Active contours methods with respect to Vickers indentations

We investigate different Vickers indentation segmentation methods and especially concentrate on active contours approaches as these techniques are known to be precise state of the art segmentation methods. Particularly, different kinds of level set-based methods which are improvements of the traditional active contours are analyzed. In order to circumvent the initialization problem of active contours, we separate the segmentation process into two stages. For the first stage, we introduce an approach which approximately locates the indentations with a high certainty. The results achieved with this method serve as initializations for the precise active contours (second stage). This two-stage approach delivers highly precise results for most real world indentation images. However, there are images, which are very difficult to segment. To handle even such images, our segmentation method is incorporated with the Shape from Focus approach, by including 3D information. In order to decrease the overall runtime, moreover, a gradual enhancement approach based on unfocused images is introduced. With three different databases, we compare the proposed methods and we show that the segmentation accuracy of these methods is highly competitive compared with other approaches in the literature.