Well in this case it works without image processing ;-)
Anyway mrz is not "official" Tesseract training and there are people who
play with it, so it will take some time to search and dig
their findings/experience/expertise....
Zdenko
so 27. 1. 2024 o 12:02 sara waheed <sarawaheed3...@gmail.com> napísal(a):
> if I didn't research how would I know Tesseract needs image processing? I
> am new to OCR and in the learning phase please be kind and help thanks :)
>
> On Saturday, January 27, 2024 at 3:26:40 PM UTC+5 zdenop wrote:
>
>> What about reading docs and a little bit googling?
>>
>> tesseract two-page-passport-mrz-detected.jpeg - --psm 6 -l mrz
>>
>> IDAUT10000999<6<<<<<<<<<<<<<<<
>> 7109094F1112315AUT<<<<<<<<<<<6
>> MUSTERFRAU<<ISOLDE<<<<<<<<<<<<
>>
>>
>> Zdenko
>>
>>
>> so 27. 1. 2024 o 11:19 sara waheed <sarawah...@gmail.com> napísal(a):
>>
>>> I am trying to read the passport mrz string from the image i am using
>>> Tesseract and OpenCV for image processing i have tried three different ways
>>> none of them worked
>>>
>>> **Attempt 1**
>>> I have this image when i do ocr on it teseract read as
>>>
>>> IDAUT10000999<6<<<<<<<<<<<<<<<
>>> 7109094F1112315AUT<<<<<<xcc<<6
>>> MUSTERFRAU<<ISOLDE<<<<<<<<cc<<
>>>
>>> which is incorrect it treats <<< as x or c or k when I use the
>>> `mrz-java` library to read the details from the string it gives the
>>> following error
>>>
>>> [error] Error parsing MRZ string: Failed to parse MRZ MRTD_TD1
>>> IDAUT10000999<6<<<<<<<<<<<<<<<
>>> [error] 7109094F1112315AUT<<<<<<xcc<<6
>>> [error] MUSTERFRAU<<ISOLDE<<<<<<<<cc<<
>>> [error] at 24-25,1: Invalid character in MRZ record: x
>>>
>>> **Attempt 2**
>>>
>>> then I converted the image to grayscale and binarized it using `OpenCV`
>>> Here is the below code
>>>
>>> val roiImagePath =
>>> "src/main/resources/ocr/passport/two-page-passport-mrz-detected.jpeg"
>>>
>>> val grayScaleROI = new Mat()
>>> val roiImage = Imgcodecs.imread(roiImagePath)
>>> Imgproc.cvtColor(roiImage, grayScaleROI,
>>> Imgproc.COLOR_BGR2GRAY)
>>> val roiGaryImagePath =
>>> "src/main/resources/ocr/passport/two-page-passport-mrz-detected-gray.jpeg"
>>>
>>> Imgcodecs.imwrite(roiGaryImagePath, grayScaleROI)
>>> val binary = new Mat()
>>> Imgproc.adaptiveThreshold(grayScaleROI, binary, 255,
>>> Imgproc.ADAPTIVE_THRESH_MEAN_C, Imgproc.THRESH_BINARY , 15, 25)
>>> val roiBinaryImagePath =
>>> "src/main/resources/ocr/passport/two-page-passport-mrz-detected-binary.jpeg"
>>> Imgcodecs.imwrite(roiBinaryImagePath, binary)
>>>
>>> val tesseract = new Tesseract()
>>> tesseract.setDatapath("/usr/share/tesseract-ocr/4.00/tessdata")
>>> tesseract.setVariable("user_defined_dpi", "600")
>>> val result = tesseract.doOCR(new File(roiBinaryImagePath))
>>> val mrzStr = result.replace(" ", "")
>>> println(s"two page passport mrz string is: "+mrzStr)
>>>
>>> it created the following binary image
>>>
>>> and the code output is
>>> tesseract reads mrz string from the binary image as
>>>
>>> IDAUT1DODD999<E<KK<KKKKEKEKEK
>>> 7AD9D9GF1TEZSISAUTKKKKKKKKKEKG
>>> MUSTERFRAUSKISOLDEKKKKKKKKKKK
>>> and `mrz-java` reads the string and generates the following error
>>>
>>> [error] Error parsing MRZ string: Failed to parse MRZ null
>>> IDAUT1DODD999<E<KK<KKKKEKEKEK
>>> [error] 7AD9D9GF1TEZSISAUTKKKKKKKKKEKG
>>> [error] MUSTERFRAUSKISOLDEKKKKKKKKKKK
>>> [error] at 0-0,0: Different row lengths: 0: 29 and 1: 30
>>>
>>> **Attempt 3**
>>>
>>> then I resized the image
>>>
>>> Val width = 1000 // Increase width proportionately (adjust based on
>>> your needs)
>>> val height = (width * binary.rows()) / binary.cols() // Maintain
>>> aspect ratio
>>>
>>> val resizedRoiImage = new Mat()
>>> Imgproc.resize(binary, resizedRoiImage, new Size(width, height),
>>> 0.0, 0.0, Imgproc.INTER_NEAREST)
>>>
>>> val resizedImageROIPath =
>>>
>>> "src/main/resources/ocr/passport/two-page-passport-mrz-detected-binary-resized_image.jpg"
>>> Imgcodecs.imwrite(resizedImageROIPath, resizedRoiImage)
>>>
>>> mrz string read by Tesseract
>>>
>>> TOAUTIOOOOIISKhcceccccddddddce
>>> FIOPOSAFIFESSISAUTReececeececs
>>> MUSTERFRAUCCKISOLDECKccccdcddd
>>>
>>> and the error is
>>>
>>> [info] 15:54:04.200 633 [main] MrzParser INFO - Check digit
>>> verification failed for document number: expected 0 but got h
>>> [error] Error parsing MRZ string: Failed to parse MRZ MRTD_TD1
>>> TOAUTIOOOOIISKhcceccccddddddce
>>> [error] FIOPOSAFIFESSISAUTReececeececs
>>> [error] MUSTERFRAUCCKISOLDECKccccdcddd
>>> [error] at 15-16,0: Invalid character in MRZ record: c
>>>
>>>
>>> can anyone please help how I read the text properly also I have tried
>>> one regex to convert c or k back to <<< it did not work either if anyone
>>> can suggest some workaround or any improvement in code please help me with
>>> that thanks
>>>
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>>>
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