On 27/04/2017 12:15, Adam Funk wrote:
On 2017-04-26, Dave Plowman (News) wrote:

In article ,
NY wrote:
What is interesting is that even the whitest light, which appears
slightly blue to the eye, shows on a digital camera as being a little
warmer than full sunlight (about 5000K). A "daylight" CFL alongside it
(OK, I was curious so I did a comparison!) looks slightly warmer by eye
but the camera sees it as being cooler than the LED.

This goes to show that the eye is a very poor indicator of colour
temperature, and that it has a lot of auto-adjustment built into the
eye/brain mechanism.

Colour temperature to the eye is subjective. The real problem with many of
this sort of light source is they ain't continuous or smooth over the
visible light spectrum. Which can make colours - like paint - appear a
different colour (or shade) than in daylight, or halogen.

This may not matter much in a domestic living setting, but certainly can
in a workshop, etc. Or even a kitchen.

I saw an interesting science demonstration once where the presenter
had a box painted white on the inside, with three lights of different
colours (RBG, I think) shining into it. He turned down the house
lights & adjusted the brightness of each one until the audience
generally agreed that the inside of the box looked white. Then he put
various fruits & vegetables in the box & they did not look right.


Thats because the eye doesn't see a continuous range of colour.
It only sees the relative levels of colours in three fairly wide bands
and the brain constructs the colours from that information.

Its quite easy to fool the brain about the actual colour and what you
think you see.
There are images where you can move a square of material from one spot
to another and its perceived colour changes.
Add in that the sun is not a black body emitter of light and has some
very strong yellow lines in it and you can see why colour varies so much
from person to person.