Check your tesseract version (tesseract -v). Here is mine:
tesseract 5.1.0-70-g0df5
leptonica-1.83.0 (Jun 24 2022, 17:48:50) [MSC v.1929 LIB Release x64]
libgif 5.2.1 : libjpeg 6b (libjpeg-turbo 2.0.91) : libpng 1.6.37 :
libtiff 4.4.0 : zlib 1.2.12 : libwebp 1.2.2 : libopenjp2 2.5.0
Found AVX2
Found AVX
Found FMA
Found SSE4.1
Found libarchive 3.5.1 zlib/1.2.11 liblzma/5.2.4 bz2lib/1.0.6 libzstd/1.4.9
Found libcurl/7.75.0 zlib/1.2.12 libssh2/1.10.1_DEV
+ try to use (eng) data file from tessdata_best[1] (also just tessdata[2]
produce a result)
Regarding image:
1. I took output from your code "cv2.imwrite('pH.jpg', ph)" (jpg is not
good format for ocr)
2. I opened it as grayscale and I see 2 problems covered by
documentation:
- it needs to be inverted
- it needs to be resized to the height of letters is between 30-40
points.
3. I guess sharpening (to increase space between dot and 3) would help
to recognize dot.
4. Binarize/threshold image by yourself. Tesseract has some binarize
algorithms, but you can another one that better fit your case.
I suggest doing image preprocessing in the image editor (to check what
helps) and then implementing it into code.
[1] https://github.com/tesseract-ocr/tessdata_best
[2] https://github.com/tesseract-ocr/tessdata
Zdenko
ne 26. 6. 2022 o 0:23 Hervé <herve.hey...@gmail.com> napísal(a):
> Sorry I am really noob
>
> When I do : tesseract pH_treshr.png -
> I have :
> Empty page!!
> Empty page!!
>
> How do you achieve to have this image ? and why can't I tesseract it like
> you ? I am on buster with tesseract 5.1
>
> is there a way to discuss ? discord ?
>
> thanks for your patience and help
>
> Le samedi 25 juin 2022 à 14:34:06 UTC+2, zdenop a écrit :
>
>> Sorry - I mean Rescaling:
>>
>> Tesseract works best on images which have a DPI of at least 300 dpi, so
>> it may be beneficial to resize images. For more information see the FAQ.
>> "Willus Dotkom" made interesting test for Optimal image resolution with
>> suggestion for optimal Height of capital letter in pixels:
>> https://groups.google.com/g/tesseract-ocr/c/Wdh_JJwnw94/m/24JHDYQbBQAJ
>>
>>
>> After that, you can get output (but the dot is missing) with the command
>> line: "tesseract pH_treshr.png -"
>>
>> I was able to get the decimal point separator with the letsgodigital data
>> file
>> https://github.com/arturaugusto/display_ocr/blob/master/letsgodigital/letsgodigital.traineddata
>> tesseract pH_treshr.png - -l letsgodigital
>>
>> Or have a look at SSD https://github.com/Shreeshrii/tessdata_ssd
>>
>> Zdenko
>>
>>
>> so 25. 6. 2022 o 12:17 Hervé <herve....@gmail.com> napísal(a):
>>
>>> I am on tesseract 5
>>>
>>> Inverting images
>>>
>>> While tesseract version 3.05 (and older) handle inverted image (dark
>>> background and light text) without problem, for 4.x version use dark text
>>> on light background.
>>> isn'it the same than :
>>> (thresh, im_bw) = cv2.threshold(gray, 128, 255, cv2.THRESH_BINARY |
>>> cv2.THRESH_OTSU)
>>> im_bw = cv2.bitwise_not(im_bw)
>>>
>>> for resizing, I take my picture in full HD, do increasing resolution
>>> will allow tesseract to better OCR ?
>>>
>>> thanks
>>>
>>>
>>> Le samedi 25 juin 2022 à 11:25:50 UTC+2, zdenop a écrit :
>>>
>>>> Why you did not try more relevant hits like inverting and resizing?
>>>>
>>>> Zdenko
>>>>
>>>>
>>>> so 25. 6. 2022 o 10:56 Hervé <herve....@gmail.com> napísal(a):
>>>>
>>>>> I tried gray image, black and white, and I use
>>>>>
>>>>> custom_psm = r'--psm 7'
>>>>>
>>>>> didn't try others parameters
>>>>> Le samedi 25 juin 2022 à 10:32:14 UTC+2, zdenop a écrit :
>>>>>
>>>>>>
>>>>>>
>>>>>> so 25. 6. 2022 o 8:15 Hervé <herve....@gmail.com> napísal(a):
>>>>>>
>>>>>>> Hi
>>>>>>> I just tried some, without real success
>>>>>>>
>>>>>>> Please be specific: what did you try and what was the result?
