You might want to save your selections for future use as well.  To do so you use the Channels Palette .

Load Selection, Save Selection, Create, Delete Channels

Restore the fudog image to its original state by using the History Palette  or by reloading the image.  Create a Selection using any one of the Selection Tools you wish, but make sure Feathering  is set to 0.  {Click} the Channels Tab in the Layers  Palette  Group .  You will see four channels: RGB, Red, Green, and Blue.  The RGB channel is a composite of the Red, Green, and Blue channels.

Color Channels
There are two types of Channels in Photoshop : Alpha and Color.  The fudog image is made of a combination of three color Channels, each containing a range of data relating to the primary colors in digital imaging, Red, Green, and Blue.  Recall that combining variations of Red, Green, and Blue can produce over 16 million colors.  Photoshop keeps the primary color information separate for editing purposes, most specifically for modifying color.  We will use Channels further on.  For now, {Click} the Visibility (the eye) Toggle beside the Channel thumbnails to Toggle the visibility of a color channel.  Notice how the color in the image drastically changes.  To restore the Channels simply {Click} the visibility Toggle beside each invisible channel or {Click} the Visibility Toggle of the RGB Channel to activate all the Channels.

Alpha Channels
We use Alpha Channels  to save our Selections .  Alpha Channels do not store color data, rather they store grayscale data used to define and store Selections.  {Click} Save Selection as Channel at the bottom of the Channels Palette .  An Alpha Channel is added below the color channels titled, “Alpha 1.”  To rename the channel simply {Double-Click} the Channel Box.  Rename accordingly.

The Selection is saved as an Alpha Channel

Examine the Alpha Channel thumbnail.  You’ll notice that the channel is made up of pure black and white.  The black indicates the area of the image not selected and the white the area of the image selected.  If you haven’t already, deselect the Selection.  {Click} the Visibility Toggle beside the Alpha Channel.  The resulting composite now has a pinkish hue over the image with regular color showing through where the Selection was.  {Click} the Visibility Toggle of all the color channels to make them invisible.  Only the Alpha Channel is visible.  Notice again that the black area represents the area of the image not selected, while the white area represents the area of the image that is selected.  In effect, you can look at the Alpha Channel as a mask.  The white area is the hole in the mask.  When active as a Selection we can only manipulate the area of the image we see through that hole.

Recall that we mentioned Alpha Channels  store grayscale data to define and store Selections .  Our current Alpha Channel has only black and white.  Different values or levels of gray indicate transparency when working with Selection Masks, that is, as the color range shifts from black, which is absolute transparency, to white, which is absolute opacity, various levels of transparency occur.  Recall what occurs when we feather a Selection.  The edge of the Selection gradually shifted to complete transparency.  Anything below the translucent or partially transparent areas shows through or mixes with the image above.

To demonstrate lets create an elliptical Selection with a Feather value of 20.  First, Toggle the visibility of the Alpha Channel to off and restore the color channels by toggling the visibility of the RGB Channel to on.  Next, select the Elliptical Selection Tool and set Feathering  to 20 in the Options  Palette.  Create an elliptical Selection with the fudog image.  Now use the Channels Palette  to create an Alpha Channel based on your new Selection.  Deselect your Selection and examine the new Alpha Channel by toggling the visibility of the other Channels.  Notice the elliptical area is pure white at the center and fades close to complete transparency toward the edge as color shifts to various shades of gray.  This is why Alpha Channels  work in grayscale, using 256 shades of gray to define transparency.

Restoring Your Selection
We created Alpha Channels  based on our Selections  so that we can restore the Selections at a later time.  When you save an image as a Photoshop  native document the Alpha Channels are saved with the file.  We’ll pretend that we saved the fudog image and have just reloaded it.  (You can save it as fudogchannel if you wish, close it and reopen it.)  Make sure both Alpha Channels are not visible by toggling visibility in the Channels Palette .  Make sure that you Toggle the visibility of the RGB Channel to on.  To restore your selection select Select/Load Selection.  The Load Selection dialog box appears.

Load Selection dialog box

Source
Indicates the source filename of the Alpha Channels , in this case “fudogchannel.psd.”

Channel
Use the drop-down arrow to select which channel you want to restore the Selection from: either Alpha 1 or Alpha 2 unless you renamed the channels.

Invert
{Clicking} Invert  reverses the Alpha Channel values, switching black to white, white to black, and any intermediate grays accordingly.  As a result, your Selection will be inverted or reversed.  Modifications occur in the area of the image you did not initially select.

Operation
Select New Selection, Add to Selection, Subtract from Selection, and Intersect  with Selection as you desire.  For the most part, you will select New Selection.  The other options are only available if the image already has an existing Selection active.  Experiment with these settings if you wish.

{Click} OK.  Your Selection is restored.

Exercises

• Open the window image from the chapter004 folder.   Use the Magnetic Lasso Tool  or the Magic Wand  to create a Selection around the window.

• Use the Channels Palette  to convert the Selection into an Alpha Channel.

• Open the landscape image from the chapter004 folder.

• Experiment with the History Palette  by painting on the image with the Airbrush Tool .  Try to select different colors by {Double-Clicking} the Foreground Color Swatch in the Toolbox.

• Use the History Palette  to remove your modifications and make new Snapshots.