6.14. Compositing With Blend Modes

HitFilm includes multiple blend modes, which are used to control how layers and effects are combined visually.

A layer’s blend mode can be changed from its contextual menu on the timeline or from the Control panel. Some effects have their own blend modes, and masks also have a selection of blend modes.

Each blend mode combines pixels together in a unique manner. Before any blend mode calculations are performed, the color values are mapped from the RGB range of 0-255 to a range of 0.0-1.0, where 0.0 is pure black, and 1.0 is pure white. Blend modes fall into several categories, based on the general effect they have on the combined layers.

• Add, Color Dodge, Divide, Lighten, and Screen: All of these options brighten the image. In all of these modes, any black areas in the blended layer will disappear and have no effect.
• Darken, Color Burn, Multiply, and Subtract: All darken the image. In all of these modes, any white areas in the blended layer will disappear and have no effect.
• Hard Light, Overlay and Soft Light: These modes all increase the contrast in the image.Areas of 50% grey in the blended layer will have no effect, while areas closer to black or white will have a greater impact on the contrast of the resulting image.
• Difference and Exclusion: Both invert luminance or color values in the resulting image.
• Color, Hue, Lightness and Saturation: These modes all look at the blended layer in HSL color space, and then apply one or two of the three HSL components of the blend layer to the base layer.

Blend Modes

Below is a list of all available blend modes and details of how they work. Blend Layer will refer to the to layer, to which the blend mode is being applied. Base Layer refers to the layer below the blend layer, which the blend layer will be blended with.

• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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 crating undesirable color halos or artifacting.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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).