Working with a green screen? Allow us to show you how chroma keying works within Final Cut Pro. Chroma Keying allows you to take certain colors and make them transparent. This is the process used for removing green screens, allowing you to place any background behind your subject. We'll use a chroma key to place a background behind these parrots. First, we'll add the foreground clip to the primary storyline... ...and drag the background clip right below it. Select the foreground clip in the timeline, then open the "Effects" menu on the right. In the Effects browser, we'll locate the "Keyer" effect. We'll do this by clicking on "all" and typing "key" into the search bar. Then we'll drag the effect to the foreground clip. As you can see, the key effect analyzed our clip for the dominant green color and removed it automatically. I've got the keys to this chroma. Now that we've applied the effect, we can adjust it. Navigate to the Inspector on the top right. If the Inspector is not visible, click on this icon and select the video icon to access the key effect controls. Now let's see how we can refine the effect. First, we can check how accurate our key is. This is easier to see if we click the "Map" view. In this video, white means visible, while black means transparent. So ideally you want your subjects to be completely white and your background to be completely black. The key mistakenly erased the green feathers on the parrots, so we'll need to bring those back using the key controls. But first, let's go over a few things. Heads up- please subscribe, comment, and share, and like, and do everything you can, because this tutorial is awesome. If we need to resample the color that gets
keyed out, we'll use these refined key controls. We'll click on the sample color thumbnail image and draw a rectangle in the viewer over the color range that we want to make transparent. So here, the rectangle covers the green screen and the blue of the parrot's feathers. To adjust the range, we can drag to move our selection around. And since we're in composite view, we'll see an updated preview as we work. To add more colors to our selection, we can drag additional rectangles. If we want to refine any difficult areas such as hair or feathers, we can use the "Edges" tool. With this we can draw a line around the difficult area with one end in the area to keep, and the other in the area to remove. Unfortunately sometimes it won't work well, like in this case where it's selecting too many colors to make transparent. In these cases, moving the edge tool or adjusting it may help. For a shortcut, we can hold the "Shift" key and drag to draw a sample color adjustment rectangle.
Or, hold the "Command" key to add an edge adjustment line. It looks like there's too many of these selections to make a difference, so we'll go ahead and undo these. Let's continue checking out these controls. The "Strength" parameter defines the sensitivity of the key. So let's see what happens if we take it down to zero. We can see a difference already, but let's click on the matte view to get a better look. Since the strength is so weak, some of the green screen is starting to come back on the right. That is not what we want, so we'll switch back to composite view and adjust the strength of the transparency to our liking. We already showed you these views, but here's a better explanation for how to use them. "Composite" shows us a preview of the final keyed image. "Matte" shows a grayscale representation of the keyed areas, making it ideal for checking our accuracy. Again, we want our subjects to be in white and everything else in black. And "Original" shows the original unkeyed foreground image making it good for identifying colors that we want to key out. Okay, now let's address the elephant in the room. You may have noticed that the key picked up the green in the parrot's feather, changing them to a weird brown color. So let's explore these controls and see if we can help that out. "Fill holes" is a helpful tool for solidifying areas that were partially transparent. An "Edge Distance" lets you change where the fill hole parameter ends. The lower the edge distance, the closer the filled area gets to the edge of the subject. And increasing the edge distance too much could result in some unwanted transparent sections that should be solid. Next, to control how much the keyed out background color affects the foreground image, adjust the "Spill Level" control. This is exactly what we needed to bring back the green feathers on the parrots. "Invert" reverses the keying operation, creating more of a window effect. Uncheck it to revert to normal. And to mix the keyed effect with the unkeyed effect, adjust the "Mix Control." Now let's check out our result by playing the video. These results are not perfect, but in the next video we'll dive into more advanced controls to show you how to get as close to perfect as possible. Like, share, subscribe, tell your friends, tell your neighbors! Don't forget to check out Pixel Film Studios, where you can find Final Cut Pro plugins designed for beginners and professionals alike to take your projects to the next level.
