The effect of exposure distribution in an image recording layer on the tone reproduction curve shape was investigated for three imaging processes; photo-migration imaging, tanningdeveloped AgX photography and photo-chemical conversion of Rhodamine B film. The exposure distribution was modulated by adopting top and through-base exposures. The two exposure modes markedly changed the tone reproduction curve as well as the spectral response of each of these psocesses. Such results were explained by taking into consideration a development (or imaging event) probability function depending on the distance from the base surface. The significance of filter effect for the tone reproduction in an image recording system based on image display by light absorption is discussed.