真正使视频脱颖而出的通用编辑技术是使用绿(editing technique)屏视频(screen video)。在视频制作中使用绿屏作为在后期制作中编辑所需的特殊效果、过渡或背景的一种方式。
绿屏的“绿色”由视频编辑程序识别，然后您可以将其替换为另一个视频或图像(video or image)。这是一种流行的技术，广泛用于媒体，从当地天气预报到音乐视频，再到好莱坞大片(Hollywood blockbuster)。
Adobe Premiere Pro作为一个视频编辑程序，确实有能力通过一种叫做色键的方法来编辑绿(chroma keying)屏素材(screen footage)。在Premiere中，您可以使用Ultra Key 效果(Ultra Key effect)来对素材进行色度键控。
按照本教程，您将能够在视频 中无缝地融入绿屏效果。(screen effect)
如何为色度键设置素材(How to Set Up Your Footage for a Chroma Key)
在应用Ultra Key 效果(Ultra Key effect)之前，您需要清理绿屏素材以使最终产品看起来(product look)更好。您将为您的视频应用遮罩，这样您就可以摆脱不需要进行色度键控(chroma keying)的区域。
- 将绿屏素材放入时间线后，打开效果面板并转到Video Effects > Obsolete。如果您有一个更简单的主题(simpler subject)作为您的绿屏前景(screen foreground)，请从这里选择八点垃圾遮罩(Eight-Point Garbage Matte)。如果您的主题更复杂，请选择十六点。(Sixteen-Point)下面我使用八点垃圾遮罩(garbage matte)，因为主题只是一个圆圈。
- 您可以在“效果控件( Effect Controls)”窗口中单击效果，这将突出显示预览中的遮罩点。您可以通过这种方式用鼠标移动它们，或者在效果控件(Effects Controls)中更改点位置的值。
剪辑完视频后，我们将继续将Ultra Key 和 Chroma 键(Ultra Key and Chroma key)应用于您的视频。
如何在 Premiere Pro 视频编辑器中设置色度键(How to Chroma Key In Premiere Pro Video Editor)
应用遮罩后返回“效果”选项卡以找到Ultra Key 效果(Ultra Key effect)。请按照以下步骤应用它。
- 转到Video Effects > Keying > Ultra Key。单击(Click)并将此效果拖动到您的剪辑上。
- 在“效果控件(Effects Controls)”面板中的“超键”(Ultra Key)效果下，选择吸管工具(eyedropper tool)。使用它来选择您的绿屏背景颜色(screen background color)。如果您的素材中的绿屏照明均匀，您可以选择任何地方。但是，如果有部分比其他部分更亮，请选择更暗的区域(darker area)。
- 一旦您选择了绿屏颜色(screen color)，您将看到其余颜色消失(color disappear)。现在您可以开始微调键，使其顺利地适应您选择的任何背景。
有几种不同的方法可以微调拍摄对象的边缘，使其自然地融入背景。首先(First)，在输出(Output)下拉列表中，选择Alpha通道。这会将您的素材更改为黑白，因此您可以更轻松地查看哪些区域需要一些工作。如果Alpha 通道(Alpha channel)中的白色看起来更半透明，则意味着所选颜色在此处可能更明显。
您还可以将Setting下拉菜单更改为Aggressive。这将选择更多您使用吸管选择的颜色范围。
您还需要查看“遮罩清理(Matte Cleanup)”部分下方。在这里，您会看到一些称为“扼流(Choke)”和“软化(Soften)”的效果。扼流圈(Choke)将在您的主题边缘以硬线闭合。软化(Soften)也会在边缘闭合，但具有更大的羽化效果。
为您的绿屏添加背景(Adding in a Background for Your Green Screen)
现在，您可以将您选择的背景添加到视频中，这很有趣。(fun part)此步骤操作简单，可以帮助您了解是否需要进一步更改键的任何部分以获得自然效果。
- 在媒体(Media)箱 中找到要用于绿屏的背景素材。(background footage)
- 单击(Click)并将素材拖动到您的时间轴中。确保它位于绿(Make)屏素材(screen footage)下方的图层上。
- 所选素材(chosen footage)现在将出现在您的绿屏主题(screen subject)下方。
您现在可以看到您的主题与新背景素材(background footage)的匹配程度，并使用上述工具进行必要的更改。
编辑色度键的提示(Tips for Editing Your Chroma Key)
还有一些工具可用于清理您的密钥，使其与您的背景或效果(background or effect)很好地融合在一起。
透明度(Transparency)
您可以在Matte Generation(Matte Generation)下找到此设置。降低此设置的值将使拍摄对象的边缘变硬并清理干净，而提高它会使边缘变软。此设置适用于细化困难的边缘，例如头发或毛皮(hair or fur)、纤维或其他复杂的对象。
座(Pedestal)
更改基座(Pedestal)值可确定主体周围有多少背景可见。降低这个值会增加这种效果，提高它会产生更清晰的边缘。
阴影(Shadow)
该值将改变主体边缘周围的可见“阴影”效果，使边缘更柔和。这有助于使您的主题在添加的环境中显得更自然。
在 Premiere 中使用绿屏视频创建令人兴奋的效果(Create Mind-Blowing Effects With Green Screen Video in Premiere)
对于视频编辑初学者来说，学习如何在绿屏剪辑上使用(screen clip)色度(Chroma)键效果是一项需要掌握的重要技能。绿屏编辑可以以多种格式使用，并且可以真正帮助添加您可能无法添加的效果。
无论您希望添加何种视觉效果或视频背景，使用Adobe Premiere Pro都可以轻松完成绿屏工作(screen work)。如果您是Adobe Premiere 的完全初学者(complete beginner on Adobe Premiere)，这是一项需要掌握的基本技能。
How to Edit Green Screen Video in Adobe Premiere Pro
A versatіle editing technique to really make videos stand out іs the use of green screen video. Green screens are used in video production as a wаy to edit in desired special effects, transitions, or backgrounds in post-production.
