Re: Monitor White Point Confusion
Re: Monitor White Point Confusion
- Subject: Re: Monitor White Point Confusion
- From: Louis Dina <email@hidden>
- Date: Tue, 05 Mar 2019 10:17:37 -0600
Thanks to everyone for your responses about monitor calibration. They all
helped.
Refik...
The first paragraph of your response helped me clear up my confusion (I
think!). I guess I always thought of Lab colors as absolute. So, when I saw
100/0/0 Lab, to me that meant dead neutral. But, thinking about it more, I
realize that was probably my biggest confusion. An Adobe RGB image with a
pure white patch reads 255/255/255 RGB and 100/0/0 Lab in the Info Palette,
and within that color space, it is dead neutral. But that will only
"appear" dead neutral on my monitor if it is calibrated so white displays
as dead neutral. If calibrated to 7500K, 255/255/255 and 100/0/0 will
display as bluish white, and if calibrated to 5000K, the same 255/255/255
and 100/0/0 will appear warm white. Checking Paper White uses the monitor's
current white point as its baseline.
I thought all profiles (monitor, print, working spaces) included white
point information and I figured all conversions would take this into
account. Somehow, I figured the CMM would see a 6500K monitor as being a
cool white and normalize it to dead neutral during soft proofing (when
Paper white is checked), then show the paper color relative to dead
neutral. Apparently, that is not the case, which is clear from my
experimentation.
So, at least on my system, my viewing lights, my custom printer profiles,
and most of my printing papers, I find that a monitor WP of about
5800K, +/- 200K, gives me a good monitor soft proof to print match (with
Paper white checked). There's probably a reason why our CMM can't correct
for the monitor white point when soft proofing. It seems to be it would be
nice to calibrate to 6500K for the internet, and be able to see accurate
soft proofs on screen by comparing white points in all the profiles in the
chain. Then, 6500K would work for all papers. But, maybe not.
At any rate, I now know that any correction for Paper White is relative to
the calibrated WP of the monitor.
Thanks,
Lou
On Mon, Mar 4, 2019 at 3:12 PM Refik Telhan <email@hidden> wrote:
> Hi Lou,
>
> The answer to your question:
>
> "But, when you soft proof, with the Paper White box checked, shouldn't the
> soft proof look the same on a 5000K and a 6500K MONITOR?"
>
> No, they will not look the same, The paper white simulation is "relative
> to your monitor white point". EIZO ColorNavigator or X-Rite's i1Profiler's
> monitor profiling modules offer validation against CMYK standards. At the
> end of the validation, the measured value of paper white for FOGRA39
> verification can be reported to be very close to 95,0, -2. But do not let
> this measurement mislead you. This is only true "relative" to the monitor
> white (native or any other monitor white that you have picked) which now
> serves as the 100, 0, 0 reference. You can set the white point of
> calibration to any temperature in the 5000 to 6500 K range and after every
> calibration/profiling round the validation may tell you that Patch # 63
> (paper white) of UGRA/FOGRA Media Wedge v3 is measuring within a
> deltaE(2000) less than 1 against 95, 0, -2. But in absolute terms the
> simulated color on the screen is different every time. In the verification
> module of DisplayCAL, you can switch "Simulate whitepoint" and "Relative to
> display profile whitepoint" on or off to measure the actual color of the
> monitor white.
>
> Soft proofing heavily relies on the adaptive capability of the eye. Just
> try to find the color temperature that is right for you using a proper
> light box and the print substrate that you frequently use. And this pick
> will only work for your eyes. Recently, I have calibrated a monitor at 100
> K increments in the 4800 to 6500 K range. Next to it was a desktop viewer
> with fresh lamps illuminating a sheet of FOGRA39 compatible print stock.
> The whole screen was simulating FOGRA39 paper white in Photoshop. Going
> through the profiles one after the other, my colleagues have asked 6
> different people which color temperature gave them the best match. No two
> picked the same temperature. As the monitors create the illusion of white
> by using 3 narrow band emissions at blue, green and red regions of the
> visible spectrum. One monitor, as a light source, may have a CRI value of
> 37 (3 very narrow band emission) and the other may have a CRI value of 93
> with no gaps in the spectral emission curve. In fact, I repeated the test
> with this high CRI monitor and more people agreed on the color temperature
> that gave the best match. Monitors are very different from each other, you
> may find very different display panels in monitors of a certain brand.
>
> Best regards,
>
>
> --------------------------------------------------------
> Refik Telhan, EE B.Sc.
>
> Light and Color Management Consultancy
>
> Aydogdu Sokak 12A, Tarabya Mahallesi
> Sariyer, 34457, Istanbul, Turkey
>
> Mobile: + (90) (532) 426 21 87
> --------------------------------------------------------
>
>
> On 04.03.2019 19:40, "colorsync-users on behalf of Louis Dina"
> <colorsync-users-bounces+rtelhan=email@hidden on behalf of
> email@hidden> wrote:
>
> I have some confusion on the selection of white point when calibrating
> my
> monitors.
>
> I have always used Native White Point and had good results with my Dell
> Adobe RGB LCD monitor. A good monitor to print match is important to
> me.
> The Native WP on this monitor is around 5700-5800K, which works well
> with
> the somewhat neutral to warm papers I print on.
>
> I know that an image displayed in Photoshop without an active soft
> proof
> will be mapped to monitor white . So, a monitor calibrated to 6500K
> will
> display cooler than a monitor calibrated to 5000K.
>
> But, when you soft proof, with the Paper White box checked, shouldn't
> the
> soft proof look the same on a 5000K and a 6500K MONITOR? As I
> understand
> it, two "conversions" occur. The first conversion is from the document
> working space to the printer profile. Then a second conversion occurs
> from
> the printer profile numbers to the monitor using RC rendering. If
> neither
> Black Ink or Paper White boxes are checked, the simulation on screen
> ignores paper color and weak blacks. But, if Paper White is checked,
> shouldn't the paper color and reduced dynamic range appear the same on
> monitors that are calibrated differently. That doesn't seem to be my
> experience. I'm assuming that the monitor profiles accurately
> characterize
> the current calibration of each monitor.
>
> I'd prefer to calibrate to 6500K, but I find my prints always come out
> too
> yellow because I am adding more yellow to my image on screen to
> compensate
> for the cooler display. When printed, the warmth of most of my papers
> results in skin tones that are too yellow.
>
> What am I missing?
>
> Thanks, Lou
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> colorsync-users mailing list (email@hidden)
> Help/Unsubscribe/Update your Subscription:
>
>
> This email sent to email@hidden
>
>
>
>
_______________________________________________
Do not post admin requests to the list. They will be ignored.
colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden