Read and Write TIFF Tags and Comments - Java

This tutorial shows how to read and write TIFF tags and comments using the LEADTOOLS SDK in a Java application.

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 - Java tutorial.

Create the Project and Add the LEADTOOLS References

Start with a copy of the project created in the Add References and Set a License tutorial. If that project is unavailable, follow the steps in that tutorial to create it.

The references needed depend upon the purpose of the project. References can be added by local .jar files located at <INSTALL_DIR>\LEADTOOLS21\Bin\Java.

For this project, the following references are needed:

• leadtools.jar
• leadtools.codecs.jar

This tutorial uses LEADTOOLS Codec library support. For a complete list of which JAR files are required for your application, refer to Files to be Included with your Java 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 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 and Tags Code

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

Open the Main.java class in the Project Explorer. Add the following statements to the import block at the top.

// import block at the top 
import leadtools.*; 
import leadtools.codecs.*; 
 
import java.io.IOException; 
import java.nio.file.*; 
import java.util.List; 

Add a new method called ReadAndWriteTifCommentsTags(), and call it in the main() method as shown below.

public static void main(String[] args) throws IOException  
{ 
    Platform.setLibPath("C:\\LEADTOOLS21\\Bin\\CDLL\\x64"); 
    Platform.loadLibrary(LTLibrary.LEADTOOLS); 
    Platform.loadLibrary(LTLibrary.CODECS); 
         
    SetLicense(); 
 
    ReadAndWriteTifCommentsTags(); 
} 

Add the below code inside the newly created method to write a new TIFF comment, read the comment, and then display it to the console. Also, add the below code inside the new method to read the XResolution from the TIFF image and then modify it.

static void ReadAndWriteTifCommentsTags() 
{ 
    String fileName = "C:\\LEADTOOLS21\\Resources\\Images\\clean.tif"; 
    ILeadStream stream = new LeadFileStream(fileName); 
    RasterCodecs codecs = new RasterCodecs(); 
    	 
    // Write the comment to the file 
    RasterCommentMetadata writeComment = new RasterCommentMetadata(); 
    writeComment.setType(RasterCommentMetadataType.SOFTWARE); 
    writeComment.fromAscii("LEADTOOLS Demo"); 
         
    codecs.writeComment(stream, 1, writeComment); 
         
    // Read the comment 
    RasterCommentMetadata readComment = codecs.readComment(stream, 1, RasterCommentMetadataType.SOFTWARE); 
    System.out.println("The following comment has been read:\n" + readComment.toAscii() + "\n"); 
 
    // Read the resolution tag and modify it 
    RasterImage image = codecs.load(stream); 
    RasterImageFormat format = image.getOriginalFormat(); 
    List<RasterTagMetadata> tags = null; 
 
    if (RasterCodecs.tagsSupported(format)) 
    { 
    	tags = codecs.readTags(stream, 1); 
    	if (tags != null) 
    	{ 
    	    final int XresTagID = 282; 
    	    RasterTagMetadata ReadTag = codecs.readTag(stream, 1, XresTagID); 
    	    RasterMetadataURational[] rational = ReadTag.toURational(); 
    	    rational[0].setNumerator(rational[0].getNumerator() * 5); 
    	    rational[0].setDenominator(rational[0].getDenominator() * 1); 
    	    ReadTag.fromURational(rational); 
 
    	    codecs.writeTag(stream, 1, ReadTag); 
    	    System.out.println("Resolution changed successfully."); 
    	} 
    	else 
    	{ 
    		System.out.println("No tags found"); 
    	} 
    } 
    codecs.dispose(); 
} 

Run the Project

Run the project by pressing Ctrl + F11, or by selecting Run -> Run.

If the steps were followed correctly, 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 it, 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