Method for observing a sample comprising the following steps: a) illuminating the sample using a light source, able to emit a light wave that propagates towards the sample; b) acquiring, using an image sensor, an image ( I 0) of the sample, said image being formed in a detection plane ( P 0), the sample being placed between the light source and the image sensor, the acquired image being representative of a light wave transmitted by the sample under the effect of said illumination, the acquired image comprising interference patterns formed by interference between the light wave emitted by the light source and a light wave diffracted by the sample; and c) calculating a complex image A z k A 0 k representative of the sample; the calculation of said complex image of the sample comprising the following substeps: i) defining an initial image A 0 k = 0 of the sample in the detection plane, on the basis of the image ( I 0) acquired by the image sensor; ii) determining a complex image A z k of the sample in a reconstruction plane ( P z) by applying a propagation operator to the initial image A 0 k = 0 of the sample, i.e. to the image defined in substep i), or to the image A 0 k − 1 of the sample, in the detection plane, resulting from the preceding iteration; iii) calculating a noise indicator ( ε k) on the basis of the complex image A z k obtained in substep ii), the noise indicator depending on a reconstruction noise affecting said complex image A z k, the noise indicator being representative of fluctuations appearing in said complex image, the calculation of the noise indicator comprising ▪ for various pixels ( x,y), calculating a quantity ( ε k ( x,y)) associated with each pixel, depending on the value of the complex image A z k determined in substep ii) for said pixel, or on a dimensional derivative of said complex image for said pixel; and ▪ combining the quantities ( ε k ( x,y)) calculated for different pixels ( x,y), so as to obtain the noise indicator ( ε k); iv) updating the image A 0 k of the sample in the detection plane ( P 0) by adjusting phase values φ 0 k − 1 x y of the pixels of the initial image A 0 k = 0 or of the image A 0 k − 1 of the sample resulting from the preceding iteration, in the detection plane, the adjustment being carried out depending on a variation in the noise indicator calculated in substep iii) depending on said phase values; v) reiterating substeps ii) to iv) until a convergence criterion is reached, so as to obtain a complex image of the sample in the detection plane ( P 0), or in the reconstruction plane ( P z). a) illuminating the sample using a light source, able to emit a light wave that propagates towards the sample; b) acquiring, using an image sensor, an image ( I 0) of the sample, said image being formed in a detection plane ( P 0), the sample being placed between the light source and the image sensor, the acquired image being representative of a light wave transmitted by the sample under the effect of said illumination, the acquired image comprising interference patterns formed by interference between the light wave emitted by the light source and a light wave diffracted by the sample; and c) calculating a complex image A z k A 0 k representative of the sample; i) defining an initial image A 0 k = 0 of the sample in the detection plane, on the basis of the image ( I 0) acquired by the image sensor; ii) determining a complex image A z k of the sample in a reconstruction plane ( P z) by applying a propagation operator to the initial image A 0 k = 0 of the sample, i.e. to the image defined in substep i), or to the image A 0 k − 1 of the sample, in the detection plane, resulting from the preceding iteration; iii) calculating a noise indicator ( ε k) on the basis of the complex image A z k obtained in substep ii), the noise indicator depending on a reconstruction noise affecting said complex image A z k, the noise indicator being representative of fluctuations appearing in said complex image, the calculation of the noise indicator comprising ▪ for various pixels ( x,y), calculating a quantity ( ε k ( x,y)) associated with each pixel, depending on the value of the complex image A z k determined in substep ii) for said pixel, or on a dimensional derivative of said complex image for said pixel; and ▪ combining the quantities ( ε k ( x,y)) calculated for different pixels ( x,y), so as to obtain the noise indicator ( ε k); ▪ for various pixels ( x,y), calculating a quantity ( ε k ( x,y)) associated with each pixel, depending on the value of the complex image A z k determined in substep ii) for said pixel, or on a dimensional derivative of said complex image for said pixel; and ▪ combining the quantities ( ε k ( x,y)) calculated for different pixels ( x,y), so as to obtain the noise indicator ( ε k); iv) updating the image A 0 k of the sample in the detection plane ( P 0) by adjusting phase values φ 0 k − 1 x y of the pixels of the initial image A 0 k = 0 or of the image A 0 k − 1 of the sample resulting from the preceding iteration, in the detection plane, the adjustment being carried out depending on a variation in the noise indicator calculated in substep iii) depending on said phase values; v) reiterating substeps ii) to iv) until a convergence criterion is reached, so as to obtain a complex image of the sample in the detection plane ( P 0), or in the reconstruction plane ( P z).