New to Photoshop CS4, the Adjustments panel offers an extensive list of presets (Levels Presets, Curves Presets, Exposure Presets, Hue/Saturation Presets, Black & White Presets, Channel Mixer Presets, and Selective Color Presets). Sometimes an image only needs one adjustment, other times it may need several. There are two ways to apply an adjustment. It can either be applied directly to the image or as a separate layer. Furthermore, an adjustment layer can affect all visible layers or just the currently selected layer. It all depends on how the adjustment layer is created and set up.