Braille

Creator:Louis Braille
Date: 1824
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Braille is a tactile writing system used by the blind and visually impaired.

Braille was the first writing system with binary encoding. Character encoding that mapped characters of the French alphabet to tuples of six bits (the dots).

Contents

1   Etymology

Braille is named after its creator, Frenchman Louis Braille.

2   Substance

Braille characters are small rectangular blocks ("cells") that contain tiny palpable bumps ("raised dots"). Within an individual cell, the dot positions are arranged as two columns of three positions. A raised dot can appear in any of the six positions, producing sixty-four (2^6) possible patterns. The number and arrangement of these dots distinguish one character from another.

Different assignments of braille codes (or code pages) are used to map the character sets of different printed scripts to the six-bit cells. Braille assignments have also been created for mathematical and musical notation.

Because the six-dot braille cell allows only 64 (26) patterns, including the space, the characters of a braille script commonly have multiple values, depending on their context. That is, character mapping between print and braille is not one-to-one. For example, the character â ™ corresponds in print to both the letter "d" and the digit "4".

Since the various braille alphabets originated as transcription codes of printed writing systems, the mappings (sets of character designations) vary from language to language.

Braille cells are not the only thing to appear in embossed text. There may be embossed illustrations and graphs, with the lines either solid or made of series of dots, arrows, bullets that are larger than braille dots, etc.

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Braille book in museum of Louis Braille.

3   History

Braille went blind following a childhood accident. In 1824, at the age of 15, Braille developed his code for the French alphabet as an improvement on `night writing`_.

Braille was based on a tactile military code called night writing, developed by Charles Barbier in response to Napoleon's demand for a means for soldiers to communicate silently at night and without light. In Barbier's system, sets of 12 embossed dots encoded 36 different sounds. It proved to be too difficult for soldiers to recognize by touch, and was rejected by the military. In 1821 Barbier visited the Royal Institute for the Blind in Paris, where he met Louis Braille. Braille identified two major defects of the code: first, by representing only sounds, the code was unable to render the orthography of the words; second, the human finger could not encompass the whole 12-dot symbol without moving, and so could not move rapidly from one symbol to another. Braille's solution was to use 6-dot cells and to assign a specific pattern to each letter of the alphabet. At first, braille was a one-to-one transliteration of French orthography, but soon various abbreviations, contractions, and even logograms were developed, creating a system much more like shorthand. For the blind today, braille is an independent writing system rather than a code of printed orthography.

4   Production

Braille is traditionally written with embossed paper.