RE: How to translate log density readings to percent?

Thanks for the long post Etienne,

Shortly, you're saying that the formulas I used in my first message (to
form the sample table) are correct (that was my original question -
thanks for the confirmation). In the other hand, I understand that both
you and Dave say that I shouldn't map dmax to 100% (and the remainder
values accordingly). BUT, I don't aim for 50% "absolute" density in the
print that was exposed under 50% negative - I aim for 50% "relative"
density (relative to the dmax figure of the emulsion/paper combo). Is
that so wrong? (I guess there's a point that I'm not able to grasp...)

Thanks,
Loris.

> -----Original Message-----
> From: Etienne Garbaux [mailto:photographeur@softhome.net]
> Sent: Wednesday, September 08, 2004 2:24 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: How to translate log density readings to percent?
>
>
> My apologies if this appears twice -- it is AWOL since this morning.
>
> The task is to map a logarithmic scale to a linear scale.
> First, note that the log scale is ratiometric and the percent
> scale is absolute. Therefore, there is no finite log value
> for 100%. Zero transmission (100% density) would be
> represented as log (1/0), or log density infinity.
> ...
Received on Wed Sep 8 04:52:32 2004