Click the color swatch to set a mask
color, and enter the degree of transparency. Set the mask color with
the basic colors of the image in mind. Choose a contrasting color that will
be easy to see, even at low transparencies.
Select the paintbrush tool to brush
in the selection. At this point, the active color is very important.
In Quickmask mode, the color palette reverts to grayscale, and a black value
adds to the mask, and a white value deletes the mask. Shades of gray indicate
a feathered selection, where a mid-tone 50% gray paints an area that is
50% selected, with more selected as the tones get darker. Therefore, with
black as the foreground color, the paintbrush adds to the mask. Switching
to white allows the paintbrush to erase from the mask. The eraser works
the same way, where the background color dictates how the eraser effects
the mask.
