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Alpha Channels and Masks > Alpha Channels and Masks - Pg. 144

| PaintShop Photo Pro X3 for Photographers FIG 5.7 This selection was made using the Elliptical selection tool feathered by 200 pixels. The corresponding alpha channel shows the selected area in the center, gradually fading to black, and the bottom right image shows the actual selected pixels. with a soft edge gradually fading to black. Any editing applied to image pixels selected using an alpha channel with gray pixels will have a partial effect, which is extremely useful for subtle image editing without `hard' edges. It means you can apply filters and other effects with a gradually tapering effect. At their simplest, alpha channels are simply a useful method for permanently storing selections. To do this, all you have to do is click Selections > Load/ Save Selection/Save Selection to Alpha Channel. Usually, you'll want to save a selection to the image you created it from, but you can also save and load selections into other documents. Masks Masks are a little like alpha channels in that they use a grayscale image to determine what happens to corresponding image pixels. Masks are in fact a special kind of layer. Grayscale mask pixels determine the opacity of image pixels in underlying layers. Masks provide a useful means of hiding image pixels without actually deleting them. By directly editing masks (and, for that matter, alpha channels) you can perform sophisticated image-editing tech- niques in a non-destructive way, without altering the pixel values in the affected layer. 144