Matrox Vio, Установка и справочник по оборудованию

Страница: 33 / 60

32 Chapter 3: Matrox Vio Duo Hardware Reference
image are displayed unless they are equal to the keying color, in which case the
corresponding pixels of the underlay image are displayed instead. The overlay
image size should equal the size of the underlay image to avoid corrupting the
image.
Color space converter and formatter
The color space converter and formatter can crop captured images, downscale
them (subsample), and convert their color format. Images can be flipped vertically
as well.
The color space converter and formatter can crop captured images (ROI capture)
or arbitrarily downscale them to 1/16th of a field or frame. Downscaling is
implemented using a configurable pixel subsampling engine, which allows for
integer subsampling values between 0 (no subsampling) and 16 (1 pixel out of
16). This can be useful to implement custom software-based motion detection
because at a reduced scale, comparison is faster.
The color space converter and formatter can convert YCbCr 20-bit images to
BGR packed 24-bit, 32-bit, or 48-bit images, or to YUV 16-bit images. The color
space converter and formatter can extract the Y component from a YUV stream;
it can also extract R, G, or B from the result of the conversion. The color space
converter and formatter can also perform
color kill, which first converts data to
grayscale and then converts it to its appropriate destination format. Each color
component is transferred to the destination in packed mode; however, planar
transfer mode is available for all output color formats in SD. Planar transfer mode
is not sustainable for real-time transfers in HD.
The equations for the conversion from YCbCr to RGB are described in the
following table:
Color space conversion Equations
YCbCr-to-RGB (SD) • R = 1.164Y + 1.596Cr - 222.912
• G = 1.164Y - 0.813Cr - 0.391Cb +135.488
• B = 1.164Y + 2.018Cb - 276.928
YCbCr-to-RGB (HD) • R = 1.164Y + 1.793Cr - 248.128
• G = 1.164Y - 0.534Cr - 0.213Cb + 76.992
• B = 1.164Y + 2.115Cb - 289.344