Re: Monitor White Point Confusion
Re: Monitor White Point Confusion
- Subject: Re: Monitor White Point Confusion
- From: Nagy Péter <email@hidden>
- Date: Thu, 07 Mar 2019 08:33:55 +0100
To Graeme: thanks for the explanation. Now I have a better understanding why
the softproofs in Photoshop rarely have any practical use.
To Claas: Would you mind suggesting us some softproofing applications? The only
one I know about is iColor Proof, which wasn’t even released officially by
Quato, just before they ceased operation.
Kind regards,
Péter
Colorcom
> On 2019. Mar 6., at 21:00, email@hidden wrote:
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> Today's Topics:
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> 1. Re: colorsync-users Digest, Vol 16, Issue 5 (Louis Dina)
> 2. Re: Monitor White Point Confusion (Graeme Gill)
> 3. Re: Monitor White Point Confusion (Claas Bickeböller)
> 4. CFP Open - CIC27 21-25 October 2019 | Paris, France
> (Roberta Morehouse)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 05 Mar 2019 14:15:27 -0600
> From: Louis Dina <email@hidden>
> To: email@hidden
> Subject: Re: colorsync-users Digest, Vol 16, Issue 5
> Message-ID:
> <CAOTaQcJUN=GHgBV+DNPcXbSbF7o3N3BbUxUUOXgSKAr=tw38=email@hidden>
> Content-Type: text/plain; charset=UTF-8
>
> Peter Miles and Peter Nagy,
>
> Thanks, you both confirmed what Refik (thank you) shared and what I have
> just learned. This was always a bit of a muddle to me, but finally it is
> clear. I've been using 5600-5800K monitor WP for years with great soft
> proofing success, and now I know why it works so well, and why 6500K
> doesn't.
>
> Mystery solved! Thanks everyone.
>
> Lou
>
>
>> Message: 3
>> Date: Tue, 05 Mar 2019 04:26:58 +0000
>> From: "Miles, Peter" <email@hidden>
>> To: "email@hidden"
>> <email@hidden>
>> Subject: Re: Monitor White Point Confusion
>> Message-ID: <email@hidden>
>> Content-Type: text/plain; charset=utf-8
>>
>>
>> Hi Lou.
>> I can confirm what Refik is saying from having made on-screen
>> measurements• using an i1pro and Spectrashop a few years back.
>>
>>
>> Regards
>> Peter Miles
>>
>>
>> *A few years back I wanted to clarify in my mind the same question Lou
>> asked.
>> So I measured the on-screen colour of a soft proof in photoshop when the
>> 'simulate paper color’ was on. I compared that to measurements I made of
>> the display white point. I did this on a profiled Eizo at a 3 different
>> white point settings .
>>
>> From the measurements it was clear that the on-screen colour of the
>> soft-proof (with ‘Simulate Paper Color’ on) was different for each display
>> white point used.
>> And from comparing the ab plots in Spectrashop it was also clear that the
>> on-screen colour of the soft-proof (with ‘Simulate Paper Color' on) was
>> being shifted ‘relative' to the white point of the display.
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Tue, 05 Mar 2019 08:46:00 +0100
>> From: Nagy Péter <email@hidden>
>> To: email@hidden
>> Subject: Re: Monitor White Point Confusion
>> Message-ID: <email@hidden>
>> Content-Type: text/plain; charset=utf-8
>>
>> Hi Lou,
>>
>> What you would like to do is IMHO possible in theory, but you have to take
>> into account the capabilities of the math model and the devices you use. If
>> you try to mimic the actual printed piece on your screen (meaning you
>> switch to soft-proof mode in Photoshop) you’re working in the 8-bit realm
>> of the current graphics software and device drivers. If you’re far away
>> from the target (eg. on a screen calibrated to a white point of 6500K) the
>> color management engine has to perform a large correction to achieve the
>> desired result. Measurement and profiling errors add up, and the color you
>> see on screen will not be perfect.
>>
>> On the other hand, your original approach (calibrating to 5700-5800) is
>> almost perfect, as that’s the ‘perceived’ white point of today’s
>> OBA-stuffed coated papers under 5000K lighting. In this case, the color
>> management engine performs a relatively small conversion on the white
>> point, so the errors will be smaller or negligible.
>>
>> Until we don’t have 10 or more bit ‘deep’ device drivers and monitors (and
>> work with 16 bit images in Photoshop), the best you can do is to calibrate
>> to the closest perceived white. Another consideration might be to employ
>> displays which are more conservative on the contrast; we don’t need 1:10000
>> for soft proofing.
>>
>> Kind regards,
>>
>> Peter Nagy
>>
>> ------------------------------
>>
>> **********************************************
>>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 06 Mar 2019 12:53:42 +1100
> From: Graeme Gill <email@hidden>
> To: ColorSync <email@hidden>
> Subject: Re: Monitor White Point Confusion
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=windows-1252
>
> Nagy Péter wrote:
>
> Hi,
>
>> What you would like to do is IMHO possible in theory, but you have to take
>> into account
>> the capabilities of the math model and the devices you use. If you try to
>> mimic the
>> actual printed piece on your screen (meaning you switch to soft-proof mode in
>> Photoshop) you’re working in the 8-bit realm of the current graphics
>> software and
>> device drivers.
>
> 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.
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 06 Mar 2019 07:44:22 +0100
> From: Claas Bickeböller <email@hidden>
> To: ColorSync <email@hidden>
> Subject: Re: Monitor White Point Confusion
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=utf-8
>
> Hi,
>
> I can recommend to read the Fogra Softproof Handbook
>
> https://www.fogra.org/index.php?menuid=626&reporeid=200&getlang=en
>
> A lot of theory with a lot of practical advise.
>
>> Am 06.03.2019 um 02:53 schrieb Graeme Gill <email@hidden>:
>>
>> Nagy Péter wrote:
>
>> On the other hand, your original approach (calibrating to 5700-5800) is
>> almost perfect, as that’s the ‘perceived’ white point of today’s OBA-stuffed
>> coated papers under 5000K lighting.
>
> 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
>
> ------------------------------
>
> Message: 4
> Date: Wed, 06 Mar 2019 19:21:32 +0000
> From: Roberta Morehouse <email@hidden>
> To: "email@hidden"
> <email@hidden>
> Subject: CFP Open - CIC27 21-25 October 2019 | Paris, France
> Message-ID: <5E4BB1820DF48448AD0F4B07705195925FDD9706@us0-sb01>
> Content-Type: text/plain; charset=iso-8859-1
>
> The IS&T Twenty-seventh Color and Imaging Conference (CIC27), 21-25 October
> 2019, is the premier annual technical gathering for scientists,
> technologists, and engineers working in the areas of color science and
> systems, and their application to color imaging. This year, CIC27 is
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> 21-25 October 2019 | Paris, France
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> TOPICS:
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> End of colorsync-users Digest, Vol 16, Issue 6
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