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 The threshold values are 0.5216 and 0.2 and normalized to formula_8 for original image and applied white top-hat transform respectively. Top-hat transform In mathematical morphology and digital image processing, top-hat transform is an operation that extracts small elements and details from given images. There exist two types of top-hat transform: The "white top-hat transform" is defined as the difference between the input image and its opening by some structuring element; The "black top-hat transform" is defined dually as the difference between the closing and the input image. Top-hat transforms are used for various image processing tasks, such as feature extraction,