Transformation of text

Transformations of text are strategies to perform geometric transformations on text (reversals, rotations, etc.), particularly in systems that do not natively support transformation, such as HTML, seven-segment displays and plain text.

Many systems, such as HTML, seven-segment displays and plain text, do not support transformation of text. In the case of HTML, this limitation in display may eventually be addressed through standard cascading style sheets (CSS), since proposed specifications for CSS3 include rotation for block elements. In the meantime, several ways of producing the visual effects of text transformations have come into use.

The most common of these transformations are rotation and reflection.

Unicode supports a variety of characters that resemble transformed characters, primarily for various forms of phonetic transcription. Each of these character names indicates what kind of transformation the characters have undergone:

Strategies can be used to render words upside down in languages such as HTML that do not permit rotation of text; using Unicode characters (especially those in the IPA), a very close approximation of upside-down text (also called flip text) can be achieved. The letters s, x, z and o are rotationally symmetrical, while pairs such as b/q, d/p and n/u are rotations of each other. The rest of the letters have been encoded into the Unicode IPA section, generating a complete set of upside-down lowercase letters. With the addition of the Fraser alphabet to the Unicode standard in version 5.2, full (or at least near-full) support for upside-down capital letters is now available. Number support is incomplete; four numbers are universally strobogrammatic (0, 8, and 6/9), and the upside-down versions of numbers 2 and 3 have been provisionally assigned Unicode points for use in dozenal notation; however, other numbers still are not supported. Punctuation (by use of such characters as the interpunct and the inverted question mark and exclamation point) is mostly covered. Several Internet utilities exist for the transformation of regular text to (and sometimes from) upside-down text; each has its own slightly different algorithm for letters not precisely or well covered. A list of converters and algorithms can be found at the list below.

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