BMP Steganography Hider
Hide text or files inside BMP images using pixel LSB, palette, or reserved field methods. AES-256 encrypted. Real-time distortion preview.
Try the demo instantly
Loads a 50×50 gradient BMP — no upload needed
Drop a BMP here or click to browse
24-bit or 8-bit uncompressed BMP · Max 50 MB
100% Client-Side Processing
Your BMP is processed entirely in this browser tab. Nothing is uploaded to any server.
How to Hide a Message in a BMP (5 steps)
- Upload your BMP image (24-bit or 8-bit recommended)
- Enter the secret text or upload a file to hide
- Choose encoding method (Pixel LSB, Palette LSB, or Reserved)
- Adjust bit depth for capacity vs. quality trade-off
- Click Encode and download your stego BMP
BMP Steganography Methods — Algorithm Comparison
| Method | Technique | Capacity | Best For |
|---|---|---|---|
| Pixel LSB | Modifies LSBs of pixel color values | High — ~3 bits per pixel (24-bit BMP) | 24-bit/32-bit BMPs, large payloads |
| Palette LSB | Modifies LSBs of color palette entries | Medium — ~96 bytes (256 colors) | 8-bit indexed BMPs, smaller payloads |
| Reserved Bytes | Stores data in BMP header reserved fields | Low — 3 bytes only | Tiny payloads, quick hiding, CTF hints |
Frequently Asked Questions
What's the difference between Pixel LSB and Palette LSB?
Pixel LSB modifies the actual pixel color values in the image data. Palette LSB modifies the color table entries (for indexed/8-bit BMPs only). Pixel LSB offers much higher capacity for 24/32-bit images.
Why can't I use Palette LSB with my image?
Palette LSB only works with indexed-color BMPs (8-bit or lower) that have a color palette. 24-bit and 32-bit BMPs store colors directly in pixels without a palette.
What is bit depth and how does it affect capacity?
Bit depth determines how many bits per color channel are used for hiding. 1-bit is most subtle but lowest capacity. Higher bit depths (2-4) increase capacity but may introduce visible artifacts.
Will my image look different after encoding?
With 1-bit LSB encoding, changes are typically imperceptible to the human eye. Higher bit depths or larger payloads may cause subtle color shifts, especially in flat/solid color areas.
Can this survive image compression?
No. BMP steganography is fragile to any re-encoding. If the BMP is converted to JPEG or PNG, the hidden data will be destroyed. Share the BMP file directly.
What's the Reserved Bytes method for?
It's a very simple hiding technique using the BMP header's reserved bytes (3 usable, after 1 byte is spent on a length prefix). Good for CTF challenges or tiny secrets. Easily detected by viewing the hex dump of the file header.