compress pdf with large images via java
I used code below for a proof of concept... Works a treat :) Thanks to Bruno for setting me on the right path :)
package compressPDF;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.pdf.PRStream;
import com.itextpdf.text.pdf.PdfName;
import com.itextpdf.text.pdf.PdfNumber;
import com.itextpdf.text.pdf.PdfObject;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.parser.PdfImageObject;
public class ResizeImage {
/** The resulting PDF file. */
//public static String RESULT = "results/part4/chapter16/resized_image.pdf";
/** The multiplication factor for the image. */
public static float FACTOR = 0.5f;
/**
* Manipulates a PDF file src with the file dest as result
* @param src the original PDF
* @param dest the resulting PDF
* @throws IOException
* @throws DocumentException
*/
public void manipulatePdf(String src, String dest) throws IOException, DocumentException {
PdfName key = new PdfName("ITXT_SpecialId");
PdfName value = new PdfName("123456789");
// Read the file
PdfReader reader = new PdfReader(src);
int n = reader.getXrefSize();
PdfObject object;
PRStream stream;
// Look for image and manipulate image stream
for (int i = 0; i < n; i++) {
object = reader.getPdfObject(i);
if (object == null || !object.isStream())
continue;
stream = (PRStream)object;
// if (value.equals(stream.get(key))) {
PdfObject pdfsubtype = stream.get(PdfName.SUBTYPE);
System.out.println(stream.type());
if (pdfsubtype != null && pdfsubtype.toString().equals(PdfName.IMAGE.toString())) {
PdfImageObject image = new PdfImageObject(stream);
BufferedImage bi = image.getBufferedImage();
if (bi == null) continue;
int width = (int)(bi.getWidth() * FACTOR);
int height = (int)(bi.getHeight() * FACTOR);
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
AffineTransform at = AffineTransform.getScaleInstance(FACTOR, FACTOR);
Graphics2D g = img.createGraphics();
g.drawRenderedImage(bi, at);
ByteArrayOutputStream imgBytes = new ByteArrayOutputStream();
ImageIO.write(img, "JPG", imgBytes);
stream.clear();
stream.setData(imgBytes.toByteArray(), false, PRStream.BEST_COMPRESSION);
stream.put(PdfName.TYPE, PdfName.XOBJECT);
stream.put(PdfName.SUBTYPE, PdfName.IMAGE);
stream.put(key, value);
stream.put(PdfName.FILTER, PdfName.DCTDECODE);
stream.put(PdfName.WIDTH, new PdfNumber(width));
stream.put(PdfName.HEIGHT, new PdfNumber(height));
stream.put(PdfName.BITSPERCOMPONENT, new PdfNumber(8));
stream.put(PdfName.COLORSPACE, PdfName.DEVICERGB);
}
}
// Save altered PDF
PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
stamper.close();
reader.close();
}
/**
* Main method.
*
* @param args no arguments needed
* @throws DocumentException
* @throws IOException
*/
public static void main(String[] args) throws IOException, DocumentException {
//createPdf(RESULT);
new ResizeImage().manipulatePdf("C:/_dev_env_/TEMP/compressPDF/TRPT_135002_1470_20131212_121423.PDF", "C:/_dev_env_/TEMP/compressPDF/compressTest.pdf");
}
}
Just to update the excellent answer from @Daniel, I update his code to be compatible with iText7.
package opencde.builder.compresspdf;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Iterator;
import javax.imageio.ImageIO;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.itextpdf.io.image.ImageDataFactory;
import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfStream;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.xobject.PdfImageXObject;
import com.itextpdf.layout.element.Image;
public class ResizeImageV7 {
// Logging
private static Logger logger = LoggerFactory.getLogger(ResizeImageV7.class);
/**
* Manipulates a PDF file src with the file dest as result
*
* @param src the original PDF
* @param dest the resulting PDF
* @param resizeFactor factor to multiplicate to resize image
* @throws IOException
*/
public void manipulatePdf(String src, String dest,Float resizeFactor) throws IOException {
//Get source pdf
PdfDocument pdfDoc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
// Iterate over all pages to get all images.
for (int i = 1; i <= pdfDoc.getNumberOfPages(); i++)
{
PdfPage page = pdfDoc.getPage(i);
PdfDictionary pageDict = page.getPdfObject();
PdfDictionary resources = pageDict.getAsDictionary(PdfName.Resources);
// Get images
PdfDictionary xObjects = resources.getAsDictionary(PdfName.XObject);
for (Iterator<PdfName> iter = xObjects.keySet().iterator() ; iter.hasNext(); ) {
// Get image
PdfName imgRef = iter.next();
PdfStream stream = xObjects.getAsStream(imgRef);
PdfImageXObject image = new PdfImageXObject(stream);
BufferedImage bi = image.getBufferedImage();
if (bi == null)
continue;
// Create new image
int width = (int) (bi.getWidth() * resizeFactor);
int height = (int) (bi.getHeight() * resizeFactor);
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
AffineTransform at = AffineTransform.getScaleInstance(resizeFactor, resizeFactor);
Graphics2D g = img.createGraphics();
g.drawRenderedImage(bi, at);
ByteArrayOutputStream imgBytes = new ByteArrayOutputStream();
// Write new image
ImageIO.write(img, "JPG", imgBytes);
Image imgNew =new Image(ImageDataFactory.create(imgBytes.toByteArray()));
// Replace the original image with the resized image
xObjects.put(imgRef, imgNew.getXObject().getPdfObject());
}
}
pdfDoc.close();
}
/**
* Main method.
*
* @param src the original PDF
* @param dest the resulting PDF
* @param resizeFactor factor to multiplicate to resize image
* @throws IOException
*/
public static void main(String[] args) throws IOException {
//Get input parametres
if (args.length<3 ) {
System.out.println("Source PDF, Destination PDF and Resize Factor must be provided as parametres");
} else {
String sourcePDF=args[0];
String destPDF=args[1];
Float resizeFactor=Float.valueOf(new String(args[2]));
logger.info("Inovking Resize with args, source:" + sourcePDF
+ " destination:" + destPDF
+ " factor:" + resizeFactor);
//Call method to resize images
new ResizeImageV7().manipulatePdf(sourcePDF,destPDF,resizeFactor);
logger.info("PDF resized");
}
}
}