Screen Mode: Screen mode is the inverse of Multiply mode. Painting in screen mode will create lighter colors because the result is the inverse multiple of the base and blend colors. If either your base color or your blend color is black, the result will be black, and if either is white, the result will be white. Think of it this way: if you were to take pure Red, Blue and Green and blend them in Screen mode, you would get White in accordance with proper additive model color theory. This is hard to adjust to; however, as we generally are taught as children to mix colors more in accordance with Multiply mode.
Overlay Mode: Overlay is a “Smart” mode, applying Screen or Multiply depending on the base color. Overlay mode will attempt to preserve the value of the base color in the result color while mixing it to some degree with the blend color. So if you were trying to change the color of the lighting in a picture without changing the overall range of values, you might try Overlay mode. However, as it has the strengths of both Multiply and Screen, it also shared their weaknesses, and will not be apparent when the base color is white or black.
Soft Light Mode: This mode allows you to paint in highlights OR shadows that you might see when using a soft, diffused light source. If the blend color is relatively light (less in value than 50% gray), the result color will be lighter than the base color. If the blend color is relatively dark (greater in value than 50% gray), the result color will be darker than the base color. The lighter or darker your blend color, the greater the difference will be.
Hard Light Mode: Like Soft Light Mode, this mode will allow you to add both light AND shadow depending on your blend color. However the effect is much greater than in soft light mode – similar to the difference between the lighting of a harsh spotlight and a diffuse overhead room light.
Color Dodge Mode/Color Burn Mode: I put these two together to save time. If you have a pretty good understanding of how the dodge and burn tools work, then you will understand the principles of these two modes. Both affect the base color based on the value of the blend color. Dodge will make a lighter result color, while Burn will make a darker result color, depending on the value of the blend color.
Darken Mode/Lighten Mode: Again, I’ve put two modes together because one is the polar opposite of the other. Each mode compares the base and blend color. In the case of Darken, the result color is the darker of the two for any pixels lighter than the blend color. In Lighten, the result is the lighter of the two for any pixels darker than the blend color. Confused? Just remember that darken won’t change pixels which are darker than the blend color, and lighten won’t change pixels lighter than the blend color.
