Re: gamma 1.8 or 2.2
Re: gamma 1.8 or 2.2
- Subject: Re: gamma 1.8 or 2.2
- From: Carlo Lavatori <email@hidden>
- Date: Fri, 16 Sep 2005 20:30:41 +0200
On Sep 16, 2005, at 3:45 PM, Maarten van der Spek wrote:
Can someone explain to me which gamma I must choose when calibrating
my monitor. As user of Mac is advised me both 1.8 and 2.2. The monitor
who is calibrated is Quato Intelli Proof 213 (similar with the Eizo
CG210 and in comparing test even something better performing).
Thanks for the explanation.
Maarten van der Spek.
--------------------------
I have been following Andrew's (and other's) advice and I have always
carefully calibrated my Eizo CG21 on a Mac OS X system with an EyeOne
Pro spectro and BasICColor Display at 2.2 Gamma
Until last week I realized that all the certified chromalin I get made
from the High Definition scans I get done at my PrePress service, were
correct only if I calibrated my monitor at 1.8 (as my service does)
otherwise they are always too bright on my monitor (looked at under a
Just Normlicht viewer)
So if I want to have my Eizo very close to what it seems to be the best
proofing system around (Dupont Certified Chromalin), I have to keep my
monitor calibrated at 1.8
plus, being puzzled by the fact, I did a little research and I wonder
if this below means anything, or if it is an old, outdated info:
http://www.siggraph.org/education/materials/HyperGraph/
gamma_correction/gamma_intro.html
System Gamma
The idea of system gamma, is the gamma correction that should be
applied in the software to reproduce an accurate image on the monitor
for an uncorrected image on a particular computer "system."
Macintosh
The Macintosh has built-in gamma correction of 1.4. This means that
after the software sends the signal to the framebuffer, there are
internal hardware corrections which will further process the signal,
specifically by gamma correcting it another 1.4 - That is, the signal
is raised to the 1/1.4. Therefore, to get full correction, the software
itself should first adjust the signal by raising it to the 1/1.8 power.
(2.5/1.4 = 1.8) Thus the system gamma on a Macintosh is 1.8.
PS
Let me add that the files I get from the prepress service are not color
managed, as this is their choice of workflow. (No profiles)
So I have no choice but to keep them that way
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