Re: [SAGE] Color identifiers and products like Nagios ...

[Brad Knowles <brad@stop.mail-abuse.org>]

At 8:05 AM -0800 2005-11-30, Richard Chycoski wrote:

>  When using red and green for status displays, consider the rather
>  large portion of the male (and a *very* small number of the female - it
>  takes two broken genes in XX chromosomed humans :-) population who are
>  red-green colour blind

	Yup, this is a big issue that most people don't consider.

>  BTW, The human eye has the least resolution discerning red, it does
>  much better at the blue end of the spectrum.

	Not so much in the blue, but definitely a lot in the green.

>                                                That's why the NTSC (Never
>  The Same Colour) television standard is biased to give more resolution at
>  the blue end of the spectrum.

	I can't speak for NTSC, but I can tell you that most digital 
cameras use an "RGBG" pattern to their CMOS and CCD imaging chips, 
because humans are most sensitive to green, so they capture twice as 
much green information as any other color.

>                                 And as for standing out - that shocking
>  lime green colour that you see on some firetrucks is supposed to be the
>  colour that stands out best, at least in outdoor situations. Try looking
>  at a red-on-black terminal window, then switch to blue-on-black. The
>  latter should appear sharper.

	Blue on black usually hurts the eyes, but light blue on navy blue 
usually works okay.  But sensitivity to the green spectrum is why the 
early generation night vision goggles used green as their display 
color, and is why most CRT terminals used a "green screen" display.

	However, you've also got to consider how your eyes act in low 
light.  Red doesn't destroy your light sensitivity, if you've been in 
low light situations for an extended period of time.  This is why red 
is the color of flashlights used by pilots when flying at night.


	Then there are issues like color vibration.  A bright blue on a 
bright red (or bright red on bright blue) will really hurt your eyes 
unless you are totally colorblind, and there's just nothing you can 
do about that.  Light from extreme ends of the color spectrum, and in 
close proximity, will do that to you.

	This is why I've never understood why certain sub-brands of VW 
cars will use bright red in close proximity to bright blue on their 
dashboard displays at night.

-- 
Brad Knowles, <brad@stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.