Hi Peter, There have been several attempts made by the scientific community to quantify observer metameric mismatch during the past couple of decades. Finally IEC (International Electrotechnical Commission) has published the technical specification on 2023-11-01 as “IEC TS 61966-13:2023”. (https://webstore.iec.ch/en/publication/67769) -------------------------- IEC Technical Specification 61966-13 IEC TS 61966-13:2023 Multimedia systems and equipment - Colour measurement and management - Part 13: Measurement method of display colour properties depending on observers IEC TS 61966-13:2023 defines an objective colour difference metric and a measurement method for observer metamerism caused by displays with different spectral power distributions. This document also specifies the measuring equipment, conditions and methods that are necessary to obtain the metric. This document applies to light-emitting or backlit transmitting colour displays measured under dark-room conditions. -------------------------- You can read more on the topic in a recent issue of the ID magazine published by The Society for Information Display (Volume 40, Issue 1, https://sid.onlinelibrary.wiley.com/toc/2637496x/2024/40/1) The above technical specification is mentioned in the article “Measuring Subjective Differences Objectively” by Johan Bergquist in the same issue. https://sid.onlinelibrary.wiley.com/doi/10.1002/msid.1453 Johan Bergquist happens to be one of the members of the technical committee that developed the specification. https://www.iec.ch/dyn/www/f?p=103:14:510370051608773::::FSP_ORG_ID,FSP_LANG... The January/February 2024 issue of the ID Magazine is dedicated to “Understanding Wide Color Gamut Displays”. At this point in time, I am not aware of the presence of any measurement device that is capable of measuring/reporting the OMMI (Observer Metameric Mismatch Index) out of the box. “If they were all looking at the same objects in a viewing booth, what sort of magnitude of potential colour differences would they be seeing?” Viewing real product samples, inkjet contract proofs or real prints in a viewing booth is somewhat a different ball game. Observer metameric mismatch is related with the interaction of the individual CMFs of the observers and the spiky nature of the SPDs of the pigments in the product/inkjet inks and printing inks. We just have to assume that the viewing booth has a full spectrum very high CRI light. Hence the visual mismatch between what the observers is seeing will be related to the spectral structures of the pigments. Visual mismatch takes place when the narrow band peaks of the incoming light hits the CMFs of different individual observers at different points. Best regards, - Refik PS. I have sent this message originally on 28 July 2024. However, the iCloud mailing system only sent the notification today that message has not been delivered. Hope it will reach its destination this time. -----Original Message----- From: Peter Miles via colorsync-users <colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>> Reply-To: Peter Miles <P.Miles@massey.ac.nz <mailto:P.Miles@massey.ac.nz>> Date: 22 July 2024 Monday 09:07 To: ColorSync <colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>> Subject: Re: Why 2 degree observer measurements for ICC profiles? Thanks Graeme, and everyone for your responses. A lot of food for thought. Refik I had a looked at the “Individual Colorimetric Observer Model” paper, however I don’t have a training in color science to fully grasp the significance of what I am reading. Is there a way of qualifying what sort of size colour differences these observer variations are causing in the normally sighted population? If they were all looking at the same objects in a viewing booth, what sort of magnitude of potential colour differences would they be seeing? FYI: A few years ago I had a lens replaced in one of my eyes and so I now have two quite different ‘observers’ when it comes to assessing colour. Thanks Peter Miles From: Graeme Gill via colorsync-users <colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>> Date: Friday, 19 July 2024 at 8:49 PM To: ColorSync <colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>> Subject: Re: Why 2 degree observer measurements for ICC profiles? Peter Miles via colorsync-users wrote:
So why do ICC profiles, for print production, still use 2degree observer measurements instead of 10 degree observer measurements?
A standard often has a momentum of its own. But in the case of color in media that is looked at in detail (such as images), 2 degree is appropriate. AFAIK, one of the reasons that the 10 degree observer is often recommended is that it was created with more observers and in a more refined way, and is technically a bit more accurate. In subsequent experience it has often turned out that the 10 degree standard matches people more accurately than the earlier 2 degree observer, even though it is not the appropriate viewing angle. Note that there are many subsequent more refined standards or proposed standards such as the 2012 2 and 10 degree observers. These are not in widespread use though, whereas every graphic arts instrument will return 1931 2 degree values. And of course there is nothing to stop you making ICC profiles using any observer you like :-) They may not be technically interchangeable with profiles using the 1931 2 degree observer, but that matters less in practice, and not at all if all the profiles you use the same observer. Cheers, Graeme Gill. _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/rtelhan%40icloud.com <https://lists.apple.com/mailman/options/colorsync-users/rtelhan%40icloud.com> This email sent to rtelhan@icloud.com <mailto:rtelhan@icloud.com>