An information processing method includes: converting voxel data to node data in which a voxel, which has a brightness value that is outside a certain brightness value range, is set as a first node, and a voxel, which has a brightness value that is within the certain brightness value range, is set as a second node that has a capability to extract relating nodes based on a neighborhood relationship between voxels; performing, for each second node, a calculation processing to calculate an output value of a reaction-diffusion equation by using a value corresponding to a brightness value of the second node and values corresponding to brightness values of relating nodes extracted from the second node, a predetermined number of times; and determining a brightness value of each second node from the output value of the reaction-diffusion equation after performing the calculation processing the predetermined number of times.