According to metal label image characteristic, the pressed protuberant characters segmentation method is proposed based on shape index. The pressed protuberant characters and the print character image is withdraws with the morphology processing. obtains the surface gradient is gathered through the shape from shading method, then obtains the shape index operator, and realizes the classification by this as the feature vector through the support vector machines method. Compares with the classics image segmentation algorithm, this algorithm has the very big serviceability when grayscale image distribute is non-uniform. This method algorithm is simple, the effect is fine, not label layout restraint.