Texas Instruments TVP5147M1PFP manual Luminance Processing, Color Transient Improvement

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. A peaking filter (edge enhancer) amplifies high-frequency components of the luminance signal. Figure 2−9 shows the characteristics of the peaking filter at four different gain settings that are user-programmable via the I2C interface.

			Gain
IN	Peak	Bandpass	⋅	Peaking
	Detector	Filter		Filter
				Delay	+	OUT

Figure 2−8. Luminance Edge-Enhancer Peaking Block Diagram

	7					Peak at
	6					f = 2.64 MHz
						Gain = 2
	5
− dB	4					Gain = 1
Amplitude	3					Gain = 0.5
	2
	1
	0
	−1					Gain = 0
	0	1	2	3	4	5	6	7
			f − Frequency − MHz

Figure 2−9. Peaking Filter Response,

NTSC/PAL ITU-R BT.601 Sampling

2.2.4 Color Transient Improvement

Color transient improvement (CTI) enhances horizontal color transients. The color difference signal transition points are maintained, but the edges are enhanced for signals which have bandwidth-limited color components.

14 TVP5147M1PFP SLES140A—March 2007