Selection Mask Quick Hacks
From the ExtremeTech book, Hacking Photoshop CS2 by Shangara Singh, published by John Wiley and Sons. (Reprinted with permission.)

The following hacks cover some of the methods most commonly used for creating selection masks. They are presented here in one place for your consumption. Feast on them from time to time when you feel hungry.

• Switching Lasso Tool Modes. When you use the Lasso tool to draw freehand selections, press Alt (Windows), Opt (Mac OS) to draw in straight lines. To revert to freehand, raise the tool modifier key after a click.

• Switching Polygonal Lasso Tool Modes. When you use the Polygonal Lasso tool to draw straight lines, press Alt (Windows), Opt (Mac OS) to draw freehand. To revert to straight lines, raise the tool modifier key after a click.

• Changing Sample Size for Magnetic Lasso Tool. When you use the Magnetic Lasso tool, use a large width for smooth areas and a small width for detailed areas. You can change the width of the sample area by using the square bracket keys or clicking the pen icon in the options bar if you use a pen and tablet.

• Moving Selections. To move a selection marquee while drawing, hold down the Spacebar and drag to a new position.

• Moving Selection Content. To move a selection marquee and the enclosed content, select the Move tool and then click and drag or use the arrow keys. You can access the Move tool temporarily by holding down Ctrl (Windows), cmd (Mac OS), except when the active tools are the Hand, Pen, shape, path selection, or slice tools.

• Moving and Duplicating Selection Content. To move a selection marquee and duplicate the content at the same time, select the Move tool, hold down Alt (Windows), Opt (Mac OS), and then drag or use arrow keys. Alternatively, hold down Ctrl+Alt (Windows), Opt (Mac OS) and then drag.

• Hiding the Marching Ants. Press H to hide marching ants (marquee boarder). Press once more to reveal. What is hidden or not hidden by the keyboard shortcut can be specified in View > Show > Show Extras Options.

• Positioning Active Selection Precisely. You can reposition an active selection mask by selecting a marquee or lasso tool, placing the tool pointer in the selection, and then dragging the selection to a new position. If you need to position it precisely and you know the coordinates of where you want to reposition it, choose Select > Transform Selection, or select the command from the contextual menu and then enter the coordinates in the options bar. You can also use the arrow keys to nudge the selection, regardless of whether it’s being transformed.

• Selecting Similar Colors. To select colors next to similar colors with the Magic Wand tool, create a Levels or Curves adjustment layer, increase the contrast, make the selection, and then delete the adjustment layer.

• Resizing Marquees Proportionally. To create a marquee half the size of your document, regardless of the size, select Fixed Size in the options bar and then, in the Height and Width fields, enter 100% in one and 50% in the other. Try other combinations; for example, enter 50% in both fields.

• Modifying Selections. To modify a selection, choose Select > Modify; then, from the submenu, choose Border, Smooth, Expand or Contract and enter a value in pixels in the pop-up dialog box.

• Adding, Subtracting, and Intersecting Selections. You can add to, subtract from, or intersect with a selection while creating it or after the event. To do so, press Shift to add; Alt (Windows), Opt (Mac OS) to subtract; Alt+Shift (Windows), Opt+Shift (Mac OS) to intersect. You can also specify an option for the selection tool in the options bar before you use it by clicking one of the buttons. The options are, from left to right, New Selection, Add to Selection, Subtract from Selection, and Intersect with Selection.

• Rotating Selections. When you need to rotate a selection, you have two choices.

• Choose Select > Transform Selection and then drag the pointer outside the bounding box.
*If you need more control, after choosing Transform Selection, insert the curser in the Set Rotation text field on the options bar (third from the right and marked with a protractor icon) and then ride the Up and Down Arrow keys.

• Inversing Selections. To select unselected areas and deselect selected areas, choose Select > Inverse or press Ctrl+Shift+I (Windows), cmd+Shift+I (Mac OS). Press again to revert.

• Growing Selections. Having used the Magic Wand tool to select a range of colors, you can add to the range by holding down Shift and clicking another sample area. However, sometimes that can yield unexpected results. Instead, use the Grow command in the Select menu to add adjacent pixels that fall within the tolerance set for the Magic Wand tool. For example, if you set Tolerance to 10 and click a pixel with a value of 120, Photoshop selects all pixels that have values between 110 and 130.

• Adding Similar Colors. To add noncontiguous pixels with a similar color value to a selection, choose Select > Similar. As with the Grow command, Photoshop uses the tolerance set for the Magic Wand tool to determine which pixels to add to the selection.

• Loading Selections from Open Documents. To load a selection from another open document, you can either drag and drop between source and target document windows or save the selection as an alpha channel from the Channels palette and then choose Select > Load Selection. In the Load Selection dialog box, choose the source document and the alpha channel from the pop-up menus. This method has the added advantage of giving you the option of adding, subtracting, or intersecting the incoming selection with any active selection in the target document.

• Resurrecting Selections. When creating selections, you can easily click in the document window with the selection tool and obliterate the selection, or so it would appear. The selection is still lurking somewhere and requires only the right command to bring it back. Provided that you haven’t made another selection, choose Select > Reselect, or Ctrl+Shift+D (Windows), cmd+Shift+D (Mac OS) and, voilà, instant resurrection.

• Transforming Selections. To adjust a selection after it has been drawn, right-click (Windows), Ctrl-click (Mac OS) in the selection and choose Transform Selection. To scale, skew, distort, and change perspective, hold down the Ctrl, Alt (Windows), cmd, Opt (Mac OS), or Shift keys singularly or in combos and then move handles; you can also scale in one direction by dragging a corner handle or rotate by dragging outside the bounding box (the companion Web site for this book, at www.wiley.com/go/extremetech, has information about keyboard shortcuts available).

Summary
Regardless of whether you call them selections, selection masks, or just masks, being able to isolate an area of an image to work on is an essential part of image editing. With the techniques, hints, and tips included in this chapter, you should be well armed for creating selection masks that fit the bill for almost any image-editing assignment.*  

When you have the various techniques under your belt, try to use them in a unconventional way and thereby discover new shortcuts, workarounds, and techniques. For example, sometimes it’s easier to use the Magic Wand tool to select the areas that you want to mask rather than select and then inverse the mask, so that the masked areas become the selected areas, which is what you wanted in the first place.

Previous section — Editing And Modifying Selection Masks




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