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[filmscanners] Re: opinions? Reviews? of Primefilm 1800 ?



Laurie writes:

> That is nice; is this also true when one works
> in color as opposed to grayscale or black and white?

Usually, if the number of bits for each color is the same.  Note, however,
that in so-called high color, each pixel requires 16 bits: 5 for red, 5 for
blue, and 6 for green.  The number of gray levels for high color, then, is
only 32, as this is the highest number of bits available for each primary
color (if you try to use odd values for the green levels, the gray scale
won't be truly gray, but will cycle from gray to pale violet to pale green,
etc.).

> Would I be wrong to generalize this and say
> "bits equal potentially available tonal levels
> per pixel" in which the tone can be any
> hue or color?

No, this is correct.

> However, the question in issue, I believe,
> was not the meaning of "bits" but if "bit depth"
> was intended to be a measure of "dynamic range" or of
> "density range, of the "contrast range" from
> white point limit to black point limit or of
> the ability to discriminate between shades
> or tones within that contrast range ...

Bit depth determines the number of discrete tones available, not the dynamic
or density range.  If the tonal scale is linear, then the dynamic range of
n-bit representation is log2(n); if it is non-linear, just about any range
can be represented.  However, the greater the range represented, the greater
the difference between levels, and at some point posterization occurs, when
the jump from one level to another becomes readily visible to the eye.



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