1. An endoscopic system that processes a color image data of a subject from an imager mounted on an endoscope and records the processed image data in an image recorder/display unit, the endoscopic system comprising: a storage that stores matrix data for forming a spectral image; a still-image memory that stores a still image obtained based on freeze operation on the color image data, the still-image memory being frontward of the spectral-image forming circuit, and a spectral-image forming circuit that forms (i) a spectral image in a selected wavelength band according to a matrix operation of the matrix data in the storage and the still image wherein an operator selects a desired wavelength band thereby extracting a particular tissue type of interest and (ii) a standard image according to a matrix operation of standard-image matrix data and the still image, the standard-image matrix data being matrix data for forming the standard image, wherein the standard image matrix data satisfies the equation 
 [lamda — 1; lamda — 2; and lamda — 3]=[100; 010; 001 ]×[R; G; B] where lamda — 1, lamda — 2, and lamda — 3 represent standard image signal and R, G, and B represent the color image data.