Digital BW, The Print

BTW.....

Recalling my question of the 20th:

"3.  I'd like to understand why linearisation is best done with respect to
L* and not XYZ_Y which is where the scaling is done.  This obviously
requires the first item to be understood.  I would guess it has something to
do with the linearity of L* as a concept and ease of interpolation but then
on that I am just guessing."


.... there ought to be no reason why one couldn't incorporate into a RIP a
"smart linearisation" (for want of a better term) which incorporated a
transform from the unlinearised data to linear data and a transform to bpc
and white point scaled output - all in one hit.  We are just doing this in
two steps with the advantage that we gain a soft proofing tool and, very
importantly, separation from a defined workspace.  (These are not
insignificant advantages.)

The scaled output is a curve but an ICC profile still has to interpolate
such a curve as would the RIP.  I would be interested if there is any
difference in the maths at the end of the day - I suspect not.  I have no
idea how it would complicate the mixing of two curves though.

The ICC approach is dramatically more flexible but a RIP designer without
these skills could reprogram their linearisation function for a defined
workspace and achieve most of the same result.







> From: Steve Kale <stevekale@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Sat, 22 Oct 2005 03:20:14 +0100
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Conversation: [Digital BW] ICC v. Transfer Function in Epson driver
> Subject: Re: [Digital BW] ICC v. Transfer Function in Epson driver
> 
> I believe that the graph in the document "Linear vs ICC L* Output" is a much
> more accurate depiction of the effect of QTR ICC colour management of my QTR
> HPR greyscale curves.
> 
> http://homepage.mac.com/stevekale/stevekale2/FileSharing37.html
> 
> Please correct me if I am wrong!  I read the L* in the Lab info palette for
> each patch given my GG2.2 workspace and plotted this expected number vs the
> actual output of the print.
> 
> 
>> From: Steve Kale <stevekale@...>
>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Date: Sat, 22 Oct 2005 02:50:52 +0100
>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Conversation: [Digital BW] ICC v. Transfer Function in Epson driver
>> Subject: Re: [Digital BW] ICC v. Transfer Function in Epson driver
>> 
>> I agree though that for each colour managed line I should have plotted the
>> L* expected by the colour patch given my workspace against the actual
>> achieved, rather than the "step vs the L*" - I agree the step is no longer
>> valid - and compared this against the linear line of the non colour-managed
>> output.