Image
Compression. This is more detail that is needed for the class. Look
at the parts that you find interesting.
JPG,
GIF & PNG notes Very interesting and easy to read. Please read.
JPEG
simple overview
How BMPs
work
Byte order
of data
Data Compression:
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Remove Repetition such as in RLE
(Run Length Encoding). This is a lossless compression scheme.
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Averaging. This is lossy.
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Range Reduction. Using less bits. Lossy as well.
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Selective Compression
BMP - Bitmaps
GIF (Lossless) - Graphics Interchange Format
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Flat, limited colors, good for cartoon and illustrations
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Not good for real world images, or images of more than 256
colors.
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87
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89a
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Can be Interlaced
PNG - Portable Network Graphics
JPG (Lossy) - Joint Photographics Experts Group
The human eye is less sensitive to saturation changes.
Example
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24 bit color.
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Photographs and images of mixed color patterns. Not good for
cartoons or text.
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Averaging a pixel grid, say 8x8 for example. Find the average
color for the grid and then store the differences for the pixels.
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Basically it tricks the eye by using less information for the
image in hopes the user can not tell. Less quality, means a poor image.
Higher quality, less compression, the user sees a good scene.
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Can be Progressive or baseline (top to bottom)