Use the buttons to view the traditonal, raw focus invariant, and filtered focus invariant images
Intermediate images are raw sampled images from focus-invariant systems. These system are physically a traditional optical imaging system modified by a special-purpose optical element or mask. This mask theoretically absorbs no optical power. An image of the optical mask is found here . The intermediate images are not as sharp and clear as the infocus image from the traditional system. But, the intermediate images are nearly the same for each value of misfocus, especially when compared to the changes in the images from the traditional system with misfocus. Digital filtering of these intermediate images restores the spatial resolution to that of the traditional system.
Linear digital filtering of the intermediate images produces the final focus-invariant imagery. Only a single linear digital filter was used to restore all parts of each of the images. The spatial resolution of the geometrically extreme misfocus image is nearly the same as that of the geometrically infocus image and all of the focus-invariant images are comparable to the infocus image produced from the traditional system. For this experiment an off-the-shelf analogue video camera with roughly six bits of dynamic range was used.