Digital Signal Processing Reference
In-Depth Information
Images are sampled spatially, in vertical and horizontal
directions. In video sampling, we add the time, or temporal
dimension, where the sampling rate is equal to the frame rate.
Intensity and hues (YCrCb) or colors (RGB) are also sampled
separately and sometimes at different resolutions.
There remains one last issue related to sampling, which is
quantization, which is concerned with how many bits are used to
represent each sample. For video processing we need to have
a sufficient number of bits to represent the color and intensity
differences that our eyes are capable of discerning. The most
common is to use 10 bits per sample, which results in 2
10
or 1024
different levels per sample. Other common sample resolutions
are 8- and 12-bits, giving 256 or 4096 levels respectively. These
10
12 bit resolutions are normally sufficient for video. Where
quantization becomes important is in video compression, which
will be covered in subsequent chapters.
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