>>>>>>
>>>>>>
>>>>>>
>>>>>>> could I learn digits from pictures ? maybe this font is not well
>>>>>>> recognized
>>>>>>>
>>>>>>
>>>>>> Any training is useless if the failure is at the image preprocessing
>>>>>> stage.
>>>>>>
>>>>>>
>>>>>>> thanks
>>>>>>>
>>>>>>> Le vendredi 24 juin 2022 à 17:12:44 UTC+2, zdenop a écrit :
>>>>>>>
>>>>>>>> Did try to implement suggestion from documentation?
>>>>>>>> https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md
>>>>>>>>
>>>>>>>>
>>>>>>>> Zdenko
>>>>>>>>
>>>>>>>>
>>>>>>>> pi 24. 6. 2022 o 16:59 Hervé <herve....@gmail.com> napísal(a):
>>>>>>>>
>>>>>>>>> Hi, I need some help to make tesseract-OCR recognize digits :
>>>>>>>>> can't achieve to make this work with
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> https://img.super-h.fr/images/2022/06/24/9a03414616bc4c6bd6e4bdb78e9d6783.jpg
>>>>>>>>>
>>>>>>>>> here is my code :
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> import cv2
>>>>>>>>> import pytesseract
>>>>>>>>>
>>>>>>>>> pytesseract.pytesseract.tesseract_cmd ="C:\\Program
>>>>>>>>> Files\\Tesseract-OCR\\tesseract.exe"
>>>>>>>>>
>>>>>>>>> def process_image(img):
>>>>>>>>> #cv2.imshow('Img',img)
>>>>>>>>> #cv2.waitKey(0)
>>>>>>>>>
>>>>>>>>> ### passage en niveau de gris
>>>>>>>>> gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
>>>>>>>>> #cv2.imshow('Img',gray)
>>>>>>>>> #v2.waitKey(0)
>>>>>>>>>
>>>>>>>>> ###analyse de l'image
>>>>>>>>> valeur = pytesseract.image_to_string(gray)
>>>>>>>>> print(valeur)
>>>>>>>>>
>>>>>>>>> ##passage en noir et blanc
>>>>>>>>> (thresh, im_bw) = cv2.threshold(gray, 128, 255,
>>>>>>>>> cv2.THRESH_BINARY | cv2.THRESH_OTSU)
>>>>>>>>> im_bw = cv2.bitwise_not(im_bw)
>>>>>>>>> #cv2.imshow('Img',im_bw)
>>>>>>>>> #cv2.waitKey(0)
>>>>>>>>> # cv2.imwrite('ph.png',im_bw)
>>>>>>>>> print(pytesseract.image_to_string(im_bw))
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ###ouverture de l'image
>>>>>>>>> img = cv2.imread('ocr5.png')
>>>>>>>>> # cv2.imshow('Img',imgcoupee)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ###on rogne
>>>>>>>>> imgcoupee = img[1056:1517,950:1862]
>>>>>>>>> #img = cv2.imwrite('ocrcoupee.png',imgcoupee)
>>>>>>>>> # cv2.imshow('Img',imgcoupee)
>>>>>>>>>
>>>>>>>>> ### decoupage de la partie correspondant au PH
>>>>>>>>> ph= img[516:625, 616:815]
>>>>>>>>>
>>>>>>>>> #cv2.imwrite('pH.jpg', image_pH)
>>>>>>>>>
>>>>>>>>> ### partie chlore
>>>>>>>>> cl = img[516:625, 882:1056]
>>>>>>>>>
>>>>>>>>> ### partie dÃ:copyright:faut flow
>>>>>>>>> #flow= img[1302:1398,1054:1400]
>>>>>>>>>
>>>>>>>>> ### process
>>>>>>>>> #process_image(imgcoupee)
>>>>>>>>> process_image(ph)
>>>>>>>>> process_image(cl)
>>>>>>>>> #process_image(flow)
>>>>>>>>>
>>>>>>>>> digits seems to be clear enough, but it does'nt work, if someone
>>>>>>>>> could help me ?
>>>>>>>>>
>>>>>>>>> thanks !
>>>>>>>>>
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