The shadow/highlight tool (Image > Adjustments > Shadow/Highlight) is a quick and dirty way to bring out details lost in muddy shadows or bright images. The basic settings come up as default, with just two sliders, one for recovering detail and generally darkening down brighter areas and one that does just the opposite in the shadows. Checking Show More Options brings up more detailed sliders; Tonal Width controls just how much of the image is considered in the shadows, Radius controls how much to blend between the areas being affected and not. Color correction adjusts for shifts in saturation in color, which is particularly important for highlight adjustments. Midtone contrast is a basic contrast adjustment for those areas between shadows and highlights. Best used when on night scenes with even but dark lighting.