Abstract: In conventional radiography, X rays which pass through an object along different paths are differentially absorbed, and the intensity pattern of the emerging beam records the distribution of absorbing materials within the sample. A non-conventional X-ray radiography-phase-contrast imaging is described, which records variations of the phase of the emerging radiation, shows dramatic contrast enhancement for low density or weakly absorbing materials with hard X-ray. A general treatment of X-ray image formation by Fresnel diffraction theory is presented. According to the optical transfer function, the distance of object-image and spatial frequency on the imaging phase-contrast is discussed. Resolution and contrast are the criteria used to specify the visibility of an image, resolution in turn