Cold cathode illumination is a low-temperature fluorescent light source commonly used in diffusion-type photographic enlargers. By producing a soft, evenly distributed light, it helps reduce harsh shadows, although it can also slightly lower contrast and edge definition in prints. This type of illumination is popular in black-and-white and fine art darkroom photography because it allows for smoother tonal gradations and minimizes the visibility of dust, scratches, or imperfections on the negative, helping photographers achieve clean, high-quality prints.