Fortunata Obrapalska (1909-2004) was one of the most outstanding avant-garde photographers of late 1940s in Poland. The most characteristic of all her eminent and frequently rewarded works (portrait, landscape and genre) is the cycle 'Diffusion in liquid'. She took part in several most important exhibitions of photography and modern art such as 1st and 2nd Exhibition of Polish Artistic Photography in Poznan (1947, 1948), Modern Polish Photography in Warsaw (1948), Exhibition of Modern Art in Cracow (1948), and two exhibitions of the artistic group '4F + R' (1949, 1956) in Poznan. Her retrospective exhibitions were held in Poznan in 1958 and in Poznan and Wroclaw in 1960. The last period of her photographic career (until 1958) was dominated by photographs in which the most important thing was not the theme itself but the expressiveness, clarity of form and modern use of photographic language. In these works Obrapalska made use of special processing techniques (e.g. solarization, pseudo-solarization, inversion, bromography), working out some of the motives in several versions.