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Digital Processing of Analog Television Lior Zimet EE392J Final Project Winter 2002. 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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Digital Processing of Analog TelevisionLior ZimetEE392J Final Project Winter 2002
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
System Block Diagram Display
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 =( (Ycenter+Ccenter) + (YupperCupper)) / 2 C = ((Ycenter+Ccenter) (YupperCupper)) / 2
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
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
Y/C Separation Example
De-interlacing • Merge fields or interpolate in the pixel domain • Use motion detector to decide
Decoded Frame from “Cheer Leader”
Motion Detection • Apply small motion and large motion detection using adjacent fields Small Motion Large Motion