A measuring apparatus for measuring an optical characteristic of a sample, the optical characteristic being a bidirectional reflectance distribution function or a bidirectional transmittance distribution function, the apparatus comprising: an optical system (102, 103) configured to project light from a light source onto the sample and to receive light via the sample to form an image of the light source; an imaging device configured to take the image of the light source via the optical system, the light source being an object corresponding to the taken image with respect to the optical system; and a processor configured to obtain the optical characteristic of the sample based on the taken image and a coefficient of a Wiener filter, characterized in that the processor is configured to: estimate a degree of diffusion of the projected light by the sample based on (i) a provisional optical characteristic obtained based on a provisional coefficient of a Wiener filter, a Fourier transform of the taken image, and a Fourier transform of the light source, or (ii) a correlation between the taken image and the light source, determine a coefficient c of the Wiener filter with respect to the estimated degree of diffusion based on data of coefficients of the Wiener filter with respect to different degrees of diffusion of a sample, and obtain a Fourier transform B(m,n) of the optical characteristic by substituting the determined coefficient c of the Wiener filter, the Fourier transform I(m,n) of the taken image and the Fourier transform G(m,n) of the light source into the expression B m n = ∑ n = 0 N n − 1 ∑ m = 0 N m − 1 I m n G m n G m n 2 G m n 2 + c exp − i 2 πN m 0 N m + − i 2 πN n 0 N n and obtain the optical characteristic by subjecting the obtained B(m,n) to an inverse Fourier transform. an optical system (102, 103) configured to project light from a light source onto the sample and to receive light via the sample to form an image of the light source; an imaging device configured to take the image of the light source via the optical system, the light source being an object corresponding to the taken image with respect to the optical system; and a processor configured to obtain the optical characteristic of the sample based on the taken image and a coefficient of a Wiener filter, characterized in that the processor is configured to: estimate a degree of diffusion of the projected light by the sample based on (i) a provisional optical characteristic obtained based on a provisional coefficient of a Wiener filter, a Fourier transform of the taken image, and a Fourier transform of the light source, or (ii) a correlation between the taken image and the light source, determine a coefficient c of the Wiener filter with respect to the estimated degree of diffusion based on data of coefficients of the Wiener filter with respect to different degrees of diffusion of a sample, and obtain a Fourier transform B(m,n) of the optical characteristic by substituting the determined coefficient c of the Wiener filter, the Fourier transform I(m,n) of the taken image and the Fourier transform G(m,n) of the light source into the expression B m n = ∑ n = 0 N n − 1 ∑ m = 0 N m − 1 I m n G m n G m n 2 G m n 2 + c exp − i 2 πN m 0 N m + − i 2 πN n 0 N n and obtain the optical characteristic by subjecting the obtained B(m,n) to an inverse Fourier transform. estimate a degree of diffusion of the projected light by the sample based on (i) a provisional optical characteristic obtained based on a provisional coefficient of a Wiener filter, a Fourier transform of the taken image, and a Fourier transform of the light source, or (ii) a correlation between the taken image and the light source, determine a coefficient c of the Wiener filter with respect to the estimated degree of diffusion based on data of coefficients of the Wiener filter with respect to different degrees of diffusion of a sample, and obtain a Fourier transform B(m,n) of the optical characteristic by substituting the determined coefficient c of the Wiener filter, the Fourier transform I(m,n) of the taken image and the Fourier transform G(m,n) of the light source into the expression B m n = ∑ n = 0 N n − 1 ∑ m = 0 N m − 1 I m n G m n G m n 2 G m n 2 + c exp − i 2 πN m 0 N m + − i 2 πN n 0 N n and obtain the optical characteristic by subjecting the obtained B(m,n) to an inverse Fourier transform.