From Applied Science Fiction:
The Digital SHO Professional Plug-In is software that automatically adjusts the shadows and highlights so that more detail is visible. Typically in photography, images can be adjusted to bring out details in the shadows or the highlights. With the Digital SHO Professional Plug-In, details in both the shadows and the highlights can be enhanced simultaneously. By manipulating the Threshold slider, the user can adjust the break point between what is considered a shadow within the image as well as what is deemed a highlight. The individual sliders (Highlight Detail, Shadow Detail) will determine the strength of the effect in each area. Version 1.0.2 may include unspecified updates, enhancements, and bug fixes.