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Channels

Digital images generally consist of the four standard channels: red, green, blue, and alpha. Nuke allows you to create or import additional channels as masks, lighting passes, and other types of image data.

 

Introduction

A Nuke script can include up to 1023 uniquely named channels per compositing script. For example, you can combine multiple render passes from a 3D scene - an image from the red, green, and blue channels, a depth mask (z-depth channel), a shadow pass, a specular pass, lighting passes, and multiple mattes all stored within one image sequence in your composite.

Note:  When a script is saved, any channels that are not referenced in the script are discarded automatically.

When creating channels and layers, bear in mind these good practice guidelines:

• Ensure that all layers use the same channel names in the same order. This avoids complications with multilayer .exr files imported into Nuke.

• Always use proper names for channels, never just a single letter.

• Always create a custom layer for custom channels, don't add to the existing default layers.

• Never use more than four channels per layer. Nuke only has a four channel interface.

Quick Start

Here's a quick overview of the workflow:

1.

Channels in Nuke are always a part of a layer. You can create new channels and layers using the new option in the channel selection dropdown menus (such as output and mask) in a node’s properties panel. For more information, see Object Material Properties.

2.

Using the channel selection controls you can select which channels the node is processing and outputting, or using as a mask when color correcting for instance. For more information, see Calling Channels and .

3.

The channels can also be linked to other channel controls through the Link menu. For more information, see Linking Channels Using the Link Menu.

4.

Using the Shuffle and ShuffleCopy nodes, you can rearrange your input channels and apply the result in the output. For more information, see Swapping Channels.