S-UNIWARD is an adaptive spatial-domain steganography method for uncompressed images. It is part of the UNIWARD family of distortion functions and uses image content to guide where embedding changes should be made.
Use in tools
S-UNIWARD is used by HStego 0.4 for uncompressed images. This should be read as a method implemented by that tool version, not as a separate algorithm named “HStego 0.4”.
For detectability experiments, StegoWatch also relies on the S-UNIWARD simulator included in Aletheia. A separate S-UNIWARD research implementation is available in StegoLab.
Detectability results
In the evaluated setting, the S-UNIWARD simulator is much less detectable than simple LSB replacement methods. Its relative position against HILL depends on the payload range shown in the chart.
Simulator-based results should be interpreted as method-level results. Embedding simulators are usually slightly harder to detect than real end-user tools such as HStego, because they embed close to the theoretical limit and do not include all practical constraints of a complete tool.