Opera hat characteristic snapping sound heard upon opening a gibus suggested a third name, the "chapeau claque", "claque" being the French word for "slap". 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
Top-hat transform 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, background equalization, image enhancement, and others. Let formula_1 be a grayscale image, mapping points from a Euclidean space or discrete