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-   -   Re: Tweaking monitor calibration (http://www.velocityreviews.com/forums/t745489-re-tweaking-monitor-calibration.html)

nospam 03-21-2011 05:35 PM

Re: Tweaking monitor calibration
 
In article <87k4fsmgww.fld@apaflo.com>, Floyd L. Davidson
<floyd@apaflo.com> wrote:

> isw <isw@witzend.com> wrote:
> >I've been trying to get a good color calibration on my 2006 MacBook's
> >screen; seems to me it was better when it was newer. I think the
> >fluorescent tube may have aged and changed its color. Things way way too
> >blue.
> >
> >Problem is, when the calibrator is invoked, it doesn't start from the
> >previous settings, it starts from scratch, every time. If the color
> >errors are subtle, repeated calibrations don't make it "better" they
> >just wind up "different" -- and still wrong.

>
> I haven't got a clue what kind of software is available
> for calibration of a MacBook, nor what kind of a
> colorimeter you are using.


there is no colorimeter, and if you don't have a clue about what's
available for a mac, why are you even replying?

> I use Argyll software under Linux. It allows
> calibrating to different color temperatures, to
> different brightness levels, and to different gamma
> corrections. There are probably other variations that
> I've forgotten are also possible to use, but those are
> the ones that I have adjust.


that's wonderful. the original poster has a mac, not a linux box.

> If you want to use a web browser that is not color
> managed to view images on the web, your monitor should
> be calibrated to gamma 2.2, a temperature of 6500K, and
> whatever brightness is appropriate for the ambient
> light.


mac browsers are colour managed (as is almost everything on a mac),
including the now obsolete microsoft internet explorer from a decade
ago.

> If you want to view images for printing, a calibration
> using gamma 2.4 or 2.5 and a temperature from 5000K to
> 5800K is probably more appropriate, and the brightness
> should be down to perhaps 90 cd/m2.


gamma should be 2.2 and the white point should be d65 or ideally, the
native white point for the lcd. lower than that is much to warm for
normal purposes, including printing.

> >What I'd like, is a way to tweak the current calibration, similar to how
> >you can tweak a photo in GIMP or Photoshop -- just cut a bit of blue in
> >the highlights, or whatever.
> >
> >Is there any way of doing that? Any tools that make it possible/easy?

>
> Read the manual for the software you use to calibrate
> the monitor with. That shouldn't be hard to do. Color
> temperature is what you want to change.


what he was using is not separate software. it's *part of the system*.

it also doesn't work very well since there's no hardware puck.

nospam 03-21-2011 07:16 PM

Re: Tweaking monitor calibration
 
In article <3rcfo6pjto24r8j52fsua5lrg5fg3pnd76@4ax.com>, Better Info
<binfo@address.info> wrote:

> >gamma should be 2.2 and the white point should be d65 or ideally, the
> >native white point for the lcd. lower than that is much to warm for
> >normal purposes, including printing.

>
> Mac platforms are at gamma 1.7, or used to be.


nope. macs used to be 1.8 and now they're 2.2. most people calibrated
to 2.2 before it was the default (not that it matters that much either
way).

nospam 03-21-2011 11:51 PM

Re: Tweaking monitor calibration
 
In article <877hbsma1t.fld@apaflo.com>, Floyd L. Davidson
<floyd@apaflo.com> wrote:

> >> >I've been trying to get a good color calibration on my 2006 MacBook's
> >> >screen; seems to me it was better when it was newer. I think the
> >> >fluorescent tube may have aged and changed its color. Things way way too
> >> >blue.
> >> >
> >> >Problem is, when the calibrator is invoked, it doesn't start from the
> >> >previous settings, it starts from scratch, every time. If the color
> >> >errors are subtle, repeated calibrations don't make it "better" they
> >> >just wind up "different" -- and still wrong.
> >>
> >> I haven't got a clue what kind of software is available
> >> for calibration of a MacBook, nor what kind of a
> >> colorimeter you are using.

