Invisible Watermark (LSB Steganography)

The Invisible Watermark tool uses Least Significant Bit (LSB) steganography to hide secret text messages inside images. Unlike a visible Image Watermark that overlays text on the image surface, LSB steganography modifies the least significant bit of each color channel in the pixel data. The changes are so small — at most a difference of 1 out of 256 per channel — that the human eye cannot distinguish the watermarked image from the original.

The tool works in two modes. Embed mode takes your image and a secret message, encodes the text as UTF-8 bytes, prepends a 32-bit length header, and writes each bit into the LSB of the red, green, and blue channels sequentially. The alpha channel is left untouched to avoid transparency artifacts. The result is a pixel-perfect-looking PNG that carries your hidden payload.

Extract mode reverses the process: it reads the LSBs from the uploaded image, reconstructs the length header, then reassembles the hidden bytes back into readable text.

For added security, you can set an optional password. When provided, the message bytes are XOR-encrypted with the password before embedding. Without the correct password, the extracted data will be unintelligible. For stronger encryption needs, consider generating a key hash with the Hash Generator and using that as your password.

All processing is performed entirely on the client side using the HTML Canvas API. Your images and messages never leave your browser — no data is uploaded, stored, or transmitted to any server. You can verify this by monitoring your browser's network tab.

Capacity depends on image dimensions: a 1000 x 1000 pixel image can store approximately 375,000 characters. The tool displays the exact capacity after you upload an image. A pixel difference visualization (amplified 255x) lets you see exactly which pixels were modified, confirming the changes are imperceptible under normal viewing.

Important limitation: LSB steganography is fragile. Any lossy operation — JPEG compression, resizing, cropping, or taking a screenshot — will destroy the hidden data. Always save and share the watermarked image in PNG format. If you need a watermark that survives compression, consider using a visible Image Watermark instead.

1. Select the Embed tab to hide a message, or the Extract tab to reveal one.
2. In Embed mode, click the upload area or drag and drop a PNG or other image file. The tool displays the image dimensions and character capacity.
3. Type or paste your secret message into the Secret Message text area. The byte counter shows how much capacity you are using.
4. Optionally enter a Password to XOR-encrypt the message before embedding. Anyone extracting the message will need the same password.
5. Click Embed Message (or press Ctrl+Enter). The tool shows the original and watermarked images side by side, plus an amplified pixel difference map.
6. Click Download Watermarked PNG to save the result. Always use PNG — JPEG will destroy the hidden data.
7. To extract, switch to the Extract tab, upload the watermarked PNG, enter the password if one was used, and click Extract Message. Copy the result with Ctrl+Shift+C.