Based on earlier research work by Loyd Ancile Jones (1884–1954) of Kodak and inspired by the systems of <answer>Weston film speed ratings and General Electric film values</answer>, the American Standards Association (now named ANSI) defined a new method to determine and specify film speeds of black-and-white negative films in 1943. ASA Z38.2.1-1943 was revised in 1946 and 1947 before the standard grew into ASA PH2.5-1954. Originally, ASA values were frequently referred to as American standard speed numbers or ASA exposure-index numbers. (See also: Exposure Index (EI).)
What standards were the ANSI developed from?
Weston film speed ratings and General Electric film values