Using Alpha Channel Transparency with 12 Premiere Video Effects

Of Premiere's 79 video effects, 14 either have an alpha channel or have special adjustments for clips with alpha channels. I'll go over 12 of them. The two others have limited value.

In previous hours I've touched on all of these and noted some of their Alpha Channel characteristics so I'll try to avoid too much repetition.

I've placed them in two groups: Video Effects with Alpha Channels and Effects that work well with Graphics that have Alpha Channels.

Video Effects with Alpha Channels

Six Premiere video effects have built-in alpha channels:

  • Basic 3D

  • Camera View

  • Lens Distortion

  • Strobe Light

  • Tiles

  • Transform

Typically these effects move clips around the screen, revealing a background. You generally can choose a background color or opt to use the alpha channel to make the background transparent, revealing a clip beneath it on the timeline.

Revealing a Clip with Basic 3D

When you use this effect to manipulate a clip in 3D space, the default setting is to show a black matte behind it.

Instead, use it to reveal another clip as I've illustrated in Figure 15.8. Here's how:

  1. Place two clips, one above the other, on Video 1 and Video 2.

  2. Apply Basic 3D to the clip on Video 2 and move that clip off to one side. You'll see only black behind it.

  3. To reveal the clip below it, open the Video 2 clip's Transparency Settings dialog box and select Alpha Channel. Click OK.

Figure 15.8. Use Basic 3D's alpha channel to reveal a clip below it on the timeline.


This reveals the clip on Video 1. You can layer and reveal multiple clips using Basic 3D.

Opting to Reveal a Clip Using Camera View

This effect works a lot like Basic 3D with a few additional controls thrown in. It's not an After Effects (AE) effect, so you have the option to open its Settings dialog box. Follow these steps to try out Camera View:

  1. Replace Basic 3D in the Effect Controls palette with Camera View.

  2. Click Setup.

  3. As I've highlighted in Figure 15.9, uncheck the Fill Alpha Channel box. If this is left checked, you can create a background color other than the default white. You'll note that despite unchecking the Fill Alpha Channel box, the Camera View Settings dialog box's preview screen does not display the clip on Video 1 behind the Video 2 clip. To remedy that, click OK.

    Figure 15.9. Uncheck the Camera View effect's Fill Alpha Channel box to display the clip below it on the timeline.


  4. Make your slider adjustments in the Effect Controls palette and watch your handiwork in real time in the Program Monitor screen.


In each of the following alpha channel examples, make sure you do two things:

  • Delete the previous video effect from the Effect Controls palette.

  • Keep the Video 2 clip's Transparency setting at Alpha Channel.

Twisting Away an Image with Lens Distortion

This effect works much like Camera View in that it's a non-AE video effect and its Settings dialog box has a Fill Alpha Channel check box (see Figure 15.10). Try this out on the Video 2 clip.

Figure 15.10. Lens Distortion has the same Fill Alpha Channel check box as Camera View.


Flashing a Second Image with Strobe Light

Here you face a number of options about the characteristics of the strobe-like effect. To try this effect, follow these steps:

  1. Apply Strobe Light to your clip on Video 2.

  2. Using the drop-down menu highlighted in Figure 15.11, select Makes Layer Transparent. This means that each strobe flash will reveal the layer below it.

    Figure 15.11. Strobe Light flashes can reveal the layer beneath it on the timeline.


For an interesting effect, do the following:

  1. Add another video track to the timeline (unless you already have a Video 3 track) by right/Option-clicking the timeline and selecting Add Video Track. Move the clip on Video 2 to Video 3. Open its Transparency Settings dialog box and select Alpha Channel.

  2. Drag Strobe Light to that clip. Set a short Duration (0.2 or so). Set a strobe period about twice as long (0.4 or so). Put some randomness in (5% works well). Also, under Strobe, set Make Layer Transparent.

  3. Add a graphic with an alpha channel to Video 2, drag its ends to match the length of the other two clips, and set Transparency to Alpha Channel.

  4. Give the graphic on Video 2 some motion, keeping it within the screen. The faster it moves the better, so feel free to give it a convoluted and long motion path, forcing it to zip around the screen.

