Francisco Cribari <[email protected]> writes:

> After I calibrated my monitor I noticed that my B&W photos had a
> slight brownish tint.

In addition to what others already said ...

You shouldn't take your monitor calibration as an 100%-correct absolute
reference. First, no colorimeter is perfect. I had to send my ColorHug
back for a refund because it was producing an unusably red display for
me (I mean, unusable not just for image processing, really, really
read). It works fine for other people.

Then, one difficulty is to decide what "white" means. For a sheet of
paper, "white" means "reflects all colors equally". Actually, this means
that a white paper is as white as the light it receives, but the same
paper have totaly different color inside with artificial lighting and
outside for example. But your eyes have automatic white-balance and see
the paper as more or less the same color anyway. For a screen, it's
different because the screen emits its own light, so "reflects all
colors equally" means nothing. It's tempting to think that white means
"same amount of light for every color", but then you have to define what
"same amount of light" means (same number of photons, same power, with
our without taking into account the eye's sensitivity which is not the
same for all colors). So, you (and your calibration system) have to
decide arbitrarily what "white" means. Usually, people take 6500K which
means "same color as black body at temperature 6500k" (modulo some more
complicated details I never understood ^^). Anything considered "black
and white" (or more generally neutral grey) by your computer will
displayed as close as possible to this arbitrary color.

I have a monitor in front of a white wall. The white of the wall is the
one of my room's lighting (artificial or sunlight depending on the
time), and the white of my monitor is the one of my computer. One white
is rarely the same as the other.

So, if you're not happy with how neutral greys are displayed by your
computer, then you should not change the colors, but the way they are
rendered (calibration hardware or parameters), or the way you see them
(e.g. the lighting in your computer's room can influence your eye's
"auto white balance" and change your subjective perception of colors).

-- 
Matthieu Moy
http://www-verimag.imag.fr/~moy/

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