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Is it possible to have a signature image transparent?

Can I set the transparency of the image that goes into the setSignatureAffinityStream api?

===== code ==================================
// 2. create PdfFileSignature instance
PdfFileSignature pdfSign = new PdfFileSignature();

	// 3. bind the source PDF by reading contents of Stream
	PKCS7 pkcs7 = new PKCS7(new ByteArrayInputStream(certByte), certPw);
	pdfSign.bindPdf(new ByteArrayInputStream(((ByteArrayOutputStream) out).toByteArray()));
	pdfSign.sign(1, true, new Rectangle((int)(width-70), (int)(height-70), 65, 65), pkcs7); // 수직시 사용
	//pdfSign.sign(1, true, new Rectangle((int)(height-70), (int)(width-70), 65, 65), pkcs7); // 수평시 사용
	try {
		pdfSign.setSignatureAppearanceStream(new FileInputStream(new File(imagePath))); //<=== Can I set transparency of the image ?
	} catch (Exception e) {
		throw new  EdocException(this.getClass().getName()+".setCertificate : "+ e.getMessage(), e.toString(), "imagePath(URL) : " +  imagePath);
	} finally {
		try {
		} catch (IOException e) {



We need to further investigate this requirement of your. Can you please share an expected output PDF that you want to generate using the API with transparent signature image? We will log an investigation ticket in our issue management system and share the ID with you.

I want to give transparency like image number 1 so that I can see the letters.
image.png (295.8 KB)


We have checked the image that you shared. However, as requested earlier, can you please share the sample PDF document as well? It would help us investigating the functionality appropriately by replicating the scenario in our environment.

I uploaded a sample PDF.

CTR210700026-0_signed.pdf (582.9 KB)


The image in the PDF has been added as a watermark or image stamp. It does not look like a signature image. You can add such images in the PDF with transparency using ImageStamp Class. This class offers you an option to set the opacity of the image as you can see in the linked code example. Please try using it and let us know if your requirements are met.

Can’t I set the opacity option for the signature image?

pdfSign.setSignatureAppearanceStream(new FileInputStream(new File(imagePath))); //<===Can’t I set the opacity option for the signature image?


We have logged an investigation ticket as PDFNET-50449 in our issue management system to analyze your requirements. We will check the feasibility and let you know as soon as the ticket is resolved. Please be patient and spare us some time.

We are sorry for the inconvenience.