An electro-optic system using linear photosensitive Charge Coupled Devices(CCDs) having dummy pixels has been proposed for realzation of linear prodictor in the differential pulse code modulation(DPCM). The system consists of three components as conventional system:input light source, spatial filter(mask) and CCD line scanning sensor. For the delay time due to the dummy pixels in CCD, modifying conventional mask, a new dispersive mask is proposed, of which every prediction coefficient is dispersed on the more than one element, the characteristics of the system using the proposed dispersive mask are analyzed theoretically and verified with experiment.