User Manual

Working with Color Spaces in HD Projects
55
Newer HD technologies can display detailed images with sharp changes in color. Because some
color data is missing, YCbCr media does not take full advantage of HD display hardware. The
limited color information available in YCbCr also means that the results of effects processing are
not as good as they could be with RGB media.
Understanding the RGB Color Space
RGB produces higher quality images and effects, but takes up more space.
RGB separates images into their constituting colors: red (R), green (G), and blue (B) and does
not discard any of the chrominance data. As a result, video images look sharper, particularly
those with fast motion or abrupt changes in color. Newer HD formats support RGB only.
Because no color data is lost, your Avid editing application can make more precise calculations
when processing effects using RGB media. The quality improvement over YCbCr processing is
most noticeable in effects that perform color analysis, such as chroma keyers. Even if the
original video data is in YCbCr, your should consider converting to RGB to process effects as
precisely as possible.
The disadvantage of RGB is file size. Media that uses RGB takes up more disk space than media
that uses YCbCr, and more bandwidth is required to play it. Some systems might not be able to
handle playback of RGB material smoothly, particularly when you use the J-K-L keys to play at
greater than normal speed or to play in reverse.
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RGB media requires high bandwidth. For effective playback of multiple streams of video at
higher resolutions, you should distribute the video tracks as evenly as possible among available
drives, and target separate drives for audio and video.
Choosing a Color Space for Your Project
Your choice of a color space depends on both your input/output hardware and your desired
output. For information on how to define the color space for a project, see “Changing the Project
Color Space for an HD Project” on page 57.
If your hardware supports both RGB and YCbCr, choose the color space that corresponds to your
output needs.
If your hardware supports only YCbCr, you can choose RGB for your project color space to
maintain maximum quality throughout your workflow. Your Avid editing application converts
your material to YCbCr right before sending it to the hardware for monitoring or output.
The project color space specifies how your Avid editing application processes effects in real
time. Your Avid editing application supports native processing of effects in either the RGB or
YCbCr color spaces. For example, this means that RGB media does not need to be converted to
YCbCr for processing, maintaining maximum video quality until the final output.