Python Pillow - Add Watermark to Image

Python Pillow - Add Watermark to Image

You can add a transparent watermark to an image using Pillow library in Python.

Watermarks are generally added to images to specify the branding, or specify copyright information, or in such cases.

To add a watermark to an image using the Python Pillow library (PIL), you can overlay a transparent watermark image on top of the original image at specific position using Image.paste().

Let us go through some examples. The following are the input images.

Original Image

Watermark Image

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1. Add watermark to image using Image.paste() in Pillow

We are given two images: input_image.jpg, and watermark.jpg. We have to add the water mark image to the original image input_image.jpg at top left corner, precisely at location (10, 10).

Steps

1. Open original image using Image.open().

original_image = Image.open('input_image.jpg')

2. Open the watermark image using Image.open(). You may replace 'watermark.png' with your watermark image file.

watermark = Image.open('watermark.png')

3. Define the position where you want to place the watermark. Adjust these coordinates to place the watermark as desired. This position must be a tuple of two integers, specifying the distance (in pixels) from top and left respectively.

position = (10, 10)

4. Paste the watermark onto the original image using Image.paste().

original_image.paste(watermark, position, watermark)

5. Save the modified image object to local file, say output_image.jpg.

original_image.save('output_image.jpg')

5. Finally, close both the original image and watermark image.

original_image.save('output_image.jpg')

Program

The complete program to add a watermark to an image using Image.paste() is given below.

Python Program

from PIL import Image

# Open the original image
original_image = Image.open('input_image.jpg')

# Open the watermark image
watermark = Image.open('watermark.png')

# Coordinates to place the watermark
position = (10, 10)

# Add watermark
original_image.paste(watermark, position, watermark)

# Save the image with the watermark
original_image.save('output_image.jpg')

# Close both images
original_image.close()
watermark.close()

Output Image

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2. Set transparency to watermark image

In the previous example, we have seen how to add a watermark image to an original image. Now, we take it a step further by adding transparency to the watermark image.

The additional step would be, after reading the watermark image, take a transparency value that can range from 0 to 255 where 0 represents fully transparent watermark, and 255 represents fully opaque watermark. And use this transparency value for the alpha channel of the watermark image.

Program

The complete program to add a watermark with a specific transparency to an image is given below.

Python Program

from PIL import Image

# Open the original image
original_image = Image.open('input_image.jpg')

# Open the watermark image
watermark = Image.open('watermark.png')

# Transparency level (0 for fully transparent, 255 for fully opaque)
transparency = 150

# Make the watermark image transparent by adjusting the alpha channel
watermark = watermark.convert('RGBA')
watermark_with_transparency = Image.new('RGBA', watermark.size)
for x in range(watermark.width):
    for y in range(watermark.height):
        r, g, b, a = watermark.getpixel((x, y))
        if not (r == 0 and g == 0 and b == 0):
            watermark_with_transparency.putpixel((x, y), (r, g, b, transparency))

# Coordinates to place the watermark
position = (10, 10)

# Add watermark
original_image.paste(watermark_with_transparency, position, watermark_with_transparency)

# Save the image with the watermark
original_image.save('output_image.jpg')

# Close both images
original_image.close()
watermark.close()

Output Image

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Summary

In this Python Pillow tutorial, we learned how to add watermark to an image using Pillow library in Python, with examples. We have taken an input image, a transparent watermark image, and then added the watermark image to the input image.