ByteScout Barcode Reader SDK – VB.NET – Barcode Image Preprocessing Filters

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ByteScout Barcode Reader SDK – VB.NET – Barcode Image Preprocessing Filters

printable version:
ByteScout-BarCode-Reader-SDK-VB-NET-Barcode-Image-Preprocessing-Filters.pdf

barcode image preprocessing filters in VB.NET and ByteScout BarCode Reader SDK

Write code in VB.NET to make barcode image preprocessing filters with this How-To tutorial

The documentation is designed to help you to implement the features on your side. ByteScout BarCode Reader SDK was made to help with barcode image preprocessing filters in VB.NET. ByteScout BarCode Reader SDK is the barcode decoder with support for code 39, code 128, QR Code, Datamatrix, GS1, PDF417 and all other popular barcodes. Can read barcodes from images, pdf, tiff documents and live web camera. Supports noisy and damaged documents, can split and merge pdf and tiff documents based on barcodes. Can export barcode decoder results to XML, JSON, CSV and into custom data structures.

The SDK samples like this one below explain how to quickly make your application do barcode image preprocessing filters in VB.NET with the help of ByteScout BarCode Reader SDK. To do barcode image preprocessing filters in your VB.NET project or application you may simply copy & paste the code and then run your app! Code testing will allow the function to be tested and work properly with your data.

Free trial version of ByteScout BarCode Reader SDK is available on our website. Get it to try other samples for VB.NET.

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Module1.vb

      Imports Bytescout.BarCodeReader

Module Module1
    ''' <summary>
    ''' This exmaple demonstrates the use of image filters to improve the decoding or speed.
    ''' </summary>
    Sub Main()

        Using reader As New Reader("demo", "demo")

            ' Set barcode type to find
            reader.BarcodeTypesToFind.Code128 = True


            ' WORKING WITH LOW CONTRAST BARCODE IMAGES

            ' Add the contrast adjustment for the low contrast image
            reader.ImagePreprocessingFilters.AddContrast(40)

            Console.WriteLine("Image {0}", "low-contrast-barcode.png")

            ' -----------------------------------------------------------------------
            ' NOTE: We can read barcodes from specific page to increase performance .
            ' For sample please refer to "Decoding barcodes from PDF by pages" program.
            ' ----------------------------------------------------------------------- 

            Dim barcodes As FoundBarcode() = reader.ReadFrom("low-contrast-barcode.png")

            If barcodes.Length = 0 Then
                Console.WriteLine("No barcode found!")
            Else
                For Each barcode As FoundBarcode In barcodes
                    Console.WriteLine("Found barcode {0} with value '{1}'", barcode.Type, barcode.Value)
                Next
            End If

            reader.ImagePreprocessingFilters.Clear()
            Console.WriteLine()


            ' WORKING WITH NOISY BARCODE IMAGES

            ' Add the median filter to lower the noise
            reader.ImagePreprocessingFilters.AddMedian()

            Console.WriteLine("Image {0}", "noisy-barcode.png")

            barcodes = reader.ReadFrom("noisy-barcode.png")

            If barcodes.Length = 0 Then
                Console.WriteLine("No barcode found!")
            Else
                For Each barcode As FoundBarcode In barcodes
                    Console.WriteLine("Found barcode {0} with value '{1}'", barcode.Type, barcode.Value)
                Next
            End If

            reader.ImagePreprocessingFilters.Clear()
            Console.WriteLine()


            ' WORKING WITH DENSE AND ILLEGIBLE BARCODES

            ' Add the scale filter to enlarge the barcode to make gaps between bars more distinguishable
            reader.ImagePreprocessingFilters.AddScale(2) ' enlarge twice

            Console.WriteLine("Image {0}", "too-dense-barcode.png")

            barcodes = reader.ReadFrom("too-dense-barcode.png")

            If barcodes.Length = 0 Then
                Console.WriteLine("No barcode found!")
            Else
                For Each barcode As FoundBarcode In barcodes
                    Console.WriteLine("Found barcode {0} with value '{1}'", barcode.Type, barcode.Value)
                Next
            End If

            reader.ImagePreprocessingFilters.Clear()
            Console.WriteLine()


            ' REMOVE EMPTY MARGINS FROM IMAGE TO SPEED UP THE PROCESSING

            ' Add the crop filter to cut off empty margins from the image.
            ' This will not improve the recognition quality but may speed up the processing 
            ' if you enabled multiple barcode types to search. 
            reader.ImagePreprocessingFilters.AddCropDark()

            Console.WriteLine("Image {0}", "barcode-with-large-margins.png")

            barcodes = reader.ReadFrom("barcode-with-large-margins.png")

            If barcodes.Length = 0 Then
                Console.WriteLine("No barcode found!")
            Else
                For Each barcode As FoundBarcode In barcodes
                    Console.WriteLine("Found barcode {0} with value '{1}'", barcode.Type, barcode.Value)
                Next
            End If

            reader.ImagePreprocessingFilters.Clear()
            Console.WriteLine()

        End Using

        Console.WriteLine("Press any key to exit..")
        Console.ReadKey()

    End Sub

End Module