Editing Channels

A channel allows certain types of editing not possible in a selection.

You can paint in a channel or apply effects to it. Feathering a channel softens the transitions between light and dark areas.

You can also fill a channel with a color, pattern, gradient, or weave. You can fill an entire channel or an area of a channel, or you can fill a channel based on existing color. For more information, refer to "Filling Images Based on Color".

When you edit a channel, you are making modifications to the channel, and not the image. You can use shades of gray only; no colors are available. This is because the alpha channel is a grayscale image, separate from the RGB image. The resulting channel can be used afterwards to make changes to your image.

If you want to modify a specific area of a channel, you can create a selection. The current selection is available to the RGB image and all channels. For more information, refer to "Creating Selections".

Editing a channel does not affect how the channel displays. For information about setting the color and opacity of the displayed channel overlay, refer to "Setting Channel Attributes".

To paint in a channel

1. On the Channels palette, display and select the channel you want to work with.

If you want to paint only on a specific area of the channel, make a selection.

2. Choose the Brush tool from the toolbox.
3. On the Brush selector bar, choose a brush category and variant.

The Pen and Airbrush categories make good choices.

4. On the Colors palette, choose a color.

Only grayscale values are available. Black adds to the channel. White erases from it.

When you paint in the channel, hue is irrelevant. The channel carries 8 bits of information and you need only set a level in that range. The value scale is between black and white.

5. On the property bar, type a value in the Opacity box, or adjust the pop-up slider.
6. Type a value in the Size box, or adjust the pop-up slider.
7. Paint in the document window.

To apply an effect to a channel

1. On the Channels palette, display and select the channel you want to work with.

If you want to apply the effect to a specific area of the channel, make a selection.

2. Choose an effect from the Effects menu.

To learn more about image effects, explore "Using Image Effects".

To feather a channel

1. On the Channels palette, display and select the channel you want to work with.
2. Click the palette menu arrow, and choose Feather.
3. In the Feather dialog box, type a number of pixels.

A channel - before and after feathering.

To fill a channel

1. On the Channels palette, display and select the channel you want to work with.

If you want to fill only a specific area of the channel, make a selection.

2. In the toolbox, choose a color, pattern, gradient, or weave from the corresponding selector.
3. Choose Effects menu > Fill.
4. In the Fill dialog box, enable one of the following to fill with:

• Current Color
• Pattern
• Gradient
• Weave

Current Color fills with the current shade of gray.

5. Adjust the Opacity slider.

• For more information on the Fill command, refer to "Filling an Area with Media".

To fill a channel based on color

1. On the Channels palette, display and select the channel you want to work with.
2. Choose the Paint Bucket tool from the toolbox.
3. On the property bar, click the Fill Image button .
4. Choose one of the following from the Fill pop-up menu:

• Current Color-fills with the current color-a shade of gray.
• Grad-fills with the selected gradient.
• Clone Source-fills using the current clone source image. If you haven't defined a clone source, Corel Painter fills with the current pattern.
• Weave-fills with the selected weave.

5. Choose the specific material you want from the Fill selector.
6. To specify the range of gray to be filled, type a value in the Tolerance box, or adjust the pop-up slider.
7. To specify the fill opacity for pixels outside the Tolerance range, type a value in the Feather box, or adjust the pop-up slider.

If you want to create intermediate fill values on the boundaries, enable the Anti-Alias check box. This gives soft edges to the fill. Anti-aliasing is desirable when Feather is zero or extremely low.

8. Click the area of the channel you want to fill.

If the result is not what you want, undo the fill, change the settings, and try again.

• The Paint Bucket applies a fill only to a visible channel. Make sure the channel's eye icon is open before using the Paint Bucket.
• For complete information on Paint Bucket controls, refer to "Filling Images Based on Color".

• You can return to the default Paint Bucket settings by clicking the Reset Paint Bucket button on the property bar.