Sony MLS-X1 Users Guide - Page 121

Chroma Key When chroma key is selected as the key type, you can configure and adjust the chroma key. Overview A key signal based on a particular color is used to cut out the background, and a key fill is then inserted to create an image. In an image created using a chroma key, the image at the rear is called the background and the inserted image is called the foreground. Two mixing methods, normal mix and additive mix, are available. Normal mix The background which is cut out by a key signal is mixed with the foreground which is cut out by the key signal. Additive mix The background which is cut out by a key signal is mixed with the unchanged foreground. This is effective for a natural-looking composite when the scene includes glass or other translucent objects. In an additive mix, the blue (background color) parts of the foreground must be converted to black using the color cancel function. For details about color canceling, see "Adjusting color cancel" (page 123). Plane function In an additive mix, since the background is mixed with the unchanged foreground, an uneven blue background may appear in the composed image. You can specify a specific luminance level and remove parts of the blue background with lower luminance to avoid this unevenness. Auto chroma key You can specify a specific color of the foreground that automatically generates a chroma key. Immediately after an auto chroma key is executed, manual fine tuning is effective, if required. The following settings can be adjusted manually. • Key active • Color cancel • Window • Y balance • Shadow • Foreground color correction Chroma key adjustments Automatic adjustment using an auto chroma key and separate manual adjustment of required processing can be performed. Auto chroma key You can specify a specific color (blue background, for example) of the foreground to automatically generate a chroma key. Key active When the key active function is enabled, the composite image is output to a monitor, and you can adjust the composition while viewing the monitor. When the key active function is disabled, only the foreground image is output, and you can make color cancel adjustments while viewing the monitor. Color cancel If the background color is leaking into the foreground image, enabling the color cancel function allows you to eliminate this leakage. Window When the window function is enabled, you can adjust the detection range used to create the key signal. When the window function is disabled, the default range is used for image adjustment. A chroma key generates a key signal based on a specific color (blue background, for example) of the foreground. In the window function, you can specify a range of colors around a reference color to create a key signal. The region that makes up the key signal in the foreground (to be replaced by the background) appears as a fan shape with a cropped vertex when viewed on a vectorscope. This region is adjusted by two parameters: an [Angle] parameter (opening angle) and a [Crop] parameter (degree of vertex cropping). Crop a) Angle a) Hue b) Region remaining as the foreground Region where the key signal is created (replaced by the background) a) The [Angle] parameter and [Crop] parameter values do not change even if you use the auto chroma key function. b) Reference color hue value 121