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Re: [QuadtoneRIP] Re: QIDF versus ICC

2016-07-31 by Roy Harrington


On Sat, Jul 30, 2016 at 9:06 AM, Le Mois de la Photo à Uqbar info@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:


I have never used the print tool, but thank you for that tip I’ll investigate. Perhaps naively I wasn’t aware of any ICC QTR problems.

Is it possible that windows users did not experience these Epson / Adobe / Apple changes since CS3, or could these changes be unapparent to windows users? I’m still using QTR profiles much as I did in CS3 with seemingly no difference.


The matrix of all the combinations of OS's, OS versions, PS versions, etc etc is too large to
make any clear statement of what happens in a specific case.

Given what you say that the QTR relative table does not include BPC, Is it conceivable that converting to the QTR profiles in an ICC work flow using the relative table would allow printers to use a target adjustment to manually remap DMAX and threshold values? I ask this question because here and elsewhere when I have inquired about QTR with relative rendering, I am simply told the QTR profiles must be used with the perpetual table.


You need to try it. I don't know what you are really trying to accomplish.

I think I‘m starting to get an inkling of the paradigm shift between what we are calling ICC workflow and QTR linearization curves. If my inkling is correct then these curves are meant to be far more than media type (ink level) settings which attempt simply to even out the distribution of ink on various papers. If I understand the discussion here, these curves seem to play a role in translating data to those levels. In which case, they would be replacing colour management on a data to specific paper/printer combination basis, as long as the same source space was always being used.


QTR is a very low level driver. All it does is take Gray values (0-255) that it is fed for each
pixel, it translates that to a specific number of ink drops of each ink based on the .quad
tables which are the QTR curves. Except for the usage of QTR linearization (straight line
graph of gray values vs Lab patches) nothing at this level knows a thing about anything else.

All ICC stuff is a much higher level bunch of code. It's all about translating Lab values in
source files to gray values to be sent to driver. In Windows the QTR level is entirely in
QTRgui so windows issues do not show up at all. On Mac sending data from any printing
app to the driver goes through the system and potentially hidden conversions are being done.

Roy

Is that a fair appraisal?

Eugene


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