Digital BW, The Print

Robert wrote:

>Paul, are your figures % of dmax?  Or did you correct for the log scale?
>Just trying to figure out how they correspond to mine changes.

I use a scanner to measure the differences, scanning the test strip along
with the control strip.  I then use the Photoshop Histogram tool to measure
luminance and RGB values.  When I look at fading, all I'm doing is taking
the percentage of fade (lightening) of the selected area (for example the
50% patch of the 21-step test file print) relative to the starting
luminance/brightness of the particular patch.

Paul


On 9/12/01 8:53 AM, "Paul Roark" <paul.roark@...> wrote:

> Mike,
>
> You asked:
>
>> Has anyone else measured the actually loss in density of Piezo prints?
>
> I ran a comparison fade test in my florescent light tester with MIS
> (standard quads) and Piezo inks.  Both were on Epson Archival Matte, and
> both were in the fader at the same time, so other possible variables were
> kept to a minimum.  After 300 hours the MIS 50% patch had lost 4.6%
density.
> The Piezo test strip had lost 7.6% in the 50% patch. (The two blacks had
> both faded 15%, but because of the intensity of the light, the black would
> absorb more and heat up more.  So, I think the test conditions exaggerate
> the relative fading of the dark tones.)
>
> For most parameters I'm looking at, by 300 hours in my fader the rate of
> change has slowed considerably.  So, while these prints may never totally
> stabilize, I think at the 300 hour point we can see what the prints will
> look like after the prints have "warmed" completely.
>
> While the Piezo faded 65% more than MIS, neither had really faded that
> dramatically.  I continue to agree with the consensus of south-window
> testers that color shifting is more significant than fading.  I'll send
the
> scans of the test strips and control strips to Martin to put in the files
> section of the forum.  (See Fade-MIS-Pzo-300Hr.jpg)
>
> I would be curious if the scanned images look like what south-window
testers
> see, and how long it takes for south-window prints to take on this color.
>
> EAM is the champ when it comes to fade resistance among the paper I've
> tested.  I don't know what paper was being used below, but the alleged 2
> stop fading in 60 days seems extreme.  I would guess there are some
factors,
> perhaps including display conditions, that we don't know about.
>
> Paul
> http://www.PaulRoark.com
>
> ______________________________________________
>
>
> -----Original Message-----
> From: Michael J. Kravit [mailto:kravit@...]
> Sent: Wednesday, September 12, 2001 5:16 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Piezo - Loss of Density
>
>
> Last eveing I was speaking with another photographer by telepone. He
> told me that in California Huntington Witheral is ready to give up on
> Piezo because his display prints are losing 2 stops of density after
> just 60 days on display.
>
> Supposedly he has spoken with Jon Cone and Cone told him it was his
> paper. So he has tried numerous papers and has not been able to keep
> the prints from losing density (fading).
>
> Has anyone else measured the actualy loss in density of Piezo prints?
>
> MIke