Once the channel is initialized, selected (highlighted in blue), visible (eye-icon in the
dialog), and displayed as you want (color and opacity attributes), you can start to work
with all the paint tools. The colors used are important. If you paint with some color other
than white, grey, or black, the color Value (luminosity) will be used to define a gray
(medium, light, or dark). When your mask is painted, you can transform it to a selection
by clicking on the Channel to selection button or from the context menu.
You can work in selection masks not only with the paint tool but also with other tools. For
instance, you can use the selection tools to fill areas uniformly with gradients or patterns.
By adding many selection masks in your list you can easily compose very complex
selections. One can say that a selection mask is to a selection as a layer is to an image.
As long as a selection mask is activated you are working in the mask and not in the
image. To work in the image you have to deactivate all selection masks. Don't forget also
to stop displaying masks in the image by removing the eye icon. Check also that all RGB
and Alpha channels are activated and displayed in the image.
A Quick Mask is a Selection Mask intended to be used temporarily to paint a selection.
Temporarily means that, unlike a normal selection mask, it will not be saved in the list
after its transformation to selection. The selection tools sometimes show their limits when
they have to be used for doing complex drawing selection, as progressive. In this case,
using the QuickMask is a good idea which can give very good results.
• The QuickMask can be activated in the following order, from the image-menu:
• The QuickMask can also be activated by clicking the left-bottom button showed in
red on the screenshot.
• It can also be activated by using Shift+Q shortcut.
Creating a Quick Mask
To initialize a Quick Mask, click the bottom-left button in the image window. If a
selection was active in your image, then its content appears unchanged while the
border is covered by a tranlucent red color. If no selection was active then all the image is
covered by a tranlucent red color. At every moment you can hide the maskby clicking on
the eye icon in front of the QMask. From the channel dialog you can double click on the
name or the thumbnail to edit the QMask attributes. Then you can changethe Opacity and
its filling color. Once a quick mask is initialized click on it to be sure it is selected and blue
highlighted in the list, and start to paint on it with any Gimp paint tool. The mask is coded
in gray tones, so you must use white or gray to decrease the area limited by the mask
and black to increase it. The area painted in light or dark gray will be transition areas for
the selection like feathering. When your mask is ready, click again on the bottom-left
GNU Image Manipulation Program
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