File compression

There are several ways to reduce the size of PDF documents through PDF Clown:

• Compact serialization — PDF documents can be serialized retaining either the previous versions (incremental update) or the last one only (compact serialization).

  import org.pdfclown.files.File;
  import org.pdfclown.files.SerializationModeEnum;
  
  . . .
  
  File file = new File(myFilePath);
  . . .
  file.save(SerializationModeEnum.Standard); // Compact serialization.
  

• Compressed serialization — PDF documents can be either plain (no object compression) or compressed (full object compression). Note that compressed serialization was introduced by PDF spec 1.5; therefore, if you needed to extend their compatibility to older versions, you should stick with plain compression instead.

  import org.pdfclown.files.File;
  import org.pdfclown.files.SerializationModeEnum;
  import org.pdfclown.files.XRefModeEnum;
  
  . . .
  
  File file = new File(myFilePath);
  . . .
  file.getConfiguration().setXRefMode(XRefModeEnum.Compressed); // Full object compression.
  file.save(SerializationModeEnum.Standard);
  

• Unused objects removal — PDF documents can be optimized removing objects without references.

  import org.pdfclown.files.File;
  import org.pdfclown.files.SerializationModeEnum;
  import org.pdfclown.files.XRefModeEnum;
  import org.pdfclown.tools.Optimizer;
  
  . . .
  
  File file = new File(myFilePath);
  . . .
  Optimizer.removeOrphanedObjects(file); // Removes unused objects.
  file.getConfiguration().setXRefMode(XRefModeEnum.Compressed);
  file.save(SerializationModeEnum.Standard);
  

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