STV3550 datasheet(35/144 Pages) STMICROELECTRONICS

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STV3550

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This function is used to reduce the global contrast on an over-contrasted sequence or to reveal

details in the dark and bright areas. The Black and White Shrink function acts in the opposite

manner of the Grey Stretch function.

3.3.7

Spectral Processing

3.3.7.1 Adaptive Peaking

The luminance bandwidth must be improved when processing decoded composite signals and

especially when a notch filter from the external digital video decoder is used. Luminance is

improved in the STV3550 by adaptive peaking which increases the signal amplitude of a high-

frequency spectrum.

This improves the outline of objects in a picture and increases the sharpness of the image.

Peaking effect is auto-adaptive and depends on image brightness.

In addition to the typical horizontal peaking, a vertical peaking mode can be selected in which

vertical luminance components are used in the peaking algorithm. In this mode, vertical edges are

also amplified. In this case, the vertical sharpness is much more sensitive to input noise and should

be disabled.

3.3.7.2 Coring

If certain noisy sources are input (RF broadcast or VCR, for example), noise may be present in the

signal. To prevent peaking due to noise amplification, certain coring thresholds must be used to

suppress any increase of small-amplitude high-frequency signals (noise). The coring effect is

programmable from 0 to 16 LSB.

Figure 24: Black and White Shrink Diagram

STV3550 数据表(PDF) 35 Page - STMicroelectronics