  5. Turn the clip on Video 1 into a freeze frame by right/Option-clicking it, selecting Video Options, Frame Hold, Hold On (select In Point, Marker 0, or Out Point). Then Click OK.

  6. Now preview that section. The top clip should do the strobe thing, and if the graphic moves fast enough it should bounce all over the freeze frame.

Breaking Up a Clip Using Tiles

This video effect, too, can reveal the clip below it on the timeline.

Keeping the three clips layered on the timeline, apply Tiles to the clip on Video 3.

As I've demonstrated in Figure 15.12, to display more of the two lower clips, increase Maximum Offset to something more than 50%. This widens the gaps between the jittering tiles.

Figure 15.12. When using Tiles on a clip in a superimposed video track, increasing the Maximum Offset setting displays more of the clip(s) beneath it.


Trying Two Transparencies at Once with Transform

As with Basic 3D and Camera View, Transform moves your clip in an apparent 3D space. Once displaced from a normal full-screen aspect, it leaves black gaps around the edges of the clip. With that clip's Transparency set to Alpha Channel, you can see what's below it on the timeline.

One strength of this effect is its built-in Opacity slider, highlighted in Figure 15.13. You could use the opacity rubberband on the expanded video track to accomplish the same thing, but this is much more convenient.

Figure 15.13. Transform skews a clip to reveal either black or the clip(s) beneath it.


Effects That Work Well with Graphics That Have Alpha Channels

The following six video effects work best with a graphic:

  • Alpha Glow

  • Bevel Alpha

  • Channel Blur

  • Drop Shadow

  • QuickTime Cloud

  • QuickTime Fire

You can use Veloman.eps or any other graphic with an alpha channel.

I'll ask you to take a different tack in this section. Instead of trying each effect separately, I'll have you apply these effects to the same clip, eventually running all six at once. Admittedly, by that time, the graphic will be a hodgepodge.

Adding a Soft Edge Using Alpha Glow

This effect adds a nice, soft edge to a graphic. Follow these steps:

  1. Delete or move the clip on Video 3 off to one side so it's no longer above the clips on Video 1 and 2.

  2. Turn off the motion for the graphic on Video 2 (its Transparency setting still should be Alpha Channel).

  3. Drag Alpha Glow to the graphic on Video 2 and open its Settings dialog box by clicking Setup in the Effect Controls palette.


This is one of those Premiere video effect control anomalies. When in the Effect Controls palette, Alpha Glow is missing two user-selected items?Fade Out and End Color. So you need to use the Alpha Glow Settings dialog box to access them. However, that means you don't get a real-time view of how the graphic with the effect applied looks over the lower clip. You can get around this by clicking Setup, selecting an end color, making your Fade Out selection, and returning to the Effect Controls palette. Then you can make the other settings there and use the Program Monitor screen to watch the effect change in real time over the clip on Video 1.

As shown in Figure 15.14, Alpha Glow changes the width of the effect. Increasing the Brightness setting actually increases the opacity of the effect. Checking the Fade Out box lets the effect gradually disappear around the outside edges. Leaving it unchecked creates a hard edge. Finally, the end color creates a second, outer color.

Figure 15.14. Alpha Glow creates a halo around a graphic.


Giving a Graphic a 3D Feel with Bevel Alpha

Applying this effect gives the graphic a nice 3D feel. I've applied it with the Alpha Glow effect in Figure 15.15.

Figure 15.15. Bevel Alpha adds a 3D edge to the graphic.


Drag it to the Effect Controls palette for the graphic clip on Video 2.

The greater the Edge Thickness and Light Intensity values, the more obvious the effect. In Figure 15.15, I set these items to approximately 9 and 0.9, respectively. Plus, I selected a light color to increase contrast.

Adjusting Colors by Applying Channel Blur

This shifts individual color values?red/green/blue?as well as blurs the graphic. Feel free to make adjustments using all the sliders.


As illustrated in Figure 15.16, as you make changes using the Channel Blur effect sliders, the Bevel Alpha and Alpha Glow effects change. You may want to experiment as you add even more effects to the same clip.

Figure 15.16. Because Channel Blur is, for the moment, the lowest effect in the Effect Controls palette, it blurs all effects above it.


