Digital BW, The Print

Luminance (the Y in XYZ) = IF(A6>7.9996248, ((A6+16)/116)^3,(A6*27)/24389)


Where A6 is Lab L*.  Then

Density = -LOG10(Luminance)


> From: Shilesh Jani <shileshjani@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 12 Jan 2006 16:01:28 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Convert LAB to Density Was: QuadTone RIP vs Epson inks
> 
> What is the formula for converting LAB values to density? My puny
> mind is incapable of thinking in "L".
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
>> 
>> I have heard that dye has likely been reintroduced with the K3
> inks,
>> possibly into the resin that encapsulates the pigment.  If I were
> Epson I'd
>> neither confirm nor deny this however and so we are unlikely to
> ever really
>> know for sure.  The MK ink, however, is the same from K2 to K3 and
> so this
>> speculation would not apply to MK.
>> 
>> BTW I have been playing around with the Nanochromes.  Dmax on HPR
> is Lab
>> 10.5, 1.3, -1.6.   The same (black) ink on EPSG has Lab figures of
> 5.3, 1.5,
>> -3.5.  Epson Archival Matte paper has "normal" performance with
> 14.8, 1.4,
>> 0.4.  Of course we know nothing about longevity yet but if
> it's "ok" in that
>> respect then this could make a very nice universal black ink if
> nothing
>> else.  No bronzing at all that I can see so far on EPSG but I have
> a lot
>> more testing to do (I can't see any bronzing in the 918 target and
> the
>> finish to the inks is very nice).  So far I have just been making
> ICC
>> profiles for EAM, HPR and EPSG and also looking at the results of
> printing
>> the QTR Calibration Chart, all on my 2100.  The figures quoted
> above are
>> from the calibration page printed at 100% ink limit and reading
> the 55%, 40%
>> and 80% patches, ie in creating a QTR curve one would likely limit
> K on HPR
>> to at least 55%.  If I recall correctly, this is a lot lower than
> what I
>> used to use with the MIS UCs or Epson Ucs - I guess that would
> save some
>> ink.  LK is quite cool - 100% ink has Lab figures of 28.9, 0.3, -
> 5.7 (55%
>> ink patch has 39.2, 0.2, -5.7).  It's late here and I'll type up
> more of my
>> preliminary work tomorrow and post profiles for those interested
> in gamut.
>> I must say though, a density of 1.92 on HPR looks very nice.
>> 
>> 
>>> From: Paul Roark <paul.roark@v...>
>>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>> Date: Wed, 11 Jan 2006 15:05:42 -0800
>>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>> Subject: RE: [Digital BW] Re: QuadTone RIP vs Epson inks
>>> 
>>>> The Epson matte black has a dye component, ...
>>> 
>>> I don't think this is correct.  Do you have an Epson source for
> this?
>>> 
>>> I've fade tested the UC MK, and it is very good -- right up
> there with
>>> Eboni.  The "hybrid" Epson blacks according to how they react in
> my fade
>>> tests are the Durabrite and "Archival" black inks.
>>> 
>>> Paul
>>> www.PaulRoark.com
>> 
> 
> 
> 
> 
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