Drawing Light Areas Using the "Screen" Blending Mode
Lighten some areas using a layer whose [Blending mode] is set to [Screen]. A color lighter than the layer below is created for the content drawn on the [Screen] layer, making this mode ideal for highlights and other light areas. If the color on the layer below is pure black, there is no change to the color. The lighter the color on the layer below, the lighter the color that is created relative to the layer below.