The most common way to make one image fade into another is to add a Layer Mask and then use the Gradient tool. In a Layer Mask, areas that are pure black become completely transparent, and areas that are pure white become completely opaque. Shades of gray in a Layer Mask will make the image become partially transparent. So, if you would like one image to fade into another, apply a gradient to a Layer Mask with the Gradient tool set to Black, White (Figures 15.45 to 15.47).