Re: BasICColor and "vcgt" tag
Re: BasICColor and "vcgt" tag
- Subject: Re: BasICColor and "vcgt" tag
- From: Bob Burnett <email@hidden>
- Date: Thu, 19 May 2005 13:50:10 -0700
The Eizo CG21 display has simulated gain controls that enable the
setting of the maximum brightness of the red, green and blue channels.
In addition, it has a single 10 bit lookup table that will allow you to
apply a luminance correction across the tonal range which is used to
achieve the correct gamma. Because there is only one lut table in the
display there is no color correction being applied in the grays.
The Color Navigator software doesn't worry so much about the color of
the grays. It is making the assumption that the monitor's color is
linear from white to black so all that is needed is a single correction
for white and the rest of the tonal range will simply fall into line.
BasICColor does not make that assumption. It calibrates the color
temperature for white and applies a luminance correction just like the
Color Navigator software does. But then it keeps going and iterates on
a series of grayscale points to fine tune the color temperature and
luminance all along the tonal range. Now, since the CG21 only has a
single lut curve color corrections have to be applied through the vcgt
tag in the graphics card. If you look at that vcgt tag I bet it is
basically straight with very minor tweaks here and there. These minor
tweaks are so small you won't have any of the banding issues you might
get if you did the entire color correction in the vcgt tag.
Eizo's new CG210 and CG220 displays are a bit more advanced than the
CG21 in that they have three internal luts to apply luminance and
grayscale corrections to. If you calibrate one of these three lut
displays with basICColor the grayscale tuning does get applied within
the display luts and so the vcgt tag will remain perfectly straight.
Hope this helps clear up the differences.
Bob
On May 19, 2005, at 12:03 PM, email@hidden
wrote:
------------------------------
I don't know if what I am saying makes any sense,
but from what I understood so far about calibrating/profiling LCD
monitors such as Eizo CG 21,
the best thing a calibrating/profiling soft can do is to make all the
necessary adjustment in the monitor video card through DDC/CI since
it's got more bit depth than the apple video card does
Correct?
My question is:
I created two profiles for my Eizo through an Eye-One spectrophotometer
First Profile with Color Navigator 3.0.1 - D50 Gamma 2.2 -
90 Cd/m2
Second Profile with BasICColor 3.0.4 - D50 Gamma 2.2 - 90 Cd/m2
The profile created with ColorNavigator has a "vcgt" tag (apple
display card table) with the RGB channels set at gamma 1.0, minimum 0
maximum 1 - a straight line - therefore I assume the values of the LUT
in the computer video card have not been touched
The profile created with BasICColor 3.0 has a "vcgt" tag which is not
straight for the 3 RGB channels,
each channel has it's individual curve/correction,
for example, blu has a minimum value of 0,001 and maximum of 0,984
Am I wrong to assume that therefore BasICColor has changed somehow the
values in the computer video card's LUT?
Carlo
---
[This E-mail scanned for viruses by Declude Virus]
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden