写真像の粒状性-1-現像銀のサイズとWiener spectrum

概要

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Fourier analysis of grain pattern of photographic materials is known to be valuable to express its optical characteristics. This paper presents a relation of mean grain size of developed silver halide to Wiener spectrum of grain pattern. A high sensitivity negative film and eight kinds of developers were used in order to make specimens. Mean grain size of developed silver halide was determined from its electron photomicrographs, and Wiener spectrum was determined with the use of a device composed of a high speed scanning microphotolneter and a frequency analyser. Bandwidth of Wiener spectrum determined from grain pattern in this experiment were smaller than that expected from the mean grain size. This fact shows the existence of mottles formed by aggregation of grains. Mean size of mottles can be estimated by the use of the bandwidth of Wiener spectrum. Authors defined the mottle size obtained by this procedure as Expected Mottle Size and found that it was about six times as large as the grain size of developed silver halide in dimension in the case of specimens used in this experiment. Expected Mottle Size gives us practical means to evaluate the mottles of grain pattern. Grain size of developed silver halide was correlated well with color tone of images.
社団法人日本写真学会の論文