import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.tools.imageio.ImageIOUtil;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class CropBoxImage {
    static final String destFolder = "/Users/victor/Downloads/";
    static final Float SCALE = 4f;

    public static void main(String[] args) throws IOException {
        Integer pageNum = 12;
        saveToImg(pageNum);
        saveToPDF(pageNum);
    }

    public static void saveToImg(Integer pageNum) throws IOException {
        Integer dpi = 300;

        String outFilename = String.format("samsung.crop.page.%d.image.jpg", pageNum - 1);
        PDDocument ppdDocument = PDDocument.load(new File(destFolder, "Samsung_TV_UserManual_ENG-US_NMATSCJ-1.103-0330.pdf"));
        PDPage ppage = ppdDocument.getPage(pageNum - 1);
        //commenting out the setCropBox correctly outputs the page to image
        ppage.setCropBox(new PDRectangle(40f, 680f, 510f, 100f));

        PDFRenderer renderer = new PDFRenderer(ppdDocument);
        BufferedImage img = renderer.renderImage(pageNum - 1, SCALE);
        ImageIOUtil.writeImage(img, destFolder + outFilename, dpi);
        ppdDocument.close();
    }

    public static void saveToPDF(Integer pageNum) throws IOException {
        PDDocument ppdDocument = PDDocument.load(new File(destFolder, "Samsung_TV_UserManual_ENG-US_NMATSCJ-1.103-0330.pdf"));
        PDPage ppage = ppdDocument.getPage(pageNum - 1);
        ppage.setCropBox(new PDRectangle(40f, 680f, 510f, 100f));
        ppdDocument.save(new File(destFolder, "samsung.v3-page12cropped.pdf"));
        ppdDocument.close();
    }
}