Ghostmark
A lightweight image steganography tool by NQR
Seeded, randomized LSB steganography with grayscale plus Floyd-Steinberg dithering. Encode and decode in your browser.
Tip: After choosing images, use the selection box in the Stego preview to position and resize the hidden image. Drag corners/edges to resize (hold Shift to lock aspect ratio). Drag the center to move.
Seed:
By default, the seed is also written to the image header (top-left 8x8) for plug-and-play decoding.
If checked, the decoder must manually enter the same seed.
Flip the hidden image before encoding.
Rotation:
Rotate the hidden image (degrees).
Strength:
0 = do not embed; 1 = full embed. Intermediate values randomly keep some original LSBs.
Stego Image Preview
Hidden Image Preview
Algorithms: grayscale = ITU-R BT.601 luma (0.299R, 0.587G, 0.114B). Dithering = Floyd-Steinberg (7/16, 3/16, 5/16, 1/16).
LSB parity randomized per pixel with a Mulberry32 PRNG from a 32-bit seed; channel choice randomized per pixel.
MIT License
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Copyright (c) 2025 NQR
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.