Apple

Am 19.05.2005 um 21:04 schrieb Carlo Lavatori:

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?

You are absolutely right.

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?

You are right again.

basICColor display uses a unique technique in calibrating monitors. If you have a "hardware-calibratable" monitor like the EIZO CG21, display will first measure the tonal response curve, calculate a correction curve and load it into the monitor. Then display measures the corrected values again and iterates until the deltaE values are as small as possible.

In the case of the CG21, display can only do a tonal response correction, not a gray balance in the hardware of the monitor, since the CG21 has only 1 LUT for all three channels, R,G and B. The successor, CG210, has 3 LUTs.

If display detects only one LUT, it corrects the gray balance on the graphics card, in addition to the tonal response calibration in the monitor. If it detects 3 LUTs in the monitor, you will see a straight line in the vcgt and thus in your video card.

So, it´s not a bug, it´s a feature! basICColor display generates the most accurate calibration possible.

Best regards,

Karl Koch