5.6.1. Blending modes

Blending modes define how the colors in the selected layer (Blend Layer) are combined with the layers beneath it in the layer stack (Base Layer). They are divided into groups based on general behavior, though the groups are not labeled in the software.

Normal blending modes

• Normal: The default blend mode. Layers are not mixed at all. The Blend Layer is displayed without mixing any of the colors with the Base Layer. The Blend Layer will completely obscure the Base Layer, unless the Blend Layer contains its own masking or alpha channel.
• Dissolve: For each pixel, the value is randomly picked from either the Base or Blend Layer. Some pixels will use the color data of the Base, and others will use the color data from the Blend. When first applied it often appears as if the blend mode has no effect, because its results depend on adjustment to the layer opacity. At 100% opacity of the layer, all pixels will take values from the Blend Layer. At 0% opacity, all pixels use Base values. At any value in between, pixels will be randomly chosen from the Base and Blend Layers. Dissolve does not apply any kind of smoothing, blurring or anti-aliasing, so the result tends to look very grainy.

Knockout blending modes

• Knockout: Removes the shape of the Blend Layer from the alpha of all layers beneath it.
• Clip: Clips the alpha transparency of all layers beneath it to the exact shape of the Blend Layer.

Darkening blending modes

• Darken: For each pixel, Darken compares the color value of the Base Layer to that of the Blend Layer and displays whichever is darker. Darken can be useful for combining the black areas of multiple layers when creating or refining masks. It is the opposite of Lighten.
• Multiply: Multiplies the Base value by the Blend value, resulting in a darker image overall. Any color multiplied by black (0.0) creates black, and any color multiplied by white (1.0) remains unchanged. Thus multiply can be effective for removing white areas of the Blend Layer. It gives the opposite result of the Screen blend mode.
• Color Burn: Simulates “burning” film in a darkroom by increasing the contrast of the Base Layer, based on the color values of the Blend Layer. To do this it inverts the values of the Base Layer, divides the result by the Blend Layer, then inverts the results. Like Multiply, Color Burn darkens the image overall, but reduces highlights even more, and gives more saturated mid-tones. It is basically the opposite of Color Dodge.

Lightening blending modes

• Lighten: For each pixel, Lighten compares the color value of the Base Layer to that of the Blend Layer and displays whichever is lighter. Lighten can be useful for combining the white areas of multiple layers when creating or refining masks. It is the opposite of Darken.
• Screen: The pixel values of both layers are inverted, multiplied, then inverted again, resulting in a brighter picture. Effective for compositing transparent stock elements such as smoke and glows. It is similar to Add in its results, but tends to be more subtle. It gives the opposite result of the Multiply blend mode.
• Color Dodge: Simulates the effect of “dodging” film in a darkroom by decreasing the contrast of the Base Layer based on the color values present in the Blend Layer. To do this it inverts the values of the Blend Layer, then divides the Base Layer by those inverted values. Like Screen mode, Color Dodge lightens the overall image, but tends to result in intense, saturated mid-tones and blown-out highlights. It is basically the opposite of Color Burn.
• Add: Pixel values are added together, resulting in a brighter image. Any pixels where the sum of the addition produces a value higher than 1.0 will be clipped to 1.0 and will display as white. Useful for compositing light-based visual effects such as light flares, muzzle flashes, lightswords and stock explosions.Similar to Screen blend, but with somewhat more intense results.

Contrast enhancing blending modes

• Overlay: Increases contrast using a combination of Multiply and Screen blend modes. Overlay applies the Screen Blend mode to areas where the Base layer contains values greater than 50%, and applies the Multiply Blend mode to areas where the Base Layer contains values less than 50%. Similar to Soft Light and Hard Light in the results it produces. It is essentially the same as Hard Light, except that Overlay is based on the values of the Base Layer.
• Soft Light: Increases overall contrast and vibrance of an image, in a manner similar to Hard Light and Overlay. Soft Light applies a half-strength Screen Blend mode to areas of the Blend Layer with values greater than 50%, and applies the half-strength Multiply Blend mode to areas of the Blend Layer with values less than 50%. The results are more subtle than Hard Light and Overlay.
• Hard Light: Increases contrast using a combination of Multiply and Screen blend modes. Hard Light applies the Screen Blend mode to areas of the Blend Layer with values greater than 50%, and applies the Multiply Blend mode to areas of the Blend Layer with values less than 50%. Hard Light is similar to Overlay and Soft Light, but more extreme than both. It is essentially the same as overlay, except that Hard Light is based on the values of the Blend Layer.

