Patent ID: 8363915

Claim:
An image component separation device comprising: component separating means for separating bone and soft tissues as predetermined components from more than one radiographic images inputted thereto, the image components respectively representing more than one predetermined components in a site to be examined of a human body, each radiographic image being formed by radiation transmitted through the site, each radiographic image representing degrees of transmission and attenuation through the site of each of different patterns of radiation having different energy distributions, the component separating means separating the image components by calculating weighted sums using predetermined weighting factors for each corresponding pixel among the radiographic images; and pixel value converting means for applying nonlinear conversion to a pixel value of each pixel of at least one of the radiographic images based on a value of a parameter obtained from at least one of the radiographic images, the parameter having a predetermined relationship with a thickness of each of the more than one predetermined components or a thickness of the site at each pixel of the radiographic images, the nonlinear conversion bringing the radiographic images closer to achieving a relationship where a ratio between radiation attenuations in the radiographic images is constant regardless of the thickness of each predetermined component or the thickness of the site, wherein the component separating means carries out independent component analysis on the image converted by the pixel value converting means to obtain separation factors for separating the bone and soft tissues as predetermined components from the converted images and uses the separation factors as the predetermined weighting factors, wherein the radiographic images are formed by a multi-shot method in which imaging is carried out more than once using different patterns of radiations having different energy distributions, and wherein the pixel value converting means carries out to relatively increase, within regions having larger radiation attenuation in the radiographic images, a gain in one of the radiographic images formed by exposure to higher energy radiation so that the gain in the one of the radiographic images becomes larger than a gain in the other of the radiographic images formed by exposure to lower energy radiation.