Channels

The Channels panel lets you view and edit the image in separate channels. Channels are halftone images providing information about the brightness of color components. The channel list contains a composite image, color mode channels (RGB, CMYK, Lab, Grayscale), the transparency channel of the current raster layer (alpha channel), current selection channel, and the active layer mask channel. Each channel in the palette corresponds to a thumbnail image that displays all changes made to this channel.

You can adjust the size of thumbnails by clicking the button at the top of the Channels panel.

Channels Panel for CMYK Channels Panel for CMYK

The active (editable) channel is highlighted with a dark gray background in the list. To select another channel, click on its name. When selecting a single channel, the image is shown as grayscale.

Displaying Green Channel Displaying Green Channel
Green Channel is Selected Green Channel is Selected

The visibility icon next to the inactive channel means that this channel is shown in the Image Window but is not editable. If several channels are visible, the image is displayed in color.

Displaying Green & Red Channels Displaying Green & Red Channels
Green & Red Channels are Selected Green & Red Channels are Selected

If you select the composite channel, all component channels become visible and active. The composite image is always located at the top of the list and is selected by default.

Displaying All Color Components Displaying All Color Components
RGB Channel is Selected RGB Channel is Selected

To edit a channel, use the usual drawing tools. Painting on a channel with white results in 100% intensity of the corresponding color. Different shades of color result in varying color intensity. The black color completely removes a color channel.

 

In the Alpha channel, by default, opaque areas are shown in white, transparent areas in black, and semitransparent areas in gray.

You can adjust the view mode for the alpha channel in the pop-up menu: Grayscale, Trimap, or Highlighted in Red.

Grayscale Grayscale

Trimap Trimap

Right-click on the alpha channel to open the context menu with the following commands:

 

The Mask channel displays the current layer mask, if available: black marks protected areas, white marks unprotected areas, gray marks the transition zone. The mask channel has 6 view modes.

Highlighted in Red Highlighted in Red

Inverted Red Inverted Red

Right-click on the mask channel to open the context menu with the following commands:

 

The Selection channel indicates the area of the current selection: white marks selected areas, black marks unselected areas, gray marks the transition zone. For this channel, 6 view modes are available.

Black Background Black Background

White Background White Background

Right-click on the selection channel to open the context menu with the following commands:

 

View Modes:

You can change the displaying of contents of the alpha, mask, and selection channels in the Image Window by clicking the icon to the right of the channel's name and choosing from the options: