User Guide

GNU Image Manipulation Program

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marching-ant mode. You can also activate the QuickMask by selecting in the image window menu Select → Toggle QuickMask,

or by using the Shift-Q shortcut.

Activating the QuickMask shows you the selection as though it were a translucent screen overlying the image, whose transparency

at each pixel indicates the degree to which that pixel is selected. By default the mask is shown in red, but you can change this if

another mask color would be more convenient. The less a pixel is selected, the more it is obscured by the mask. Fully selected

pixels are shown completely clear.

When you are in QuickMask mode, many image manipulations act on the selection channel rather than the image itself. This

includes, in particular, paint tools. Painting with white causes the painted pixels to be selected; painting with black causes them

to be unselected. You can use any of the paint tools, as well as the bucket ﬁll and gradient ﬁll tools, in this way. Advanced users

of the GIMP learn that ‘painting the selection’ is the easiest and most effective way to delicately manipulate it.

Tip

To save the selection done by the Quickmask to a new channel; Make sure that there is a selection and that Quickmask

is not active in the image window. Select in the image menu Select/Save to Channel. This will create a new channel in

the channel dialog called SelectionMask 1.

Tip

When QuickMask is active, Cut and Paste act on the selection rather than the image. You can sometimes make use of

this as the most convenient way of transferring a selection from one image to another.

You can learn more on Quickmask and Selection masks in the section dedicated to the channel dialog.

7.3.2 Properties

There are two QuickMask properties you can change by right-clicking on the QuickMask button.

• Normally the QuickMask shows unselected areas ‘fogged over ’ and selected areas ‘in clear’, but you can reverse this by

choosing ‘Mask Selected Areas’ instead of the default ‘Mask Unselected Areas’.

• By choosing ‘Conﬁgure Color and Opacity’, you can bring up a dialog that allows you to set these to values other than the

defaults, which are red at 50% opacity.

7.4 Using the Quickmask

1. Open an image or begin a new document;

2. Activate the Quickmask using the left-bottom button in the image window. If a selection is present the mask is initialized

with the content of the selection;

3. Choose any drawing tool. Paint on the Quick Mask using black color to remove selected areas and white color to add

selected areas. You can use grey colors to get partially selected areas.

You can also use selection tools and ﬁll these selections with the Bucket Fill tool. This does not destroy the Qmask

selections!

4. Toggle off the Quickmask using the left-bottom button in the image window: the selection will be displayed with its

marching ants.