Datasheet

Functional Description
15
SLES099C—March 2007 TVP5147PFP
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 2−12 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. A peaking filter (edge enhancer) amplifies high-frequency
components of the luminance signal. Figure 2−13, Figure 2−14, and Figure 2−15 show the characteristics of
the peaking filter at four different gain settings that are user-programmable via the I
2
C interface.
Bandpass
Filter
×
Gain
Peaking
Filter
IN
+
OUT
Delay
Peak
Detector
Figure 2−12. Luminance Edge-Enhancer Peaking Block Diagram
f − Frequency − MHz
−1
0
1
2
3
4
5
6
7
01234567
Gain = 0
Gain = 2
Gain = 1
Gain = 0.5
Peak at
f = 2.40 MHz
Amplitude − dB
f − Frequency − MHz
−1
0
1
2
3
4
5
6
7
01234567
Gain = 0
Gain = 2
Gain = 1
Gain = 0.5
Peak at
f = 2.64 MHz
Amplitude − dB
Figure 2−13. Peaking Filter Response, NTSC
Square Pixel Sampling
Figure 2−14. Peaking Filter Response,
NTSC/PAL ITU-R BT.601 Sampling