How to apply a semi-transparent watermark to an image using Python

watermark.py

from PIL import Image, ImageDraw

def main():
    # Open the original image
    main = Image.open("12voltm.jpg")

    # Create a new image for the watermark with an alpha layer (RGBA)
    #  the same size as the original image
    watermark = Image.new("RGBA", main.size)
    # Get an ImageDraw object so we can draw on the image
    waterdraw = ImageDraw.ImageDraw(watermark, "RGBA")
    # Place the text at (10, 10) in the upper left corner. Text will be white.
    waterdraw.text((10, 10), "The Image Project")

    # Get the watermark image as grayscale and fade the image
    # See <http://www.pythonware.com/library/pil/handbook/image.htm#Image.point>
    #  for information on the point() function
    # Note that the second parameter we give to the min function determines
    #  how faded the image will be. That number is in the range [0, 256],
    #  where 0 is black and 256 is white. A good value for fading our white
    #  text is in the range [100, 200].
    watermask = watermark.convert("L").point(lambda x: min(x, 100))
    # Apply this mask to the watermark image, using the alpha filter to 
    #  make it transparent
    watermark.putalpha(watermask)

    # Paste the watermark (with alpha layer) onto the original image and save it
    main.paste(watermark, None, watermark)
    main.save("12volt-watermarked.jpg", "JPEG")

if __name__ == '__main__':
    main()

How to set watermark in position of 10 pixel from bottom?

Doesn't work for me.

i want to use it not only for a single image ... a bunch of image fetching from database ,how can i use it?I am using django.

Works like a charm. To be able to use this from the command line I suggest to add #!/usr/bin/env python.

My recipe for those who want a watermark to be a vector image or want to use a blend mode as well as semi-transparency.

Thank you! This works like a charm.

@ehsansh84 here is the improved one (quick draft of mine) that puts in the bottom + uses custom font:

#!/usr/bin/env python
import os
from PIL import Image, ImageDraw, ImageFont

def work(filename):
    # Open the original image
    main = Image.open("without_watermark/"+filename)

    # Create a new image for the watermark with an alpha layer (RGBA)
    #  the same size as the original image
    watermark = Image.new("RGBA", main.size)
    # Get an ImageDraw object so we can draw on the image
    waterdraw = ImageDraw.ImageDraw(watermark, "RGBA")
    # Place the text at (10, 10) in the upper left corner. Text will be white.

    font_path = "/System/Library/Fonts/Palatino.ttc"
    font = ImageFont.truetype(font_path, 30)

    im = Image.open("without_watermark/"+filename)
    width, height = im.size
    print height
    print width
    waterdraw.text((10, height-35), "www.reactjs.co", fill=(128,128,128,128), font=font)

    # Get the watermark image as grayscale and fade the image
    # See <http://www.pythonware.com/library/pil/handbook/image.htm#Image.point>
    #  for information on the point() function
    # Note that the second parameter we give to the min function determines
    #  how faded the image will be. That number is in the range [0, 256],
    #  where 0 is black and 256 is white. A good value for fading our white
    #  text is in the range [100, 200].
    watermask = watermark.convert("L").point(lambda x: min(x, 100))
    # Apply this mask to the watermark image, using the alpha filter to 
    #  make it transparent
    watermark.putalpha(watermask)

    # Paste the watermark (with alpha layer) onto the original image and save it
    main.paste(watermark, None, watermark)
    main.save("watermark/"+filename, "PNG")

if __name__ == '__main__':
    li = os.listdir('without_watermark')
    for f in li:
        if("gif" in f): continue
        print  f
        work(f)

Thanks. Great to have a bit of working code.