Basta instalar a linguagem ocr necessária usando isto:
sudo apt-get install tesseract-ocr-[lang]
Onde [lang] pode ser
all
OR
afr
amh
ara
asm
aze
aze-cyrl
bel
ben
bod
bos
bul
cat
ceb
ces
chi-sim
chi-tra
chr
cym
dan
dan-frak
deu
deu-frak
dev
dzo
ell
enm
epo
est
eus
fas
fin
fra
frk
frm
gle
gle-uncial
glg
grc
guj
hat
heb
hin
hrv
hun
iku
ind
isl
ita
ita-old
jav
jpn
kan
kat
kat-old
kaz
khm
kir
kor
kur
lao
lat
lav
lit
mal
mar
mkd
mlt
msa
mya
nep
nld
nor
ori
pan
pol
por
pus
ron
rus
san
sin
slk
slk-frak
slv
spa
spa-old
sqi
srp
srp-latn
swa
swe
syr
tam
tel
tgk
tgl
tha
tir
tur
uig
ukr
urd
uzb
uzb-cyrl
vie
yid