This paper suggests an hierarchical region based representation to implement detection of shapes in gray-scale images. The Max-Tree structure has demonstrated to be useful for this purpose, offering a semantic objects vision of the image, therefore, reducing the number of elements to process in relation to the pixel based representation. In this way, a particular thresholding information, associated with a specific shape analysis, can be used to determine the segmentation or filtering of regions of interest with lesser computational effort. For to demonstrate this technique, a generic application of detection of lines is proposed using the distance transform approach on each connected component from the depth searching in the mentioned tree.