The “green” of the green screen is identified by a video editing program, and you can then replace it with another video or image. This is a popular technique, widely used in media from local weather forecasts, to music videos, to Hollywood blockbuster films.
Adobe Premiere Pro, as a video editing program, does have the ability to edit green screen footage through a method called chroma keying. In Premiere you can use the Ultra Key effect in order to chroma key your footage.
Follow this tutorial and you’ll be able to seamlessly incorporate a green screen effect in your videos.
How to Set Up Your Footage for a Chroma Key
Before applying the Ultra Key effect, you’ll want to clean up your green screen footage to make the final product look better. You will be applying a matte to your video so that you can get rid of the areas you don’t need for chroma keying.
- After placing your green screen footage in your timeline, open the effects panel and go to Video Effects > Obsolete. From here choose the Eight-Point Garbage Matte if you have a simpler subject as your green screen foreground. Choose the Sixteen-Point if your subject is more intricate. Below I’m using an eight-point garbage matte since the subject is just a circle.
- You can click on the effect in the Effect Controls window, which will highlight the points of the matte in the preview. You can move them around with your mouse this way, or change the values of the points location in Effects Controls.
Once you’ve trimmed the video, we’ll move on to applying the Ultra Key and Chroma key to your video.
How to Chroma Key In Premiere Pro Video Editor
Go back to the Effects tab after you’ve applied the matte to find the Ultra Key effect. Follow the steps below to apply it.
- Go to Video Effects > Keying > Ultra Key. Click and drag this effect onto your clip.
- In the Effects Controls panel, under the Ultra Key effect, select the eyedropper tool. Use this to choose your green screen background color. If the green screen lighting in your footage is even, you can select anywhere. However, if there are portions that are lighter than others, select a darker area.
- Once you select the green screen color, you’ll see the rest of the color disappear. Now you can begin to fine-tune the key to fit it smoothly into whatever background you choose.
There are a few different ways you can fine-tune the edges of your subject so it fits into the background naturally. First, in the Output dropdown, select the Alpha channel. This will change your footage to black and white so you can more easily see what areas need some work. If the white in the Alpha channel looks more translucent, that means the selected color may be more visible there.
You can also change the Setting dropdown to Aggressive. This will select more range of the color you chose with the eyedropper.
You’ll also want to look underneath the Matte Cleanup section. Here you’ll see some effects called Choke and Soften. Choke will close in the edges of your subject with hard lines. Soften also closes in edges, but with a greater feathering effect.
Adding in a Background for Your Green Screen
Now you can do the fun part of adding in the background of your choice into your video. This step is simple to do, and can help you see if you need to change any part of your key further for a natural effect.
- Find the background footage you want to use for your green screen in your Media bin.
- Click and drag the footage into your timeline. Make sure it’s on the layer underneath the green screen footage.
- The chosen footage will now appear underneath your green screen subject.
You’ll be able to see how well your subject fits in the new background footage now, and make necessary changes using the tools outlined above.
Tips for Editing Your Chroma Key
There are a few more tools that will be useful for cleaning up your key so that it blends well into your background or effect.
Transparency
You can find this setting under Matte Generation. Lowering the value of this setting will harden and clean up the edges of your subject, while raising it will soften out the edges. This setting is good for refining difficult edges such as hair or fur, fibers, or other complex subjects.
Pedestal
Changing the Pedestal value determines how much of the background is visible around the subject. Lowering this value will increase that effect, and raising it will create much crisper edges.
Shadow
This value will change the visible “shadow” effect around the edges of your subject, making the edges softer. This is good for making your subject appear more natural in the added surroundings.
Create Mind-Blowing Effects With Green Screen Video in Premiere
For video editing beginners, learning how to utilize a Chroma key effect on a green screen clip is an important skill to master. Green screen editing can be used in a variety of formats and can really help add effects you may not be able to otherwise.
No matter what visual effects or video backgrounds you wish to add, green screen work can be done easily using Adobe Premiere Pro. If you’re a complete beginner on Adobe Premiere, this is a fundamental skill to master.
