RLE Compression - Pocket PC 2002 SDK
LEADTOOLS offers more
compression options than any other Pocket PC 2002 toolkit
on the market. LEADTOOLS supports industry standard and
proprietary alternative compression algorithms including:
RLE / PackBits
RLE is an acronym for Run Length Encoding.
Images frequently contain the same character repeated many
times in a row. For example, text files use multiple spaces
to separate sentences, indent paragraphs, format tables
& charts, etc. Images can also have runs of the same
pixel color. A perfect example of this would be a document
image; the white background would create very long runs
in certain areas of the image.
A flavor of RLE compression used in TIFF files is PackBits. PackBits
uses a control byte to indicate how the next byte or run
of bytes to be used. The high bit in the control byte indicates
if the following byte or bytes should be a run or as they
are. The lower 7 bits indicate the count of bytes that follow
are effected by the control byte. For example, if you have
an image with the following values 2,3,2,4,4,4,4,4: The
output after being compressed would look something like
this: 2,2,3,2,-4, 4. (The control bytes are
bold.)
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PC 2002 Main Page
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704-332-5532 | sales@leadtools.com
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