Friday, December 6, 2013
Thursday, December 5, 2013
Chroma Key, Green/Blue Screen and the Pulling Thereof In Final Cut Pro (FCP)
Top of the morning to you!
I was recently asked how to do a green screen effect with Final Cut Pro. So here it is.
NOTE: I am using FCP Version 7.0.3 not FCP X.
NOTE: I am using FCP Version 7.0.3 not FCP X.
For video keying any color background will work as long as there is a significant difference between what you are keying out and the color of the background. Along with many shades of blue and green I have successfully keyed with grey, black, white and red backgrounds. Final Cut Pro has several tools for keying but I have had the best luck using Chroma Keyer for most applications.
For example if your subject is wearing a color that has the same color as the background, that doesn't work so well because it will also key it out, leaving a hole in your subject. That can be good if you intend to have a hole in your subject, or bad if that's not your intention!
For example if your subject is wearing a color that has the same color as the background, that doesn't work so well because it will also key it out, leaving a hole in your subject. That can be good if you intend to have a hole in your subject, or bad if that's not your intention!
Green and Blue backgrounds have been used with the understanding that those colors are the farthest from skin tone and because, at least in the case of green screen color, is too ugly for anyone to wear intentionally.
The green or blue screen or Chroma key effect is also called "pulling a chroma key" "pulling a green screen" pulling a key" etc. you get the idea.
There are three critical elements to consider when "pulling" a green screen effect. The camera needs to be the highest definition you can afford. Standard Definition (SD) footage will work fine for the back ground but the green screen subject needs to be shot in HD.
There are three critical elements to consider when "pulling" a green screen effect. The camera needs to be the highest definition you can afford. Standard Definition (SD) footage will work fine for the back ground but the green screen subject needs to be shot in HD.
Standard definition green screen effects are very difficult to clean up. They look jagged around the edges and you have to use so much edge blur that it looks like it was shot in the 70's and 80's. A frightful time in television history! I was there. I remember it and I bear the scars...
First let's start with a subject, a green screen, lights and a Hi def camera. In this case a Sony XDCAM.
Light the green screen as evenly as possible. Avoid using too much light as it will bounce onto the back of your subject showing up on the edges of hair and clothing. You can crop left, right top or bottom to clean up uneven lighting, just make sure your subject does not move beyond the cropped area.
The screen shot below shows fairly even background lighting but it could be better. Notice the darker edges. This shot will still key very well but the background lighting is a bit sloppy.
The screen shot below shows fairly even background lighting but it could be better. Notice the darker edges. This shot will still key very well but the background lighting is a bit sloppy.
 |
| Subject is evenly lit with acceptable background lighting but the background lighting could be more even. |
Light the subject to match the background image (the image or video that you will use to fill the green space) light source if possible, and spend a great deal of time getting the camera's focus and iris setting perfect. For a news style, even studio lighting is fine. If you are trying to make it look like your subject is really part of the background then light it more harshly with your light in the same location as the background image light. Then manipulate the studio light(s) like you would on location with reflectors etc. This is where you can make or break a green screen effect.
If there are lots of reflections from traffic or water, add that to your green screen subject. If there is action happening, explosions or flashing lights you can add those when you shoot the green screen. It's amazing how much fun adding that stuff is! Don't limit your lighting sources to studio lights. You can use fireworks, flash lights, fire, welders etc.
Lighting can be the most creative and fun part of your production!
To get critical focus you can over expose the shot and then focus. I use the back focus for this purpose, then reset the iris. For good non-action green screen shots, keep your talent from moving around too much.
Once the subject is shot and you tell her thank you, hand her the check and say "good bye," the fun begins!
Import the footage into Final Cut Pro.
Once in Final Cut Pro, (FCP) create a project and save it.
Organization is key to not going insane trying to reconnect images and video if you move them around.
Avoid using your desktop for storing clips, images and graphics. It gets cluttered extremely quickly. Did I mention organization?
I use an Xserve RAID for video imports (capture scratch) and an additional internal drive to store graphics, animations and images. I try not to use the system drive for media storage. Editing on a Mac with only one drive for everything will work, but adding at least one drive for video capture will help the process. Lots of memory is a good thing also!
I use an Xserve RAID for video imports (capture scratch) and an additional internal drive to store graphics, animations and images. I try not to use the system drive for media storage. Editing on a Mac with only one drive for everything will work, but adding at least one drive for video capture will help the process. Lots of memory is a good thing also!
Once your video is imported drag your background onto the first level of the timeline (the image below shows that I put it in the timeline second from the bottom). Correct the color, setup and video level using the proc amp filter.
Now drag your green screen video just above the background video.
This is called layering.
This is called layering.
NOTE: If you plan to add graphics or other layers between the background layer and the green screen layer you can leave blank slots in the timeline. Empty layers will not affect the outcome of your green screen effect.
Once in the time line click the green screen clip so FCP knows which one you want to work on then use the drop down menu item labeled effects-video filters-key and click on chroma key.
Now you have set the Chroma Key filter to the clip you want to work on.
Click on the filter item labeled Chroma Key and then you will see the six tools with sliders to "pull" the key.
Using the eye dropper tool drag to the green screen video and click it somewhere in the the green. This will begin the process of pulling your key. Adjust the handles and spread out the color a bit. Then using the sat and luma controls adjust until the green begins to disappear around the subject.
Fine tune each of these until it begins to look pretty good. It will still look a bit harsh but don't worry, the next step takes care of that.
Fine tune each of these until it begins to look pretty good. It will still look a bit harsh but don't worry, the next step takes care of that.
Using the edge thinning tool slide it around until you can see a definite change in what is being keyed. When your subject begins to lose hair or other features around the edge, back off a bit and move to the softening tool.
The softening tool will blur the edges a bit. A little softening goes a long way so play with it until you like what you see.
Then if you notice a bit of green light spilling from the background onto your subject you can use the enhance tool which should get rid of the green. Again play with it to get it right as too much enhance will turn the edge red. You want to just barely get rid of the green tint on the edge.
Now you can add a name super, key image and there you go!
You can then add other graphics like name supers or video to make your shot more interesting. Remember that motion is key to interest, in foreground and back grounds!
Experiment until you like what you see. Pulling an effective key is more art than mechanics so spend some time and make magic happen!
For more in depth information on Hollywood style key effects visit: http://filmmakeriq.com/lessons/5-elements-of-a-great-chromakey/
My next tip will show you how to make multiple shadows falling on a keyed background to give a multiple light shooting effect. Remember it's all about the illusion of "real!"
Thanks for visiting. More later.
D
Wednesday, December 4, 2013
FCP Glitch #763
Good Afternoon!
This may be common knowledge but this is the first time I have experienced the following Final Cut Pro (FCP) glitch.
This may be common knowledge but this is the first time I have experienced the following Final Cut Pro (FCP) glitch.
I Just thought I would share glitch #763 from Final Cut Pro 7. FCP 7.0.3 is the version I have stuck with as the "upgrade" to FCP X took a U-turn to stupidity... Anyhoo I digress...
FCP glitch #763 - If you are using an external drive like a 1TB Seagate, transfer the clip(s) you need from the external to your scratch drive then eject the external USB drive. I forgot to do that and when I went to use Compressor it kept screwing it up time after time after time... until I unplugged the external drive.
In conclusion: if you are having errors with Compressor make sure it is not trying to scrape a video clip out of an external USB drive.
D
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