Re: 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=icloud.com@lists.apple.com on behalf of lou@loudina.com> 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 > > _______________________________________________ Do not post admin requests to the list. 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On Mar 7, 2019, at 12:04 AM, Refik Telhan <rtelhan@icloud.com> wrote:
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.
I’d heartily agree that more research is called for, and that many will wish to do their own experimentation to find what they’re most comfortable with. But there’s also an elephant in the room whose general direction you’re pointing at, and we should also be addressing the elephant. Specifically...we have all these high-precision technologies for measuring color — and yet, in the graphic arts industry, the consumers of the products are doing their own evaluations with their own eyes. It has the feeling to me of a T-shirt maker using engineering techniques suited for jet engine manufacture. When you buy a T-shirt, you don’t expect it to be a perfect custom fit. Nor do you expect it to fit the same way after you wash it — and, for that matter, you don’t even expect it to fit the same way after you gorge yourself on a Thanksgiving dinner. You especially don’t expect the same shirt to fit anybody else the same way. Color perception is potentially even more dramatically variable. Go outside on a sunny day. Close both eyes, but cover one (and only one) especially well with your hand or your arm. Point your face at the sun for a minute or three. The closed-but-uncovered eye will have lots of long / red cone fatigue. The closed-and-covered eye will be heading towards dark adaptation. The color perception differences between the two eyes will be very dramatic! Never mind the perennial philosophical pondering of “Is your red the same as my red?” Your own red is never _exactly_ the same any two times in your life — so why should you expect anybody else’s red to ever be exactly the same as yours? This is not, of course, to suggest that we should just throw our hands in the air and give up. It _is,_ however, a suggestion that we should stop measuring with micrometers and instead start marking with chalk. Let’s say your monitor and viewing booth are both perfectly matched, your ambient lighting is a perfect D50 spectral match, walls are all neutral gray, and you’re even wearing a neutral gray body suit... ...so what? Your client is going to be reading your magazine in a doctor’s office with flickering greenish fluorescent tubes with fifteen-year-old ballasts. Your print is going to be hung over the receptionist’s desk, where it’s going to reflect the glare from her $50 Dell monitor — and never mind the fluorescent pink athleisure top she’s wearing today. So...make sure your editing environment is one your clients would be happy to spend some time in. For most, that means a nice office setting without any really glaring colors — and maybe put some effort into getting better-than-average lighting. Calibrate your monitor to a white point roughly (+/- 1000K) the same as ambient (and get a good profile of the monitor). If you can’t make proof prints on the same stock as the final, at least get something with a similar amount of OBA. Use a good ICC-aware color management chain — and always use perceptual rendering unless you know exactly why you want something different. (A good perceptual rendering is going to “bake in” common human visual system quirks better than any of the colorimetric ones; since the final consumer is almost always an human and not a colorimeter, that’s typically what you want.) And then don’t think about color again until you actually have a problem you need to solve. Even then, suspect that your problem is more likely to be with out-of-gamut colors (including poor gamut mapping) than with your display calibration or the like. Instead, focus more on the content and artistry of the work you’re trying to reproduce.... Cheers, b&
"athleisure top” baaaaahahahaaha -- Dan Bergstrom | Color Technology and Quality | PR1MARY COLOR primarycolor.com <http://www.primarycolor.com/> | C 949.616.4986 | T 949.660.7080 On 3/7/19, 9:17 AM, "colorsync-users on behalf of Ben Goren" <colorsync-users-bounces+danbergstrom=primarycolor.com@lists.apple.com on behalf of ben@trumpetpower.com> wrote:
athleisure top
participants (3)
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Ben Goren
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Dan Bergstrom
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Refik Telhan