PANAVISION Genesis, User Manual

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Panavision Genesis Manual v1.3
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224
V39
22. 4 Linear CCD versus non-linear Film
For the most part, each pixel of the CCD acts like an analog linear
device – like a light meter. That is, the more light goes in, the more
signal comes out.
On the other hand, the whites ( shoulder) and blacks ( toe) of the
film response curve are non-linear:
- In the white areas this means that, above a certain light level,
adding more light does not increase the density of the negative
much.
- In the dark areas this means that, below a certain light level, dark
tones blend together since a dark value yields roughly the same
density as an even darker value.
Practically speaking, the CCD’s linear response means that you get
shadow details with the Genesis that you don’t get with film, but
you must also be more attentive to over-exposure with Genesis
than you would be with film.
22.5 Analog CCD to 14 bit lin
In the Genesis camera, the analog signal from the CCD’s pixels are
transformed to a digital signal by means of an A to D (Analog to
Digital) Converter which outputs a 14 bit digital signal for Red
Green and Blue. This 14 bit signal is linear (or “lin”): the more light,
the higher the signal.
22.6 14 bit lin = 16 k possible values per pixel
The 14 bit signal defines the latitude, or the number of possible
values for each pixel. In a binary system, 14 bits yields 2 to the
14
th
, or 2x2x2x2x2x2x2x2x2x2x2x2x2x2 = 16 383 possible values
between black and white.