Reflectance spectra estimation and colour space conversion using reference reflectance spectra

A personal computer (PC) and (2) adjust the color of the picture received from the digital camera (3) in order to generate the presumed reflection spectrum, and/or in order to change a color into a new color space. First, in order to compensate the sensitivity to the light of the wavelength from which the camera (3) used for generation of a picture differs, and the irradiation spectrum which enters into the object body related to a picture, input compensation transformation is generated, for example based on the Macbeth color chart in a picture. Next, in order to presume a reflection spectrum, reflection-spectrum presumption transformation is generated by PC (2). In order to change the color of a picture into a new color space, color space conversion transformation is generated by PC (2). Each of reflection-spectrum presumption transformations and color space conversion transformations is based on the standard reflection spectrum and input compensation transformation which were stored in the standard reflection-spectrum database (4).