A pyramid-based method of dynamic thresholding where the Gaussian pyramid is used to support a “coarse-to-fine” search strategy is presented. At the top level of the pyramid the image is divided into four subimages, and in each subimage, the gray-level variance is analyzed to find whether there is an edge. The hierarchical search is continued until the bottom level of the pyramid, or the original image, is reached. At the bottom level the threshold values of those subimages where an edge is present are estimated, and the value of zero is assigned to those subimages where no edge is present. Finally, by using interpolations of subimage and pixel threshold values, the dynamic threshold values are found.
['Shuwu Song', 'Mengyang Liao', 'Jiamei Qin']
Multiresolution image dynamic thresholding