Digital Processing of Analog Television

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Digital Processing of Analog Television Lior
ZimetEE392J Final Project Winter 2002
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Project Goals

• Digitize an analog NTSC signal and decode it in
  software
• Use digital processing to perform
• Luminance and Chrominance separation
• Color demodulation
• Interlace to progressive conversion

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System Block Diagram
Display
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NTSC 1D Analog Signal
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Composite Video Spectrum
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Y/C Separation 1D Comb Filter

• Resampling at 4xFsc will take advantage of the
  alternate phase in the color modulation
• Y/C separation can be done within the field

Y ( (YcenterCcenter) (Yupper?Cupper)) / 2 C
((YcenterCcenter) ? (Yupper?Cupper)) / 2
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Y/C Separation 2D Adaptive Comb Filter

• 1D comb filter works perfectly only for
  vertically orientated structures in a picture
• 2D adaptive comb filter
• Weighs the upper line and lower line combing
  according to horizontal edge detection
• Uses notch filter in cases where 1D fails

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Y/C Separation 3D Comb Filter

• In still image, pixels are identical from frame
  to frame
• The Chrominance phase is alternating
• Must be disabled when motion is present

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Motion Artifacts Example
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Y/C Separation 3D Adaptive Comb Filter
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Y/C Separation Example
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Color Information
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Color Demodulation

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De-interlacing

• Merge fields or interpolate in the pixel domain
• Use motion detector to decide

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Snell Wilcox Pattern
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Sequence from Cheer Leader
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Decoded Frame from Cheer Leader
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Motion Detection

• Apply small motion and large motion detection
  using adjacent fields

Small Motion
Large Motion