What is blind_watermark?

guofei9987/blind_watermark — explained in plain English

Analysis updated 2026-06-24

★ 12,811PythonAudience · developerComplexity · 2/5Setup · easy

Mindmap

mindmap
  root((blind watermark))
    What it does
      Invisible watermarks
      Blind extraction
      Attack resistance
    Payload types
      Text strings
      Small images
      Binary data
    Security
      Password protected
      No original needed
    Usage
      pip install
      Command line
      Python API

mindmap root((blind watermark)) What it does Invisible watermarks Blind extraction Attack resistance Payload types Text strings Small images Binary data Security Password protected No original needed Usage pip install Command line Python API

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What do people build with it?

USE CASE 1

Embed a hidden copyright notice in images you publish online so you can prove ownership if they are stolen.

USE CASE 2

Watermark photos with a password-protected identifier before sharing so only you can extract and verify the mark.

USE CASE 3

Track where a confidential image was leaked by embedding different watermarks in copies sent to different recipients.

USE CASE 4

Process large batches of images in parallel to add invisible ownership marks before distribution.

What is it built with?

Python

How does it compare?

	guofei9987/blind_watermark	jacobgil/pytorch-grad-cam	datalux/osintgram
Stars	12,811	12,802	12,800
Language	Python	Python	Python
Setup difficulty	easy	easy	moderate
Complexity	2/5	3/5	2/5
Audience	developer	researcher	researcher

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · easy Time to first run · 5min

Install via pip, requires Python 3.5+ and works on Windows, Linux, and macOS with no external services.

So what is it?

blind_watermark is a Python library for embedding hidden watermarks inside images and then extracting them later, without needing the original image at extraction time. That is what the word "blind" means here: the extraction process works on a modified or attacked copy of the image on its own. The watermark is invisible to the human eye. It is embedded by applying a chain of mathematical transforms to the pixel data, specifically the DWT (discrete wavelet transform), DCT (discrete cosine transform), and SVD (singular value decomposition). The result looks identical to the original image, but contains a hidden message that can later be decoded. What makes the approach practical for copyright protection is that the watermark survives common modifications to the image. The readme shows a table of attack tests: rotating the image 45 degrees, cropping a random section, adding masks or noise, resizing it, or reducing its brightness all leave the embedded watermark recoverable. This means someone cannot easily strip or destroy the watermark by casually editing the image. You can embed text strings, small image files, or raw binary data as the watermark payload. A password is used at both embed and extract time, so the watermark is keyed and cannot be read by someone who does not know the password. The library can use multiple CPU cores in parallel to speed up processing on large images. Installation is through pip, the standard Python package manager. The command-line tool lets you embed and extract watermarks with a single shell command. A Python API is also available for use inside scripts or other programs. The project is available on Windows, Linux, and macOS and requires Python 3.5 or newer.

Copy-paste prompts

Prompt 1

Using the blind_watermark Python library, write a script that embeds the text 'Copyright 2024 MyBrand' into all JPEG files in a folder using a password, and saves the watermarked versions to an output folder.

Prompt 2

Show me how to use blind_watermark to extract a hidden watermark from an image that has been cropped and resized, using the original password.

Prompt 3

I want to use blind_watermark to watermark images before uploading them to social media. Write a Python function that takes an image path and a secret key, embeds a watermark, and returns the watermarked image as bytes.

Prompt 4

Explain what DWT, DCT, and SVD mean in plain English and why blind_watermark uses all three together to make watermarks that survive image edits.

Frequently asked questions