Digital BW, The Print

> From: koloshor [mailto:wiz@...]
>
> It's a three band narrow band densitometer. It shines a white
> light, and has three photodiodes with narrow band red, green, and
> bleu filters. When you measure how much red light is reflected,
> you now know the "density" of the cyan (red absorbing) ink or dye
> in a print. Similarly, the amount of green reflected tells you
> the density of magenta (green absorbing) dye, and the amount of
> blue reflected tells you the density of yellow (blue absorbing)
> dye. So it measures (and reports) the densities of the three
> subtractive primaries: cyan, magenta, and yellow.
>
> They're very useful for checking colors when the colors are
> produced by cyan, magenta, and yellow dyes or inks, such as a
> color photograph, a CMKY printing press, or a CMYK printer. The
> narrowband filters cause substantial color errors whenever the
> printing process doesn't use CMY dyes.

Isn't that normally called a "colorimeter" because it reads color? I suppose
we're haggling over terminology here, but I've always been told that a
densitometer measures a one-dimensional quantity, a colorimeter measures a
three-dimensional quantity, and a spectrophotometer measures the entire
visible spectrum in (typically) 10nm slices.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...