Opera hat which means hat, and "claque", which means "tap" or "click". The "chapeau claque" is thus a hat that folds with a click, and unfolds likewise. In English the hat model is usually referred to as a "collapsible top-hat", "gibus" or more often "opera hat"- The construction may originally have been inspired by an historical hat model called "chapeau bras" ("arm hat"), made as bicorne or tricorne to be carried folded under the arm On May 5, 1812, a London hatter called Thomas Francis Dollman patented a design for "an elastic round hat" supported by ribs and springs. His patent was
Top-hat transform controlled by the choice of the structuring element formula_7. The bigger the latter, the larger the elements extracted. Both top-hat transforms are images that contain only non-negative values at all pixels. One of its most important uses in image segmentation is to adjust nonuniform lighting conditions on an image and provide a better threshold value for separating objects. Assume we are only interested in small blobs on the image and we want to remove the larger bright objects. In this case, the white top-hat transform can remove larger bright objects and retain small blobs by selecting the size of the