Final answer:
Image brightness differences can be converted to phase differences to enhance visibility and permit mathematical analysis, a technique employed by phase-contrast microscopes.
Step-by-step explanation:
Image brightness differences can be converted to phase differences, which makes them much more apparent to the eye and also allows mathematical analysis. This concept is particularly utilized in a type of microscope known as a phase-contrast microscope, which enhances the contrast of images by capitalizing on wave interference and phase differences in light. In this type of microscopy, light rays passing through different parts of a phase plate are superimposed in the image plane, producing contrast due to interference effects.