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Use Image Preprocessing Filters - PowerShell

Text Recognition SDK sample in PowerShell demonstrating ‘Use Image Preprocessing Filters’

ImagePreprocessingFilters.ps1
# Add reference to ByteScout.TextRecognition.dll assembly
Add-Type -Path "c:\Program Files\ByteScout Text Recognition SDK\net40\ByteScout.TextRecognition.dll"

$InputDocument = "skewed.png"
$OutputDocument = ".\result.txt"

# Create and activate TextRecognizer instance
$textRecognizer = New-Object ByteScout.TextRecognition.TextRecognizer
$textRecognizer.RegistrationName = "demo"
$textRecognizer.RegistrationKey = "demo"

try {
    # Load document (image or PDF)
    $textRecognizer.LoadDocument($InputDocument)

    # Set the location of OCR language data files
    $textRecognizer.OCRLanguageDataFolder = "c:\Program Files\ByteScout Text Recognition SDK\ocrdata_best\"

    # Set OCR language.
    # "eng" for english, "deu" for German, "fra" for French, "spa" for Spanish, etc. - according to files in "ocrdata" folder
    # Find more language files at https://github.com/bytescout/ocrdata
    $textRecognizer.OCRLanguage = "eng"


    # Add deskew filter that automatically rotates the image to make the text horizontal.
    # Note, it analyzes the left edge of scanned text. Any dark artifacts may prevent 
    # the correct angle detection.
    $textRecognizer.ImagePreprocessingFilters.AddDeskew()

    # Other filters that may be useful to improve recognition
    # (note, the filters are applied in the order they were added):

    # Improve image contrast.
    #$textRecognizer.ImagePreprocessingFilters.AddContrast()

    # Apply gamma correction.
    #$textRecognizer.ImagePreprocessingFilters.AddGammaCorrection()

    # Apply median filter. Helps to remove noise.
    #$textRecognizer.ImagePreprocessingFilters.AddMedian()

    # Apply dilate filter. Helps to cure symbols erosion.
    #$textRecognizer.ImagePreprocessingFilters.AddDilate()

    # Lines removers. Removing borders of some tables may improve the recognition.
    #$textRecognizer.ImagePreprocessingFilters.AddHorizontalLinesRemover()
    #$textRecognizer.ImagePreprocessingFilters.AddVerticalLinesRemover()


    # Recognize text from all pages and save it to file
    $textRecognizer.SaveText($OutputDocument)

    # Open the result file in default associated application (for demo purposes)
    & $OutputDocument
}
catch {
    # Display exception
    Write-Host $_.Exception.Message
}

$textRecognizer.Dispose()

run.bat
@echo off

powershell -NoProfile -ExecutionPolicy Bypass -Command "& .\ImagePreprocessingFilters.ps1"
echo Script finished with errorlevel=%errorlevel%

pause

Download Source Code (.zip)

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