Its been 5 years, I think these answers need some TLC. Here is a complete solution.
The following is tested with Python 2.7
Install dependencies
pip install reportlab
pip install pypdf2
Do the magic
from reportlab.pdfgen import canvas
from PyPDF2 import PdfFileWriter, PdfFileReader
# Create the watermark from an image
c = canvas.Canvas('watermark.pdf')
# Draw the image at x, y. I positioned the x,y to be where i like here
c.drawImage('test.png', 15, 720)
# Add some custom text for good measure
c.drawString(15, 720,"Hello World")
c.save()
# Get the watermark file you just created
watermark = PdfFileReader(open("watermark.pdf", "rb"))
# Get our files ready
output_file = PdfFileWriter()
input_file = PdfFileReader(open("test2.pdf", "rb"))
# Number of pages in input document
page_count = input_file.getNumPages()
# Go through all the input file pages to add a watermark to them
for page_number in range(page_count):
print "Watermarking page {} of {}".format(page_number, page_count)
# merge the watermark with the page
input_page = input_file.getPage(page_number)
input_page.mergePage(watermark.getPage(0))
# add page from input file to output document
output_file.addPage(input_page)
# finally, write "output" to document-output.pdf
with open("document-output.pdf", "wb") as outputStream:
output_file.write(outputStream)
References:
pypdf project page:
https://pypi.org/project/pypdf/
Reportlab docs:
http://www.reportlab.com/apis/reportlab/2.4/pdfgen.html
Reportlab complete user guide:
https://www.reportlab.com/docs/reportlab-userguide.pdf