Re: Two monitors, side by side
Re: Two monitors, side by side
- Subject: Re: Two monitors, side by side
- From: Refik Telhan via colorsync-users <email@hidden>
- Date: Sat, 08 Feb 2020 19:00:38 +0300
- Thread-topic: Two monitors, side by side
Hi Edmund,
EIZO’s CG210 is a robust, stable and uniform monitor with an sRGB gamut. I
still see them in action after about 20 000 or even 25 000 hours of use albeit
at reduced luminance levels, such as 75-80 nits. They are still useful tools.
The gamut of your Samsung T something monitor was most probably also sRGB with
a similar spectral output. This may explain why your setup worked.
With all the different display technologies -QLED, OLED, mini-LED and micro-LED
to name a few- that are competing today, getting things aligned is becoming
harder. You can see how different they can be on Roger N. Clark’s web site:
https://clarkvision.com/articles/color-spaces/
While the Green (peaking at around 450 nm) and Blue (peaking at 530 nm) filters
from different devices appear to be closer to each other [and to the response
of the S (peaking at 430 nm) and M (peaking at 534 nm) cones], the Red (peaking
between 617 - 653 nm) filters vary widely from eacn other [and from the L
(peaking at 564 nm) cone].
Getting monitors with different spectral emissions and gamuts aligned to each
other and to a desktop viewer with an ever-aging T8 tube can become tiring, to
say the least.
Best,
Refik
From: edmund ronald <email@hidden>
Date: 8 February 2020 Saturday 14:16
To: "email@hidden" <email@hidden>
Cc: "'colorsync-users?lists. apple. com' List" <email@hidden>
Subject: Re: Two monitors, side by side
A long time ago I had a Samsung T something and a CG210 - the latter which I
still own.
I used Basicolor Display to measure the CT of one and used that as a basis for
the calibration of the other.
I know it shouldn't have worked, but it worked quite well, both monitors were
perfectly usable for photo retouch. .
I displayed Colorcheckers on both when doing the setup, and had a young lady
help me and we agreed we had quite a good match.
I still occasionally use the CG210 and don't consider it obsolete.
Edmund
On Sat, Feb 8, 2020 at 6:35 AM Refik Telhan via colorsync-users
<email@hidden> wrote:
Hi Roger,
Just measure the spectral response of these two monitors that you have set to
be at the same chromaticity and luminance, you will see that the Blue, Green
and Red band-pass filters used in their panels are very different in terms of
width and position on the wavelength axis.
In a study I made few years back, I have tested two physically identical
desktop viewers equipped with fresh 60 cm T8 tubes from two different
manufacturers and two displays. And have tried to get the two displays to match
each other as well as an unprinted FOGRA39-certifed proofing stock placed in
the desktop viewers. To get them visually close to each other and to the real
samples, I had to set them to different white points. I have to point out that
the fresh T8 tubes from the two manufacturers that were advertised to be ISO
3664:2009 compliant, gave visibly/considerably different results. Getting
things aligned has not been easy or complete. And things got even harder when I
called in other people to find their best match.
When I tried to test the visual match with a total of 6 people, they all
disagreed. I have then let each of them to find their best match by
calibrating/profiling each monitor to a different white point; all came up with
different results. But there was a marked difference between the two monitors.
While people set Monitor A to quite different white points to achieve their
best match, the white point picked for Monitor B have been very close to each
other. While Monitor A had a pinkish cast at all of the white point settings,
Monitor B had a neutral white appearance.
Below are the spectral power distribution curves for the two monitors. Their
white points were both set to 5400ºK during calibration/profiling process.
Monitor A
https://www.dropbox.com/s/51p73dmypuuetcu/Monitor A 5400K.png?dl=0
Monitor B
https://www.dropbox.com/s/2ng8bmp576k3xg7/Monitor B 5400K.png?dl=0
When you have narrow-non-overlapping RGB filters (and when the Red filters is
closer to the right end of the visible spectrum) the disagreement between the
observers grow. Monitor B, with its wide-overlapping filters, is behaving like
a light box on which you can view transparencies.
As I have made the measurements in “Ambient” mode in a dark room from a
distance of about 30 cm, you will also see the CRI values, (as well as the
slightly shifted CCTs):
Monitor A - CRI: 37
Monitor B - CRI: 93
I have made similar measurements on displays from different manufacturers. They
all have quite different SPD curves. The narrower the band pass filters, the
greater becomes the disagreement between the observers. If the Red filter peaks
at somewhere around 650 nm, what most people observe is a pinkish cast in the
white point and light grays.
Most monitor profiling software packages also have a built-in verify module.
Most of those which can do CMYK simulation, do it “relative to display profile
white point” and the verifier says OK, even if you calibrate/profile your
monitor to a range of CCTs, say between 5200 to 5800ºK. Florian Hoech’s
DisplayCAL 3 lets you to switch this off. You can then see where your monitor
is actually sitting.
https://www.dropbox.com/s/kbaeij6z1w73578/DisplayCAL 3 Verify.png?dl=0
Apparently, in the world of soft-proofing/monitor proofing everything seems to
be “relative”.
Best regards,
Refik Telhan
Light and Color Management Consultancy
--------------------------------
On 05.02.2020 20:21, "colorsync-users on behalf of Roger Breton via
colorsync-users" <colorsync-users-bounces+rtelhan=email@hidden on
behalf of email@hidden> wrote:
I managed to pull my old CG-21 of the moth balls, to serve as a second
display - how could have I ever lived without this convenience? Crazy.
Of course, first thing I did was to try to make it "look" like my NEC
PA271W. They're both LCD monitors yet, at the same chromaticity and
Luminance, they don't look the "same". One is "reddish" (CG-21) while the
other (NEC) is "greenish".
Any suggestions?
/ Roger
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