Photoshop Tutorials - Alpha-Channels
Pretty often you have to select the same image are several times during your work with it. If the shape of the selection is complex, this becomes laborious.
Alpha-channels allow you to save the selections. Alpha-Channels contain masks, as you can save selections with various opacity levels. Masks are scales of grey where white color stands for selected areas, black color stands for areas that are not selected and grey stands for partly selected areas. Working with Alpha-channels is similar to working with Quick Mask.
I will teach you how to save and load Alpha-channels. First I will teach you how to save the Alpha-channels:
Open the image and select an object there
Go to Select > Save Selection. Save Selection window will open. There you will see the following options: Document, Channel, Name and Operation. Document dropdown menu selects for what object the Alpha-channel is saved. Channel option sets whether the channel is saved as a new channel. Name sets the name of the saved channels.
Save selection as a new channel. It is not necessary to enter the name, unnamed channels will be saved as Alpha 1, Alpha 2,etc in the order of appearance.
Open the Channels palette. In addition to the color channels now it has the channel you have saved. Working with Alpha-channels is similar to working with layers. You can set the visibility by clicking the eye icon. Selections can be turned to channels and back using the buttons in the bottom of Channels palette.
Click RGB channel to activate it. If you will see the image covered with the colored mask (similar to Quick Mask tool) then Alpha-channel is visible. This is done to simultaneously edit the selection in alpha-channel and see the image underneath it. Make alpha-channel invisible by clicking the eye icon beside it in the Channels palette. Remove selection by pressing Ctrl+D.
To restore selection go to Select > Load Selection. Invert option in the window that will appear will allow you to invert selection.
Now you see how easy it is to save your selection and restore it later when you need to with Alpha channels.