ADOBE AFTER EFFECTS
Here we will go into a short, yet extensive, tutorial on using bluescreen techniques using Adobe After Effects. In this tutorial, we'll composite together a shot of the Millenium Falcon flying over an apartment. I will usese the original footage shot on VHS tape outside the apartment. To import it into After Effects, where you can work with it, you'll use the File, Import, Footage File. Once the file is input (in this case, it's an AVI file), you'll want to create a new Composition. When After Effects imports footage, you'll see all the information you'll need right in the Project Window. In this case, the footage was 320x240, 10:15 at 30:00fps. 10 seconds and 15 frames, running at 30 frames per second (standard video recording speed). You'll want to keep these settings for the Composition you make. Same frame size, same frame rate, same length. You'll see the blank window pop up on your screen. Now go into the Project Window and drag the footage file into the Composition you just made. You'll see the picture pop up in the Composition Window.
We'll be dealing with only one frame, for the purposes of the tutorial. This is, however, a 10 second shot, and all the effects and work we do here will effect the ENTIRE clip. I chose this frame because the ship is at it's closest, and I can demonstrate the how-to's and the why's. Below is the shot of the Falcon itself, against a bluescreen. The ship was created as a 3D model in Lightwave, with the final render done with a flat blue background, to simulate a bluescreen. Since the footage I shot was captured at 320x240, 30fps, I did the same thing in Lightwave, telling it to render the movie in that size at that frame rate. I saved the rendered file as a sequence of RGB images in 24-bit IFF format. To import this into After Effects, use the usual File, Import, Footage File feature. When you highlight one of those frames, you'll see an option pop up at the bottom of the Open Window that, in this case, read "Amiga IFF sequence". Check next to that and hit OK. Then entire sequence will be input as footage. Create another Composition using the same settings you used before, and drag this new footage into it.
Now we get into it. Go to the Effects menu, Keying submenu. Choose Color Difference Key. This is your major bluescreening tool. As soon as you click this, you'll see the change immediately.
The blue has been replaced by black. In After Effects, it's quite simple to see how something will come out if you remember this simple rule: If it's black, it WON'T show up in the final shot. So we can see from the above shot that the ship will be inserted, but the blue background will be completely removed. At this point, it's possible to go ahead and insert the ship into the final sky shot.
But wait.. what's this? Are those clouds and trees I see right through the ship? Why, yes it is. This is why we start getting into the detailed parts. We'll need to go into the Effects Window for our Falcon shot. You'll see two small pictures at the top of the window. One will show the "before" image, the other shows the "after" image. Click on the small "B" underneath the "after" window.
Now, the "B" channel is the actual matte that the program uses to composite the images.
Note how the ship looks a grayish color. Remember our rule: If it's black, it's taken out. If it's white, it stays in. If it's gray, like this shot, the ship will take on a translucent appearance, because the ship is not being composited at full opacity.
As a matter of fact, using the old optical technology for bluescreening, this was sometimes used on purpose. If you watch the Hoth battle scene from Empire Strikes Back, you'll notice that during the interior shots of the snowspeeders, you can often see right through the ship to the snow beyond it. This was done to reduce the tell-tale black line around the ships when superimposed on a white background.
Luckily, with today's digital technology, we don't have to worry about the black line. The computer will get rid of it for us. So here's what we'll do with this matte shot. In the Effects Window, go down to the "Partial B Gamma" slide, and max it out.
What we've done is bleach out the image to where the ship is solid white, or as close as we can get it. Remember, if it's white, it stays in.
Note that the clouds and trees are no longer visible. Yes, it does kinda look like you can still see the trees, but that's just the coloration on the ship. It's solid. But now it brings up another problem. The Falcon is in front of the trees. The tops of the trees are over 30 feet away. Makes the ship look like a little model I filmed. So what we have to do now is put the trees in front of the ship. First step is to create a third Composition. Once you've created it, drag the original sky footage into this new composition. We'll be doing some bluescreen work with this shot using the sky as the world's biggest bluescreen. Once you've imported the footage, apply the Color Difference Key to it. The only thing you'll see is the image get a little darker. In order for this shot to work, we'll have to do much more fiddling with the mattes than we did before. Go into the Effects Window and look at those preview shots. First thing we want to do is look at the "A" channel. The "A" channel, so far as I know, shows you what will be staying in the shot, in a picture sort of format.
The first thing we want to do is adjust the "Partial A Gamma". Reduce it to NOTHING. The screen will turn solid black, meaning that nothing will be composited, but we're not done yet. What we've done is get rid of the sky. Now look at the "B" channel. This is your matte.
The white is the trees, which will stay in. We want to adjust the "Partial B Gamma" again. Move it up the maximum. The screen will look almost solid white. Now click on the "alpha" symbol under the preview window. You'll see the same bright white shot that was in the "B" channel. (the alpha channel is a blend of the A and B channels). What we're looking for is white trees, black sky. Keep the trees, get rid of the sky. To ensure we get the proper matte, we'll go down to the "Matte in Black" slide, and move it up to around 200. This gets rid of the sky, and leaves the trees nice and white.