> >
> >there is no colorimeter, and if you don't have a clue about what's
> >available for a mac, why are you even replying?

>
> Because I understand the problem. Which is knowing how
> to properly calibrate the monitor.


i also understand the problem, and unlike you, i am very familiar with
how it's done on a mac and what's available.

> If the OP has no colorimeter, which means no possiblity
> of generating an accurate profile or having a
> "calibrated" monitor, that needs to be made clear.


it was very clear to someone who is familiar with macs.

> >> If you want to use a web browser that is not color
> >> managed to view images on the web, your monitor should
> >> be calibrated to gamma 2.2, a temperature of 6500K, and
> >> whatever brightness is appropriate for the ambient
> >> light.

> >
> >mac browsers are colour managed (as is almost everything on a mac),
> >including the now obsolete microsoft internet explorer from a decade
> >ago.

>
> "as is almost everything" is the key.


the key for what? on a mac, colour management is part of the operating
system, not an afterthought.

> Regardless, the OP does have to have an accurately
> calibrated monitor in order to use color management.


yes, that's true and it's not going to happen by eyeballing it, but he
really just wants his images to not be too blue. i doubt he's doing
colour critical work, or even cares about colour management at all.

> >> If you want to view images for printing, a calibration
> >> using gamma 2.4 or 2.5 and a temperature from 5000K to
> >> 5800K is probably more appropriate, and the brightness
> >> should be down to perhaps 90 cd/m2.

> >
> >gamma should be 2.2 and the white point should be d65 or ideally, the
> >native white point for the lcd. lower than that is much to warm for
> >normal purposes, including printing.

>
> Only if you want to look at images posted to the web.


nope. that's the best setting for a display for both printing and
looking at images.

> >> >What I'd like, is a way to tweak the current calibration, similar to how
> >> >you can tweak a photo in GIMP or Photoshop -- just cut a bit of blue in
> >> >the highlights, or whatever.
> >> >
> >> >Is there any way of doing that? Any tools that make it possible/easy?
> >>
> >> Read the manual for the software you use to calibrate
> >> the monitor with. That shouldn't be hard to do. Color
> >> temperature is what you want to change.

> >
> >what he was using is not separate software. it's *part of the system*.

>
> It's software.


everything is software. there you go trying to weasel out of it. what
he used is part of the operating system itself. there's nothing to
install and there is no manual specifically for it. there's not much to
it either, it's fairly self explanatory, which if you had a clue about
macs (your words), you would know.

> >it also doesn't work very well since there's no hardware puck.

>
> I'd expect that to be true; but the OP did not clarify
> that point,


as i said, it was clear from his description, as anyone who has done it
on a mac would know.

> and therefore my response was generic to
> either with or without the proper hardware and with a
> obvious hint that the proper hardware absolutely is
> necessary.


you said you 'haven't got a clue what kind of software is available for
calibration of a MacBook, nor what kind of a colorimeter you are
using,' so there really isn't much help you can offer, is there?

> Whatever, your post was not helpful, had absolutely no
> value to anyone, and followups that are the same will
> be ignored.


neither was yours.

nospam 03-22-2011 05:46 AM

Re: Tweaking monitor calibration
 
In article <48kgo6ph6kq6grbj9j9bb6le8fs714f480@4ax.com>, Eric Stevens
<eric.stevens@sum.co.nz> wrote:

> >i also understand the problem, and unlike you, i am very familiar with
> >how it's done on a mac and what's available.

>
> You don't seem to know the gamma on a Mac. But He Ho, what does tat
> matter.


i have been doing colour management for over a decade, i know what the
gamma is on a mac and when it changed.

> >yes, that's true and it's not going to happen by eyeballing it, but he
> >really just wants his images to not be too blue. i doubt he's doing
> >colour critical work, or even cares about colour management at all.

>
> Ho No! That's why he posted his query to this new group.


he posted to comp.sys.mac.system (where i first saw it) and
rec.photo.digital.

