Corel Painter Help | Saving selections as alpha channels

Quick links to procedures on this page:

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To save a selection to a new alpha channel

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To combine a selection with an existing alpha channel

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To load a selection from an alpha channel

Saving selections as alpha channels

You can create alpha channels to store multiple selections in a document. An alpha channel is a temporary storage area for both path-based and pixel-based selections. To reuse a selection in other documents, you can store the selection in the Selection Portfolio. It is important to note that the Selection Portfolio stores only path-based selections. For more information see, Working with the Selection Portfolio.

You can create an alpha channel from the current selection to copy its editable and protected areas. You can also combine a new selection with one that was previously stored in an alpha channel. To reactivate a selection that was previously saved as an alpha channel, simply load it in the image. Loading a selection reactivates it on the canvas, where it controls painting and image effects.

Combining selections when saving or loading alpha channels

When you save or load alpha channels, you can combine the current selection with an existing alpha channel by adding, subtracting, or intersecting with the selection. Adding to a selection combines it with the existing channel. Subtracting a selection cuts it out of the existing channel. When intersecting a selection, you include only those parts that are common to the selection and the existing channel.

In the following set of owl images, the artist created and saved selections for each area that she wanted to work with separately — the eyes, the beak, and the outline. To show the selections clearly in these images, the selections were saved to channels, reloaded, and displayed as red overlays. For more information, see To view or hide a channel.

The following images show the step-by-step creation of a precise "face" selection that excludes the beak and eyes. The purpose of the precise selection of the face is to control the brushstrokes and constrain effects.


The image
The eye and beak channels (saved selections) are loaded and added. The combined selection is saved to the "eyebeak" channel.
The "outline" channel is loaded.
The "eyebeak" channel is loaded and subtracted from the "outline" channel. The resulting selection is saved to the "head" channel.
A "face" selection is drawn roughly by using the Lasso tool. The eyes, the beak, and a portion of the background are included.
The "head" channel (the outline with eyes and beak subtracted) is loaded and intersected with the rough "face" selection. This step removes the eyes, beak, and background portion. The resulting selection is saved to the "face" channel.

To save a selection to a new alpha channel

1

Create a selection.

2

Choose Select

Save Selection.

3

Choose New from the Save To list box.

If you want to specify a name, type a name in the Name box.

Alpha channels are pixel based, therefore, any path-based selections are saved as pixel-based selections.

If you do not specify a name, the new channel is named incrementally with the previous channel: Alpha 1, Alpha 2, and so on.

You can also save a selection to a channel by clicking the Save Selection As Channel button in the Channels panel.

To combine a selection with an existing alpha channel

1

Create a selection.

2

Choose Select

Save Selection.

3

Choose a channel from the Save To list box.

4

In the Operation area, enable one of the following options:

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Replace Mask — replaces the channel with the current selection

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Add to Mask — combines the current selection with the chosen channel

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Subtract From Mask — subtracts the current selection from the chosen channel

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Intersect With Mask — determines the intersection of the selection and the chosen channel, and saves the intersection to the channel

You can also save a selection to a channel by clicking the Save Selection As Channel button in the Channels panel.

To load a selection from an alpha channel

1

Choose Select

Load Selection.

2

Choose a channel from the Load From list box.

3

In the Operation area, enable one of the following options:

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Replace Selection — replaces the current selection with the chosen channel

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Add To Selection — adds the channel to the current selection

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Subtract From Selection — subtracts the channel from the current selection. In other words, the channel is "cut away" from the selection.

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Intersect With Selection — determines the intersection of the channel and the current selection. This intersection becomes the new selection.

You can also load a selection from an alpha channel by clicking the Load Channel As Selection button in the Channels panel.

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