Device for capturing an image of a print of a body part, comprising an image-acquiring module having an optical field covering an acquisition zone through which the body part may move, a light source that produces a spatially uniform illumination of the body part and a graticule-projecting module that projects a luminous graticule onto said body part perpendicularly to a direction of movement of the finger, characterized in that: the luminous graticule is a repetitive pattern of lower light intensity than the uniform illumination, said repetitive pattern being in the same wavelength range as said light source; and said device is able: to simultaneously activate the light source, the graticule-projecting module and the image-acquiring module in order to allow an image of the print, called the acquired image, to be acquired; to model the variations in light intensity of the projection of the graticule on the body part by determining parameters of a preset 1D parametric mathematical model, said preset parametric model being a 1D model defined per row of pixels and depending on a pixel number in said row; to generate an image of the projection of the graticule on the body part, called the synthetic image, on the basis of said model and using the parameters determined beforehand, and to subtract the synthetic image from the acquired image in order to obtain a graticule-free image of the body part, said graticule-free image of the body part being able to be used (45, 46) to carry out an identification or an authentication. the luminous graticule is a repetitive pattern of lower light intensity than the uniform illumination, said repetitive pattern being in the same wavelength range as said light source; and said device is able: to simultaneously activate the light source, the graticule-projecting module and the image-acquiring module in order to allow an image of the print, called the acquired image, to be acquired; to model the variations in light intensity of the projection of the graticule on the body part by determining parameters of a preset 1D parametric mathematical model, said preset parametric model being a 1D model defined per row of pixels and depending on a pixel number in said row; to generate an image of the projection of the graticule on the body part, called the synthetic image, on the basis of said model and using the parameters determined beforehand, and to subtract the synthetic image from the acquired image in order to obtain a graticule-free image of the body part, said graticule-free image of the body part being able to be used (45, 46) to carry out an identification or an authentication. to simultaneously activate the light source, the graticule-projecting module and the image-acquiring module in order to allow an image of the print, called the acquired image, to be acquired; to model the variations in light intensity of the projection of the graticule on the body part by determining parameters of a preset 1D parametric mathematical model, said preset parametric model being a 1D model defined per row of pixels and depending on a pixel number in said row; to generate an image of the projection of the graticule on the body part, called the synthetic image, on the basis of said model and using the parameters determined beforehand, and to subtract the synthetic image from the acquired image in order to obtain a graticule-free image of the body part, said graticule-free image of the body part being able to be used (45, 46) to carry out an identification or an authentication.