Inversion blending modes

• Difference: Takes the color value for each pixel, and subtracts the Base value from the Blend value. The difference between these values is used as the new color value for the pixel. If the resulting number is negative the positive equivalent value is applied (Example: “-64” would become “64”). If the Blend color is pure white (255,255,255), the Base color will be inverted. This effect can yield dramatic and psychedelic color shifts. Difference can be very useful for comparing identical layers to ensure correct alignment. The Difference Key effect is based off this blend mode: a clean “background plate” is used, and the identical areas in the footage to be keyed go completely to black, allowing the areas isolated by the Difference blending to be enhanced and separated by means of a luma key.
• Exclusion: Similar to Difference blending. However, in Exclusion the calculation ignores positive/negative values, using absolute values only. This means similar values tend to get shifted to mid-greys rather than black, resulting in a lower contrast image. Unlike Difference, which can be used in keying, Exclusion is pretty much only useful for surreal, solarized color effects.
• Subtract: Subtracts the Blend Layer value from the Base Layer value, resulting in a darkening of the overall image. Negative values are clipped to 0 (black).
• Divide: Divides the Base value by the Blend value, resulting in a lightening of the image. Since any value divided by itself results in 0, this can be useful for removing color tints or casts from an image. By using a plane of the color you want to remove as the Blend Layer, any areas in the Base Layer containing the color of the plane will be neutralized to grey.

Component blending modes

• Average: Adds the Base value and Blend value, then divides by the number of layers (2) to get an average value for each pixel.
• Hue: Converts both layers to HSL color, then combines the Luminance and Saturation values of the Base Layer with the Hue of the Blend Layer. Used carefully, this can alter colors while retaining the tonal and saturation values of the image, which can result in accurate, subtle tonal shifts.
• Saturation: Converts both layers to HSL color, then combines the Luminance and Hue values of the Base Layer and the Saturation values of the Blend Layer. This can be used for artistic effects, or for selectively de-saturating parts of an image.
• Color: Converts both layers to HSL color, then combines the Hue and Saturation values from the Blend Layer with the Luminance values of the Base Layer. This is often used to quickly tint images, by using the Blend Layer as a color map.
• Luminosity: Converts both layers to HSL color, then combines the hue and saturation values from the Base Layer with the Luminance values of the Blend Layer. Luminosity can be particularly useful for sharpening. By blending a sharpened greyscale duplicate of a layer back onto the full color original, you can effectively sharpen the image without creating undesirable color halos or artifacting.

Blend-If blending mode

Blend-If is a simple way to blend layers based on their tonal values. It is the only blend mode to include additional controls for managing the blend. By adjusting the sliders, you can control what areas of the layer are visible, based on the contents of the layer you are on, or based on the contents of the underlying image. These sliders can be used independently or in conjunction. The top and bottom control handles are linked in pairs. The distance between the two handles in each pair controls the feathering of the blend.

• This Layer: This slider uses the contents of the selected layer itself to determine what areas of the layer will be visible. The slider has four control handles:
  • Bottom Black: Areas of the selected layer darker than this tone will be completely invisible. Tonal values between the bottom black and top black sliders will gradually be more opaque as they move toward the top black slider.
  • Top Black: Areas of the selected layer lighter than this tone will be completely visible. All tones within the selected layer that fall between the top black handle and the top white handle will be completely visible.
  • Bottom White: Areas of the selected layer lighter than this tone will be completely invisible. The tones between the top white and bottom white sliders will gradually be more transparent as they move toward the bottom white slider.
  • Top White: Areas of the selected layer darker than this tone will be completely visible. All tones between the top black handle and the top white handle will be completely visible.
• Underlying Layer: This slider uses the contents of all layers below the selected layer to determine what areas of the selected layer will be invisible and allow the lower layers to show through. The slider has four control handles:
  • Bottom Black: Areas of the underlying image which are darker than this tone will show through the selected layer. Tonal values of the underlying image that fall between the bottom black and top black sliders will gradually be more transparent as they move toward the top black slider.
  • Top Black: Areas of the underlying image which are lighter than this tone will be completely invisible. All tones within the underlying image that fall between the top black handle and the top white handle will be completely invisible.
  • Bottom White: Areas of the underlying image which are lighter than this tone will show through the selected layer. Tonal values of the underlying image that fall between the top white and bottom white sliders will gradually be more opaque as they move toward the bottom white slider.
  • Top White: Areas of the underlying image which are darker than this tone will be completely invisible. All tones of the underlying image that fall between the top black handle and the top white handle will be completely obscured by the selected layer.