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Saving and Reading TIFF Tags and Comments
  1. Start Visual Studio .NET.
  2. Start with the project that you created in Loading and Displaying an Image
  3. Drag and drop a button onto Form1. Change the following properties:
    PropertyValue
    Name:btnCommentReadWrite
    Text:Comment Read\Write
  4. Add the following code for the btnCommentReadWrite control’s click procedure:

    Visual Basic

    
Private Sub btnCommentReadWrite_Click(ByVal sender As System.Object, ByVal e 
   As System.EventArgs) Handles btnCommentReadWrite.Click
      'Write the following comment to the image
      Dim writeComment As RasterCommentMetadata = New RasterCommentMetadata()
      writeComment.Type = RasterCommentMetadataType.Software
      writeComment.FromAscii("LEADTOOLS Demo")

      codecs.WriteComment("C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\clean.tif", 
                           1, writeComment)

      'Read the Comment
      Dim readComment As RasterCommentMetadata = 
         codecs.ReadComment("C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\clean.tif", 
                             1, RasterCommentMetadataType.Software)
                             Console.WriteLine("The following comment has been read:")

      MessageBox.Show(readComment.ToAscii(), "The following comment has been read:")
End Sub

    C#

    
private void btnCommentReadWrite_Click(object sender, EventArgs e)
{
   //Write the comment to the file
   RasterCommentMetadata writeComment = new RasterCommentMetadata();
   writeComment.Type = RasterCommentMetadataType.Software;
   writeComment.FromAscii("LEADTOOLS Demo");

   codecs.WriteComment(dlg.FileName, 1, writeComment);

   //Read The Comment
   RasterCommentMetadata readComment = 
      codecs.ReadComment(dlg.FileName, 1, RasterCommentMetadataType.Software);

   MessageBox.Show(readComment.ToAscii(), "The following comment has been read:");
}
  5. To read or write TIFF tags, drag and drop a button onto Form1. Change the following properties:
    PropertyValue
    Name:btnReadWriteTags
    Text:Read\WriteTags
  6. Add the following code for the btnReadWriteTags control’s click procedure:

    Visual Basic

    
Private Sub btnReadWriteTags_Click(ByVal sender As System.Object, 
                                   ByVal e As System.EventArgs) Handles btnReadWriteTags.Click
      'This code reads the Xresolution from a TIFF image and modifies the value 
       and saves it back.
      Const XresTagID As Integer = 282
      Dim tag As RasterTagMetadata
      tag = New RasterTagMetadata()

      Dim ReadTag As RasterTagMetadata = codecs.ReadTag(FileName, 1, XresTagID)
      Dim Rational As RasterMetadataURational() = ReadTag.ToURational()
      Rational(0).Numerator = rational(0).Numerator * 5
      Rational(0).Denominator = rational(0).Denominator * 1
      ReadTag.FromURational(rational)
      codecs.WriteTag(FileName, 1, ReadTag)
End Sub

    C#

    
private void btnReadWriteTags_Click(object sender, EventArgs e)
{
   //This code reads the Xresolution from a TIFF image and modifies the value and saves it back.
   const int XresTagID = 282;
   RasterTagMetadata tag;
   tag = new RasterTagMetadata();

   RasterTagMetadata ReadTag = codecs.ReadTag(FileName, 1, XresTagID);
   RasterMetadataURational[] rational = ReadTag.ToURational();
   >Rational(0).Numerator = rational(0).Numerator * 5;
   Rational(0).Denominator = rational(0).Denominator * 1;
   ReadTag.FromURational(rational);
   codecs.WriteTag(FileName, 1, ReadTag);
}

    Note: Normally you do not have to modify this Tag because LEADTOOLS automatically sets the resolution tags to the bitmap's DPI values whenever the Save method is used. This code only shows how to modify it without loading and saving the image itself.

  7. Compile and run your project.