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HolePunchRemoveCommand Class

Finds and removes hole punches.
public class HolePunchRemoveCommand : RasterCommand 
public class HolePunchRemoveCommand 
    extends RasterCommand 
public ref class HolePunchRemoveCommand : public RasterCommand   
class HolePunchRemoveCommand(RasterCommand): 

This command is available in the Document/Medical Toolkits.

  • This command detects and removes hole punches that are common in scanned documents. The behavior of this command can be modified by using the HolePunchRemoveCommandEventHandler delegate method.
  • This command works only on 1-bit black and white images.
  • Hole punch configurations may consist of 2 or more holes.
  • If a region is selected, only the selected region will be changed by this command. If no region is selected, the whole image will be processed.
  • This command does not support signed data images.
  • This command does not support 32-bit grayscale images.
  • Before calling this function, ensure that the hole punch is free of any other stray marks. If you do not, the hole will not be recognized. Use the LineRemoveCommand command to remove any horizontal or vertical lines from the image. Use the other Document Cleanup functions to remove other imaging artifacts such as dots, blobs, borders, inverted text, bumps and nicks. This will have the added benefit of making your image smaller when compressed.

For example, the following image must have the vertical line removed:


Once the image has been cleaned, as shown in the following figure, the hole punch can be removed:


For more information, refer to Cleaning Up 1-Bit Images.

Hole Punch Remove Function - Before

Hole Punch Remove Function - Before

Hole Punch Remove Function - After

Hole Punch Remove Function - After

View additional platform support for this Hole Punch Remove function.


Run the HolePunchRemoveCommand on an image.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Core; 
public void HolePunchRemoveCommandExample() 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Clean.tif")); 
   // Prepare the command 
   HolePunchRemoveCommand command = new HolePunchRemoveCommand(); 
   command.HolePunchRemove += new EventHandler<HolePunchRemoveCommandEventArgs>(HolePunchRemoveEvent_S1); 
   command.Flags = HolePunchRemoveCommandFlags.UseDpi | HolePunchRemoveCommandFlags.UseCount | HolePunchRemoveCommandFlags.UseLocation; 
   command.Location = HolePunchRemoveCommandLocation.Left; 
   command.MaximumHoleCount = 4; 
   command.MinimumHoleCount = 2; 
private void HolePunchRemoveEvent_S1(object sender, HolePunchRemoveCommandEventArgs e) 
   MessageBox.Show("Size " + "( " + e.BoundingRectangle.Left + ", " + e.BoundingRectangle.Top + ") - " + "( " + e.BoundingRectangle.Right + ", " + e.BoundingRectangle.Bottom + ")" + 
      "\n Hole Index " + e.HoleIndex.ToString() + 
      "\n Holes Total Count " + e.HoleTotalCount.ToString() + 
      "\n Black Count " + e.BlackCount.ToString() + 
      "\n White Count " + e.WhiteCount.ToString()); 
   e.Status = RemoveStatus.Remove; 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 

Target Platforms

Help Version 22.0.2023.3.31
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Leadtools.ImageProcessing.Core Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.