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Unit 34 Park House Watford Business Park Greenhill Crescent Watford Herts GB WD18 8PH
Reg. No. 2855535 Telephone: +44 (0) 1923 256 000 Fax: +44 (0) 1923 256 100 email: [email protected]
Figure 4-4 - YUV Legaliser Structure
4.2.4
Comp + RGB mode
The video signal is legalised as described in 4.2.1 above and then the legalised
signal is passed through a second legaliser and legalised as in 4.2.2 above.
4.2.5
Clip & Knee
Many of the legaliser functions present Clip and Knee parameters to the user.
The Clip parameters specify the maximum and minimum values the system
legaliser will allow to pass. Figure 4-5 shows an illegal input to the clipper with
detail in the illegal highlight and lowlight areas of the signal. When the knee
values are set to the same value as their respective Clips the legaliser operates
as a hard-clipper as shown in Figure 4-6 show shows the now legal signal but the
detail in the highlights and lowlights has been lost. Figure 4-7 shows the same
input signal legalised with a 10% difference between the Clips and their
respective Knees. The highlight/lowlight detail has been compressed into the
legal region at the expense of some of the dynamic range of the originally legal
part of the waveform.
