A method of providing image data for constructing a high-resolution image of a region of a target object, comprising the steps of: providing incident radiation, from a radiation source, at the target object; via at least one detector, detecting the intensity of radiation scattered by said target object with a post target object aperture at a first position with respect to the target object, re-positioning the aperture relative to the target object, subsequently detecting the intensity of radiation scattered by said target object with the aperture at a second position with respect to the target object; or via at least one detector, detecting the intensity of radiation scattered by said target object with the incident radiation at a first position with respect to the target object, re-positioning the incident radiation relative to the target object, subsequently detecting the intensity of radiation scattered by said target object with the incident radiation at a second position with respect to the target object; and characterized by: selecting said second position so that a first area of the region of the target object selected in said first position at least in part overlaps with a second area of the region of the target object determined in said second position; and responsive to at least the detected intensity at said first and second positions, providing said image data via an iterative process and using a softly varying transmittance function or illumination function movable with respect to said target object wherein the softly varying transmittance or illumination function is a bandwidth limited function not composed of high spatial frequencies providing incident radiation, from a radiation source, at the target object; via at least one detector, detecting the intensity of radiation scattered by said target object with a post target object aperture at a first position with respect to the target object, re-positioning the aperture relative to the target object, subsequently detecting the intensity of radiation scattered by said target object with the aperture at a second position with respect to the target object; or via at least one detector, detecting the intensity of radiation scattered by said target object with the incident radiation at a first position with respect to the target object, re-positioning the incident radiation relative to the target object, subsequently detecting the intensity of radiation scattered by said target object with the incident radiation at a second position with respect to the target object; and characterized by: selecting said second position so that a first area of the region of the target object selected in said first position at least in part overlaps with a second area of the region of the target object determined in said second position; and responsive to at least the detected intensity at said first and second positions, providing said image data via an iterative process and using a softly varying transmittance function or illumination function movable with respect to said target object wherein the softly varying transmittance or illumination function is a bandwidth limited function not composed of high spatial frequencies selecting said second position so that a first area of the region of the target object selected in said first position at least in part overlaps with a second area of the region of the target object determined in said second position; and responsive to at least the detected intensity at said first and second positions, providing said image data via an iterative process and using a softly varying transmittance function or illumination function movable with respect to said target object wherein the softly varying transmittance or illumination function is a bandwidth limited function not composed of high spatial frequencies