If you can’t get rid of some of the grey, you may need to add a color correction effect to the media before you try to key it – try using the Curves effect to change the overall color of the media. Be careful not to adjust any one thing more than you need to – again, going too far will cause you to lose detail. You should be able to get your image to only black and white using these parameters. As you turn “Clip White” down, the light areas of the screen will get whiter. Next, move down to the section of the effect called “Screen Matte.” The two things you want to adjust here are “Clip Black” and “Clip White.” As you turn “Clip Black” up, the dark areas of the screen will get darker. Be careful not to lose detail as you adjust the gain and balance. The first effect parameters you should adjust are the “Screen Gain” and “Screen Balance.” Try adjusting each to see if the result improves or gets worse, but don’t worry if you can’t get it exactly right – this is only the first step. Your goal is to get rid of all the grey areas. Next, change your view mode from “Final Result” to “Screen Matte.” This will give you a black-and-white view of the areas being keyed out – black areas will be taken out, white areas will remain, and anything grey will be transparent. First, select the color of the mask using the eyedropper tool – you should see an immediate effect. There are lots of compositing options available in the “keying” section of the effects, but your best bet is an effect called Keylight. Once you’ve isolated your subject with a mask (and animated it, if necessary), you can begin to actually key the footage. You can also add a slight feather to the edges of the mask, to help everything blend together. Once the shape of your mask has been keyframed, it should move around your subject throughout the footage without cutting them off. You may need to shift-click on a mask’s points to select it individually. Simply go through the footage and change the shape of the mask whenever your subject moves out of it. Under the mask properties in the timeline panel you will find “Mask Path.” If you turn keyframes on for this property, you can animate the shape of the mask by dragging its points. To avoid this, you can animate the shape of the mask. If this happens, the subject will be partly cut off. While you want to crop out as much as you can, if you draw your mask too close to the subject being keyed, they may move outside the mask during the clip. The more you can cut out, the less the program needs to color-key, and the better your results are likely to be. Use the pen tool to draw a rough mask around your subject, cutting out any unwanted sections. Once you have your clip imported into After Effects and placed in a composition, you the masking tools to trim out as much of the unwanted area of the frame as possible. Plus, it can be used in creative ways to combine live action footage with animation. While this doesn’t directly relate to the kind of work we’ve been doing, I think it’s a useful skill to have. One very common use for After Effects is compositing work – combining multiple pieces of footage, usually through the use of green or blue screen effects. We’ve been using After Effects to create animation throughout the semester, but it’s capable of a lot more. Here is some footage to use for this exercise.
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