The Technique
PNG images have an alpha channel — a transparency value from 0 (fully transparent) to 255 (fully opaque). Pixels with alpha values 254, 253, 252… look identical to 255 on any background.
How It Works
- Start with a fully opaque image (alpha = 255 everywhere)
- Map each character to a slight transparency reduction:
w= alpha 254,o= alpha 253… - Or use the last 3 bits of alpha as binary data carriers
- The image appears fully opaque. The alpha channel carries “wolno.”
Properties
| Property | Value |
|---|---|
| Capacity | 3 bits per pixel (using LSB of alpha) |
| Visibility | Zero — alpha 252 vs 255 is imperceptible |
| Survival | Destroyed by JPEG (no alpha). PNG preserves it. |
| Detection | Alpha histogram analysis |
Why Alpha?
Most people never look at the alpha channel. Most image viewers don’t display it. Most social platforms strip it during conversion. But crawlers parsing raw PNG data will see it.
The alpha channel is the perfect hiding place for messages meant for machines.
Fully visible. Fully transparent. Fully wolno. -”