A shadow optical imaging method comprising: receiving, at a single detector of a lensless optical imaging system, an optical shadow cast thereon by an object disposed in immediate proximity to said single detector and irradiated with a single diverging monochromatic wavefront of light; acquiring multiple sets of optical data with said single detector over a period of time, each set of optical data representing a respectively-corresponding first image of said optical shadow formed with said wavefront at a respectively-corresponding point in time within said period, wherein spatial positions and orientations of said detector, said object, and said light source remain unchanged during said acquiring; wherein said wavefront has a rate of spatial divergence that remains unchanged in time and an optical axis the spatial orientation of which remains unchanged during said period of time, wherein said first image is characterized by a first spatial resolution; forming a second image of said object from said multiple sets of optical data using a computer processor, wherein said forming includes anisotropic diffusion filtering of a set from said multiple sets, that has been up-sampled by a factor k using the Lanczos interpolation, to correct geometrical information of each first image, wherein the anisotropic diffusion filtering works by performing smoothing on the image but at the same time preserving boundaries between adjacent regions, wherein said second image is characterized by a second spatial resolution, the second spatial resolution being higher than the first spatial resolution. receiving, at a single detector of a lensless optical imaging system, an optical shadow cast thereon by an object disposed in immediate proximity to said single detector and irradiated with a single diverging monochromatic wavefront of light; acquiring multiple sets of optical data with said single detector over a period of time, each set of optical data representing a respectively-corresponding first image of said optical shadow formed with said wavefront at a respectively-corresponding point in time within said period, wherein spatial positions and orientations of said detector, said object, and said light source remain unchanged during said acquiring; wherein said wavefront has a rate of spatial divergence that remains unchanged in time and an optical axis the spatial orientation of which remains unchanged during said period of time, wherein said first image is characterized by a first spatial resolution; forming a second image of said object from said multiple sets of optical data using a computer processor, wherein said forming includes anisotropic diffusion filtering of a set from said multiple sets, that has been up-sampled by a factor k using the Lanczos interpolation, to correct geometrical information of each first image, wherein the anisotropic diffusion filtering works by performing smoothing on the image but at the same time preserving boundaries between adjacent regions, wherein said second image is characterized by a second spatial resolution, the second spatial resolution being higher than the first spatial resolution. wherein spatial positions and orientations of said detector, said object, and said light source remain unchanged during said acquiring; wherein said wavefront has a rate of spatial divergence that remains unchanged in time and an optical axis the spatial orientation of which remains unchanged during said period of time, wherein said first image is characterized by a first spatial resolution; forming a second image of said object from said multiple sets of optical data using a computer processor, wherein said forming includes anisotropic diffusion filtering of a set from said multiple sets, that has been up-sampled by a factor k using the Lanczos interpolation, to correct geometrical information of each first image, wherein the anisotropic diffusion filtering works by performing smoothing on the image but at the same time preserving boundaries between adjacent regions, wherein said second image is characterized by a second spatial resolution, the second spatial resolution being higher than the first spatial resolution.