Mari 4.5v2 docs:

Channels Palette

The Channels palette and the controls that can be found on it are described in the table below. When controls also bring up additional dialogs, these are referenced for more information.

What It Does

The Channels palette displays:

• a list of channels in the project,

• buttons to add, convert, or remove channels,

• options for creating quick channels, and

• channel attribute information.

Note: Channels provide a foundation that layers and layered shaders are built on. These channels can be diffuse, bump, or specular channels, to name only a few. Channels are assigned to lighting shaders, and sliders in that palette give you fine control over aspects of each channel.

Channels Palette Fields

Control	Type	What it does	Dialog	Notes
Quick Channel
	swatch	Creates a channel filled in black. The created channel is named Quick Channel. If there are multiple Quick Channels, then the name is followed with a number.
	swatch	Creates a channel filled in white. The created channel is named Quick Channel. If there are multiple Quick Channels, then the name is followed with a number.
	swatch	Creates a channel filled in mid-gray. The created channel is named Quick Channel. If there are multiple Quick Channels, then the name is followed with a number.
	swatch	Creates a channel filled in transparent. The created channel is named Quick Channel. If there are multiple Quick Channels, then the name is followed with a number.
<channel size>	dropdown	Sets the channel size used when creating a Quick Channel, from the options: • 256x256 • 512x512 • 1024x1024 • 2048x2048 • 4096x4096 • 8192x8192 • 16384x16384 • 32768x32768		Ensure this is set to the size you want before creating Quick Channels.
<channel depth>	dropdown	Sets the channel depth used when creating a Quick Channel, from the options: • 8bit (Byte) • 32bit (Float) • 16bit (Half)		Ensure this is set to the depth you want before creating Quick Channels.
Channels panel
	button	Opens an individual palette that displays the layers of that channel only.
	icon	Indicates whether the channel is tagged for Channels Palette. - The data in the image-set/channel is considered as color data and is being color managed. - The data in the image-set/channel is considered as non-color data, specifically scalar data, and has no color management applied.
	icon	Indicates the color depth of the channel: - 8bit (Byte) - 16bit (Half) - 32bit (Float)
	button	Indicates an unlocked state. Clicking the icon changes the channel state to locked.
	button	Indicates a locked state. Clicking the icon changes the channel state to unlocked.
	button	Adds a new channel to the channels list.	Add Channel Dialog
	button	Converts the channel into either 8bit (Byte), 16bit (Half), 32bit (Float).	Convert Type Dialog
	button	Channels can be shared into the layer stack of another channel in the Channels palette. This button shows with which channel it is shared.	Sharing Channels
	button	Removes the channel.
General
File Space	dropdown	Set whether the channel is Normal, Vector, Vector (flipped Y), or Normal (flipped Y).
Size	information	Lists the size of the patches in the channel.
Depth	information	Lists the color depth of the channel.
User Attributes
MriImport Path	information	Lists the import path of the channel.
MriImport Template	information	Lists the import file name of the channel.
Color Data
Data Colorspace (advanced color management mode only) or Colorspace (intermediate color management mode only)	dropdown	The colorspace of the channel. Automatic is determined by the file name, size, and type of data in the channel. Changing the colorspace of the channel changes all the color pickers and swatches when working on that channel.
Working Colorspace (advanced color management mode only)	dropdown	Select the colorspace to use for painting, lighting, applying filters, and similar operations.
Output Colorspace (advanced color management mode only)	dropdown	Select the colorspace to use for the output.
Raw Data (advanced and intermediate color management modes only)	checkbox	The colorspace of the channel masks. Automatic is determined by the file name, size, and type of data in the channel. Changing the colorspace of the channel changes all the color pickers and swatches when working on that channel.
Scalar Data	checkbox	When checked, the data in the image-set/channel is considered as non-color data such as masks, heights, normals, and depths.
Mask Data
Data Colorspace (advanced color management mode only) or Colorspace (intermediate and basic color management modes only, read only for basic mode)	dropdown	The colorspace of the channel mask. Automatic is determined by the file name, size, and type of data in the channel. Changing the colorspace of the channel mask changes all the color pickers and swatches when working on that mask.
Working Colorspace (advanced color management mode only)	dropdown	Select the colorspace to use for painting, lighting, applying filters, and similar operations.
Output Colorspace (advanced color management mode only)	dropdown	Select the colorspace to use for the output.
Raw Data (advanced and intermediate color management modes only)	checkbox	The colorspace of the channel masks. Automatic is determined by the file name, size, and type of data in the channel. Changing the colorspace of the channel mask changes all the color pickers and swatches when working on that mask.
Scalar Data	checkbox	When checked, the data in the image-set/channel is considered as non-color data such as masks, heights, normals, and depths, so Mari stops applying the viewport colorspace LUT when such channel/image-set is displayed in isolation. For example, when you are viewing a scalar channel through "Current Channel" shader, Mari applies no viewport colorspace LUT.		See Color Data and Scalar Data for more information.