Combining Images ­ Layers and Masks | corresponding pixels in underlying layers. Adjustment layers are also gray- scale and their effect on underlying layers is likewise dependent on the pixels within the mask. Black pixels apply no correction, white pixels apply the full amount of correction, and gray pixels apply varying amounts of correc- tion in between. You can vary the overall effect of an Adjustment layer using its Opacity slider in the Layers palette. Alternatively, you can apply the Adjustment layer to a selection, or paint directly on to it to isolate the parts of the layer you want the adjustment to affect. Layer Types You can add the following types of Adjustment layer: · · · · · Color Balance Hue/Saturation/Lightness Channel mixer Brightness/Contrast Curves