by Julieanne Kost
The third group of Blend modes have a neutral color of black. This means that black as a blend color will have no effect on the result color. These blend modes all have stronger effects as the blend color becomes lighter. Using the Fill slider on Layers palette and using blend modes from this group may modulate this effect rather than performing a simple opacity blend the way normal mode does. The lightening modes are essentially the inverses of the darkening modes.
• Lighten – Looks at the color information in each channel and selects the lighter of the base or blend color as the result color. Pixels darker than the blend color are replaced, and pixels lighter than the blend color do not change.
• Screen – Looks at each channel’s color information and multiplies the inverse of the blend and base colors. The result color is always a lighter color. The effect is similar to projecting multiple photographic slides onto the same screen. Screen reduces contrast and can produce and effect similar to painting an area with bleach.
• Color Dodge – Looks at the color information in each channel and brightens the base color to reflect the blend color by decreasing the contrast. Color Dodge is an exception to the neutral color rule in this group – it is the only lightening mode that preserves blacks. Color Dodge is similar to moving the input white triangle in Levels. As such, color dodge increases contrast but may clip the brighter portions of the lower colors to white.
• Linear Dodge – Looks at the color information in each channel and brightens the base color to reflect the blend color by increasing the brightness. Linear dodge is the combination of color dodge and screen. As such, it has a stronger lightening effect than either of them. Linear Dodge will clip bright values, unlike Screen.
• Lighter Color Compares the total of all channel values for the blend and base color and displays the higher value color. Lighter Color does not produce a third color, which can result from the Lighten blend, because it chooses the highest channel values from both the base and blend color to create the result color.