A new technique is presented for automatically determining whole-field interference fringe orders. The modulated fringe pattern is collected and processed with an image processing system. The mechanics information included in the fringe pattern is obtained by a demodulating calculation. Special software is designed for photoelastic, holographic, moire, and speckle fringe patterns. The procedure is demonstrated, and some main subroutines are described in detail. The technique is applied to different examples with satisfactory results.