1. A method of generating a tomography image, the method comprising: performing a depth scan on one spot on a surface of a subject using modulated light received from a spatial light modulator configured to modulate either one or both an intensity and a phase light received from a light source according to a pattern for each of a plurality of patterns of the spatial light modulator; obtaining depth scan data for each of the plurality of patterns of the spatial light modulator by repeating the depth scan on the spot for each of the plurality of patterns of the spatial light modulator; forming a matrix R representing a vector space based on a correlation of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator; performing a matrix decomposition on the matrix R; dividing the vector space represented as a sum of subspace components into a noise subspace and a signal subspace based on a threshold and a matrix obtained by the matrix decomposition, wherein the threshold is determined based on characteristics of the subspace components or noise levels of the signal values; reconstructing a vector space based on either one or both of components of the signal subspace and components of the noise subspace; and generating the tomography image based on the reconstructed vector space.