Image and Video Compression
Communication Systems
EECE 453
Hassan Mansour
Image Compression
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Most popular techniques:
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Color subsampling
Transform Coding (JPEG, JPEG2000,…)
Fractal Coding
Available Compression standards:
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JPEG, JPEG2000, JPEG-LS, JBIG, JBIG2 (ISO)
GIF, PNG, TIFF, BMP, WMP,…
JPEG compression
DCT(x-128)
Zig-Zag Scan
JPEG
file
Entropy Coding
Quantization
JPEG quality per compression ratio
Original
Compressed to 6%
Compressed to 12%
Compressed to 2%
Video Compression (MPEG)
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Started with MPEG-1/H.261 (1991, video CD)
MPEG-2 was launched in 1994 and became
the standard for DVDs.
Finally, MPEG-4 was introduced in 1998.
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MPEG-4 ISO is based on H.263
MPEG-4/AVC is the new H.264 standard used in
HD-DVD and Blu-ray Disc.
Both MPEG-4 ISO and H.264/AVC are used for
mobile video.
Basic Compression Algorithm
Picture N
Picture N+1
Difference
-Encode picture N as JPEG
-Perform Motion Estimation/Compensation on picture N+1 using picture N
-Encode the difference as JPEG
Motion Estimation /
Compensation
:
Decoding example
Residual
Signal
MotionCompensated
+
Decoded
Signal
Video Compression Reference
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http://mia.ece.uic.edu/~papers/WWW/Mul
timediaStandards/chapter7.pdf