Infinity DMC 1000, User Manual

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DMC 1000 Digital Media Camcorder User’s Guide (v1.15) 77
Chapter 5 - Video setup
5.11.3 Knee
The knee function is used to compress highlights and to give a tonal graduation in the highlight
areas. The pivoting knee circuit adapts both the knee point and the compression ratio
according to the highlight content of the picture to emulate the softly limiting S-shaped transfer
characteristics of film. Digital True Color Knee circuitry maintains the correct hue for
compressed highlights, reproducing colors faithfully, even overexposed skin tones. The knee
parameters are set in the
VIDEO / LEVELS /KNEE
menu. Set knee compression to off, auto or
manual.
The automatic knee mode overrides the manual settings. The higher the signal in, the more
this automatic circuit tries to compress the signal, and compensate for overexposure of the
highlights.
The manual mode allows specific adjustment in the highlight region of the image:
• The point M item adjusts the level (between 70% and 100%) at which the knee circuitry
starts to compress highlights in the manual mode. The higher the number, the higher this
level is.
• The slope M item adjusts the slope of the knee curve in manual mode. Higher numbers
lower the slope giving more detail in highlight information.
A desaturation control defines the point at which the output is colorless in the compressed
highlight areas.
5.11.4 Gamma
To compensate for the non-linear response of display devices, a gamma correction is
introduced into the video signal. The gamma correction adjusts the tonal response of the
characteristic curve. The choices in the
VIDEO / LEVELS /GAMMA
menu are Nominal, Low, and
Pre. This selection determines how mid-range tonal values are reproduced. The camcorder
reproduces more tonal graduations (less picture contrast) in Nom than in Low.
Gamma control:
• Nom position (76) = gamma 0.45 (default)
• Low position (50) = gamma 0.65
• Pre position (0 …100) = lets you adjust the slope manually (M, R, G, B).
– Master gamma adjusts the slope of the characteristic curve using the range 0 to100.
When set to the default, 76, it is equivalent to Nom, a slope of 0.45 and when set to 50
it is equivalent to Low, a slope of 0.65. The adjustable range under master gamma
equates to slopes that range from 0.35 to 1.0.
– Red gamma adjusts the slope of red gamma response curve between 0 and100.
– Green gamma adjusts the slope of green gamma response curve between 0 and 100.
– Blue gamma adjusts the slope of blue gamma response curve between 0 and 100.
Changing the slopes of the individual color gamma curves alters the purity of white in the mid-
range tonal values.