Example of iText that repeats an image all over a page and draws a semi-transparent yellow line on top.

itext.java

import java.awt.Color;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.MalformedURLException;

import com.itextpdf.text.BaseColor;
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfGState;
import com.itextpdf.text.pdf.PdfShading;
import com.itextpdf.text.pdf.PdfShadingPattern;
import com.itextpdf.text.pdf.PdfSpotColor;
import com.itextpdf.text.pdf.PdfWriter;


public class Main {

  /**
	 * @param args
	 * @throws DocumentException 
	 * @throws IOException 
	 * @throws MalformedURLException 
	 */
	public static void main(String[] args) throws DocumentException, MalformedURLException, IOException {
		// TODO Auto-generated method stub
		// Create new PDF document
        Document document = new Document(PageSize.A4);
        // Create an output stream of PDF file.
        OutputStream out = new FileOutputStream("PDF_Absolute_Position_Image_Example.pdf");
        // Get a PdfWriter instance to write in PDF document.
        PdfWriter writer = PdfWriter.getInstance(document, out);
        // Open the PDF document
        document.open();
        for (int i=0; i<14; i++){
        	for (int j=0;j<19;j++){
	            Image image = Image.getInstance("logo.jpg");
	            // Set the position of image
	            image.setAbsolutePosition((i*42), j*44);
	            // Add paragraph to PDF document.
	            document.add(image);
        	}
        }

        PdfContentByte cb = writer.getDirectContent();
        cb.setLineWidth(10.0f);
        PdfGState gState = new PdfGState();
        gState.setStrokeOpacity(0.5f);
        cb.setColorStroke(BaseColor.YELLOW);
        cb.setGState(gState);
        //cb.setGrayStroke(0.5f);
        cb.moveTo(100, 100);
        cb.lineTo(500, 800);
        cb.stroke();
        
        // Close the PDf document after use.
        document.close();
	}

}