Green screen editing help

[monsignor]

hi

I need help editing some footage in adobe Premiere.

I have some footage of blue ripples and some footage of a stationary blue bottle filmed in front of a green screen.

I would like the bottle to appear in the middle of the ripples.

how would I go about editing this together in Premiere.
I've got a vague idea that the green has to be trasnspearant but other than that I need a little help.

Many thanks
monsignor

[BJ_M]

its called chroma keying and some apps for this run in the mega bucks but you can do it with really cheap video editors also -- premiere can do it also
.. prob the cheapest way to do it is w/ mgi video wav .. if you got the bucks .. you can get a better program ... here is how it is done w/ mgi video wave:

How does it work?
Record an actor/object performing in front of a large, solid-colored backdrop or screen (usually blue or green). Software later removes all of the blue or green pixels around the actor and replaces them with a background graphic or video. The result is your actor composited, or layered, on top of the fake background.


You can make cool digital videos with chroma key technology. The following tutorial will show you everything you need to know about shooting and editing special effects in flicks.


Shooting your video
Chroma keying can be used in all sorts of situations, but for this example we'll stick with compositing an actor into a new background. Here's how to record your raw video.



Select a backdrop
You'll need a big sheet or wall that is one color. Bright blue or green works best, but any solid bright color will do. Just make sure your actor isn't wearing any colors that match the background. If you wear a blue shirt in front of a blue screen, the software might remove the blue pixels of your shirt in addition to the blue pixels of the background, leaving a floating head with no body.


Light the scene
Good lighting can improve the quality of your chroma key. Record outside if possible, or use several lights if you're inside. Make sure the actor and the backdrop are illuminated well. In particular, make sure the backdrop is evenly lit and the actor's shadows don't show up in the video frame.


Frame the shot
Study the graphic or video you plan to use as the fake background for your actor. Figure out exactly how the actor fits into that scene and frame the shot accordingly. Maybe you need the actor to stand on the left side of the video frame and be seen from the waist up. Or maybe a close-up would work better.

It's also important to make sure that the colored background fills the background of the frame. If you can see past the edges of the colored wall or sheet in the video window, the chroma key won't work properly.



Record the performance
Do this as you would with any other video, but don't move the camera during recording. A moving camera looks really weird against a background that doesn't move, and the framing is likely to get screwed up. So if possible, put the camera on a solid surface or tripod.

Editing your video
This tutorial is written for MGI VideoWave II, an inexpensive video-editing software package for PCs. However, several digital video editors offer chroma keying, and most of these techniques apply to all.



Import the video
After opening VideoWave, right-click in the video clip window and select "add file." Then pick the video files you need for this movie, including the foreground video (with colored backdrop) and the background video or graphic.


Drag the background clip into the view screen
Find the background layer clip in the video library and drag it into the view screen window.


Click the video animator button
This is on the button bar, on the left side of the video-editing window, fourth up from the bottom. Notice that the background clip appears in the small background window.


Drag the foreground clip into the foreground window
Find the foreground clip in the video library and drag it into the small foreground window in the lower left corner of the view screen panel.


Select "remove color"
Under the small foreground and background windows, you can choose between "image blend" and "remove color." Select the latter.


Pick the color you want to remove
Click the "color" button right next to "remove color." This will bring up the "color dialog" window. Click the "pick a color" button. Now you have a color selector for a cursor. Use it to select a color in the backdrop behind your actor. This is the color you want to be removed from the foreground layer. When you're done selecting, click OK.


Adjust the tolerance
Find the tolerance slider in the bottom of the view screen panel. This controls the range of colors removed from the video. The higher the tolerance, the wider the range. Play around with the levels to see what works best for your video.


Edit your movie
Finish editing your movie as usual. You can drag this new clip into the story line or add it to the video library. Look at VideoWave's help features for details. I find them very useful.

[BJ_M]

guide from SharedThunder Productions:

Basic Blue-Screening
A quick do-it-yourself guide
Blue and green screening are common techniques used in production to place actors and objects in front of backgrounds that can be shot or created separately. One common example is the news weather-person standing in front of a screen that changes to show the temperature, weather conditions, etc. With a few supplies and a video editing program, you can try this technique yourself. Additionl links are included at the end of this tutorial.

