An alpha channel defines transparency for a pixel.
In this lesson you’ll encounter some terms that might be new to you. Green-colored jewelry, for example, might turn transparent when the key effect is applied. It also needs to be a color that does not appear anywhere on your subject. For that greenscreen to work well, it needs to be a consistent color. Planning ahead can make a big difference to the quality of your compositing. In a weather report, it’s a map, but it could just as easily be any other image. Next, it’s just a question of putting the foreground video image in front of another background image. The video image of the weather reporter is used as the foreground of a composition, with some visible pixels (the reporter) and some transparent pixels (the green background). Special-effects technology uses the green color to identify which pixels should be transparent. The weather reporter is actually standing in front of a green screen. Consider chromakey, for example, the standard special effect used to allow weather reporters to appear in front of a map.
Premiere Pro has a limited number of ways of identifying which pixels you’d like to make transparent. Right at the start, you can think about how you can help Premiere Pro identify the parts of the image you’d like to be transparent. Much of the most effective compositing work begins when you are planning your production. In this case, for example, it can be it a little difficult to see the edges of the text. However, for some kinds of media, the transparency grid is an imperfect solution. Now you can clearly see which pixels are transparent. Click the Source Monitor Settings menu button and choose Transparency Grid. Think of them as the background of the Source Monitor.Ģ. It looks as if the graphic has a black background, but those black pixels are displayed in place of transparency. Open the file Theft_Unexpected.psd in the Source Monitor. You can set the Source Monitor and Program Monitor to display transparent pixels as a checkerboard, just as in Adobe Photoshop:ġ. Clips that are animations or text or logo graphics will often have alpha channels that control which parts of an image are opaque or transparent. On the 8-bit video scale of 0 to 255, this means it will be at 255. Just as you might use color correction to adjust the amount of red in a clip, you can use Opacity controls to adjust the amount of alpha.īy default, the alpha channel, or opacity, of a typical camera footage clip is at 100%, or fully visible. What matters is that you can adjust the opacity of each pixel independently of its color. Several different words are used in the world of post-production to describe this fourth channel, including visibility, transparency, mixer, and opacity.
Instead, it defines opacity-how visible the pixel is. The fourth channel defines no colors at all. You see the three channels combined as full-color video.įinally, there is a fourth grayscale channel: alpha. They are combined using what’s called Primary Additive Color to create a complete RGB image. Premiere Pro uses these three grayscale channels to produce the corresponding primary color channels. Because each channel is monochrome (just one of the three colors), they are commonly described as grayscale. Working with alpha-channel transparenciesĮverything begins with cameras selectively recording the red, green, and blue parts of the light spectrum as separate color channels.Making compositing part of your projects.Applying effects in the Audio Track Mixer.Changing clip position, size, and rotation.Using A/B mode to fine-tune a transition.Exploring Compositing Techniques by Maxim Jago Adobe Premiere Pro CC Classroom in a Book® (2014 release) Pedestal will adjust the gain for the selected shade of green, and because we still have some of the highlights to clean up, changing this value makes a difference. In this case, we are already choosing enough shades of the green, so this has no effect on our matte. Tolerance refers to how many different shades of the same color green we will key out, so the higher this value, the more shades of green we're choosing. Shadow does the same, but with the darker pixels. Highlight works by increasing or decreasing the opacity of the brighter pixels. Transparency here is transparency of the source when over a background. Now, we change the setting to custom, and we will start the matte generation process from scratch. So, we have our footage, and we have chosen the green color that worked the best using the default settings.