1. A method ( 100 ) for processing an image of an object (O) acquired by an imaging system ( 1 ), wherein the method comprises the following steps: determining a distance between the object (O) and the imaging system ( 1 ), wherein said distance determination comprises the following sub-steps: estimating ( 110 ) a modulation transfer function of the imaging system on the basis of an acquired image of the object (O), determining ( 120 ) aberration frequencies of the estimated modulation transfer function, and generating an aberration frequency vector, implementing ( 130 ) a principal component analysis of the aberration frequency vector, in order to determine a principal component of the vector, and using the principal component obtained, determining ( 140 ) the distance between the object and the imaging system by comparing said principal component to a joint distribution of probability densities of principal components of aberration frequency vectors, said distribution being obtained by interpolation between previously obtained principal components of aberration frequency vectors of modulation transfer functions for a plurality of other imaging systems, each corresponding to an other object, and the distances between each of said other imaging systems and the corresponding other objects using the determined distance of the object, selecting ( 200 ) a point spread function of the imaging system, and deconvoluting ( 300 ) the acquired image of the object by using the selected spread function of the imaging system, in order to improve sharpness of the acquired image.