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  File format in multi-character recognition mode
    (Rev. 20100201)
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Input file:
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The input file must be in PBM, PGM, or PPM format.

The width of the input image is used as the size of the
individual character image. NHocr assumes that the character
images are stacked vertically.
For example, if the size of the input image is W x H, NHocr
assumes that the file contains [H/W] character images, each of
which is with W x W pixels.

Each character image is binarized and recognized separately.

If margins are required around the character image within a
W x W-pixel window, the image must be placed on the left-top
corner. The margin(s) must be filled with 255s (complete white),
or with 0s (white background) in PBM format.




Output file:
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The file is in UTF-8.

Lines beginning with "#" are comments lines.

Items are separated by a TAB character (09h).

Character (image) block begins with a line like

IMG	n

where "IMG" is the tag and "n" is the serial number of the block
starting with 0.

The IMG line is followed by character candidate line(s) sorted
in the ascending order of the rank. Each line looks like

R	1	東	0.9	0	2.4283356e+00

The tag "R" is followed by the rank, candidate character
code(s), OCR-engine-specific confidence value (0.0-1.0),
similarity, and distance/dissimilarity.

The confidence value is not available if it is zero.
The similarity is not available if it is zero.
Both the similarity and distance fields may be omitted.
The distance field may be omitted if the similarity field exists.

The result lines are terminated by a blank line. The number of
candidates can vary depending on the recognition result.

The third field can have more than one characters in some 
special cases as follows.

  \  (backslash + SPACE) :  the result is a SPACE character
  \\ (backslash + backslash) :
      the result is a backslash character
  string of some characters :  the image seems a ligature, etc.

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