How to use the Image Steganography Tool (Hide Text in Image)
- 1. Pick an imageOpen your own picture or use the sample.
- 2. Write the messageType the text and, if you like, a password to encrypt it.
- 3. Save as PNGHide it, download the PNG, and use Reveal mode to read it back.
How LSB steganography works
Every pixel stores red, green and blue values from 0 to 255. Changing the lowest bit of a value (for example 200 to 201) is invisible to the eye. The tool writes the message one bit at a time into the least significant bit of each colour channel, after a short header that marks the image and records the message length.
So each pixel holds 3 bits. The sample image is 400 × 260 pixels: 400 × 260 × 3 ÷ 8 = 39,000 bytes, minus a 9-byte header, gives a capacity of 38,991 bytes, enough for a long letter. With a password, the text is first encrypted with AES-256-GCM using a key derived by PBKDF2-SHA256 (600,000 rounds), so even someone who finds the hidden bits cannot read them.
Limits you should know
- PNG only for the output. JPEG compression and most chat apps re-encode images and wipe the hidden bits. Send the file as a document.
- No resizing or editing after hiding, or the message is lost.
- Not invisible to experts. Statistical tests can detect LSB changes. Hiding is not the same as encrypting, which is why the password option exists.
- Transparency is removed from the output so colour values stay exact.
This tool reads only images saved by itself, since it looks for its own header. Large photos are scaled to 1,600 pixels on the long side before hiding. Images and messages never leave your device. Learn the encryption on its own with the text encryption tool, or inspect raw bytes with the hex dump viewer. Use steganography only for lawful purposes such as learning, CTF practice and watermark experiments.
Frequently asked questions
Can I hide a file instead of text?
This version hides text only. Encode a small file as Base64 text first if you need to.
Why can't I reveal a message from a WhatsApp image?
WhatsApp and most chat apps recompress photos, which destroys the hidden bits. Send the PNG as a document instead.
Is the Image Steganography Tool (Hide Text in Image) free?
Yes, the Image Steganography Tool (Hide Text in Image) is free. The first time you hide or reveal your first message, you are asked for your name and WhatsApp number once. After that, this and every other Uncodemy tool opens straight away without the form.