Some images contain transparent or semi-transparent data which allows images below it to show
through; it is visible in NPS (and most other image editors) as a gray hatched background.
NPS includes 3 different modes for working with transparent parts of an image.
To change the transparency editing mode, click Format > Transparency Editing Mode or click the
"Opaque", "Keyed", and "Alpha" buttons on the right sidebar. The functionality of different modes,
and their impact on various tools, is outlined below.
Opaque
This mode does not create new transparency in the image. Existing transparency is preserved when
moving a selection, and the area from which the selection originated is filled with white.
Likewise, the Eraser tool fills the image with white.
Microsoft Paint user tip: This is similar to enabling the "Draw Opaque" option.
Keyed
In keyed mode, the currently selected background color is used as a transparency key for
selections. For instance, if you set the background color to white and select a part of your
image containing black text on a white background, the white background will "disappear" when
you move the selection. The Eraser tool will fill the image with the background color.
Microsoft Paint user tip: This is similar to disabling the "Draw Opaque" option.
Alpha
In Alpha mode, the image's alpha channel is used as the source of transparency. (If the image is
in indexed format, the transparent color, if any, is used instead.) Moving a selection will
open a transparent region behind it, and the Eraser tool will create transparency.