The Preserve Visibility option affects all aspects of image editing. When Preserve Visibility is selected, pasted selections do not affect clear areas. Also, a pasted selection will match the transparency of the existing pixels when you defloat the selection. You must deselect Preserve Visibility to paint in clear areas of an image. Then, if you want to edit the painted areas, select Preserve Visibility again. For example, you can deselect Preserve Visibility and paint airbrush strokes in a clear image. Then, select Preserve Visibility and you can paint over the airbrush strokes to change their color, without losing the soft edge or “spilling” color into clear areas. When Preserve Visibility is selected and you use the Eraser tool, pix- els you “erase” are painted with the current background color; they are not erased to clear. Also, when you use any painting tool to apply color, you cannot make pixels more or less transparent. This is why you cannot apply any color in clear areas when Preserve Visibility is selected. When you select Preserve Visibility, you can paint and apply filters to modify pixels that are less than 100% transparent. You can change the hue, saturation, and intensity of pixels but can’t change their transparency. To paint or apply filters to an entire image, deselect Preserve Visibil- ity. This turns off the visibility mask and lets painting tools and filters affect the entire image. Tip If an image is completely clear (contains no colored pixels), you cannot alter the image when Preserve Visibility is selected.
Canvas 8 Help: Selections and channels (31 of 32)                                                   Page #681