Databases Reference
In-Depth Information
represent these values in a lossy manner to within an error in the least significant bit, we need
7 bits per pixel. Figure
11.3
is the histogram of the differences.
1200
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0
0
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F I GU R E 11 . 2
Histogram of the Sinan image.
8000
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0
-100
-50
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F I GU R E 11 . 3
Histogram of pixel-to-pixel differences of the Sinan image.
31 to 31. Therefore, if we are willing
to accept distortion in the least significant bit, for more than 99% of the difference values we
need 5 bits per pixel rather than 7. In fact, if we are willing to have a small percentage of the
differences with a larger error, we could get by with 4 bits for each difference value.
More than 99% of the pixel values lie in the range
−
In both examples, we have shown that the dynamic range of the differences between samples
is substantially less than the dynamic range of the source output. In the following sections we
describe encoding schemes that take advantage of this fact to provide improved compression
performance.
