Imaging device, imaging system, and imaging method

An imaging method performed by an imaging device comprising a filter and an imaging unit, the filter formed of four different filter regions with four different spectral transmittances that three different spectral transmittances having characteristics of a color matching function and a spectral transmittance for extracting metallic black have been linearly transformed thereinto by a linear transformation matrix, the imaging unit taking an image of light which has come out from a subject and has been collected by an optical system and then has passed through the filter, and the imaging method comprising:

• calculating a colorimetric value on the basis of pixel data output from an imaging unit;
• estimating a spectral distribution of reflected light from a subject on the basis of four kinds of pixel data output from the imaging unit;
• taking in outside light and leading the outside light to the imaging unit;
• estimating a spectral distribution of the outside light on the basis of output four kinds of pixel data obtained by the imaging unit taking an image of the led outside light;
• and
• estimating spectral reflectance of the subject by dividing the estimated spectral distribution of the reflected light from the subject by the estimated spectral distribution of the outside light.