PhotoImpact Tutorials: Selection Tools #3 - Mask Mode, and Saving Selections

Selection Tools #3 - Mask Mode, and Saving Selections

This tutorial continues from selection tutorials #1 and #2, and gives an overview of using Mask Mode, and saving selections. This tutorial was produced using PhotoImpact 8

Mask Mode: Masking is a process where changes are applied to a selected area of an image, while the rest of the image is 'masked' or protected from those changes. The mask is essentially a layer above the image that can be edited using PhotoImpacts editing tools to reveal or obscure the underlying image. Unlike other selection tools, such as the lasso, magic wand or bezier curve, masking has the advantage of creating a selection that can have varying levels of transparency. This can be useful for selecting part of an image that is not easily distinguished from its background, or for blending selections of different images into a montage.
In the example shown right, I wanted to change the colour of the grass in the original image (left). To do this meant selecting the zebras head from the background. Some parts of the zebra, such as the under part of the head and neck are clearly distinguished from the background grass, while the zebras mane is less clearly distinguished. Using a mask enabled the creation of a selection with varying levels of transparency to facilitate smooth transitions required for a successful selection (right).
Using Mask Mode: Open an image and click the Quick Mask icon on the Tool Panel. Alternatively, select Mask Mode from Edit on the Main menu bar.
When Quick Mask is activated, a semi transparent layer appears over the image (shown right). The mask now has to be edited to create the required selection. The mask is created by using PhotoImpacts editing tools, for example, a paintbrush or airbrush. Using these tools, adding white removes the mask (ie the underlying image can be seen below) while black removes none of the mask (ie, there is no selection). Applying shades of grey gives partial transparency. In effect, a mask is a greyscale buffer, which means selections are made on tonal values of the greyscale as described above.
An edited mask made with a paintbrush tool is shown above left. Note the different transparency levels between the zebras mane and background, and the underside of its face/neck and background. The former has low transparency giving a less clearly defined edge between the zebras mane and background, while the latter has higher transparency, giving a more clearly defined edge. If you make a mistake and accidently remove part of the mask, just change the foreground colour to black and paint the mask back on. Alternatively, right click the computer mouse and select Undo.
Tip: If the default mask colour is similar to the image colour or area being selected, click File, Preferences, General, and click on the coloured square. This brings up the colour picker dialog box from where another colour can be selected. The mask transparency level can also be changed here if necessary. In general, use a mask colour that contasts well with the image being edited, otherwise it may be difficult distinguishing between the two.
To change the degree of transparency required for editing a mask, click the foreground colour square on the Tool Panel (see left) and select an appropriate shade of grey from the colour picker (see below). Click OK, and continue editing as required. When working in mask mode, it may be necessary to make frequent changes to the tools being used, depending on the level of precision required. For example, if using a paintbrush, some parts of the mask may require a large brush size and soft edge to do broad strokes, while other more critical areas may need a small brush with an equally small soft edge. All these changes can be done from the Attributes toolbar, by adjusting the appropriate values (see below).

If the paintbrush tool is used to create a mask, you may find it easier to have the Brush Panel open (see left) so changes in size, shape or transparency, for example, can be done more easily.
As you work on creating a mask, its often useful to toggle the Quick Mask icon (on the Tool Panel) on and off to check progress. When quick mask is switched off, the selection will show as a dotted line on the image (see right). Continue editing the mask until its considered ok. Switch the Mask Mode off to convert it into a selection. The selection is now complete and editing tasks can be applied as required. Saving Selections (Temporary): To save a selection temporarily while working on a file, select 'Store Selection' from the Selection menu. This places a copy on the Selection Manager. To display the stored selection, click the 'Selection Manager' icon on the Panel Manager. Stored selections can be retreived and modifed if necessary, using selection tools described earlier in this tutorial.
A Note on Selections and Objects in PhotoImpact Selections: These are parts of an image created by PhotoImpact selection tools (for example, Lasso Tool) and are bordered by coloured dotted lines (known as the Selection Marquee). Selections can be expanded to include multiple parts of an image. When you edit a selection, you are editing the base image. Objects: These are selected parts of an image initially created by PhotoImpact selection tools, then converted to an Object that 'floats' above, and is independent of, the base image. When selected with the Pick Tool they have an animated black and white dotted line (often referred to as 'marching ants'). Because Objects are independent of the base image, you can move and manipulate them without effecting other objects or the base image. They also offer the opportunity for more advanced editing tasks such as adjusting transparency or using different modes to blend parts of an image together (for example, hue and saturation, luminosity etc).

Posted by Webmaster at August 2, 2005 07:58 PM