quite an extreme wrote:
But for testing it a source of a true spectrum would be required the artifical mix in computers where for violet red becomes added to blue or - depending on the cam - violet is always shown as blue only.
Did test this with a violet laser pointer which is nearly blacklight. Depends a bit of the cam but the cam adds red for the RGB displays so it looks right for most vision people. To me the violet laser looks just deep blue even more then a typical blue where the green receptors become activated more. The smartphone of my son added green to the violet so it did look kind of grey and anything but right. I like to play with blacklight sometimes.