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" <P.Miles@massey.ac.nz> To: "colorsync-users@lists.apple.com" <colorsync-users@lists.apple.com> Subject: Re: Monitor White Point Confusion Message-ID: <53F81896-AC30-4325-8C52-8A9874C4CD95@massey.ac.nz> 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.

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Message: 4 Date: Tue, 05 Mar 2019 08:46:00 +0100 From: Nagy Péter <peter@colorcom.hu> To: colorsync-users@lists.apple.com Subject: Re: Monitor White Point Confusion Message-ID: <72488E8B-6BE0-4DBF-8332-9776FADD134A@colorcom.hu> 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

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