Line Glow Effect

Create a line glow effect by using an imaging program's tools to produce a gradation of values inside a line and to produce a feathered effect outside the line. There are several ways to achieve the imagery just described, including those involving gradient fills, feathered selections, preset effects and soft-edged paint brushes.

Gradient Fill with Gaussian Blur

One way of making a line appear to glow is by using a gradient fill tool to fill the line's insides, then applying a blur effect or filter to soften the outer edges of the line. You can try this in Paint.NET by first clicking the "Magic Wand icon" from the toolbar to run the Magic Wand selection tool, which selects image regions based on color. Click a line you've drawn to select it, then click "Gradient" from the Tools drop-down list above the canvas. Drag inside the line to produce a gradient that makes the line appear to glow from inside. Click "Gaussian blur" in the Effects menu to blur the line's outer edges.

Soft Brush and Dodge

Another way of making a line glow effect is by applying an image program's dodge tool to a line drawn with a soft paintbrush. Digital photographers use the dodge tool to lighten overly dark areas of photos, but you can use it to lighten the inside of a line to make the line appear to glow. Try this approach in GIMP by first clicking the "Paintbrush icon" in the Tools panel to enter painting mode. Pick a fuzzy-edged brush from the Brush's panel, then drag on the canvas to paint a line. Click the "Dodge tool" in the Tools panel -- an icon shaped like a charcoal gray circle -- then drag back and forth inside the line to lighten the inside. The line will appear to glow.

Preset Effects

Photoshop comes with many preset styles and effects for quickly producing attractive graphics. Two of its effects are called "Inner glow" and "Outer glow." Use these to produce the effect of a glowing line. First, draw a line with the Paintbrush tool, then click the "Fx" button at the bottom of the Layers panel. Click the "Inner glow" check box and the "Outer glow" checkbox, then click "OK" on the"Layer styles dialog box to finalize the effects you chose.

Manual "Painting"

One of most intuitive ways of making a line glow is by "painting" it by hand and feathering its edges using a digital painting program. After you understand the imagery that makes up a glowing line, you can create that imagery in any painting program with tools for feathering imagery. Try it in Paint Shop Pro by first clicking the "white swatch" from the Materials panel. Click the "Paintbrush icon" from the Tools panel, then drag on the canvas to draw a white line. Click a very light gray color from the Materials panel, then draw a line on either side of the white line. Continue drawing increasingly darker lines surrounding the existing collection of lines to create a smooth gradation of values. This gradation is the essence of the glow. Click the "Freeform selection tool" -- an icon shaped like a lasso -- then drag around the lines to select them. Click "Feather" from the Selections menu, then click "OK" to soften the edges of the selection. This action adds an aura or linear halo around the glowing line.

References

• dotPDN: Paint.NET Blur
• Paint Shop Pro 9 for Dummies; David Kay
• GIMP User Manual; GIMP Documentation Team
• Photoshop CS5 Bible; Lisa Dayley