Hi guys,

I've been thinking about something regarding perceptual matching and wanted to get your take on it.

We all know the struggle: you calibrate different monitors to the exact same D65 xy coordinates, but they still look visually different due to metamerism. Usually, to fix this, we do a perceptual match to make one monitor match the other.

But this got me thinking. When doing a perceptual match, shouldn't we actually be matching the monitor's white point to a physical light source, rather than just matching it to another monitor? Specifically, I mean visually matching the display to a high-CRI (Color Rendering Index) light fixture or a bias light that accurately emits a 6500K color temperature.

Since the whole point of D65 is to represent natural daylight, doesn't it make more sense that our calibrated monitors should visually match an actual D65 physical light source if we place it right next to them?

The point of perceptually matching a monitor that suffers metameric issues to a monitor that doesn't, and has been correctly calibrated to D65, is that the monitor you are matching to is accurate to D65... so using a light source that is D65 would basically do exactly the same.

Except that any light source will be contaminated by the surroundings it is within, so you would also need a spectrally neutral 18 Percent grey background/wall/room, etc...

Using another monitor that accurately calibrates to D65 is just easier.

Steve

whrldosckaxl
Careful about trying to use 6500K as a reference for perceptual matching instead of the specified D65. D65 is a specific point on the CIE chart, while 6500K is a line ranging from a cyan- to a magenta-tinted gray, and any point on that line is 6500K. Certified D65 light sources are in some cases bordering on lab-grade and are expen$ive. You can buy a photographic light box that comes lined with what should be the proper 18% gray Steve mentioned and equipped with four different light sources for about $400 USD, but I don't think this is what you had in mind.

D65 represents afternoon sunlight, a fixed spectrum, not something like a lightbox or LED tubes.
To simulate D65, your only option is multi-channel LED simulation.