Steganography
Steganography hides the existence of a message, not only its contents. StegoPixel can place text, images or whole archives inside a photo — in its pixels or its metadata — and read them back later. Nothing leaves your machine.
Encryption protects a message whose existence is plain to anyone looking. Steganography hides the existence itself — the payload travels inside an image that still opens as an image — and StegoPixel is honest about where each approach breaks.
A payload can live in the pixels or in the metadata. Each choice survives one kind of journey and is destroyed by another, which is why the decision matters more than the encoding settings.
Payload bits go into the least-significant bits of the colour channels you choose, and the result is always written as PNG. Capacity grows with the image, the channels and the bit depth — and so does the chance that the embedding becomes visible.
The payload rides inside the file's metadata instead of its pixels, with a far larger ceiling: up to 44,984 bytes in JPEG, PNG, TIFF and WebP. It survives pixel-level recompression, but it vanishes the moment somebody cleans the file's metadata.
| Carrier | Capacity | Survives | Destroyed by |
|---|---|---|---|
Pixel LSB (STEG) | Scales with resolution, channels and bit depth | Metadata stripping | Lossy re-encoding |
Metadata channel (STGM) | Up to 44,984 bytes in JPEG, PNG, TIFF and WebP | Pixel-level recompression | A metadata cleanup |
Anything that rewrites the pixels destroys LSB data: re-saving a JPEG, resizing, or uploading to a platform that recompresses. Keep pixel carriers in PNG, TIFF or BMP when the file might be edited or re-shared, and treat a corrupted decode as a re-encoding problem first.
Encryption is optional, and it is built from standard, widely reviewed primitives rather than anything bespoke. Turn it on, and the payload is locked before it ever touches the carrier.
Steganography hides that a payload exists; encryption protects its contents if the carrier is found anyway. Use both — and remember that a high iteration count raises the cost of guessing but cannot rescue a weak passphrase.
Error correction is a second checkbox. Wrap the payload in a Reed–Solomon code and a carrier that picked up bit-level damage can still give you back what you hid.
RS(255,223) over GF(256) corrects up to 16 corrupted bytes in every 255-byte codeword.When error correction rescues a payload, the decode says so and tells you how much it had to fix. Read that number before you rely on a heavily damaged carrier.
There is no single capacity number for images — only a number for one file at one set of settings. StegoPixel calculates that number for the file in front of you and shows it before you commit.
| Channel | Capacity |
|---|---|
| Pixel LSB | (width × height × channels × bit depth) ÷ 8 − 16 bytes, where the 16 bytes are the payload header |
| Metadata channel | Up to 44,984 bytes in JPEG, PNG, TIFF and WebP — a typical maximum rather than a guaranteed ceiling |
The number to trust is the one on screen, because it comes from the file itself rather than a rule of thumb. If the payload does not fit, the encode does not start.
Half of this module faces the other direction: opening an image you were sent and asking what it carries.
STEG header across all four bit depths and reports the payload's estimated size, type and whether it is encrypted.Header detection looks for StegoPixel's own STEG and STGM markers, and payloads written by other tools do not carry them. When the signature is silent, the bit-plane, entropy, noise and modified-pixel views are how you look for disturbed ground.
A photograph carrying a payload is still a photograph. Four views show you the parts of it that changed — and they work whether the payload is yours or somebody else's.
Eight planes per colour channel, with the least-significant one laid bare. Payload bits live exactly there, and they do not look like photographic detail.
A local Shannon entropy map over 7×7 windows, normalised from 0 to 1. Embedded data pushes the local pattern towards randomness, and the map lights up where it does.
A 3×3 neighbour-difference map showing where the fine grain of the image stops behaving like the rest of the frame.
A heatmap against the original image, or an LSB anomaly scan when the original is not to hand.
They fail in opposite ways. Pixel embedding survives metadata stripping but is destroyed by any lossy re-encoding; a metadata channel holds more and survives pixel recompression, but vanishes if somebody cleans the file's metadata. Choose the carrier that survives the journey your file will actually take.
Pixel capacity scales with resolution, the number of channels and the bit depth you choose — a deeper embedding carries more and shows more. The metadata channel targets 44,984 bytes in JPEG, PNG, TIFF and WebP, a typical maximum rather than a guaranteed ceiling. The number to trust is the one the app shows before you encode.
Pixel payloads do not survive lossy re-encoding — anything that rewrites the pixels destroys LSB data. Reed–Solomon error correction can repair limited bit-level damage, but it cannot reconstruct what a JPEG re-save threw away. Keep pixel carriers in lossless formats such as PNG, TIFF or BMP.
It can report whether a STEG or STGM payload is present — with its estimated size, type and whether it is encrypted — and decode it when you have the passphrase. For carriers from other tools, the analysis views show where the pixels look disturbed, without claiming to read a format the app does not know.