In 3-D measurement of structured light system,the fringe grayscale degradation caused by the uneven reflectivity and the large curvature change of measured object surface is frequently encountered.A grayscale adjustment method is thus proposed to improve the accuracy of stripe center extraction.The modulation of each image pixel related to the object surface is obtained by projecting pure gray images to the measured object.And the modulation is applied to the fringe pattern point by point to eliminate the g...