With the development of advanced manufacture,vision measurement is re quired to be with higher accuracy, higher efficiency,more smart and more flexible.Traditional vision detection sy stem is limited in image processing power due to the state of semiconductor fabrication .In order to enhance detect ion efficiency,the optical modulation system before image formation is built in this paper.Moreove r,accurate CCD-to digital micro-mirror device (DMD) correspondence is adjusted by using the phase-shifting Moiré method.The modul ation arm subsystem is calibrated to build the transformation relationship between the CCD image coordinate and DM D addressing coordinate. Subsequently,Sobel edge detection based on the optical modulation system before image formation is proposed. Finally,the experiment of the edge feature detection of light-back marker in the 3D scan technology is implemented.Experimental results show that additive operations of the proposed m ethod are down to 3N compared with 17N operations of traditional vision detection,and multi ply operations are down t o 2N compared with 20N operation s of traditional vision detection.In conclusion,our proposed method can effec tively detect edge features of object.