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Whitelist not working #4407

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@kylefoley76

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@kylefoley76

Current Behavior

I'm using Tesseract with Python because it's too difficult to OCR when the languages are mixed between the Greek alphabet and the Latin alphabet. Too often I will get Cyrillic characters as an output. I was hoping that the whitelist feature would solve that problem. But this is not the case. When I input the following whitelist,

αςερτυθιοπλκξηγφδσζχψωβνμΣΕΡΤΥΘΙΟΠΛΚΞΗΓΦΔΣΑΖΧΨΩΒΝΜΑΖΧΨΩΒΝΜABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890/?<>{}*&,;.:-+=|1234567890

I get a reasonably good output for the Latin characters, but the Greek text is not very accurate. for example, here is an output

Contracted nouns and adjectives in -ους from -οος 63
Adjectives of material in -ots from -εος 64
Nouns in ts, -εως and -υς/-υ, -εως 65

But the correct output should be οῦς not -ots

However, even if the accuracy were 100%, that whitelist will not solve my problem because it does not use the diacritics. So when I use a whitelist with diacritics, such as

"ΆᾺΑἉἊἍἋἌᾍᾈᾌᾎᾉAΒΔΗΉἩἨἮἯἬἫἭἪῌᾞᾟᾜᾘᾙῊἜἚἝἛἘἙΈΕΓΙῚἾἿἽἻἺἼἹἸΊIΚΧΞΛΜΝὩὨῼὭὫὬὪὯὮΩΏὉὈὊὋὌὍΟΌῸῺᾨᾩᾯᾮᾪᾫᾬᾭΠΦΨῬΡΣΤΘὝὛὙΎΥὟΖᾅᾳᾇᾄᾂᾀᾷᾆᾴᾲἇἆἂἄἅἃάᾶὰαἁἀααᾁᾃβδέὲἕἓἒἔἑἐεἠῆᾖἧᾔᾐᾑἥἣᾕἡἦῄῂῇᾗηῃήὴἤἢᾒᾓγϊῖιἰἶἴἲἱΐῒὶίἷἵἳῗιικχλμνὁᾦὀοῷὧωὠᾡὦῳῶὡᾠᾧῴῲὢὤὥὣᾤᾢὅὃὄὂόὸώὼᾣᾥπφψῤῥρςστθὖϋὗῧὐὑυῦὔὒύὺὓὕῢΰυυϝξζΑΖΧΨΩΒΝΜABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890/?<>{}*&,;.:-+=|1234567890 "

I get the output:

ΝΕΗΟΓΑΑΠΚ
Α
ΑΟΗΠΓΠΟΠ
ΑΟΕΠΓ
ΑΕΠΓΟ
ΑΠ
ἸΑΓΝΠΑΟΕΕ
ΡΟΡΟΠ
ΑΙΟΓΠΊ
ΠΟΙΠΕΟΓΠΓΕΠΟΏΡΒΡ
ΑΓ Ι
ΙΠΠΠΠΊΒΠ

I've tried locating the characters that are messing things up but there are too many. But it is certainly not any of these characters: /?<>{}*&,;.:-+=|

The image I'm trying to scan is uploaded. here is the exact python code I'm using:

import pytesseract
custom_oem_psm_config = '--oem 3 --psm 6 -c tessedit_char_whitelist="{}"'.format(
"ΆᾺΑἉἊἍἋἌᾍᾈᾌᾎᾉAΒΔΗΉἩἨἮἯἬἫἭἪῌᾞᾟᾜᾘᾙῊἜἚἝἛἘἙΈΕΓΙῚἾἿἽἻἺἼἹἸΊIΚΧΞΛΜΝὩὨῼὭὫὬὪὯὮΩΏὉὈὊὋὌὍΟΌῸῺᾨᾩᾯᾮᾪᾫᾬᾭΠΦΨῬΡΣΤΘὝὛὙΎΥὟΖᾅᾳᾇᾄᾂᾀᾷᾆᾴᾲἇἆἂἄἅἃάᾶὰαἁἀααᾁᾃβδέὲἕἓἒἔἑἐεἠῆᾖἧᾔᾐᾑἥἣᾕἡἦῄῂῇᾗηῃήὴἤἢᾒᾓγϊῖιἰἶἴἲἱΐῒὶίἷἵἳῗιικχλμνὁᾦὀοῷὧωὠᾡὦῳῶὡᾠᾧῴῲὢὤὥὣᾤᾢὅὃὄὂόὸώὼᾣᾥπφψῤῥρςστθὖϋὗῧὐὑυῦὔὒύὺὓὕῢΰυυϝξζΑΖΧΨΩΒΝΜABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890\/?<>{}[]()*&,;.:-+=| "
)
str4 = pytesseract.image_to_string(img1, config=custom_oem_psm_config,lang='eng+ell')
print(str4)

I'm using pytesseract 0.3.13 and I have tesseract 5.3.8 installed. Also chatgpt informs me that sometimes tessearact cannot handle large whitelists. if that is the case then i think it would be very easy to solve that problem.

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