Plato's Cave: Information Compression
Information Compression
Consider a digital image consisting of a lighter square (pixel value
1) on a dark background (pixel value 0). The most direct
representation of this image in computer memory is as an exhaustive
list of the raw pixel values, as shown below.
The fact that this image has multiple repeated values offers an
opportunity for information compression. For example the same image
can be compressed using a run-length encoding, for example 8(0) to
represent a string of eight zero pixels.
Repetition in this compressed image offers the possibility of further
compression, for example 2(8(0)) to represent two strings of eight
zero pixels.
The symmetry in the original image allows for even further compression
by defining "+" to represent four-fold symmetry, which means that only
the upper-left quarter of the image need be encoded.
The point is that any kind of regularity or redundancy in the
original image offers an opportunity for information compression.
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