Read QR Code from scanned PDF

I'm trying to insert and read qrcode's from PDF files. To create/read qr codes from images i'm using zxing project and to manipulate the pdf i'm using Big Faceless PDF.

Everything works well if i create the QR Code, insert into my pdf, and then read the images from the pdf and convert the correct one to QR Code. However, if i try to to read images from a scanned document (with a qr code sticker attach to it), i cannot obtain the qr code image from the pdf (the only image i can get, using Big Faceless PDF, is the document it self).

Does anyone knows a Java library to search in pdf files for qr codes?

Thanks for you help