What you'll need:
Background material - To be able to place your subject against any background, you'll first need to shoot them against a painted wall or material that has a solid color on it that you can remove later in the editing process. Blue and green are used for this, because these colors are less represented in skin tone than colors such as red and yellow. Photographic supply stores should stock blue and/or green paper. You may have to go to a special supplier to get the paint, if you choose to paint your background.

Subject - Your subject should not contain the color that is used for the background. For instance, if using a green screen, don't have your subject wear a bright green shirt that matches the color of the background, unless you want their torso to appear transparent.

Background footage - You should know ahead of time what type of background you'll be eventually placing behind your subject. Your subject should be in scale with your background. For instance, a person placed against the backdrop of a city will look like a giant if the scale of the background is too large.

Lighting - Good lighting is essential to a "clean" bluescreening process. The background should be lit evenly, so that there are no dark or light patches, shiny spots or shadows. Your subject should be lit so that they do not throw a shadow on the background, if possible, and so that there is no blue or green light bouncing off the background and spilling onto the subject. Doing all this will take some trial and error, so give yourself time.

Camera - Needless to say, you want to shoot this. You can use a still camera or any other kind of camera, depending on your situation and if you want to use moving images or not. For this process, anything that will allow you to get your picture of footage into a computer will do. Digital video cameras work great, because they can connect directly to most video equipped computers.

Computer hardware/software - Many different software programs will allow you to key out colors like blue or green. Premiere (PC/Mac) and FinalCutPro (Mac) are two of the more popular ones. AfterEffects (PC/Mac) has more sophisticated keying tools, as does Ultimatte (PC/Mac).

How to do it:
1) Set up your background - Put up your paper or paint your wall, making sure that no edges, marks, creases, or wrinkles are showing.

2) Position your subject - You can lay objects flat on your background, or suspend objects from fishing wire. Be creative. Subjects can walk through the frame, and even disappear behind objects covered with your blue or green material.

3) Frame your shot - Make sure that the edges of your background don't show and that your subject is placed in the manner that you want it to appear in the final shot.

4) Light your scene - As mentioned above, pay special attention to shadows and bright spots on the background and reflected light on the subject.

5) Shoot your shot - Take as many takes as you need. This is a complicated processes, so give yourself enough footage to choose from in editing. If you move the camera, make sure that you avoid the edges of your background and that the change in perspective doesn't adversely affect the lighting.

6) Import your footage - Premiere and FinalCutPro have their own import capabilties. See the individual program you're using for info.

7) Position your background footage and bluescreened subject on different layers - You'll need to put your bluescreened subject on a video layer above the background subject, to set up the transparency. You won't be able to see the background until you apply the key effect.

8) Apply the key effect - This process is different from program to program. In Premiere, it's called Transparency. In AfterEffects and FinalCutPro, it's called Chroma Key. Other options are Bluescreen or Greenscreen. See the individual program for more info.

9) Adjust the effect - Most of the time, you'll have to adjust the parameters of the effect in order to get the "cleanest" possible results. Premiere uses "Transparency" and "Cut-off". AfterEffects uses "Tolerance" and "Edge Thin". Experiement with different types of keying effects and different parameters. You may need to apply more than one keying effect if your background had shadows or bright spots. You may need to mask out parts of the foreground, like the wire holding up your subject or the edge of the bluescreen material that got into the shot. AfterEffects is the best program for this kind of advanced work.

10) Keep practicing! The more you do of this, the more you'll learn. Have fun, and keep on dreaming!

[BJ_M]

http://www.creativemac.com/2001/05_may/tutorials/totalpremiere06/totalpremiere06-page1.htm


its a mac tutorial on blue screen w/ premiere -- but the mac and pc version of premiere are close enough for this to be a vaild tutorial for you ...

[monsignor]

thanks so much guys for your time,

very, very much appriciated indeed.

monsignor