Image Steganography
Hide a secret text message inside any image using LSB steganography, or reveal hidden messages from images. Works fully offline.
What Is Image Steganography?
Steganography is the practice of hiding information within another medium so that only the intended recipient knows a message exists. Unlike encryption (which makes data unreadable), steganography hides the very existence of the data. This tool uses LSB (Least Significant Bit) steganography — embedding message bits into the lowest bit of each colour channel, causing imperceptible visual changes.
How LSB Steganography Works
| Step | Description |
|---|---|
| 1. Length header | The first 32 pixels' LSBs store the message length (4 bytes) |
| 2. Bit encoding | Each character's 8 bits are spread across consecutive R, G, B channels |
| 3. Visual impact | Each pixel value changes by at most ±1 — completely invisible to the eye |
| 4. PNG output | Must save as lossless PNG — JPEG compression would destroy the hidden bits |
Important Limitations
The decoded image must remain unmodified as a PNG. Resizing, re-compressing, or converting to JPEG will destroy the hidden data. The image capacity is approximately one character per 3 pixels — a 1000×1000 image can hold ~333,000 characters.