Compress PDF Size with Same Quality | Optimize Reduce Minimize or Shrink PDF Size using Java

Annotation_Optimize.java

// Open document
Document pdfDocument = new Document(dataDir + "OptimizeDocument.pdf");

// Iterate through each page and annotation
for (Page page : pdfDocument.getPages())
{
    for (Annotation annotation : page.getAnnotations())
    {
        // Either flatten the annotation
        annotation.flatten();
        
        // OR delete the annotation
        // page.getAnnotations().delete(annotation);        
    }
}
// Save optimized PDF document
pdfDocument.save(dataDir + "OptimizeDocument_out.pdf");

EmbeddedFont_Streams_Compress.java

Document doc = new Document(dataDir + "Test.pdf");
OptimizationOptions opt = new OptimizationOptions();

// Either
// Unembed all fonts in PDF
opt.setUnembedFonts(true);

//OR
// only keep embedded fonts for used characters
opt.setSubsetFonts(true);

// link duplicate streams
opt.setLinkDuplcateStreams(false);

// Remove unused streams
opt.setRemoveUnusedStreams(false);

// Remove unused objects
opt.setRemoveUnusedObjects(false);

doc.optimizeResources(opt);

// Save the updated file
doc.save(dataDir + "compressingPDF.pdf");

Flatten_Form_Optimize_PDF.java

// Load source PDF form
Document doc = new Document(dataDir + "input.pdf");

// Flatten Form fields
if (doc.getForm().getFields().length > 0)
{
    for (Field item : doc.getForm().getFields())
    {
        item.flatten();
    }
}

dataDir = dataDir + "FlattenForms_out.pdf";
// Save the updated document
doc.save(dataDir);

Optimize_Color_Space.java

// Load input PDF document
Document document = new Document("input.pdf");

// Initialize RgbToDeviceGrayConversionStrategy instance
RgbToDeviceGrayConversionStrategy strategy = new RgbToDeviceGrayConversionStrategy();
for (int idxPage = 1; idxPage <= document.getPages().size(); idxPage++) {
	Page page = document.getPages().get_Item(idxPage);
        
        // Convert color space of each page to Greyscale
	strategy.convert(page);
}
// Save output PDF document
document.save("output.pdf");

OptimizePDFweb.java

// Open document
Document pdfDocument = new Document("Original.pdf");

// Optimize for web
pdfDocument.optimize();

// Save output document
pdfDocument.save("Optimized_output.pdf");

Shrink_Compress_Resize_Optimize.java

// Load input document
Document doc = new Document(dataDir + "Test.pdf");

// Initialize OptimizationOptions object
OptimizationOptions opt = new OptimizationOptions();

// Enable image compression
// Set the quality and resolution of images in PDF file
opt.getImageCompressionOptions().setCompressImages(true);
opt.getImageCompressionOptions().setImageQuality(10);
opt.getImageCompressionOptions().setMaxResolution(150);
opt.getImageCompressionOptions().setResizeImages(true);
doc.optimizeResources(opt);

// Save the updated file
doc.save(dataDir + "compressingPDFWithImages_out.pdf");