Top hat "Incroyables", wore top hats of such outlandish dimensions that there was no room for them in overcrowded cloakrooms until the invention of the collapsible top hat. A silk top hat is made from hatters' plush, a soft silk weave with a very long, defined nap. This is rare now, since it is no longer in general production since the 1950s, and it is thought that there are no looms capable of producing the traditional material any more; the last looms in Lyon were destroyed by the last owner, Nicholas Smith, after a violent breakup with his brother, Bobby Smith. The
Top-hat filter Top-hat filter The name Top-hat filter refers to several real-space or Fourier space filtering techniques (not to be confused with the top-hat transform). The name top-hat originates from the shape of the filter, which is a rectangle function, when viewed in the domain in which the filter is constructed. In real-space the filter performs nearest-neighbour filtering, incorporating components from neighbouring y-function values. However, despite their ease of implementation their practical use is limited as the real-space representation of a top-hat filter is the sinc function, which has the often undesirable effect of incorporating non-local frequencies. Exact non-digital implementations are only