If you’re new to bitmap editing in Corel PHOTO-PAINT®, one of the first skills you need to sharpen is making a selection. Whether you’re applying effects, retouching, or just correcting photographic mishaps, making selections is a critical exercise to master. I’ll explore how and why in this tutorial. The techniques I’ll cover and the program features we’ll use are virtually consistent whether you’re using a recent or past version.
The Selection-Mask Concept
In Corel PHOTO-PAINT, you’ll find the terms selection and mask often used to describe the same thing. In order to apply changes to only a specific part of a digital image, you need to have the area selected. When you make a selection, the area you define becomes the actively selected editable area, and the rest of the image becomes the non-editable area protected by a mask (see below).
The concept stems from manual (meaning nondigital) photo retouching, in which a paper or acetate overlay is cut to the shape of the area being worked on. The overlay exposes the retouched area, leaving it accessible to the retouching tools. The overlay also hides the remaining area by masking it from the retoucher’s brush strokes (hence, the term “mask”).
Using Mask Tools
When you make a selection, you define three areas: the selected area, its inverse (that is, the portions not selected), and the outline shape of your selection. While something is selected, the standard toolbar provides quick access to a few useful commands (see below). The Remove command (Ctrl+R) clears the current selection, and the Invert command (Ctrl+Shift+I) swaps the selection with the mask area. If you need to select the entire image quickly, choose Mask > Select All (Ctrl+A).
The Mask Marquee button (Ctrl+H) toggles the view of animated dashes, which indicate a selection in progress (see below). These dashes mimic the sequentially blinking bulbs on retro-style theater signs and are sometimes called “marching ants.”
To see the marquee, you’ll need to toggle the Mask Overlay off (choose Mask > Mask Overlay). Although these two interface features perform essentially the same function (they both indicate a selection), you’ll find that the Mask Overlay is much more intuitive: it enables you to quickly identify selection and mask areas, and to view mask outline properties.
You can control the Mask Marquee and Mask Tint colors by choosing Tools > Options (Ctrl+J) to access the Options dialog and clicking the Display tab (see below). This feature is especially useful if the colors in your image closely match the default colors of the mask or marquee, which would make it difficult to distinguish between the mask, the marquee, and the image itself.
In the example below, the default red Mask Tint color used to mask the background of this image of red flowers was changed to purple to improve the visibility of the mask itself.
Choosing the Right Mask Tool
From the Mask Tools group in the Toolbox (see below), you’ll find a number of tools to create selection areas of various shapes and sizes.
If your experience with these tools is limited, here’s a basic run-through. With the Rectangle Mask Tool and Ellipse Mask Tool, you can draw basic selection shapes by using diagonal click-dragging actions. With the Freehand Mask Tool, you can define atypically shaped selection areas, either by dragging or by using point-to-point single clicks. A double-click ends the selection session.
The Lasso Mask Tool is similar to the Freehand Mask Tool but has a slight automatic advantage: it enables you to instantly select well-defined areas of color by adjusting the Tolerance value on the Property Bar, which controls sensitivity (see below).
Higher tolerance values reduce the color sensitivity, enabling you to select a wider array of color. Surround the area you wish to select, and double-click to end the session. In the example below, a hang glider on a blue sky background is easily selected with a tolerance value of 20.
The Magnetic Mask Tool is a more hands-on version of the Lasso Mask Tool. It enables you to define a selection path by “magnetically” following the boundary between two well-defined color areas. Clicking once defines the first point of the selection path, and dragging your cursor along the boundary defines its course. If the cursor deviates from the path you want, a single click secures it to a specific point. Double-clicking ends the session. On the Property Bar, the Tolerance setting controls boundary detection, and the Magnetic Area setting controls how close your cursor must be to the boundary to follow the path it detects.
Although magic plays little part in how the Magic Wand Mask Tool actually works, it does let you instantly select entire areas of similar color with a single click. It works by selecting adjacent pixel colors according to the tolerance value specified on the Property Bar. Higher tolerance values extend the color selection, whereas lower values decrease it. If you are an experienced brush user, you’re probably familiar with the Brush Mask Tool, which enables you to create selections based on brush strokes. You can customize your Brush Mask Tool just as you would customize typical brushes, by using options on the Property Bar (see below). The nib shape, size, and feather characteristics can be used to tailor the selection strokes.
Adjusting Your Selection Mask
Using the mask tools, you can add, delete, or overlap on the fly to refine the shape of your selection. With any mask tool selected, you can choose one of the four modes on the Property Bar to affect how your selection is updated. When you click a mode button on the Property Bar (see below), the mask tool is fixed in that mode. Using modifier keys to switch modes on the fly is even more convenient.
