Image processing apparatus, image processing method, and non-transitory computer-readable storage medium that use a plurality of captured radiation images to obtain, by sequential approximation solution by iterative calculation, an output image

An image processing method comprising:

• using a plurality of radiation images captured using different radiation energies as input images;
• and
• obtaining, by a sequential approximation solution by an iterative calculation, an output image representing a planar distribution for a substance contained in the image,
• wherein, based on a likelihood and a prior probability using one of a pixel value of a pixel of interest or a pixel value of a peripheral pixel as an input, in the obtaining, the output image is decided such that a probability that an output is a value of the planar distribution when an input is the input image that is maximized.

An image processing apparatus comprising:

• a planar distribution obtaining unit configured, using a plurality of radiation images captured using different radiation energies as input images, to obtain an output image representing a planar distribution for a substance contained in the input image,
• wherein, based on a likelihood and a prior probability using one of a pixel value of a pixel of interest or a pixel value of a peripheral pixel as an input, the planar distribution obtaining unit decides the output image such that a probability that an output is a value of the planar distribution when an input is the input image that is maximized, the planar distribution obtaining unit obtains:
• the output image by adding pixel values of images obtained based on radiation spectra corresponding to the different radiation energies, or
• the output image by approximating radiation spectra corresponding to the different radiation energies as a radiation spectrum of a single color.