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 <sarawaheed3...@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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