The Normal (default) mode creates a new selection each time a tool is used. The Additive and Subtractive modes add or remove the selection portion from your existing selection. The Overlap mode creates a selection based on the area where the current mask and the newly created mask overlap. You can switch between any of these modes and Normal mode temporarily: hold Shift for Additive, Ctrl for Subtractive, or Ctrl+Shift for Overlap.
If you’re using the Rectangle Mask Tool or Ellipse Mask Tool to define a selection, you can also use the Mask Style menu to set the width or height of the mask to specific dimensions, or you can use the Fixed Size style to set both measures.
Adjusting the Mask Outline
Once you’ve made your initial selection, you can use mask outline commands to modify it in various ways. These specialized commands enable you to specify feathering and softening, as well as to reshape and resize the selection area, based on fixed values or adjacent pixel colors. You’ll find them in the Mask > Mask Outline submenu (see below).
Here’s a quick guide to explain what each command does:
Feather – The effect of the Feather command (see below) enables you to soften the edges of your mask outline to a pixel value between 1 and 300. You can also set the direction of your feathering effect to Average (the default), Outside, Middle, or Inside, and for the last three Direction settings, you can set the Edge style to Linear or Curved. In the example below, a mask is used to define the edge of the selection (left) and the edge is applied with a feather effect (right).
Grow, Similar – These two very powerful commands enable you to increase your selection area automatically. Choose Grow to extend your current selection to include adjacent pixels of the same colors. The Similar command extends your selection in the same way, but selects all pixels of similar color throughout your image. In the example below, the blue sky was originally selected with the Magic Wand Tool. The Grow command was used to extend the blue where pixels meet, and the Similar command was used to include in the selection all similar blue pixels throughout the image.
Border – This command creates a border from the outline of your current selection (see below). Dialog options enable you to choose a pixel thickness and soft, medium, or hard edges.
Remove Holes – This command enables you to select all the stray pixels in an area selection. Smooth – This command enables you to set a corner radius value in the dialog to remove the hard corners from your mask outline (see below).
Threshold – This command automatically removes unwanted feathering applied to a selection. The feathering is removed based on the Level value set in the dialog shown below.
Expand, Reduce – You can use these commands to automatically increase or decrease the selected area by a specific number of pixels. Keep in mind that the adjustment is applied from the perspective of the selection, not of the mask. Now That You Have Something Selected…
Making a selection may be your first step in whatever bitmap editing operation you’re performing, but it most likely won’t be your last. With a selection made, you can perform copy-and-paste operations, apply filters, create objects, and execute a myriad of tasks.
After you’ve taken such careful steps to create a perfect selection, it may be wise to save it. Given that you can inadvertently wipe out your selection with a single click, it is best to adopt the habit of saving your selection. Corel PHOTO-PAINT enables you to save and store your selections as alpha channels with your image. Once a selection is saved, you can control its various properties and recall it any time you wish.
The quickest way to save your selection is by choosing Mask > Save > Save as Channel (see below).
In the Save Mask As Channel dialog , you can give a unique name to your new channel (see below). The name you choose can be up to 39 characters in length, and you can save the channel as many times as you wish. Clicking OK saves the selection as a channel.
You can quickly recall a saved selection by choosing its name from the Mask > Save submenu (see below). If no saved selections exist, the menu lists only Alpha Channel Save as a temporary placeholder.
With your selection saved as an alpha channel, you can control its properties by using the Channels docker. To open the docker, choose Window > Dockers > Channels (Ctrl+F7). The Channels docker lists your saved selections as well as the default RGB channels for any image (see below). The docker also automatically assigns shortcut keys to the existing channels and any selections saved as channels.
To control channel properties, click a saved channel to select it, and then click the flyout arrow in the upper-right corner to access the docker options menu. Choose Channel Properties from the menu (see below).
Using options in the Channel Properties dialog (see below), you can edit the channel name, adjust the overlay tint color, or adjust the channel’s opacity from the default settings. These specific properties are preserved if you save your image in CPT format, which is the native file format of Corel PHOTO-PAINT. If you save or export your image to certain other file formats, the alpha channel properties are preserved only at the default settings. For example, alpha channel masks are supported by TIF, GIF, PNG, and PPF (version 10), all of which are compatible with Corel PHOTO-PAINT.
The Channels docker enables you to perform tasks such as loading multiple channels, creating new channels from selections, deleting saved channels, and setting docker thumbnail views. To load a saved channel as a selection, simply click the visibility icon to the left of its name.
Although we’ve covered a lot of ground in a short space, consider this set of relatively basic techniques as merely a starting point in your Corel PHOTO-PAINT learning curve. Nothing is better than hands-on experience, so practice as much as you can with the tools and commands available for making, adjusting, and controlling your selections.
Steve Bain is an award-winning illustrator and designer, and author of nearly a dozen books, including CorelDRAW: The Official Guide.