Channel Booleans Node

Channel Booleans (the 2D version, in the Composite category) is a version of Reorder without a shader interface: for each output channel (R Out, G Out, B Out, A Out) you choose:

• Which input it comes from (BG or FG).
• Which source channel (R / G / B / A / Z / U / V / etc.).
• Which math operation to apply (Copy, And, Or, Xor, Add, Subtract, Multiply, etc.).

Very powerful for handling the auxiliary channels of a multichannel EXR (Z-depth, UV, normals, motion vectors) or for repairing / rerouting alpha.

• Effects Library: Tools > Composite > Channel Booleans
• Quick add: right-click in the Node Editor → Add Tool > Composite > Channel Booleans

Channel Booleans (this node, 2D)

Works on 2D images (bitmap output). In Tools > Composite.

Channel Boolean Material (3D)

A 3D shader (material output), used inside Blinn/Cook-Torrance to combine textures at the material level. In Tools > 3D.

Same logic, different contexts. This page covers the 2D version. For 3D, see the 3D materials section.

• Background (orange) - the first image source. Sets the output resolution.
• Foreground (green) - the second source. It can be the same image as the BG or a completely different one.
• Effect Mask (blue) - optional. Limits the remix to an area.

Alpha repair (copy the alpha from another source):
Image without alpha → Channel Booleans BG
Image with a clean alpha → Channel Booleans FG
Settings: A Out = A Fg (Copy)

Viewing an auxiliary EXR channel:
Multichannel EXR → Channel Booleans
Settings: R Out = Z Bg (Copy), G Out = Z Bg, B Out = Z Bg
(= shows the Z-depth in grayscale)

Swapping R and B (inverted channels):
Image → Channel Booleans (BG = FG, same input)
Settings: R Out = B Bg, B Out = R Bg

For each output channel (R Out, G Out, B Out, A Out, Z Out):

Operation

The math mode (Copy, And, Or, Xor, Add, Subtract, Multiply, Difference, etc.).

BG source (left of the operation)

The Background input channel used: Red BG, Green BG, Blue BG, Alpha BG, Z BG, UV BG, Normal X/Y/Z BG, Vector X/Y BG, etc.

FG source (right of the operation)

The Foreground input channel. Same list. Only useful for binary operations (And, Or, Add, etc.). For Copy, only one source is used.

Enable

Disable a channel and it keeps its original value (pass-through from the BG).

Copy

Simply takes the value of the source channel. The most used operation.

Add

Adds BG + FG channel by channel.

Subtract

BG - FG. Useful to isolate differences.

Multiply

BG × FG (normalized 0-1 values). The result is darker than either input.

And / Or / Xor

Bitwise operations (rarely used in practice except for very specific needs).

Difference

|BG - FG|. Highlights the areas where the two inputs differ. Useful to compare two shots.

Solid Color / Black / White

Fills the channel with a constant value. To force a channel to 0, 1 or a fixed value.

• Alpha repair / alpha copy - an image rendered without alpha → take the alpha from another source (e.g. a manual key from another shot, roto) → A Out = A FG, R/G/B Out = R/G/B BG.
• Viewing the Z-depth of an EXR - an EXR with built-in Z-depth → Channel Booleans with R/G/B Out = Z Bg = a grayscale image of the depth visible on screen.
• Extracting a pass from a multichannel EXR - 3D render EXRs often contain diffuse, specular, reflection. Channel Booleans lets you isolate a specific pass.
• Channel swap (R ↔ B) - an image imported from a source that uses BGR instead of RGB → swap R and B.
• Converting RGB to a custom grayscale - R Out = G Bg (Copy), G Out = G Bg, B Out = G Bg = a black and white image based only on the green channel (usually the most informative for a human face).
• Channel math for effects - Add on R Out between two images = a creative channel-by-channel overlay, common in some workflows to simulate light effects or channel separations.
• Solid Alpha (forcing opacity to 1) - A Out = Solid White. Creates a fully opaque image, a must for some renders that need to be opaque.

• Copy is the most used operation - in 90% of cases, you just want to take a channel from a source and put it in an output channel. No need for complex math operations.
• Enable = ON by default for every channel - remember to disable the channels you do not want to change, otherwise they automatically pass through from the BG (which is often fine, but worth checking).
• Same input for BG and FG - if you just want to swap the channels of a single image (R ↔ B for example), connect the same source to both inputs.
• Channel Booleans 2D ≠ Channel Boolean Material - do not mix them up (different menus, different logic). This is the 2D version, not a 3D shader.
• Always check the viewer - channels can hold non-visual values (Z-depth, UV, normals). A viewer in Alpha channel mode lets you see non-RGB channels.
• Custom Tool for more control - if Channel Booleans is too limited (a custom per-pixel formula), use the Custom Tool with math expressions.