An apparatus for analyzing lightness contrast illusion or color contrast illusion, the apparatus comprising at least a storage unit and a control unit, the storage unit comprising: a filter storage unit that stores a wavelet frame with orientation selectivity or a filter bank with orientation selectivity that is a set of an approximate filter with no orientation and a plurality of detail filters with respective orientations; and an image data storage unit that stores image data; and the control unit comprising: a decomposing unit that decomposes the image data into color components in a color space including lightness and color like human color-perception and performs multiresolution decomposition on each color component of the color components by using the wavelet frame with orientation selectivity or the filter bank with orientation selectivity and obtains subband signals; a reconstructing unit that reconstructs an image by summing the subband signals that are obtained by the decomposing unit and obtains reconstructed image data; and an illusion quantifying unit that quantifies an amount of illusion by calculating a ratio or difference in the color components between the image data and the reconstructed image data; and the decomposing unit further including a coefficient processing unit that performs, in the color space including lightness and color like human color-perception, for color components of color of the image data a coefficient processing on decomposition detail coefficients that are output from the decomposition phase such that the larger an energy of the decomposition detail coefficients that is determined from the decomposition detail coefficients of color and the decomposition detail coefficients of lightness is, the more small values are further reduced, and the smaller the energy of the decomposition detail coefficients is, the more small values are increased. a filter storage unit that stores a wavelet frame with orientation selectivity or a filter bank with orientation selectivity that is a set of an approximate filter with no orientation and a plurality of detail filters with respective orientations; and an image data storage unit that stores image data; and the control unit comprising: a decomposing unit that decomposes the image data into color components in a color space including lightness and color like human color-perception and performs multiresolution decomposition on each color component of the color components by using the wavelet frame with orientation selectivity or the filter bank with orientation selectivity and obtains subband signals; a reconstructing unit that reconstructs an image by summing the subband signals that are obtained by the decomposing unit and obtains reconstructed image data; and an illusion quantifying unit that quantifies an amount of illusion by calculating a ratio or difference in the color components between the image data and the reconstructed image data; and the decomposing unit further including a coefficient processing unit that performs, in the color space including lightness and color like human color-perception, for color components of color of the image data a coefficient processing on decomposition detail coefficients that are output from the decomposition phase such that the larger an energy of the decomposition detail coefficients that is determined from the decomposition detail coefficients of color and the decomposition detail coefficients of lightness is, the more small values are further reduced, and the smaller the energy of the decomposition detail coefficients is, the more small values are increased. a decomposing unit that decomposes the image data into color components in a color space including lightness and color like human color-perception and performs multiresolution decomposition on each color component of the color components by using the wavelet frame with orientation selectivity or the filter bank with orientation selectivity and obtains subband signals; a reconstructing unit that reconstructs an image by summing the subband signals that are obtained by the decomposing unit and obtains reconstructed image data; and an illusion quantifying unit that quantifies an amount of illusion by calculating a ratio or difference in the color components between the image data and the reconstructed image data; and the decomposing unit further including a coefficient processing unit that performs, in the color space including lightness and color like human color-perception, for color components of color of the image data a coefficient processing on decomposition detail coefficients that are output from the decomposition phase such that the larger an energy of the decomposition detail coefficients that is determined from the decomposition detail coefficients of color and the decomposition detail coefficients of lightness is, the more small values are further reduced, and the smaller the energy of the decomposition detail coefficients is, the more small values are increased.