Add A White Background to a PDF File Using Groovy and iText

AddBackgroundToPdf

import com.itextpdf.text.*
import com.itextpdf.text.pdf.*

@Grab(group='com.itextpdf', module='itextpdf', version='5.5.0')
@Grab(group='org.bouncycastle', module='bcpkix-jdk15on', version='1.49')

class AddBackgroundColorToPdf {

    static def createPdfFromImageFile(String fileName) {
        def input = new FileInputStream(fileName)
        PdfReader reader = new PdfReader(input) 
        int pages = reader.getNumberOfPages()
        Rectangle pageSetup = reader.getPageSize(1)
        pageSetup.setBackgroundColor(BaseColor.WHITE) 

        Document document = new Document(pageSetup, 0, 0, 0, 0) 
        PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("./test-modified.pdf"));
        document.open()

        PdfImportedPage page

        for (int i = 1; i <= pages; i++) { 
            page = writer.getImportedPage(reader, i)
            document.add(Image.getInstance(page))
        } 

        document.close()
    }


    static void main(String[] args) {
        createPdfFromImageFile args[0]
    }
}

Results in test-modified.pdf having the updated PDF.