Blend

Blend 2 images using different blend modes.

Node Data
FilterComposeArray
Display name
Blend
Internal name
Node_Blend
Inheritances
node
node_processor
node_blend
Inputs
node_blend
surface	Background
surface	Foreground
enum	Blend Mode
float	Opacity
surface	Mask
enum	Fill Mode
enum	Output Dimension
vec2	Constant Dimension
bool	Active
bool	Preserve Alpha
enum	Horizontal Align
enum	Vertical Align
bool	Invert Mask
float	Mask Feather
vec2	Position
Outputs
node_blend
surface	Surface Out

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

Blend Modes

Blend Mode control how the surface is being mixed. Blend modes available in the this node are:

The examples are blend of 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:

Filling

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

Alignment

When Fill Mode is set to None, you can move the foreground freely in the preview panel.