Sure, the edges don't look all that good, but it's being composited right back onto itself, so the original footage will blend right in. Now what we want to do is put this into our regular sky background. There's an important thing to remember before we do this. We have to make sure that everything goes together in the correct order. Back to front. The original sky shot is already in this Composition. We want to put the Falcon in next. Then put the bluescreened trees on TOP of the Falcon, to make sure that they're in front of the ship.
Still doesn't look quite right, does it? Now what we have remember is that I'm not filming in Panavision. I used a regular old VHS camcorder, which just doesn't look all that good. The Falcon in this image is just way too sharp. Our next step is to apply a small blur to the ship. Make sure that in the Composition Window, the Falcon footage is highlighted. Now go into Effects, Blur&Sharpen, Fast Blur. In this case, I applied a Fast Blur at a 1.0 value. When you change the settings in that Falcon Composition, it also makes the changes to any other Compositions using that footage.
The shot is done! Now go into Composition, Make Movie. The Save screen will come up. Choose a directory and a filename. If you're making it into Quicktime Format, you'll need to go ahead and type the .MOV extension. Once you do that, the Render screen will come up. Go into the "Current Settings" and change the Quality to "best", Resolution to "full". Click OK, and then go into the "Lossless" settings. I changed mine to Quicktime Movie, and the Format Options to Sorenson Video, which is the same format that Lucas uses for the online trailers, and the same format that "Troops" is in. Once you change that, click on Render. Wait for it to finish, and you're done! In my case I now have footage of the Millenium Falcon flying over an apartment! I don't have a tripod, so the shaky camera kinda screws it up a couple times, but it was only a test.
PHOTOSHOP AND PREMIERE--Naboo Ship Bluescreening With Photoshop And Premiere
1. Capture the ship
To capture the ship, I placed the model on its mounting, placed the mounting on a stack of books in the hall, then draped a blue piece of cloth over the back of a couch. A Kodak DC200 digital still camera was used to photograph the ship. The camera is sitting on top of an inverted plastic Wal-Mart trash can. After each shot, I simply slid the trash can down the hall 3 inches, using a yardstick as a guide.
The Advanced Marks-A-Lot Motion Control System Notice how the picture shakes about violently as it pulls back from the ship. That's because no matter how hard you try, the camera is bound to change orientation slightly from shot to shot. If we were LucasFilm, we would have a "motion control" camera, but since we aren't and we don't--we use a Marks-A-Lot marker to make an X on the blue cloth directly where the camera is pointing--i.e. in the center of the picture.
2. Acquire a background
For my moonscape, I found an image called "Earthrise" at Axe's Bryce Gallery, and I modified it down to 320x240. Then I blew my 320x240 background up to 1152x864 and placed a bright green dot near the center of the image.
3. Frame-by-frame processing.
To process a frame, first open the source JPEG in Photoshop. Then select "Blur More" from the Filter menu. (This helps kill some of the image's noise, and won't hurt the final results since they're going to be so much smaller than the source JPEG.)
Now, select a retangular area around your ship.
Use the magic wand tool to remove the blue screen from the selection.
If it doesn't get it all, then just use it again on the remaining areas until the ship is nicely selected. Then use the marquee to add the Marks-A-Lot X to the selection.
Copy the selection into the clipboard, then close the image without saving it. Open a fresh copy of the 1152x864 background blowup, and paste the clipboard into it.
Set the opacity of the top layer to 75%, then move the layer until the Marks-A-Lot X is centered over the green dot.
Set the opacity of the top layer back to 100%, then draw a selection marquee around the X and delete it.
(If the ship is moving especially fast in this particular frame, now would be a good time to add some Motion Blur to the top layer.)
Flatten the image, erase the green dot, then shrink the image down to 320x240 and save it as a Photoshop file with a sequential frame number. (I used the same number as my digital camera gave the image, just so I wouldn't get confused.)
4. Creating the lasers
To assist with the lasers, I created a Laser Reference Frame, which is a composite of every 5th ship picture, and drew orange lines (in a separate layer) where the lasers are going to travel.
To make a particular piece of laser, simply select all the portions that you don't want and delete them.
Then select the bottom layer, knock the upper output level down to 0, and flatten the image.
Use the paintbrush with black paint to round off the ends of the beam.
Select All, Copy, then Paste. This will create two layers, each with the same orange beam. Click off the "eye" of the top layer (making it invisible), then select the bottom layer and perform these actions: Gaussian blur 5.0; upper input level 10; gaussian blur 5.0; green upper output level 0. Now make the top layer visible again and then set its mode to "Screen".
Flatten the image, shrink it down to 320x240, paste it into a clean 320x240 background image, and set the top layer to Screen (or do a "fake screen" again). Flatten the image one more time, and save it as a numbered still.
That's it! Now you're ready to import your set of numbered files into Premiere as a sequence of Numbered Stills, add sound effects, and compile. If only everything was so easy.
If you want to bluescreen actual MOVIES into premiere, do this:
Put the background clip in the top video track.
Put the greeen screen clip in the Overlay Track ( the video track which is at the bottom).
Right click on the green screen clip and choose 'Transparency' then choose from one of the options (Green Screen or chroma works best).
And Presto!
Also, when I try a few things, i can see the background image, but both the background and the foreground are at something like 50% opacity, and i can see through the actors as if they were translucent.
