Some areas in your image are are too dark although the overall brightness is fine? This can happen when shooting against the light, e.g.. AACO is the Auto Adaptive Contrast Optimization of SilverFast and the tool of choice in this case.
|Strength: determines the strength of the brightening effect on the dark areas.|
|Shadow Width: determines the brightness of the areas to be affected by AACO. Think of this as a gray scale going from black to white. Move the slider to the right to include brighter areas.|
|Saturation: the use of AACO can lead to a loss of saturation in the areas affected. Use the saturation slider to bring back the saturation for these areas without affecting the overall saturation.|
Radius: The radius must match the spacing of the shadow details for AACO to work.
A good way to work with it, is to use a high strength value to have be able to see clearly which areas of the image are affected. Find a shadow width then which includes the areas for which you want to raise the brightness. Reduce the strength until the areas are brightened up according to your liking, before you raise the saturation back to a normal level. Adjust the radius if necessary.