1. A method for estimating an image depth map of a scene, which comprises: providing an image in which the focus depends on a depth and wavelength of considered object points of the scene, using a longitudinal chromatic optical system, determining a set of spectral images from the image provided by the longitudinal chromatic optical system, deconvoluting the spectral images in order to provide estimated spectral images with extended depth of field, and analyzing a cost criterion that is dependent on the estimated spectral images with extended depth of field, in order to provide an estimated depth map {circumflex over (Z)}(x,y) of an actual depth Z(x, y) , where Z is the actual depth, of the scene, and x and y are coordinates of the actual scene.