Opera hat Opera hat An opera hat, also called a chapeau claque or gibus, is a top hat variant that is collapsible through a spring system, originally intended for less spacious venues, such as theatre and opera visits. Typically made of satin in black colour, its advantage is that it folds vertically through a push or a snap on the top of the hat, in order to be conveniently stored in a wardrobe or under the seat. Invertably, it opens in the same one moment fashion by an easy push from underneath. Its French name "chapeau claque" is a composition of "chapeau",
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,