Read and Write TIFF Tags and Comments - C# .NET Core

This tutorial shows how to read and write TIFF tags and comments in a C# .NET Core application using the LEADTOOLS SDK.

Required Knowledge

Get familiar with the basic steps of creating a project by reviewing the Add References and Set a License tutorial, before working on the Read and Write TIFF Tags and Comments - C# .NET Core tutorial.

Create the Project and Add LEADTOOLS References

Start with a copy of the project created in the Add References and Set a License tutorial. If you do not have that project, follow the steps in that tutorial to create it.

The references needed depend upon the purpose of the project. References can be added via NuGet packages.

This tutorial requires the following NuGet package:

• Leadtools.Formats.Raster.Common

For a complete list of which DLL files are required for your application, refer to Files to be Included With Your Application.

Set the License File

The License unlocks the features needed for the project. It must be set before any toolkit function is called. For details, including tutorials for different platforms, refer to Setting a Runtime License.

There are two types of runtime licenses:

• Evaluation license, obtained at the time the evaluation toolkit is downloaded. It allows the toolkit to be evaluated.
• Deployment license. If a Deployment license file and developer key are needed, refer to Obtaining a License.

Note

Adding LEADTOOLS NuGet references and setting a license are covered in more detail in the Add References and Set a License tutorial.

Add the Read/Write TIFF Comments Code

With the project created, the references added, and the license set, coding can begin.

In the Solution Explorer, open Program.cs. Add the following statements to the using block at the top of Program.cs.

using System; 
using System.IO; 
using Leadtools; 
using Leadtools.Codecs; 

In the Program class, add a new string fileName, below the set license code. Set the new string value to the file path containing the TIFF file. Add a new method named ReadAndWriteTifComments(string fileName) to the Program class. Call it in the Main() method after the fileName string value, as shown below.

static void Main(string[] args) 
{ 
    if (!SetLicense()) 
        Console.WriteLine("Error setting license"); 
    else 
        Console.WriteLine("License file set successfully"); 
 
    string fileName = @"C:\LEADTOOLS21\Resources\Images\clean.tif"; 
 
    ReadAndWriteTifComments(fileName); 
    ReadAndWriteTifTags(fileName); 
} 

Add the code below to the ReadAndWriteTifComments() method to write a comment to the TIFF file, then read the comment and display it to the console.

static void ReadAndWriteTifComments(string fileName) 
{ 
    using (RasterCodecs codecs = new RasterCodecs()) 
    { 
        // Write the comment to the file 
        RasterCommentMetadata writeComment = new RasterCommentMetadata(); 
        writeComment.Type = RasterCommentMetadataType.Software; 
        writeComment.FromAscii("LEADTOOLS Demo"); 
        codecs.WriteComment(fileName, 1, writeComment); 
        // Read The Comment 
        RasterCommentMetadata readComment = 
        codecs.ReadComment(fileName, 1, RasterCommentMetadataType.Software); 
        Console.WriteLine("The following comment has been read:\n" + 
            $"{readComment.ToAscii()}/n"); 
    } 
} 

Note

Because the RasterCodecs class implements IDisposable, make sure it is in a using statement for proper disposal.

Add the Read/Write TIFF Tags Code

In the Program class, add a new method named ReadAndWriteTifTags(string fileName), and call it in the Main() method after the ReadAndWriteTifComments() method, as shown above. Add the below code to the new method to read the XResolution of the TIFF image, modify the value, and write the tag to the file.

static void ReadAndWriteTifTags(string fileName) 
{ 
    using (RasterCodecs codecs = new RasterCodecs()) 
    { 
        // This code reads the Xresolution from a TIFF image, modifies the value, and saves it back. 
        const int XresTagID = 282; 
        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); 
        Console.WriteLine("Resolution changed successfully."); 
    } 
} 

Run the Project

Run the project by pressing F5, or by selecting Debug -> Start Debugging.

If the steps were followed correctly, the console appears and the application writes a new TIFF comment and then displays the comment in the console. Then, the application reads the XResolution from the TIFF image, modifies the resolution value and writes the tag back to the TIFF image.

Wrap-up

This tutorial showed how to use the RasterTagMetadata and RasterCommentMetadata classes to read/write TIFF comments and tags.

See Also

• LEADTOOLS RasterCommentMetadata Documentation
• LEADTOOLS RasterTagMetadata Documentation
• LEADTOOLS RasterCodecs Documentation
• LEADTOOLS SDK Download Link