Digital BW, The Print

> From: Steve Kale [mailto:stevekale@...]
>
> I was just trying to figure out how to do that with my Eye One.
> The problem
> is you don't want to take an illuminated reading just a luminance reading.
> I can't figure out how to get my Eye One to take a spot luminance reading.

I'm assuming you have the Eye-One Pro spectro. You should be able to use the
ambient light measurement tool in the Eye-One Share program as a light
meter. Since Paul wants you to measure the combination of the light emitted
from the screen and the light reflected by the screen, I think it will be
necessary to leave the diffuser off, and point the opening at the black and
white areas of the screen from sufficient distance not to block the source
of reflections. In other words, use it as a spot meter, rather than an
incident light meter. This should work fine, because the Eye-One has a nice
narrow acceptance angle.

> Someone out there must be able to convert 0.4cd/m2 into a density figure.
> That's my black point.

Density is just a base ten logarithm of the reflectance. The only reasonable
way to convert a monitor's brightness range to a density figure is to divide
the white luminance by the black luminance and take the logarithm. If you
actually get a 400:1 range, that would correspond to a density of 2.6. If
reflections reduce that to, say, 100:1, that would be like a density of 2.0.

Of course, reflections don't just reduce the apparent density of the blacks,
they distract by reflecting actual unrelated images of things. So a
measurement that shows that the monitor with your shirt reflected off it has
a black luminance of 2.7cd/m^2 doesn't mean that it has the same subjective
effect as a monitor that actually has a 100:1 contrast range in a pitch
black room.

--

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