Turn individual effects off and on by clicking the f in the check box. The order of the effects also alters the overall appearance of a clip. Drag effects to new positions in the Effect Controls palette to see what happens. For instance, as I've demonstrated in Figure 15.17, if you place Channel Blur at the top (below Transparency and Motion), any changes made when it's in that position will have a much more dramatic impact than if you place Channel Blur toward the bottom of the palette. Premiere applies video effects from bottom to top, saving Transparency and Motion (by default) for the final two compositing steps.

Figure 15.17. Placing Channel Blur at the top of the Effect Controls palette amplifies any adjustments you make to it.


Giving a Graphic Depth with Drop Shadow

Drop Shadow works real well with graphics, giving them the appearance of floating above the background clip. This is the effect you use if you rotate a graphic?using Basic 3D, Camera View, or Transform?and you want to make sure the shadow falls in the same direction rather than rotates with the graphic.

When you apply it along with these three other effects, it won't have all that dramatic an impact. Alpha Glow and Channel Blur soften the graphic so much that there isn't much substance left in it to throw a shadow.

As I've shown in Figure 15.18, you can fix that a bit by increasing Opacity to 80 or greater and dropping Softness to 0.

Figure 15.18. Drop Shadow has a subtle feel when applied to effects that have already blurred the image.



If you drag this effect to the top of the effect chain in the Effect Controls palette, it will create a very distinct drop shadow. Toward the bottom of the palette, it acts much more in character with the other effects.

Changing the Weather Using QuickTime Cloud

Both QuickTime Cloud and Fire do two things to a clip: they switch off all other effects applied to that clip and replace the clip with the effect. Try it and see.

Drag QuickTime to the Effect Controls palette, select Cloud, and click OK. Now preview that graphic clip. All you'll see is a cloud floating over the background clip on Video 1. The original clip is gone, as are the effects.

In this case, you want to incorporate Cloud into your ever-expanding collection of effects. Here's how:

  1. Make a color matte by right/Option-clicking in the white space in the Project window and selecting New, Color Matte.

  2. Select a color, name the matte, and drag it to Video 3 above the graphic on Video 2. Drag its ends to make it the same length as the graphic and background clips. Your timeline should look something like Figure 15.19.

    Figure 15.19. Use a color matte as a means to superimpose the QuickTime Cloud (or Fire) effect to clips below it on the timeline.


  3. Set the color matte's Transparency to Alpha Channel.

  4. Apply QuickTime Cloud to that color matte.

  5. Preview this three-clip sandwich. As illustrated in Figure 15.20, the cloud should float in the middle of the effect.

    Figure 15.20. How this evolving clip looks with QuickTime Cloud applied to it.



    If you want to have even more fun, add motion and rotation to the cloud. Go to the Motion Settings dialog box and create a path, rotation, and zoom to move the cloud all over the screen.

Flame-broiling Your Clip Using QuickTime Fire

This operates the same way as Cloud. To flame-broil your entire collection of effects, follow these steps:

  1. Add another video track to the timeline (unless you already have a Video 4 track) by right/Option-clicking the timeline and selecting Add Video Track.

  2. Drag the color matte from the Project window to Video 4 above the three other clips (directly above the other color matte). Lengthen it to equal the three other clips.

  3. Apply Alpha Channel in the Transparency Settings dialog box.

  4. Apply QuickTime Fire to that matte. As shown in Figure 15.21, you can use the preview window to watch as you adjust the four controls to your liking.

    Figure 15.21. The QuickTime Fire effect has four parameters that set the intensity of the flames.


Preview this combination of six video effects that all use transparent alpha channels. It should look something like Figure 15.22.

Figure 15.22. Six video effects that all use an alpha channel, juxtaposed into one colossal collection.



If you're in a particularly ambitious mood, feel free to apply keyframes to each individual video effect, except for the QuickTime effects. They do not work with keyframes. I waited until the end to suggest this because now all the effects are accessible in the drop-down menu in the upper-left corner of the keyframe track below the video track in the Video 2 expanded view. Use that drop-down menu to access each effect.

    Part II: Enhancing Your Video