Re: Monitor White Point Confusion
Re: Monitor White Point Confusion
- Subject: Re: Monitor White Point Confusion
- From: Refik Telhan <email@hidden>
- Date: Thu, 07 Mar 2019 10:04:45 +0300
- Thread-topic: Monitor White Point Confusion
Dear Lou,
The practical approach suggested by Graeme seems to be the only way out today.
On page 30 of the Fogra Softproof Handbook version 1 (ENG), that has been
suggested by Claas, it says:
“A color temperature (CCT) in the range between 5000 to 6000 K might be
optimal. Many users prefer values between 5300 and 5800 K.”
On the same page, this handbook also suggests testing different monitor white
settings to find the best match between the simulated paper white on the screen
and the real print stock.
The above paragraph goes on the say:
“The calibration to a target white point which differs from 5000K is not wrong,
but takes into account that the eyes perception of a self-luminous monitor
might be perceived somewhat different to an illuminated unprinted substrate
having an own coloration. This is due to the partly unknown „mechanics“ of
chromatic adaptation. A tolerance measured of +/- 100 K is often not critical
for the white point.”
There is a version 2 of this handbook which has only been released in German.
The Google translation of the same section says:
“The calibration to a different white point than the 5000 K generally used in
the ICC color management is not necessarily to be regarded as "wrong", but may
be necessary to achieve a visually optimized match between a lit template (e.g.
the proof print) and the self-luminous monitor. The reasons for the
sometimes-different color perception of a lit paper and its reproduction on a
monitor are not yet completely researched.”
One other complication with soft proofing is that not only it is monitor
brand/type-dependent, but it is also viewer-dependent. With a given desktop
viewing box and a monitor combination, the white point that gives the best
match depends on who is viewing. When you look at each monitor’s spectral
emission curves, you start seeing that they have vastly different backlights
and RGB band-pass filters. The widths and the peak wavelengths of the band-pass
filters are different for each monitor. Given the that absorbance curves of the
SML cone pigments for each individual is slightly different (the standard
viewer is just an average), it is not surprising that we perceive monitors
differently. A through testing is a must to find the best match for each
lightbox, monitor and viewer combination.
Best regards,
Refik
On 07.03.2019 00:05, "colorsync-users on behalf of Louis Dina"
<colorsync-users-bounces+rtelhan=email@hidden on behalf of
email@hidden> wrote:
Graeme and Claas,
Thanks for the additional information on soft proofing, monitor profiling
and achieving a better monitor to print match. I learned a lot during this
discussion and it plugged some gaps and misunderstandings in my
knowledge. Good information to know!!
Thanks again.
Lou
It's worse than that though. AFAIK, Photoshop, ICC and the desktop
> conspire against using display profiles in Absolute Colorimetric intent,
> AKA soft proofing side by side mode.
>
> 1) As I understand it, Photoshop's proofing mode only uses a
> pseudo-absolute
> mode. The print profile is set to Absolute colorimetric while the display
> profile is left in Relative Colorimetric. So this gives you an
> impression of the white shift due to the paper color, but adapted to
> the white point of the display. It isn't actually attempting
> an absolute colorimetric match.
>
> 2) ICC V4 disables display profile Absolute Colorimetric intent by
> mandating the white point tag be set to D50. So a standard CMM
> won't render the display output with the absolute intent,
> ruining any attempt at an absolute colorimetric match.
>
> 3) Even ignoring 1) and 2), if your desktop and application have
> their own GUI elements showing, they will be rendered relative
> to the native display white point, and so will upset your adaptation
> state, and make the proofing output appear too yellow.
>
> So given all these problems, the only practical approach is
> to calibrate the display so that it has a white point that
> matches the paper white. That way a Relative Colorimetric
> rendering will work for a soft proof side by side comparison.
>
> Cheers,
> Graeme Gill.
>
> ------------------------------
>
> The reason for this is that most instruments which are usually used are
> simply inaccurate in measuring CCT.
> Using an accurate instrument an adjustment of the monitor WP to the same
> CCT as your viewing cabinet gives a visual match.
> But these instruments are out of budget of a normal end user.
>
> >
> >
> > So given all these problems, the only practical approach is
> > to calibrate the display so that it has a white point that
> > matches the paper white. That way a Relative Colorimetric
> > rendering will work for a soft proof side by side comparison.
>
> Using Photoshop I agree.
> There are dedicated softproofing applications around where the absolute
> approach works though.
>
> Best regards
>
> Claas
>
>
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