Digital Processing of Analog Television Lior Zimet EE392J Final Project Winter 2002
Mar 19, 2016
Digital Processing of Analog Television
Lior 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
CompositeVideo
DCRestoration
and AGCADC
10 bit SyncDetection
and ActiveVideo
Extraction
Resampler4XFsc
Y+C Y+CY/C
Separation+Motion
Detection
Y
C
ColorDe-
modulation
De-Interlacer
Motion
YUVto
RGBDisplay
RGB Y, U, VFields
Hardware Software
Y, U, VFrames
System Block Diagram
Display
ONE LINE OF NTSC SIGNAL
HSYNC
COLOR BURST
ACTIVE VIDEO
SYNC LEVEL
BLANK LEVEL
PEAK WHITE
SIGNAL PEAK
NTSC – 1D Analog Signal
0.0 1.0 2.0 3.0 4.03.58
Amplitude
Frequency(MHz)
ChrominanceSub-carrier
Y UV
UV
F
Y U,V Y YU,V
15.734 KHz
29.97 HzSpacing
Composite Video Spectrum
Y+U
Y-U
Y+U
Y-V
Y+V
Y-V
Y-U
Y+U
Y-U
Y+V
Y-V
Y+V
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)) / 2C = ((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
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Field n-2 Field n-1 Field n Field n+1 Field n+2
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
"CHEER LEADER" WITH 3D COMB AND NO MOTION DETECTION
MOTION ARTIFACTS
Motion Artifacts Example
Notch Filter
3D CombFilter
Vertical 1DSeperator
Y
C
Vertical andHorizontal
Edge Detectorfor 2D
AdaptiveComb Filter
Y
C
MotionDetector
for 3DAdaptive
Comb filter
Y
C
Y
C
Y
C
Y+C
Y/C Separation – 3D Adaptive Comb Filter
NOTCH FILTER Y/C SEPERATION
CROSS-LUMINANCE
CROSS-CHROMINANCE
2D ADAPTIVE COMB FILTER Y/C SEPERATION
HANGING DOTS ARTIFACT
3D adaptive Y/C separation
Y/C Separation
Example
COLOR BURST INFORMATION
HORIZONTAL SYNC
PHASE
BACK PORCH
tVtUChroma cossin
Color Information
ChrominanceFrom Y/CSeparator
2cos(2 F sc t)
2sin(2 F sc t)
LPF
LPF
V
U
tVtUUttVtU 2sin2cossin2cossin
tUtVVttVtU 2sin2coscos2cossin
Color Demodulation
tcos2
tsin2
Motion?
InterpolateWithin theSame Field
Merge WithNeighbor
Field
No
Yes
ProgressiveYUV
InterlaceYUV
De-interlacing• Merge fields or interpolate in the pixel domain• Use motion detector to decide
SNELL & WILCOX WITH ADAPTIVE 3D COMB FILTER
SNELL & WILCOX WITH NOTCH FILTER SNELL & WILCOX 2D ADAPTIVE COMB FILTER
Snell & Wilcox Pattern
Sequence from “Cheer Leader”
"CHEER LEADER" WITH 3D ADAPTIVE COMB FILTER
Decoded Frame from “Cheer Leader”
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Field n-2 Field n-1 Field n Field n+1 Field n+2
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Y-C
Y+C
Field n-2 Field n-1 Field n Field n+1 Field n+2
Motion Detection• Apply small motion and large motion detection
using adjacent fields
Small Motion Large Motion