正如您在yms回答中的评论一样。“但是我可以使用什么库来提取图像并（更重要的是）将它们放回 PDF 中？”
这是一个简单的演示
1) 提取jbig2或者你可以说所有的图像来自pdf。
2）将jbig2图像转换为任何其他格式，在我的例子中是jpeg.
3) 创建新pdf的包含jpeg.
使用库jbig2-imageio和itext。
在下面的示例中，请根据需要更改资源和目录路径。
为此，我必须浏览最后将附上的几个资源。希望这可以帮助。
import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.pdf.PdfPCell;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfWriter;
import com.itextpdf.text.pdf.parser.*;
import com.levigo.jbig2.JBIG2ImageReader;
import com.levigo.jbig2.JBIG2ImageReaderSpi;
import com.levigo.jbig2.JBIG2ReadParam;
import com.levigo.jbig2.io.DefaultInputStreamFactory;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageInputStream;
public class JBig2Image {
private String filepath;
private int imageIndex;
public JBig2Image() {
this.filepath = "/home/blackadmin/Desktop/pdf/demo18.jbig2";
this.imageIndex = 0;
extractImgFromPdf();
convertJBig2ToJpeg();
createPDF();
}
private void extractImgFromPdf() {
try {
/////////// Extract all Images from pdf /////////////////////////
PdfReader reader = new PdfReader("/home/blackadmin/Desktop/pdf/orig.pdf");
PdfReaderContentParser parser = new PdfReaderContentParser(reader);
MyImageRenderListener listener = new MyImageRenderListener("/home/blackadmin/Desktop/pdf/demo%s.%s");
for (int i = 1; i <= reader.getNumberOfPages(); i++) {
parser.processContent(i, listener);
}
} catch (IOException ex) {
System.out.println(ex);
}
}
private void convertJBig2ToJpeg() {
InputStream inputStream = null;
try {
///////// Read jbig2 image ////////////////////////////////////////
inputStream = new FileInputStream(new File(filepath));
DefaultInputStreamFactory disf = new DefaultInputStreamFactory();
ImageInputStream imageInputStream = disf.getInputStream(inputStream);
JBIG2ImageReader imageReader = new JBIG2ImageReader(new JBIG2ImageReaderSpi());
imageReader.setInput(imageInputStream);
JBIG2ReadParam param = imageReader.getDefaultReadParam();
BufferedImage bufferedImage = imageReader.read(imageIndex, param);
////////// jbig2 to jpeg ///////////////////////////////////////////
ImageIO.write(bufferedImage, "jpeg", new File("/home/blackadmin/Desktop/pdf/demo18.jpeg"));
} catch (IOException ex) {
System.out.println(ex);
} finally {
try {
inputStream.close();
} catch (IOException ex) {
System.out.println(ex);
}
}
}
public void createPDF() {
Document document = new Document();
try {
PdfWriter.getInstance(document,
new FileOutputStream("/home/blackadmin/Desktop/pdf/output.pdf"));
document.open();
PdfPTable table = new PdfPTable(1); //1 column.
Image image = Image.getInstance("/home/blackadmin/Desktop/pdf/demo18.jpeg");
image.scaleToFit(800f, 600f);
image.scaleAbsolute(800f, 600f); // Give the size of image you want to print on pdf
PdfPCell nestedImgCell = new PdfPCell(image);
table.addCell(nestedImgCell);
document.add(table);
document.close();
System.out.println(
"======== PDF Created Successfully =========");
} catch (Exception e) {
System.out.println(e);
}
}
public static void main(String[] args) throws IOException {
new JBig2Image();
}
}
class MyImageRenderListener implements RenderListener {
/**
* The new document to which we've added a border rectangle.
*/
protected String path = "";
/**
* Creates a RenderListener that will look for images.
*/
public MyImageRenderListener(String path) {
this.path = path;
}
/**
* @see com.itextpdf.text.pdf.parser.RenderListener#beginTextBlock()
*/
public void beginTextBlock() {
}
/**
* @see com.itextpdf.text.pdf.parser.RenderListener#endTextBlock()
*/
public void endTextBlock() {
}
/**
* @see com.itextpdf.text.pdf.parser.RenderListener#renderImage(
* com.itextpdf.text.pdf.parser.ImageRenderInfo)
*/
public void renderImage(ImageRenderInfo renderInfo) {
try {
String filename;
FileOutputStream os;
PdfImageObject image = renderInfo.getImage();
if (image == null) {
return;
}
filename = String.format(path, renderInfo.getRef().getNumber(), image.getFileType());
os = new FileOutputStream(filename);
os.write(image.getImageAsBytes());
os.flush();
os.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
/**
* @see com.itextpdf.text.pdf.parser.RenderListener#renderText(
* com.itextpdf.text.pdf.parser.TextRenderInfo)
*/
public void renderText(TextRenderInfo renderInfo) {
}
}
参考资料：
1）jbig2从pdf （提取图像）（MyImageRenderListener）中提取。
2）转换jbig2（JBIG2ImageReaderDemo）