Luma Contrast And Brightness; Black Level Expander/Compressor (Blec); Luma Sharpness Enhancer (Lse); Dynamic Peaking - Daewoo DTF-2950-100D Service Manual

CP-850FX Service Manual

5.4.2.3 Luma Contrast and Brightness

The luminance signal is multiplied by a factor of 0...2 (contrast adjustment). The signal can be
shifted by ±100% of its maximal amplitude with the digital brightness value

5.4.2.4 Black Level Expander/Compressor (BLEC)

The black level expander/compressor modifies the luminance signal with an adjustable non-
linear function to enhance the contrast of the picture.
Dark areas are stretched to black, while bright areas remain unchanged. Advantageously, this
black level processing is performed dynamically and only if it will be most noticeable to the
viewer.

5.4.2.5 Luma Sharpness Enhancer (LSE)

Sharpness is one of the most critical features for optimum picture quality. This important
processing is performed in the LSE circuitry of DDP 3315C. It consists of the dynamic peaking,
the luma transient improvement (LTI) and an adaptive mixer. The luma input signal is processed
in the peaking and LTI block in parallel. Both output signals are combined in the mixer depending
on the selected LSE characteristic.

5.4.2.6 Dynamic Peaking

The dynamic peaking improves the details of a picture by contour emphasis. It adapts to the
amplitude and the frequency of the input signal. Small detail amplitudes are sharpened, while
large detail amplitudes stay nearly unmodified.

5.4.2.7 Luma Transient Improvement (LTI)

For small detail amplitudes the dynamic peaking is the most appropriate processing to improve
the sharpness. However, for large amplitudes even small over-and/ or undershoots of the
peaking are too annoying. The luma transient improvement enhances the slope of picture detail
without these effects by a non-linear processing. The contour correction signal calculated in this
block, is limited to the adjacent extreme values to prevent over- and undershoots. The LTI
features an adjustable gain control and an adjustable coring threshold to prevent the
enhancement of small noise amplitudes.

5.4.2.8 Mixing of Dynamic Peaking and LTI

The contour correction signals of the dynamic peaking and the LTI block are combined by the
mixer. Controlled by the amplitude of a picture edge, this circuitry fades between these two
signals. Thus, small and medium picture detail is enhanced by contour emphasis (peaking) and
large picture detail is enhanced by step-improvement (LTI).

5.4.2.9 Chroma Transient Improvement

The intention of this block is to enhance the chroma resolution. A correction signal is calculated
by differentiation of the colour difference signals. The differentiation can be selected according to
the signal bandwidth, e.g. for PAL/NTSC/SECAM or digital component signals, respectively. The
amplitude of the correction signal is adjustable. Small noise amplitudes in the correction signal
are suppressed by an adjustable coring circuit. To eliminate "wrong colours", which are caused
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