Re: again on color absorption

[Katharine Thayer <kthayer@pacifier.com>]

Ah, that makes more sense  than the explanation for a one-time only  
appearance of this phenomenom in gum (on an HSL array) which was  
advanced on the hybridphoto site, and which has been advanced on this  
list from time to time, that the tonal inversion is a function of  
underexposure, or because the "negative" had too long a density range  
for the process.  Both those explanations were easily refuted; this  
one has some merit in your case, especially if it happens every  
time.  Mine, as I said, happened only once in many printings of the  
same HSL array with the same light source and correct exposure  
time,   so this explanation wouldn't work for what happened in my  
case any better than the other ones did.

Katharine



On May 12, 2009, at 2:09 AM, Alberto Novo wrote:

> > Katharine, IIRC, the portion below the dashed line (pure color)  
> > would be
> > less colored ink(s) + more black ink (due to less lightness/ 
> > brightness -
> > depending which test pattern is used) as you progress more to bottom.
> Now I am undestanding...
>
> > So,
> > my understanding of Alberto's test would be that black ink isn't  
> > as opaque
> > to the specific light which that specific process requires as some  
> > other
> > colored inks, that's why there's reintroduction of tone. This is  
> > something
> > I experienced with Epson 890/1290 OEM dye-based inks and HP9180
> > pigment-based inks.
> You are right, the mixing of colour with black decreases the amount  
> of both. The absorption of pure black is in the last row, which is  
> a little denser (absorbing less) than pure green.
> Alberto