An image processing apparatus, comprising: a filtering unit that performs filtering on each voxel position in a three-dimensional image by convoluting a filter kernel, which represents a second order partial differential of a function representing a solid sphere, to calculate a Hessian matrix; and an evaluation unit that discriminates a structure, which is included in the image and is at least one of a local point-like, a line-like, and a plane-like structure, using eigenvalues and eigenvectors of the Hessian matrix obtained by performing eigenvalue analysis on the calculated Hessian matrix, wherein the filtering unit includes a correction unit that performs filtering on each voxel position in the image by convoluting a filter kernel, which represents a first order partial differential of a function representing a hollow sphere having the same radius as the radius of the solid sphere, to calculate a first order partial differential vector, and corrects the eigenvalues of the Hessian matrix (i) by adding projected values, which are obtained by projecting the first order partial differential vector onto directions of the eigenvectors, or by adding the projected values weighted with a predetermined coefficient to the eigenvalues, or (ii) by subtracting the projected values or the projected values weighted with a predetermined coefficient from the eigenvalues to cancel out one of response waveforms of the second order partial differential of the function representing the solid sphere in each direction, the response waveforms appearing at two positions symmetrically separated with respect to the center of the solid sphere. a filtering unit that performs filtering on each voxel position in a three-dimensional image by convoluting a filter kernel, which represents a second order partial differential of a function representing a solid sphere, to calculate a Hessian matrix; and an evaluation unit that discriminates a structure, which is included in the image and is at least one of a local point-like, a line-like, and a plane-like structure, using eigenvalues and eigenvectors of the Hessian matrix obtained by performing eigenvalue analysis on the calculated Hessian matrix, wherein the filtering unit includes a correction unit that performs filtering on each voxel position in the image by convoluting a filter kernel, which represents a first order partial differential of a function representing a hollow sphere having the same radius as the radius of the solid sphere, to calculate a first order partial differential vector, and corrects the eigenvalues of the Hessian matrix (i) by adding projected values, which are obtained by projecting the first order partial differential vector onto directions of the eigenvectors, or by adding the projected values weighted with a predetermined coefficient to the eigenvalues, or (ii) by subtracting the projected values or the projected values weighted with a predetermined coefficient from the eigenvalues to cancel out one of response waveforms of the second order partial differential of the function representing the solid sphere in each direction, the response waveforms appearing at two positions symmetrically separated with respect to the center of the solid sphere.