COMPRESSION

The file size of signals, images and videos are growing rapidly. Voice and music are recorded with high fidelity, images and videos are acquired with high resolution and large bit depths. Consequently, transmission and storage of this multimedia poses significant challenges. State-of-the art compression technologies pose viable solutions to these problems by substantially reducing the amount of bandwidth for transmission and memory for storage of such signals, images and video.

• Compression Technologies for Signals and Images
  • JPEG, LJPEG, JPEG-LS, JPEG 2000 technologies
  • Lossy and lossless compression
  • Scalable compression
  • Arithmetic coding (including MQ-coding)
  • Huffman coding (static and adaptive codes)
  • Lemple-Ziv Welch (LZW)
  • Wavelet-based (and other transform-based) codecs
  • Prediction-based coders
  • Bit plane coding

• Lossy Compression Artifacts for Images
  • Evaluation of compression ratios as a function of perceptual artifacts
  • Image degradation metrics - perceptual and nonperceptual

• Video Compression Techniques
  • H.264, H.263, H.263+, MPEG4, MPEG-2, MPEG-1, MP3, AAC
  • Chroma sub-sampling and color space conversion
  • De-interlacing and frame rate conversion
  • Motion compensation, motion estimation and quantization

Wavelet-based compression (coefficient thresholding). Left: original image, Right: wavelet compressed (lossy) image (retains 99% of original image's energy).

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