While Photoshop doesn’t offer a dashed line option, such as that found in Illustrator’s Stroke palette, you can easily simulate them by editing a brush in the Brushes palette.
The key to dashed lines is the Spacing option. Combined with Roundness in Photoshop 7, you can change a square brush into a dashed line quickly. Here’s what you need to see in the Photoshop 7 Brushes palette:
Remember that you need to open the Brushes palette from the Palette Well or the Window menu (or the F5 key). The small Brushes palette found at the left end of the Options Bar is for brush selection, not brush editing or creation. And what if the Brushes palette is grayed out and unavailable? Switch to a brush-using tool, such as the Brush tool (press B on the keyboard).
Reducing the Roundness makes a square brush flat. Increasing the Spacing moves each “instance” of the brush tip imprint farther apart. (Think of Photoshop’s brushes as applying the brush tip many times close together as you drag, rather than as a continuous stream of color, like an ink pen.) And, of course, the “dash” doesn’t need to be at 50% roundness.
Don’t forget that you can make vertical dashed lines rather than horizontal by changing the Angle setting in the Brushes palette to 90 degrees.
In Photoshop 6, you must first define a small rectangle as a brush and then adjust the spacing. (Photoshop 6 doesn’t allow you to change the Roundness value for non-round brushes.) Create a rectangle of the size of your dashes, fill with black, and use the menu command Edit> Define Brush. You can use the Rectangular Marquee tool to create the shape-make sure that Feathering is set to zero in the Options Bar.
Give the new brush a distinctive name, one that reflects both its size and purpose.
Once you’ve created your dashed line, you can use it with any brush-related tool. In addition to the Brush (Paintbrush in Photoshop 6), Pencil, History, Art History, and Eraser tools, you use brushes with the stamp, focus, and toning tools.
Remember, however, that these dashes will not follow the paths of the cursor, but instead stay oriented to the page. This figure shows the difference between a dashed line created in Photoshop (top) and one created in Adobe Illustrator (bottom). The Illustrator dashes follow the path no matter how it curves.
The orientation of the “dashes” to the path in Photoshop is insignificant when a symmetrical brush is used. A round brush, for example, never seems to be mis-oriented.
When you do need to curve a dashed line, remember the Shear filter (Filter> Distort> Shear). You can bend and twist a straight line. To save a step, draw the line vertically (the filter works only horizontally). It’s also usually a good idea to have the dashed line on a separate layer and have no active selection.
The Shear filter enables you to bend and twist. Click on the vertical line in the preview window to add an anchor point and drag. You can place several points as necessary. And if you’ll be working close to the edge of the window, click the button for Repeat Edge Pixels.
After applying the filter, the bent dashed line can be rotated and otherwise transformed.