Video_compression_2005 - Lecture notes on Image Compression...

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Lecture notes on Image Compression and Video Compression 7. Video Compression
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#2 Topics z Introduction to Image Compression z Transform Coding z Subband Coding, Filter Banks z Introduction to Wavelet Transform z Wavelet Image Compression z Perceptual Audio Coding z Video Compression
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#3 Contents z Introduction to Video Compression z MPEG 1 Video Compression z Motion Compensation z Video Compression Standards
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#4 Digital Video z A series of frames (i.e. digital images) z Can be sampled z From raster analog scan z Directly with a CCD camera z 3 color components z Usually, color components down- sampled
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#5 Color Down-sampling
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#6 The Need for Compression z Image sequences must be significantly compressed for efficient storage and transmission as well as for efficient data transfer among various components of a video system. z Examples (Motion Picture) z One frame of a Super 35 format motion picture may be digitized (via Telecine equipment) to a 3112 lines by 4096 pixels/color, 10 bits/color image. z As a result, 1 sec. of the movie takes ~1 Gbytes !
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#7 The Need for Compression - Examples z HDTV z A typical progressive scan (non-interlaced) HDTV sequence may have 720 lines and 1280 pixels with 8 bits per luminance and chroma channels. z The data rate corresponding to a frame rate of 60 frames/sec is 720 x 1280 x 3 x 60 = 165 Mbytes/sec!
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#8 Applications of Digital Video Compression z Teleconference or video phone z Very low delay (1/10 second is a standard) z Live Broadcast Video z Modest delay is tolerable (seconds is normal) z Error tolerance is needed. z Video-in-a-can (DVD, Video-on-Demand) z Random access to compressed data is desired z Encoding can take a lot of time z Decoding must always be at least the frame rate.
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#9 Approaches to Video Compression z Intraframe compression treats each frame of an image sequence as a still image. z Intraframe compression, when applied to image sequences, reduces only the spatial redundancies present in an image sequence. z
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Video_compression_2005 - Lecture notes on Image Compression...

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