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 theoretically possible. Top-hat filters can be constructed by chaining theoretical low-band and high-band filters. In practice, an approximate top-hat filter can be constructed in analogue hardware using approximate low-band and high-band filters. In Fourier space, a top hat filter selects a band of signal of desired frequency by the specification of a lower and upper bounding frequencies. Top-hat filters are particularly easy to implement digitally. The top hat function can be generated by differentiating a linear ramp function of width formula_1. The limit of formula_1 then becomes the Dirac delta function. Its real-space form is the same as the moving