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RasterCommentMetadata Class

Extends the RasterMetadata class to provide functionality for dealing with comment metadata stored within various image file formats.
public class RasterCommentMetadata : RasterMetadata 
Public Class RasterCommentMetadata  
   Inherits RasterMetadata 
@interface LTRasterCommentMetadata : LTRasterMetadata 
public class RasterCommentMetadata extends RasterMetadata implements Serializable 
public ref class RasterCommentMetadata : public RasterMetadata  

The TIFF file formats support a number of comments that are saved and loaded using predefined tags.

If the comments do not meet your needs, you can define your own tag for saving additional non-raster data in a TIFF file. For example, you may want to define a tag to save annotations.

The TIFF 6.0 Specification sets aside a range of private tags that developers can define. To avoid conflicts with files created by other developers, you can register your tag by contacting Adobe Developer Relations. The E-Mail address posted on The Unofficial TIFF Home Page is gapdevsup@adobe.com.

Some restrictions apply to this function if you use an IFD to indicate to which page to write the metadata. See the Loading And Saving Large TIFF Files topic for more information.


This example will write comments of different data types to an existing tif file then read them as a test.

using Leadtools; 
using Leadtools.Codecs; 
public void RasterCommentMetadataExample() 
	RasterCodecs codecs = new RasterCodecs(); 
	codecs.ThrowExceptionsOnInvalidImages = true; 
	string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
	string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_comments.tif"); 
	// Load the image 
	RasterImage image = codecs.Load(srcFileName); 
	codecs.Save(image, destFileName, RasterImageFormat.Tif, 24); 
	// Write some comments to the existing tif file 
	RasterCommentMetadata comment = new RasterCommentMetadata(); 
	comment.Type = RasterCommentMetadataType.Artist; 
	string artistNameWrite = "Artist name"; 
	Console.WriteLine("Writing Artist"); 
	codecs.WriteComment(destFileName, 1, comment); 
	comment.Type = RasterCommentMetadataType.GpsLatitude; 
	RasterMetadataRational[] rationalsWrite = new RasterMetadataRational[3]; 
	for (int i = 0; i < rationalsWrite.Length; i++) 
		rationalsWrite[i] = new RasterMetadataRational(i + 3, i + 2); 
	Console.WriteLine("Writing GpsLatitude"); 
	codecs.WriteComment(destFileName, 1, comment); 
	// Now read the comments from the tif file 
	// read ASCII 
	comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.Artist); 
	string artistNameRead = comment.ToAscii(); 
	Console.WriteLine("Artist: {0}", artistNameRead); 
	Assert.IsTrue(artistNameRead == artistNameWrite); 
	// read rationals 
	comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.GpsLatitude); 
	RasterMetadataRational[] rationalsRead = comment.ToRational(); 
	int size = rationalsRead.Length; 
	Console.WriteLine("GpsLatitude: size = {0} ", size); 
	for (int i = 0; i < size; i++) 
		Console.WriteLine("{0}/{1}", rationalsRead[i].Numerator, rationalsRead[i].Denominator); 
	Assert.IsTrue(rationalsRead.Length == rationalsWrite.Length); 
	for (int i = 0; i < rationalsRead.Length; i++) 
		Assert.IsTrue(rationalsRead[i].Numerator == rationalsWrite[i].Numerator); 
		Assert.IsTrue(rationalsRead[i].Denominator == rationalsWrite[i].Denominator); 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
Imports Leadtools 
Imports Leadtools.Codecs 
Public Sub RasterCommentMetadataExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
   Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp") 
   Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1_comments.tif") 
   ' Load the image 
   Dim image As RasterImage = codecs.Load(srcFileName) 
   codecs.Save(image, destFileName, RasterImageFormat.Tif, 24) 
   ' Write some comments to the existing tif file 
   Dim comment As RasterCommentMetadata = New RasterCommentMetadata() 
   comment.Type = RasterCommentMetadataType.Artist 
   Dim artistNameWrite As String = "Artist name" 
   Console.WriteLine("Writing Artist") 
   codecs.WriteComment(destFileName, 1, comment) 
   comment.Type = RasterCommentMetadataType.GpsLatitude 
   Dim rationalsWrite As RasterMetadataRational() = New RasterMetadataRational(2) {} 
   Dim i As Integer = 0 
   Do While i < rationalsWrite.Length 
      rationalsWrite(i) = New RasterMetadataRational(i + 3, i + 2) 
      i += 1 
   Console.WriteLine("Writing GpsLatitude") 
   codecs.WriteComment(destFileName, 1, comment) 
   ' Now read the comments from the tif file 
   ' read ASCII 
   comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.Artist) 
   Dim artistNameRead As String = comment.ToAscii() 
   Console.WriteLine("Artist: {0}", artistNameRead) 
   Debug.Assert(artistNameRead = artistNameWrite) 
   ' read rationals 
   comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.GpsLatitude) 
   Dim rationalsRead As RasterMetadataRational() = comment.ToRational() 
   Dim size As Integer = rationalsRead.Length 
   Console.WriteLine("GpsLatitude: size = {0} ", size) 
   i = 0 
   Do While i < size 
      Console.WriteLine("{0}/{1}", rationalsRead(i).Numerator, rationalsRead(i).Denominator) 
      i += 1 
   Debug.Assert(rationalsRead.Length = rationalsWrite.Length) 
   i = 0 
   Do While i < rationalsRead.Length 
      Debug.Assert(rationalsRead(i).Numerator = rationalsWrite(i).Numerator) 
      Debug.Assert(rationalsRead(i).Denominator = rationalsWrite(i).Denominator) 
      i += 1 
End Sub 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS22\Resources\Images" 
End Class 

Target Platforms

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© 1991-2021 LEAD Technologies, Inc. All Rights Reserved.