The use of Ektachrome infrared aero film is recommended in fundus photography to reveal melanin, especially to differentiate choroidal melanomata from metastases and other lesions containing no extra melanin. Melanin shows up dark brown while blood shows up yellow, provided the correct exposure is used.
Suckling RD, Donaldson KA. Detection of Melanin in Choroidal TumorsUse of Ektachrome Infrared Aero Film. Arch Ophthalmol. 1970;83(6):700-703. doi:10.1001/archopht.1970.00990030700005