An optical system for generating an image having extended depth of field. The system includes a phase mask and a chromatic wavefront coding lens. The chromatic wavefront coding lens provides axial color separation of light by generating specified chromatic aberration in an image created by the lens. The phase mask causes the optical transfer function of the optical system to remain substantially constant within a specified range away from the image plane, and the optical transfer function of the system contains no zeroes within at least one spectral passband of interest. Digital processing may be performed on the image to generate a final image by reversing a decrease in modulation transfer function generated by the phase mask.