Theory and experiment of a new image encoding technique using speckles modulated by different slit pupil function are described. Compared with current grating encoding, the advantages of the new technique are that there is no necessity to reprint the negative transparency into a positive one, operation is simple, and resolution is high enough. Especially in multi-signal parallel processing the Moire fringes that easily appear in grating encoding do not appear in the speckle encoding. As an example, the experimental result of white-light stereoprojection utilizing speckle encoding is given.