Blend

Combine 2 images using different blend modes.

Node Data

Display name
Blend
Internal name
Node_Blend
Inheritances
Node_Processor
Node_Blend
Inputs
Node_Blend
surface	Background
surface	Foreground
surface	Mask
bool	Invert Mask
slider	Mask Feather
enum	Output Dimension
vec2	Constant Dimension
enum	Blend Mode
slider	Opacity
bool	Preserve Alpha
enum	Fill Mode
vec2	Position
enum	Horizontal Align
enum	Vertical Align
Outputs
Node_Blend
surface	Surface Out
Attributes
Color Depth

Blending surfaces is a fundamental step in any VFX process. Blend node allows you to combine 2 surfaces under different blend equation.

Blend Mode" class="anchor">Blend Mode

Blend Mode control how the surfaces are being mixed. The table below shows the underlying equation and an example blending result of these 2 surfaces:

Mode	Operation	Example
Normal	$$C_{out} = C_{fg}C_{fg.a} + C_{bg}(1-C_{fg.a})$$
Add	$$C_{out} = C_{fg} + C_{bg}$$
Subtract	$$C_{out} = C_{fg} - C_{bg}$$
Multiply	$$C_{out} = C_{fg}C_{bg}$$
Screen	$$C_{out} = 1 - (1-C_{fg})(1-C_{bg})$$
Overlay	$$C_{out} = \begin {cases} 2C_{fg}C_{bg} & C_{fg} < 0.5 \\ 1 - 2(1-C_{fg})(1-C_{bg}) & C_{fg} \ge 0.5 \end {cases}$$
Hue	Transfer the hue of the foreground to the background
Saturation	Transfer the saturation of the foreground to the background
Luminosity	Transfer the luminosity of the foreground to the background
Maximum	$$C_{out} = max(C_{fg}, C_{bg})$$
Minimum	$$C_{out} = min(C_{fg}, C_{bg})$$
Replace	$$C_{out} = C_{fg}$$
Difference	$$C_{out} = \|C_{fg} - C_{bg}\|$$

Opacity

The intensity of the effect will be multiply by the Opacity property.

Preserve Alpha

Blend operation apply to all channel including alpha channel. Which mean some operation may erase the alpha channel of the original image. To exclude the alpha calculation, set Preserve Alpha to true.

Dimension Mixing

When blending surfaces of different sizes. You can set the blending behaviour using several properties:

Fill Mode

The Fill Mode property control the behaviour of the smaller surface.

Mode	Description
None	Do nothing, place smaller surface directly.
Stretch	Stretch the smaller surface to fit the larger surface.
Tile	Tile the smaller surface to fit the larger surface.

Position

When Fill Mode is set to None, you can set the position of the Foreground freely using the Position property.

PXC Documentation