TVP5146M2PFP_0708 Datasheet, PDF (22/108 Pages) Texas Instruments – NTSC/PAL/SECAM 4X10-Bit Digital Video Decoder With Macrovision Detection, YPbPr/RGB Inputs, 5-Line Comb Filter, and SCART Support

Functional Description
2.2.3 Luminance Processing
The digitized composite video signal passes through either a luminance comb filter or a chroma trap filter,
either of which removes chrominance information from the composite signal to generate a luminance signal.
The luminance signal is then fed into the input of a peaking circuit. Figure 2−8 illustrates the basic functions
of the luminance data path. In the case of S-video, the luminance signal bypasses the comb filter or chroma
trap filter and is fed directly to the circuit. High-frequency components of the luminance signal are enhanced
by a peaking filter (sharpness). Figure 2−9 shows the characteristics of the peaking filter at four different gain
settings that are programmable via the host port.
Gain
IN
Peak
Detector
Bandpass
Filter
x
Peaking
Filter
Delay
+
OUT
Figure 2−8. Luminance Edge-Enhancer Peaking Block Diagram
7
Peak at
f = 2.64 MHz
6
Gain = 2
5
4
Gain = 1
3
Gain = 0.5
2
1
0
Gain = 0
−1
0
1
2
3
4
5
6
7
f – Frequency – MHz
Figure 2−9. Peaking Filter Response,
NTSC/PAL ITU-R BT.601 Sampling
2.2.3.1 Color Transient Improvement
Color transient improvement (CTI) enhances horizontal color transients by delay modulation for both color
difference signals. The operation must be performed only on YCbCr-formatted data. The color difference
signal transition points are maintained, but the edges are enhanced for signals which have bandwidth-limited
color components (for example, CVBS and S-video).
14 TVP5146M2PFP
SLES141B—August 2007