Apple MA261Z/A User Manual - Page 680

Key Filters Key filters are generally used to key out background areas of video in order to isolate foreground elements to composite against a different background. Keying filters are commonly used with the Matte Choker filter. For detailed information on applying these filters, see Chapter 55, "Keying, Mattes, and Masks," on page 805. Filter Blue and Green Screen Chroma Keyer Color Key Color Smoothing - 4:1:1 Color Smoothing - 4:2:2 Result Keys the blue or green area of a clip and uses the selected color as a transparency mask for compositing foreground elements against a background scene. A View pop-up menu allows you to look at the source of the clip (with no key applied), the matte created by the filter, the final matted image, or a special composite of the source, matte, and final image for reference. A Key Mode pop-up menu allows you to select blue, green, or a blue/green difference as the key color. The Color Level slider lets you select the amount of blue or green in your clip to key out, and the Color Tolerance slider allows you to expand the key into adjacent areas containing other shades of the key color. The Edge Thin slider allows you to expand or contract the matte area to try to eliminate fringing, and the Edge Feather slider lets you blur out the edges of the matte to create a smoother key. (Before you use these sliders, try using a Matte Choker filter instead.) An Invert checkbox allows you to invert the matte, making what was masked solid and what was solid masked. Allows you to create a key using any range of color you want, including (but not limited to) the usual blue and green. You can also fine-tune your composite by adjusting the color value, saturation, and luminance ranges used to define your key, together or separately. For example, if you only want to perform a luma key, you can disable color and saturation. Even when performing a color key, you'll get superior results by manipulating the Color Range and Saturation controls separately. Keys on any color in a clip. Color controls allow you to select a color from your clip as the specified key color. Sometimes referred to as chroma key. Improves the quality of chroma keys and reduces diagonal "stair-stepping" that can occur in video clips with areas of high-contrast color. Use 4:1:1 Color Smoothing with NTSC or PAL DV-25 video sources. (The exception is PAL mini-DV/DVCAM, which uses 4:2:0 color sampling.) Use 4:2:2 Color Smoothing for DVCPRO 50, DVCPRO HD, and 8- and 10-bit uncompressed video. To improve the quality of your chroma key, apply the appropriate smoothing filter to the clip you want to chroma key first. As you add additional keying filters, make sure that the Color Smoothing filter remains the first one in the video section of the Filters tab. 680 Part IX Effects