Provided are a method and a device, for processing spectrum data of an image sensor. The method includes obtaining spectrum response signals corresponding to channels of spectrum data of light, the spectrum data being obtained from an object by an image sensor; determining a set of bases corresponding to the obtained spectrum response signals; performing, based on the determined set of bases, a change of basis on at least one basis included in the determined set of bases; and generating, by using a pseudo inverse, reconstructed spectrum data from the spectrum response signals on which the change of basis has been performed.