EnablePreprocessing Property

Summary

Enables applying auto segmentation and deep auto pre-processing to the image and then re-scanning if no barcodes of this symbology are found.

Syntax

Objective-C

C++/CLI

Python

public bool EnablePreprocessing { get; set; }

@property (nonatomic, assign) BOOL enablePreprocessing;

public:  
   property bool EnablePreprocessing 
   { 
      bool get() 
      void set(bool value) 
   }

EnablePreprocessing # get and set (PDF417BarcodeReadOptions)

Property Value

true to apply auto segmentation and deep auto pre-processing to the image then re-scanning if no barcodes of this symbology are found, otherwise; false. The default value is false.

Remarks

When reading 2D barcodes, LEADTOOLS can perform internal auto preprocessing and segmentation on the image and try again if the engine cannot detect the barcode required. This may take extra processing and increase the barcode detection time. Therefore, it is best to set EnablePreprocessing to true only in certain situations, as follows:

The application is reading barcodes of this type exclusively (for example, a dedicated barcode reader is being used). In this case, reading the barcodes is always more important than recognition speed.
The application uses barcode detection on a server. Due to network latency, the time spent on the actual barcode detection is most probably less than the time required to send the image to the server and get the result back. Thus, it makes sense to enable pre-processing in this situation.
The images provided have a small resolution (DPI) or are known to come from a source that does not always provide clean images (for example, a Fax machine or a Scanner). Enabling pre-processing here ensures that the barcodes can be read regardless of the quality of the input image.

The LEADTOOLS .NET C# Barcode demos leave pre-processing disabled by default. If the engine tries to read a barcode of this type but cannot find it, it will then ask the user if EnablePreprocessing should be enabled and reading be retried. An approach like that (or an automated one: Read. If failure, enable and read again) can also be used.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Barcode; 
using Leadtools.ImageProcessing; 
 
 
public void PDF417Barcode_Example() 
{ 
   string imageFileName = Path.Combine(LEAD_VARS.ImagesDir, "MyPDF417Barcodes.tif"); 
 
   BarcodeEngine engine = new BarcodeEngine(); 
 
   // Create the image to write the barcodes to 
   int resolution = 300; 
   using (RasterImage image = RasterImage.Create((int)(8.5 * resolution), (int)(11.0 * resolution), 1, resolution, RasterColor.FromKnownColor(RasterKnownColor.White))) 
   { 
      // Write two PDF417 barcodes 
      WriteBarcode(engine.Writer, image, "DATA1", 10, 10, true); 
      WriteBarcode(engine.Writer, image, "DATA2", 20, 20, false); 
 
      // Save the image 
      using (RasterCodecs codecs = new RasterCodecs()) 
      { 
         codecs.Save(image, imageFileName, RasterImageFormat.CcittGroup4, 1); 
      } 
   } 
 
   // Now read the barcodes again 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      using (RasterImage image = codecs.Load(imageFileName)) 
      { 
         ReadBarcodes(engine.Reader, image); 
      } 
   } 
} 
 
private void WriteBarcode(BarcodeWriter writer, RasterImage image, string value, int rows, int columns, bool topLeft) 
{ 
   // Create the barcode data 
   PDF417BarcodeData barcode = new PDF417BarcodeData(); 
   barcode.Value = value; 
   barcode.Group = 0; 
   barcode.Symbology = BarcodeSymbology.PDF417; 
 
   // We will use the alignment to position the barcodes, so use all of the image 
   barcode.Bounds = new LeadRect(0, 0, image.ImageWidth, image.ImageHeight); 
 
   // Set the write options 
   PDF417BarcodeWriteOptions options = new PDF417BarcodeWriteOptions(); 
 
   if (topLeft) 
   { 
      options.HorizontalAlignment = BarcodeAlignment.Near; 
      options.VerticalAlignment = BarcodeAlignment.Near; 
   } 
   else 
   { 
      options.HorizontalAlignment = BarcodeAlignment.Far; 
      options.VerticalAlignment = BarcodeAlignment.Far; 
   } 
 
   options.Truncated = false; 
   options.EnableGroupMode = false; 
   options.SymbolWidthAspectRatio = 2; 
   options.SymbolHeightAspectRatio = 1; 
   options.LimitByRowsAndColumns = true; 
   options.Rows = rows; 
   options.Columns = columns; 
   options.XModule = 30; 
   options.XModuleAspectRatio = 3; 
   options.ECCLevel = PDF417BarcodeECCLevel.Level0; 
   options.ECCPercentage = 0; 
 
   // Write it 
   Console.WriteLine("Writing barcode with symbol rows/columns: {0}/{1} and Data: {2}", rows, columns, value); 
   writer.WriteBarcode(image, barcode, options); 
} 
 
private void ReadBarcodes(BarcodeReader reader, RasterImage image) 
{ 
   // Setup read options 
   PDF417BarcodeReadOptions options = new PDF417BarcodeReadOptions(); 
   options.SearchDirection = BarcodeSearchDirection.Horizontal; 
   options.EnableDoublePass = false; 
   options.EnableFastMode = false; 
   options.ReadMode = PDF417BarcodeReadMode.Mode0; 
   options.ReturnCorruptedSymbolArea = false; 
   options.ReadOptionalMacroFileNameField = false; 
   options.ReadOptionalMacroSegmentCountField = false; 
   options.ReadOptionalMacroTimestampField = false; 
   options.ReadOptionalMacroSenderField = false; 
   options.ReadOptionalMacroAddresseeField = false; 
   options.ReadOptionalMacroFileSizeField = false; 
   options.ReadOptionalMacroChecksumField = false; 
   options.ReadOptionalMacro79AndAZField = false; 
   options.EnableDoublePassIfSuccess = true; 
   options.EnableNoIndicatorTrail = true; 
   options.EnablePreprocessing = true; 
 
   Console.WriteLine("Reading Barcodes"); 
   BarcodeData[] barcodes = reader.ReadBarcodes(image, LeadRect.Empty, 0, new BarcodeSymbology[] { BarcodeSymbology.PDF417 }, new BarcodeReadOptions[] { options }); 
   Console.WriteLine("{0} barcodes found:", barcodes.Length); 
   foreach (PDF417BarcodeData barcode in barcodes) 
   { 
      Console.WriteLine(" At {0} data: {1} and symbology: {2}", barcode.Bounds, barcode.Value, barcode.Symbology); 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

PDF417BarcodeReadOptions Class

PDF417BarcodeReadOptions Members

Leadtools.Barcode Namespace

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Help Version 22.0.2023.5.9

Leadtools.Barcode Assembly

Introduction

Getting Started

Namespaces

Leadtools.Barcode Namespace

Assemblies