Hi Roger, Just measure the spectral response of these two monitors that you have set to be at the same chromaticity and luminance, you will see that the Blue, Green and Red band-pass filters used in their panels are very different in terms of width and position on the wavelength axis. In a study I made few years back, I have tested two physically identical desktop viewers equipped with fresh 60 cm T8 tubes from two different manufacturers and two displays. And have tried to get the two displays to match each other as well as an unprinted FOGRA39-certifed proofing stock placed in the desktop viewers. To get them visually close to each other and to the real samples, I had to set them to different white points. I have to point out that the fresh T8 tubes from the two manufacturers that were advertised to be ISO 3664:2009 compliant, gave visibly/considerably different results. Getting things aligned has not been easy or complete. And things got even harder when I called in other people to find their best match. When I tried to test the visual match with a total of 6 people, they all disagreed. I have then let each of them to find their best match by calibrating/profiling each monitor to a different white point; all came up with different results. But there was a marked difference between the two monitors. While people set Monitor A to quite different white points to achieve their best match, the white point picked for Monitor B have been very close to each other. While Monitor A had a pinkish cast at all of the white point settings, Monitor B had a neutral white appearance. Below are the spectral power distribution curves for the two monitors. Their white points were both set to 5400ºK during calibration/profiling process. Monitor A https://www.dropbox.com/s/51p73dmypuuetcu/Monitor%20A%205400K.png?dl=0 Monitor B https://www.dropbox.com/s/2ng8bmp576k3xg7/Monitor%20B%205400K.png?dl=0 When you have narrow-non-overlapping RGB filters (and when the Red filters is closer to the right end of the visible spectrum) the disagreement between the observers grow. Monitor B, with its wide-overlapping filters, is behaving like a light box on which you can view transparencies. As I have made the measurements in “Ambient” mode in a dark room from a distance of about 30 cm, you will also see the CRI values, (as well as the slightly shifted CCTs): Monitor A - CRI: 37 Monitor B - CRI: 93 I have made similar measurements on displays from different manufacturers. They all have quite different SPD curves. The narrower the band pass filters, the greater becomes the disagreement between the observers. If the Red filter peaks at somewhere around 650 nm, what most people observe is a pinkish cast in the white point and light grays. Most monitor profiling software packages also have a built-in verify module. Most of those which can do CMYK simulation, do it “relative to display profile white point” and the verifier says OK, even if you calibrate/profile your monitor to a range of CCTs, say between 5200 to 5800ºK. Florian Hoech’s DisplayCAL 3 lets you to switch this off. You can then see where your monitor is actually sitting. https://www.dropbox.com/s/kbaeij6z1w73578/DisplayCAL%203%20Verify.png?dl=0 Apparently, in the world of soft-proofing/monitor proofing everything seems to be “relative”. Best regards, Refik Telhan Light and Color Management Consultancy -------------------------------- On 05.02.2020 20:21, "colorsync-users on behalf of Roger Breton via colorsync-users" <colorsync-users-bounces+rtelhan=icloud.com@lists.apple.com on behalf of colorsync-users@lists.apple.com> wrote: I managed to pull my old CG-21 of the moth balls, to serve as a second display - how could have I ever lived without this convenience? Crazy. Of course, first thing I did was to try to make it "look" like my NEC PA271W. They're both LCD monitors yet, at the same chromaticity and Luminance, they don't look the "same". One is "reddish" (CG-21) while the other (NEC) is "greenish". Any suggestions? / Roger _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/rtelhan%40icloud.com This email sent to rtelhan@icloud.com