformed pixel values ( U n (x, z)) are calculated by the following formula: U n x z = ∑ m = 1 M W Tn m ∑ l = l 1 l 2 W R l DS k − τ x z l m, l, m where DS(k, l, m) is a matrix of the set of data, W R is a receive weighting vector, τ(x, z, l) is a delay function adapted for the beamforming process, l is an index of a transducer in the array, comprised between l1 and l2, an aperture for beamforming a line, m is the index, comprised between 1 and M, M being the first plurality that is the number of transmitted waves inside the medium, W Tn is the transmit weighting vector, x, z are coordinates of a pixel inside the image. (a) a transmission step (101; 201) in which a first plurality of waves are transmitted inside the medium by the transducers, (b) a reception step (102; 202) in which a set of data is acquired by said transducers in response to the waves, the method being characterized in that: (c) a beamforming step (103; 203) in which the set of data is processed by a second plurality of beamforming processes for providing beamformed pixel values ( U n (x,z)) of at least a portion of the image, each beamforming process using a transmit weighting vector ( W Tn) in the calculus of the beamformed pixel values, and (d) a combining step (104; 204) in which the beamformed pixel values of said second plurality are combined together to provide a pixel value ( I(x,z)) of a pixel inside the image, and wherein the transmit weighting vectors (W Tn) are different and orthogonal one to an other one, a transmit weighting vector of index i being orthogonal to a transmit weighting vector of index j, index i being different of index j, and ∑ l = 1 L W Ti l. W Tj l = 0, L being the number of components of the transmit weighting vectors ( W Tn), wherein the transmit weighting vectors ( W Tn) are applied during the beamforming step (c), and - during the beamforming step (c), the beamforming process is a synthetic beamforming in which the beamformed pixel values ( U n (x, z)) are calculated by the following formula: U n x z = ∑ m = 1 M W Tn m ∑ l = l 1 l 2 W R l DS k − τ x z l m, l, m - during the beamforming step (c), the beamforming process is a synthetic beamforming in which the beamformed pixel values ( U n (x, z)) are calculated by the following formula: U n x z = ∑ m = 1 M W Tn m ∑ l = l 1 l 2 W R l DS k − τ x z l m, l, m where DS(k, l, m) is a matrix of the set of data, W R is a receive weighting vector, τ(x, z, l) is a delay function adapted for the beamforming process, l is an index of a transducer in the array, comprised between l1 and l2, an aperture for beamforming a line, m is the index, comprised between 1 and M, M being the first plurality that is the number of transmitted waves inside the medium, W Tn is the transmit weighting vector, x, z are coordinates of a pixel inside the image. DS(k, l, m) is a matrix of the set of data, W R is a receive weighting vector, τ(x, z, l) is a delay function adapted for the beamforming process, l is an index of a transducer in the array, comprised between l1 and l2, an aperture for beamforming a line, m is the index, comprised between 1 and M, M being the first plurality that is the number of transmitted waves inside the medium, W Tn is the transmit weighting vector, x, z are coordinates of a pixel inside the image.