Algorithm for decreasing nonlinear gamma effect with digital fringe projection images

Digital fringe projection using a digital projector is an extensively technique used for 3D surface profile. Fringe pattern images projected by digital projector, appear nonlinear gamma effect. This effect is an error of digital projector, which gamma of the fringe pattern images is not stable. The nonlinear gamma effect demonstrates strip on 3D surface image which is a significant error. Therefore, this paper proposed an algorithm for decreasing nonlinear gamma effect in digital fringe projection. First, fringe pattern images were captured by digital camera, which composed of object and background images. These images suppose to have no distortion by a digital camera. Then, the background image in y axis of image plane was used to compare between real phase and ideal phase. Output of the process was a phase different data which could be use for phase compensation on phase values of fringe pattern images. Finally, the nonlinear gamma effect could decrease by our proposed algorithm. To verify, the fringe pattern images from laboratory, which have nonlinear gamma effect, were used to compute by the proposed algorithm. Result showed smoothly and truthfully 3D surface image. Addition, the proposed algorithm can be a real time processing and independent with any digital projector and digital camera.