This rich and prolific sample source code in VB.NET for ByteScout PDF Suite contains various functions and options you should do calling the API to implement ocr with best dataset with pdf extractor sdk. Follow the steps-by-step instructions from the scratch to work and copy and paste code for VB.NET into your editor. Further improvement of the code will make it more robust.
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Imports Bytescout.PDFExtractor ' This example demonstrates the use of Optical Character Recognition (OCR) to extract text ' from scanned PDF documents and raster images. ' To make OCR work you should add the following references to your project: ' "Bytescout.PDFExtractor.dll", "Bytescout.PDFExtractor.OCRExtension.dll". Class Program Friend Shared Sub Main(args As String()) ' Create Bytescout.PDFExtractor.TextExtractor instance Dim extractor As New TextExtractor() extractor.RegistrationName = "demo" extractor.RegistrationKey = "demo" ' Load sample PDF document extractor.LoadDocumentFromFile("sample_ocr.pdf") ' Enable Optical Character Recognition (OCR) ' in .Auto mode (SDK automatically checks if needs to use OCR or not) extractor.OCRMode = OCRMode.Auto ' Set the location of OCR language data files extractor.OCRLanguageDataFolder = "c:\Program Files\Bytescout PDF Extractor SDK\ocrdata_best" ' Set OCR language extractor.OCRLanguage = "eng" ' "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/tree/master/ocrdata_best ' Set PDF document rendering resolution extractor.OCRResolution = 300 ' You can also apply various preprocessing filters ' to improve the recognition on low-quality scans. ' Automatically deskew skewed scans 'extractor.OCRImagePreprocessingFilters.AddDeskew() ' Remove vertical or horizontal lines (sometimes helps to avoid OCR engine's page segmentation errors) 'extractor.OCRImagePreprocessingFilters.AddVerticalLinesRemover() 'extractor.OCRImagePreprocessingFilters.AddHorizontalLinesRemover() ' Repair broken letters 'extractor.OCRImagePreprocessingFilters.AddDilate() ' Remove noise 'extractor.OCRImagePreprocessingFilters.AddMedian() ' Apply Gamma Correction 'extractor.OCRImagePreprocessingFilters.AddGammaCorrection() ' Add Contrast ' extractor.OCRImagePreprocessingFilters.AddContrast(20) ' (!) You can use new OCRAnalyzer class to find an optimal set of image preprocessing ' filters for your specific document. ' See "OCR Analyser" example. ' Save extracted text to file extractor.SaveTextToFile("output.txt") ' Cleanup extractor.Dispose() ' Open output file in default associated application System.Diagnostics.Process.Start("output.txt") End Sub End Class