I made this tutorial a while ago for another forum, but since I am new here I will post it here as well.
When the original Star Wars was made in 1977, special effects artists had only one way to create the scintillating glow of the lightsaber: painting the blade in by hand. Almost thirty years later, programs like Photoshop allow us to generate lightsabers more quickly and easily. There are many methods described on the internet, but not all laser swords are created equal. Many of these methods take the easy way out, hoping that casual viewers won't be disturbed by their lack of "lightsaberness." But rest assured that achieving a photorealistic lightsaber effect is a worthwhile and sensible goal. Through the method described here, that goal can now be reached.
Anatomy of the Lightsaber Effect
In order to re-create the classic lightsaber effect, one must understand the classic lightsaber effect. (This tutorial attempts to re-create Luke's lightsaber from A New Hope, as seen in Obi-Wan's house.) The classic lightsaber blade has four basic parts: core, edge glow, colored glow and base glow.
At the heart of every lightsaber is a pure white core. This core defines the shape of the blade and has a more or less hard edge. But, when seen alone, the core simply appears to be a white stick. The colored glow that surrounds it gives the blade its shimmering aura.
The innermost part of this glow, which I call the edge glow, is very bright and vary narrow. It runs around the outside of the core and is just slightly darker than the core. The edge glow usually flickers, making the blade appear to change shape slightly. Around this is a vividly colored region I simply call the colored glow. This is where most of the blade's color is and it is simply a translucent patch of color that fades outward. (The colored glow often pulsates, too, especially when the blade isn't moving much). The largest and dimmest area is the base glow, which has little color and is nearly unnoticeable in still pictures.
Together, these four elements create the appearance of a weapon capable of cutting through just about anything. Unfortunately, many techniques eliminate the edge glow and base glow, leaving a rather uninteresting and unrealistic lightsaber. The result appears to be more of a glowing stick than a blade of dynamic and volatile energy. It is important, therefore, to use a method that incorporates all four critical areas of the lightsaber effect.
(A lightsaber's appearance can be drastically improved by making the tip pointed. Most lightsabers, including many in the original movies, have blunt or rounded tips. Thus far, only Revenge of the Sith has pulled off truly bladelike tips. If you find a realistic way to do this in your videos, more power to you. However, this can be very difficult to pull off in close up shots.)
Now, let's take a look at how to actually pull off this effect.
Creating the Lightsaber Effect
Photoshop offers a number of tools that can make impressive lightsabers. The important thing is to not take the easy way out. Countless web tutorials suggest creating a white core on a separate layer and then applying a simple outer glow effect. Sadly, this simple method produces the colored glow only - the edge glow and base glow are neglected and the resulting lightsaber looks fake. In shots where the lightsaber is mostly still, the lack of realism becomes even more apparent: the glow doesn't pulsate at all. This is not the way to go.
My own method is not impossibly complex and the results are breathtaking, if I do say so myself. Here are steps to making a blue lightsaber like the one Luke inherited from his father, for use in medium distance shots. This technique works best for blue lightsabers with green lightsabers close behind and red lightsabers looking merely good. Don't be intimidated by the apparent length of the tutorial; this actually is a pretty quick process. (This tutorial assumes you are moderately proficient with the program).
Blue Lightsaber, Medium Distance
1. Create a new layer ("Core") and fill it with black. Set the blending mode to screen.
2. Locate the lightsaber blade in the frame. Make a selection of this shape. (I suggest using the polygonal lasso tool.) Fill this area on the "Core" layer with white or an extremely light shade of blue.
3. Apply a Gaussian blur of 0.7 pixels.
4. Make a copy of "Core," place it just below "Core" and rename it "Glow Base." Apply a Gaussian blur of 7.8 pixels. (This layer will serve both as the base glow and the colored glow.)
5. Open hue and saturation, check the colorize box and set the numbers to 210, 40 and 0. (In some shots, the hue may need to be a little bit higher).
6. Open the levels dialog box and set the input slider on the far right to 210.
7. Apply a Gaussian blur of 17.9 pixels and fade Gaussian blur with screen mode at 100% opacity. (This Gaussian blur makes the colored glow much larger and dimmer; fading it to screen restores the original brightness, but the base glow now appears around it. This step is critical).
8. Make another copy of "Core" and place it between "Core" and "Glow Base." Rename it "Edge Glow." Apply a Gaussian blur of 4 pixels.
9. Open levels and set the output slider on the far right to 140.
10. Open hue and saturation, check the colorize box and set the numbers to 221, 72 and 0.
11. Usually, it's a good idea to increase the saturation of the "Glow Base" layer to +30 (not set to colorize).
12. Now the glow itself is finished, but it will look exactly the same in every frame. To give the blade a realistic flicker, start by creating a new layer above "Glow Base" and group it with "Glow Base." Name the new layer "Base Flicker" and set it to the blending mode multiply.
13. Apply the clouds filter to "Base Flicker." Make a copy of the layer, rename it "Edge Flicker" and group it with "Edge Glow."
14. Open Levels for "Base Flicker" and set the input sliders to 105, 1.00 and 133. Set the left output slider to 211.
15. Open Levels for "Edge Flicker" and set the outer input sliders close to the middle of the histogram. Set the left output slider to 150.
These steps should be sufficient for most medium distance shots. Keep in mind while shooting that light colored backgrounds make any lightsaber look terrible.
Now, let's learn how to modify this effect for other colors and distances.
Green and red (and purple) lightsabers can be made with the same technique, but there are a few differences.
Green Lightsaber, Medium Distance
• In step 5, set hue and saturation to 110, 47 and 0.
• In step 9, set the right output slider to 96.
• In step 10, set hue and saturation to 203, 93 and 0.
• Omit step 11.
Red Lightsaber, Medium Distance
• In step 5, set hue and saturation to 355, 52 and 0.
• In step 8, Gaussian blur by 10.5 pixels, not 4 pixels.
• In step 9, set the right output slider to 113.
• In step 10, set hue and saturation to 23, 57 and -52.
• Between steps 10 and 11, open Levels for "Glow Base" and set the middle input slider to 1.19.
• Apply a Gaussian blur of 0.5 pixels to "Core."
Keep in mind that all settings can and should be adjusted depending on the shot and your preferences. Colors, blur radius, levels values - all of these can change from shot to shot in order to maintain a consistent and eye pleasing effect.
For close up shots with lightsabers, there are a number of considerations:
• All parts of the glow should be wider and sometimes brighter. Nearly any time you apply Gaussian blur, use a higher value.
• You may want to slightly reduce the saturation values to make the colors less cartoonish.
• It's often a good idea to repeat step 7 once or twice, using different values for Gaussian blur and/or various opacities for fade.
Good luck with your own lightsabers. I apologize for the length of this tutorial. If you have a better technique for making lightsabers, please post it! (Also, check out this thread to see examples of this effect in action).