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Re: Why D65 on monitors and D50 on lightbox?
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Re: Why D65 on monitors and D50 on lightbox?



Using the process outlined below, the visual white point calibration only
has to be done once, regardless of how many different stock colors you want
to simulate.

1. In the D50 light box (presumably a GTI SoftView) place a CMYK proof
containing a large area of pure white (0,0,0,0%) and a CMYK gray scale or
test image.

2. IN PS6+ open the exact same CMYK file that made the proof and assign the
profile of that printer to the image. Size it so the screen and proof are
about the same physical size.

3. In 'Views - Proof Setup' select 'Simulate Paper White' (very important.)

4. Now adjust both the SoftView's intensity and your monitor's RGB sliders
until the white paper AND the gray scale image match as closely as possible.
If you're working on a monitor with no RGB sliders, e.g. Apple Cinema
Display, use ProfileCity's ICC Display to manage the white point via the
vLUTs.

The misunderstanding on this list was that the monitor was tweaked to one
paper at a time. This is not true if you use 'Simulate Paper White' when
tweaking white, as you are tweaking a screen image that has already been
'loaded' to simulate the color of your actual test stock. If you subtract
that loading then the screen should theoretically be perfectly neutral, and
when the simulation is 'loaded' again to simulate a different stock your
hardware tweaks should remain valid.

If, after using this process, you still need to tweak the monitor to match
different stocks, then one or more of your printer profiles must have a
white point error in its forward tag or an erroneous white point tag. This
is most often caused by not using a UV filter in the measuring device. The
ideal solution is to identify which printer profile is wrong (assuming only
one is) and correct it in profile editing software.

In fairness to Dan, the demo I did at the GATF conference in Phoenix was
simplified for the sake of time and did not mention the Simulate Paper White
trick, hence the confusion.

Don

*************************************

Don Hutcheson
Hutcheson Consulting
(Color Management Solutions)
Phone: (908) 689 7403
Mobile: (908) 500 0341
email@hidden

*************************************




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