<s>
OCRopus	B-Language
is	O
a	O
free	B-Application
document	B-Algorithm
analysis	I-Algorithm
and	O
optical	B-Application
character	I-Application
recognition	I-Application
(	O
OCR	O
)	O
system	O
released	O
under	O
the	O
Apache	B-Application
License	I-Application
v2.0	I-Application
with	O
a	O
very	O
modular	B-Architecture
design	O
using	O
command-line	B-Application
interfaces	I-Application
.	O
</s>
<s>
OCRopus	B-Language
is	O
developed	O
under	O
the	O
lead	O
of	O
Thomas	O
Breuel	O
from	O
the	O
German	O
Research	O
Centre	O
for	O
Artificial	O
Intelligence	O
in	O
Kaiserslautern	O
,	O
Germany	O
and	O
was	O
sponsored	O
by	O
Google	B-Application
.	I-Application
</s>
<s>
OCRopus	B-Language
was	O
especially	O
designed	O
for	O
use	O
in	O
high-volume	O
digitization	O
projects	O
of	O
books	O
,	O
such	O
as	O
Google	B-Application
Books	I-Application
,	O
Internet	O
Archive	O
or	O
libraries	O
.	O
</s>
<s>
The	O
main	O
components	O
of	O
OCRopus	B-Language
are	O
formed	O
:	O
</s>
<s>
The	O
modular	B-Architecture
approach	I-Architecture
allows	O
individual	O
workflows	O
to	O
be	O
used	O
and	O
individual	O
steps	O
to	O
be	O
exchanged	O
.	O
</s>
<s>
By	O
default	O
,	O
OCRopus	B-Language
comes	O
with	O
a	O
model	O
for	O
English	O
texts	O
and	O
a	O
model	O
for	O
text	O
in	O
Fraktur	O
.	O
</s>
<s>
Recent	O
text	B-Application
recognition	I-Application
is	O
based	O
on	O
recurrent	B-Algorithm
neural	I-Algorithm
networks	I-Algorithm
(	O
LSTM	B-Algorithm
)	O
and	O
does	O
not	O
require	O
a	O
language	B-Language
model	I-Language
.	O
</s>
<s>
On	O
9	O
April	O
2007	O
,	O
OCRopus	B-Language
was	O
announced	O
as	O
a	O
Google-sponsored	O
project	O
to	O
develop	O
advanced	O
OCR	O
technologies	O
.	O
</s>
<s>
In	O
return	O
,	O
OCRopus	B-Language
was	O
also	O
used	O
for	O
automatic	O
text	B-Application
recognition	I-Application
in	O
Google	B-Application
Book	I-Application
Search	I-Application
.	O
</s>
<s>
OCRopus	B-Language
has	O
received	O
further	O
funding	O
from	O
the	O
Andrew	O
W	O
.	O
Mellon	O
Foundation	O
and	O
the	O
BMBF	O
.	O
</s>
<s>
Originally	O
,	O
the	O
software	O
was	O
developed	O
in	O
C++	B-Language
,	O
Python	B-Language
and	O
Lua	B-Language
with	O
Jam	B-Application
as	O
a	O
build	B-Application
system	I-Application
.	O
</s>
<s>
A	O
complete	O
refactoring	O
of	O
the	O
source	O
code	O
in	O
Python	B-Language
modules	B-Architecture
was	O
done	O
and	O
released	O
in	O
version	O
0.5	O
(	O
June	O
2012	O
)	O
.	O
</s>
<s>
Initially	O
,	O
Tesseract	B-Language
was	O
used	O
as	O
the	O
only	O
text	B-Application
recognition	I-Application
module	B-Architecture
.	O
</s>
<s>
Since	O
2009	O
(	O
version	O
0.4	O
)	O
Tesseract	B-Language
was	O
only	O
supported	O
as	O
a	O
plugin	O
.	O
</s>
<s>
This	O
recognizer	O
was	O
then	O
used	O
together	O
with	O
OpenFST	O
for	O
language	B-Language
modeling	I-Language
after	O
the	O
recognition	O
step	O
.	O
</s>
<s>
From	O
2013	O
onwards	O
,	O
an	O
additional	O
recognition	O
with	O
recurrent	B-Algorithm
neural	I-Algorithm
networks	I-Algorithm
(	O
LSTM	B-Algorithm
)	O
was	O
offered	O
,	O
which	O
with	O
the	O
release	O
of	O
version	O
1.0	O
in	O
November	O
2014	O
is	O
the	O
only	O
recognizer	O
.	O
</s>
<s>
The	O
source	O
code	O
is	O
managed	O
over	O
GitHub	B-Application
and	O
is	O
maintained	O
and	O
developed	O
by	O
a	O
developer	O
community	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
OCRopus	B-Language
is	O
1.3.3	O
(	O
December	O
2017	O
)	O
.	O
</s>
<s>
Thomas	O
Breuel	O
also	O
developed	O
a	O
successor	O
OCRopus	B-Language
2	O
and	O
is	O
actively	O
working	O
on	O
OCRopus	B-Language
4	O
.	O
</s>
<s>
OCRopus	B-Language
can	O
be	O
used	O
from	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
It	O
will	O
output	O
the	O
recognized	O
text	O
to	O
standard	O
output	O
directly	O
or	O
write	O
it	O
as	O
hOCR	B-General_Concept
(	O
HTML-based	O
)	O
code	O
into	O
files	O
,	O
from	O
which	O
it	O
then	O
can	O
be	O
transformed	O
to	O
a	O
searchable	O
PDF	O
.	O
</s>
<s>
If	O
more	O
precise	O
control	O
is	O
needed	O
,	O
options	O
can	O
be	O
specified	O
on	O
the	O
command	B-Application
line	I-Application
to	O
perform	O
specific	O
operations	O
(	O
e.g.	O
</s>
<s>
Example	O
for	O
the	O
OCRopus	B-Language
calls	O
to	O
recognize	O
the	O
text	O
in	O
an	O
image	O
:	O
</s>
<s>
Other	O
tools	O
concentrate	O
on	O
the	O
training	O
part	O
of	O
OCRopus	B-Language
.	O
</s>
<s>
There	O
are	O
OCRopus	B-Language
models	O
to	O
extract	O
text	O
from	O
Latin	O
,	O
Greek	O
,	O
Cyrillic	O
and	O
Indic	O
scripts	O
.	O
</s>
