In this tutorial, you will learn how to easily remove lines from your documents as a reason of preprocessing for OCR purposes or others.

Before / After

There are two ways to remove lines from your image:

1. If you want to remove all lines that usually occur in form, let the engine handle finding the lines internally.

   • VB.NET
   • C#

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   'We assume that GdPicture has been correctly installed and unlocked. Dim oGdPictureImaging As New GdPictureImaging() 'Loading the image from a file. Dim imageId As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("input.tif") 'Checking if the image resource has been loaded correctly. If oGdPictureImaging.GetStat() <> GdPictureStatus.OK Then MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) Else 'Now you clean up your lines. Dim status As GdPictureStatus = oGdPictureImaging.RemoveLines(imageId, LineRemoveOrientation.Horizontal Or LineRemoveOrientation.Horizontal) If status <> GdPictureStatus.OK Then MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) Else 'After you are done with your processing, you can save the image. status = oGdPictureImaging.SaveAsTIFF(imageId, "cleanedImage.tif", TiffCompression.TiffCompressionAUTO) If status <> GdPictureStatus.OK Then MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) End If End If oGdPictureImaging.ReleaseGdPictureImage(imageId) End If oGdPictureImaging.Dispose()

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   //We assume that GdPicture has been correctly installed and unlocked. GdPictureImaging oGdPictureImaging = new GdPictureImaging(); //Loading the image from a file. int imageId = oGdPictureImaging.CreateGdPictureImageFromFile("input.tif"); //Checking if the image resource has been loaded correctly. if (oGdPictureImaging.GetStat() != GdPictureStatus.OK) { MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } else { //Now you clean up your lines. GdPictureStatus status = oGdPictureImaging.RemoveLines(imageId, LineRemoveOrientation.Horizontal | LineRemoveOrientation.Horizontal); if (status != GdPictureStatus.OK) { MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } else { //After you are done with your processing, you can save the image. status = oGdPictureImaging.SaveAsTIFF(imageId, "cleanedImage.tif", TiffCompression.TiffCompressionAUTO); if (status != GdPictureStatus.OK) { MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } } oGdPictureImaging.ReleaseGdPictureImage(imageId); } oGdPictureImaging.Dispose();

2. If you know, what kind of lines you have (length, size, connectivity, etc) and you want to specify the details for the engine to only remove lines with those properties.

   • VB.NET
   • C#

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   'We assume that GdPicture has been correctly installed and unlocked. Dim oGdPictureImaging As New GdPictureImaging() 'Loading the image from a file. Dim imageId As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("input.tif") 'Checking if the image resource has been loaded correctly. If oGdPictureImaging.GetStat() <> GdPictureStatus.OK Then MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) Else 'Now you clean up your lines. Dim maxLineGap As Integer = 10 Dim maxLineThickness As Integer = 7 Dim maxLineLength As Integer = 500 Dim maxInterception As Integer = 5 Dim reconnectBrokenCharacters As Boolean = True Dim status As GdPictureStatus = oGdPictureImaging.RemoveLines(imageId, LineRemoveOrientation.Horizontal, maxLineGap, maxLineThickness, maxLineLength, maxInterception, _ reconnectBrokenCharacters) If status <> GdPictureStatus.OK Then MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) Else 'After you are done with your processing, you can save the image. status = oGdPictureImaging.SaveAsTIFF(imageId, "cleanedImage.tif", TiffCompression.TiffCompressionAUTO) If status <> GdPictureStatus.OK Then MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error) End If End If oGdPictureImaging.ReleaseGdPictureImage(imageId) End If oGdPictureImaging.Dispose()

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   //We assume that GdPicture has been correctly installed and unlocked. GdPictureImaging oGdPictureImaging = new GdPictureImaging(); //Loading the image from a file. int imageId = oGdPictureImaging.CreateGdPictureImageFromFile("input.tif"); //Checking if the image resource has been loaded correctly. if (oGdPictureImaging.GetStat() != GdPictureStatus.OK) { MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } else { //Now you clean up your lines. int maxLineGap = 10; int maxLineThickness = 7; int maxLineLength = 500; int maxInterception = 5; bool reconnectBrokenCharacters = true; GdPictureStatus status = oGdPictureImaging.RemoveLines(imageId, LineRemoveOrientation.Horizontal, maxLineGap, maxLineThickness, maxLineLength, maxInterception, reconnectBrokenCharacters); if (status != GdPictureStatus.OK) { MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } else { //After you are done with your processing, you can save the image. status = oGdPictureImaging.SaveAsTIFF(imageId, "cleanedImage.tif", TiffCompression.TiffCompressionAUTO); if (status != GdPictureStatus.OK) { MessageBox.Show("Error: " + oGdPictureImaging.GetStat().ToString(), "Removing lines Example", MessageBoxButtons.OK, MessageBoxIcon.Error); } } oGdPictureImaging.ReleaseGdPictureImage(imageId); } oGdPictureImaging.Dispose();