Image and Video Compression ICS 280 Visual Perception Image and Video Slide 2 ICS 280 Visual Perception 1 Formats RGB is not used for transmission of signals between capture and display devices Too expensive needs too much bandwidth Converted to luminance and chrominance formats Use standard YIQ or YUV format Slide 3 ICS 280 Visual Perception Compression Basics Simple compression Interpolation based techniques Transforms Statistical techniques Slide 4 ICS 280 Visual Perception 2 Compression Techniques How many bits we need How much frequency do we need Deals with perceptible color resolution Has to do with difference threshold Deals with perceptible frequency Both spatial and temporal How much can we perceive Slide 5 ICS 280 Visual Perception Compression Issues Bandwidth requirements of resulting stream Image quality Compression decompression speed Latency Cost Symmetry Robustness Bits per pixel bpp Tolerance of errors and loss Application requirements Slide 6 Live video Stored video ICS 280 Visual Perception 3 Bit Reduction Slide 7 ICS 280 Visual Perception Color Look Up Table Statistical Slide 8 ICS 280 Visual Perception 4 Run Length Encoding Statistical Slide 9 ICS 280 Visual Perception Interpolative Compression Acquire chrominance at lower resolution Humans have lower chrominance acquity Sub sample by a factor of four in horizontal and vertical direction Slide 10 ICS 280 Visual Perception 5 Interpolative Compression Acquire chrominance at lower resolution Humans have lower chrominance acquity Sub sample by a factor of four in horizontal and vertical direction Slide 11 ICS 280 Visual Perception Reconstruction Using bilinear interpolation Gives excellent results Slide 12 ICS 280 Visual Perception 6 Significant Compression Slide 13 ICS 280 Visual Perception Slide 14 ICS 280 Visual Perception 7 Slide 15 ICS 280 Visual Perception Slide 16 ICS 280 Visual Perception 8 Slide 17 ICS 280 Visual Perception Slide 18 ICS 280 Visual Perception 9 Slide 19 ICS 280 Visual Perception Slide 20 ICS 280 Visual Perception 10 Slide 21 ICS 280 Visual Perception Humans are not sensitive to high frequencies Slide 22 ICS 280 Visual Perception 11 DC Coefficients DPCM Slide 23 ICS 280 Visual Perception Slide 24 ICS 280 Visual Perception 12 Slide 25 ICS 280 Visual Perception Slide 26 ICS 280 Visual Perception 13 MPEG Video Compression Slide 27 ICS 280 Visual Perception Pipeline Slide 28 ICS 280 Visual Perception 14