gocr
command line text recognition tool
Synopsis
gocr
[OPTION] [-i] pnm-file
add an example, a script, a trick and tips
examples
gocr -v 33 text1.pbm
output verbose information, out30.png is created to see details
of recognition process
gocr -v 7 -c _YV text1.pbm
verbose output for unknown chars and chars Y and V
djpeg -pnm -gray text.jpg | gocr -
convert a jpeg file to pnm format and input via pipe
description
gocr is an
optical character recognition program that can be used from
the command line. It takes input in PNM, PGM, PBM, PPM, or
PCX format, and writes recognized text to stdout. If
the pnm file is a single dash, PNM data is read from
stdin. If gzip, bzip2 and netpbm-progs are installed
and your system supports popen(3) also pnm.gz, pnm.bz2, png,
jpg, jpeg, tiff, gif, bmp, ps (only single pages) and eps
are supported as input files (not as input stream), where
pnm can be replaced by one of ppm, pgm and pbm.
options
-h
show usage information
-i file
read input from file (or
stdin if file is a single dash)
-o file
send output to file
instead of stdout
-e file
send errors to file
instead of stderr or to stdout if file
is a dash
-x file
progress output to file
(file can be a file name, a fifo name or a file
descriptor 1...255), this is useful for GUI developpers to
show the OCR progress, the file descriptor argument is only
available, if compiled with __USE_POSIX defined
-p path
database path, a final slash
must be included, default is ./db/, this path will be
populated with images of learned characters
-f
format
output format of the
recognized text (ISO8859_1 TeX HTML XML UTF8 ASCII), XML
will also output position and probability data
-l
level
set grey level to level
(0<160<=255, default: 0 for autodetect), darker pixels
belong to characters, brighter pixels are interpreted as
background of the input image
-d size
set dust size in pixels
(clusters smaller than this are removed), 0 means no
clusters are removed, the default is -1 for auto
detection
-s num
set spacewidth between words in units of dots (default:
0 for autodetect), wider widths are interpreted as word
spaces, smaller as character spaces
-v
verbosity
be verbose to stderr;
verbosity is a bitfield
-c
string
only verbose output of
characters from string to stderr, more output is
generated for all characters within the string, the
underscore stands for unknown chars, this function is
usefull to limit debug information to the necessary one
-C
string
only recognise characters from
string, this is a filter function in cases where the
interest is only to a part of the character alphabet, you
can use 0-9 or a-z to specify ranges, use -- to detect the
minus sign
-a
certainty
set value for certainty of
recognition (0..100; default: 95), characters with a higher
certainty are accepted, characters with a lower certainty
are treated as unknown (not recognized); set higher values,
if you want to have only more certain recognized
characters
-u
string
output this string for every
unrecognized character (default is "_")
-m mode
set oprational mode; mode is a
bitfield (default: 0)
-n bool
if bool is non-zero,
only recognise numbers (this is now obsolete, use -C
"0123456789")
The verbosity
is specified as a bitfield:
1
print more info
2
list shapes of boxes (see -c) to stderr
4
list pattern of boxes (see -c) to stderr
8
print pattern after recognition for debugging
16
print debug information about recognition of lines to
stderr
32
create outXX.png with boxes and lines marked on each
general OCR-step
The operation
modes are:
2
use database to recognize
characters which are not recognized by other algorithms,
(early development)
4
switching on layout analysis or zoning (development)
8
don’t compare unrecognized characters to
recognized one
16
don’t try to divide overlapping characters to two
or three single characters
32
don’t do context correction
64
character packing, before recognition starts, similar
characters are searched and only one of this characters will
be send to the recognition engine (development)
130
extend database, prompts user for unidentified
characters and extends the database with users answer
(128+2, early development)
256
switch off the recognition engine (makes sense together
with -m 2)
reporting bugs
Report bugs to Joerg Schulenburg
version information
This man page documents gocr, version 0.41.
see also
More details
can be found at /usr/share/doc/gocr-X.XX/gocr.html.
Also read /usr/share/doc/gocr-X.XX/README to learn,
how to improve results.
author
Joerg Schulenburg (see
http://jocr.sourceforge.net/ for EMAIL)
First version of man page by
Tim Waugh <twaugh[:at:]redhat[:dot:]com>