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67 lines
2.3 KiB
Plaintext
67 lines
2.3 KiB
Plaintext
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UNICHARSET(5)
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=============
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NAME
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----
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unicharset - character properties for use by Tesseract
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DESCRIPTION
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-----------
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Tesseract needs to have access to the character properties isalpha,
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isdigit, isupper, islower, ispunctuation. This data must be encoded
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in the unicharset data file. Each line of this file corresponds to
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one character. The character in UTF-8 is followed by a hexadecimal
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number representing a binary mask that encodes the properties.
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Each bit corresponds to a property. If the bit is set to 1, it
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means that the property is true. The bit ordering is (from least
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significant bit to most significant bit): isalpha, islower, isupper,
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isdigit, ispunctuation.
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Each line in the unicharset file has four space-separated fields:
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......................................
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[character] [properties] [script] [id]
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......................................
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EXAMPLE
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-------
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..............
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; 10 Common 46
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b 3 Latin 59
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W 5 Latin 40
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7 8 Common 66
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= 0 Common 93
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..............
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";" is a punctuation character. Its properties are thus represented by the binary number
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10000 (10 in hexadecimal).
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"b" is an alphabetic character and a lower case character. Its properties are thus
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represented by the binary number 00011 (3 in hexadecimal).
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"W" is an alphabetic character and an upper case character. Its properties are thus
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represented by the binary number 00101 (5 in hexadecimal).
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"7" is just a digit. Its properties are thus represented by the binary number 01000
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(8 in hexadecimal).
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"=" is not punctuation nor a digit nor an alphabetic character. Its properties are
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thus represented by the binary number 00000 (0 in hexadecimal).
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Japanese or Chinese alphabetic character properties are represented by the binary number
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00001 (1 in hexadecimal): they are alphabetic, but neither upper nor lower case.
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The last two columns represent the type of script (Latin, Common, Greek, Cyrillic, Han,
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null) and id code of the character.
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HISTORY
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-------
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The unicharset format first appeared with Tesseract 2.00, which was the first version
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to support languages other than English. The unicharset file contained only the first
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two fields, and the "ispunctuation" property was absent (punctuation was regarded as
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"0", as "=" is in the above example.
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SEE ALSO
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--------
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tesseract(1), unicharset_extractor(1)
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