A new technique for archival storage of color films through a three primary color grating formed by interference between diffraction orders of black-white orthogonal Ronchi ruling in a white-light processor is described. Compared with conventional encoding method, there are some advantages suoh as no Morie fringe, the encoding frequence can be changed, and the encoding process can be simply completed in one step. The color and resolution of retrieved image are satisfactory and the results of experiment coincide with theoretical analysis.