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Hi both of you,
RGB numbers are pure abstract values, they are not
connected to any physical devices initially. Lets say the RGB space is a cube
and as I said it is an imaginary cube, your system, video card and it's
default configuration have de facto assign RGB value (255,255,255) to the
"white" of the screen whichever it's actual physical value (D50,D65,...). This
sets a single point of our cube but not the size of each side which still need
to be define. I assume your calibration device does exactly that and it must
read the value you mention below for the "black point" and since this "black
point" is on the diagonal of the cube, setting the black point also sets the
size of each side. Why not RGB (0,0,0), basically it's simple, your monitor
can't display a darker physical value then that but darker values may be
printable or used. Having the true and mesured "black point" allow you to
use darker values then that in the file and while you can't see it, it
handle by one of the function of Color Management to take care
of non-displayable value in some fashion (defined in the
profile). This also allow for darker value to be used in the file and while
you wont see them on your screen, they may be printable or not but they are
perfectly "legal" values to use.
You can find quite a lot of info on the net on
color science and color management, I find Norman Koren site to be excellent on
this topic (monitor calibration) and a lot more.
Hope this helps,
Yves
----- Original Message -----
Sent: Saturday, July 26, 2008 2:34
PM
Subject: Re: calibrating monitor
Jusdado,
That is odd that the CMYK values would shift after calibrating your
monitor. Calibrating your monitor doesn't change the values of the step
tablet. The RGB values remained correct though. I only use the RGB
values, not CMYK. I think you will be fine.
On Jul 26, 2008, at 3:35:25 AM, Jusdado <jusdado@teleline.es>
wrote:
Hello
to all:
Before calibrate
my monitor with "Eye-One Display 2", the values RGB and
CMYK measured in Photoshop for
the Step Tablet 101 PDN were:
White Pure: RGB=255; C=0%,
M=0%, Y=0%, K=0%
Black
Pure: RGB = 0; C=100%, M=100%, Y=100%, K=100%.
After calibrate the monitor
with "Eye-One Display 2", the values RGB and
CMYK measured in Photoshop for
Step Tablet 101 PDN are:
White Pure: RGB=255; C=0%,
M=0%, Y=0%, K=0%.
Black
Pure: RGB = 0; C=95%, M=83%, Y=82%, K=90%
Questions:
1. - that has happened?
2. - can I consider black pure
the current values?.
3. -
will I have to adjust another time my curves?.
Thank you and pardon for my
English, text translates for computer.
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