The trouble is that no one, including Unitrade, ever defines the ambient light when they classify colors. Anyone who has ever walked into the sunshine only to realize that they have mismatched socks or a tie they thought was a different color see the importance that ambient light plays in perceiving colors. If you go to a paint store, ask them how often folks return paint because it did not 'look the same' as the paint chip did in the store. Or next time you go into the grocery store, note how they use lighting in the produce section. They use lighting wave lengths to make certain fruit and veggies colors to 'pop'; these are proven to increase sales. http://www.promolux.com/english/retail_produce.php
So taking gettinold's image, we can emulate the wave lengths to see how the color would change based upon different ambient lighting.
And while ambient lighting is also a factor when viewing color on a monitor, the monitors and video card drivers play a bigger role. For example, Windows 10 and Macs can change the screen 'temperature' on a schedule. Looking at a digital screen before going to bed can interfere with your ability to fall asleep, so the operating systems can remove much of the display's blue wave lengths after XXPM. So if I view the stamp in this thread before 8PM on my monitor, it appears a different color then after 8:01PM.https://support.microsoft.com/en-us...r-night-time
Edit: The ambient lighting used with camera images should always be understood to affect the image colors. But even scanner images can be impacted. Scanners are calibrated from the factory with the lids closed, typically with a white scanner lid. But when you leave the scanner lid open, ambient light affects how the colors are reproduced in the image. Here is the same post office form scanned with the lid closed and the lid open.
Which one is closest to the 'real' color? Frankly I can match to either one if I change the ambient lighting I am viewing it under. So when catalog publishers define and classify colors, what are their ambient lighting conditions?