Re: Display Gamma: Factory vs calibration vs working space
Re: Display Gamma: Factory vs calibration vs working space
- Subject: Re: Display Gamma: Factory vs calibration vs working space
- From: Graeme Gill <email@hidden>
- Date: Wed, 17 Nov 2004 12:36:03 -0800
amadou diallo wrote:
The Eizo LCD is factory adjusted for 0-255 steps in a 2.2 gamma. I've
calibrated the monitor to a 2.2 gamma (6500k and 95cd/m). When creating
b/w gradients in both RGB and grayscale modes, PS working spaces with
2.2 gammas display with absolutely no banding. Work spaces with gammas
of 1.8 and 2.0 (custom) both show slight banding towards the shadow end.
AGP card is nvidia geForce4 MX. My understanding has been that hardware
gamma, calibration gamma and Ps wk space gamma do not have a direct
relationshiop and certainly don't need to be identical. What exactly is
the relationship between these 3 values? And why, with a 10bit LUT would
working space gamma changes introduce banding?
Isn't the 10 bits on the output of the display lookup table ?
If you have the display set to be 2.2, and the working space set
to 1.8, then isn't photoshop going to convert the 1.8 gamma data into
2.2 for the display in 8 bit (the depth of the pixmap), introducing
banding ?
What happens if you switch to 16 bit pixmaps in photoshop ?
[Beware also that very few standard systems are a pure gamma exponent curve
either. Most (like sRGB etc.) have a straight line segment at the
black end that makes a big difference between the exponent of the
curve segment, and the effective gamma.]
Graeme Gill.
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