Explanation:
- Black edges
- Regular edges of the trellis
- Magenta edges
- Edges responsible for cutting off the paths that can no longer result in the correct syndrome (the least significant bit of the states is 0, whereas the message bit is 1)
- Green edges
- Similar to magenta edges, corresponding to the case where the message bit is 0 (states with their least significant bit equal to one are discarded)
- Red edges
- The shortest (cheapest) path to the state with minimal weight
Below the trellis is the partial stego vector corresponding to the red path. The bits in which it differs from the cover vector are highlighted in red.