> Your post is full of misleading bullshit.


specifically, what is bullshit?

nospam 03-22-2011 03:29 PM

Re: Tweaking monitor calibration
 
In article <isw-41660C.09241022032011@[216.168.3.50]>, isw
<isw@witzend.com> wrote:

> > How old is your MacBook?

>
> It's a Core Duo -- about 2006. It was not anywhere near the first Mac I
> did color calibration on, but it has always been the "fussiest".


the problem with a macbook display (not so much on a macbook pro but it
still happens) is that it's very dependent on viewing angle.

nospam 03-22-2011 03:30 PM

Re: Tweaking monitor calibration
 
In article <isw-2C1232.09391422032011@[216.168.3.50]>, isw
<isw@witzend.com> wrote:

> > > it also doesn't work very well since there's no hardware puck.

>
> Do you have any hard evidence of that? I looked and could find none.
> Folks *who understand it* say it gives results very close to what
> hardware calibrators provide.


what folks are those? everything i've seen is that at best, it might be
close, if you know what to look for when eyeballing it. worst case it's
not close at all, especially on a display that varies with viewing
angle (i.e., most laptops).

nospam 03-22-2011 03:30 PM

Re: Tweaking monitor calibration
 
In article <ivsm58-k7p.ln1@ID-52418.user.berlin.de>, Wolfgang
Weisselberg <ozcvgtt02@sneakemail.com> wrote:

> So the Mac is colour managed, including all the browsers, just
> not very well by default. Hmmm.


actually quite well, but if the display profile is wrong, there's
nothing anyone can do.

Wolfgang Weisselberg 03-22-2011 03:48 PM

Re: Tweaking monitor calibration
 
nospam <nospam@nospam.invalid> wrote:
> In article <87k4fsmgww.fld@apaflo.com>, Floyd L. Davidson
>> isw <isw@witzend.com> wrote:


>> >Problem is, when the calibrator is invoked, it doesn't start from the
>> >previous settings, it starts from scratch, every time. If the color
>> >errors are subtle, repeated calibrations don't make it "better" they
>> >just wind up "different" -- and still wrong.


That's the reason you really want a hardware unit to calibrate
your monitor. Your eyes just aren't delivering stable, repeatable
results over different tries.

>> I use Argyll software under Linux. [...]


> that's wonderful. the original poster has a mac, not a linux box.


Argyll is --- as a very quick google would have shown you ---
available for Mac OS X.

>> >What I'd like, is a way to tweak the current calibration, similar to how
>> >you can tweak a photo in GIMP or Photoshop -- just cut a bit of blue in
>> >the highlights, or whatever.


>> >Is there any way of doing that? Any tools that make it possible/easy?


Of course there will be ways --- after all, if you can generate an
ICC to correct a measured difference between what e.g. a monitor
delivers, given a certain settings, and what it should deliver,
(and there is software and there are people who can) you can
certainly generate an ICC that instead or in addition 'just cut[s]
a bit of blue in the highlights'.

However, I doubt that there is ready made software to do that:
most anyone interested in colour correction will own at least a
cheap hardware colorimeter (or a dearer hardware spectrometer)
and will have no itch to tweak, say, the highlights manually in
the ICC --- if the hardware and the software work as designed, they
are correct and need no tweaking, otherwise either the hardware is
broken or the software is broken or just not correctly working with
the hardware. In the latter cases, the software will be corrected.

>> Read the manual for the software you use to calibrate
>> the monitor with. That shouldn't be hard to do. Color
>> temperature is what you want to change.


> what he was using is not separate software. it's *part of the system*.


And the system, or that part of the system, has no manual?

> it also doesn't work very well since there's no hardware puck.


So the Mac is colour managed, including all the browsers, just
not very well by default. Hmmm.

-Wolfgang

nospam 03-23-2011 04:15 AM

Re: Tweaking monitor calibration
 
In article <isw-6412A2.21211022032011@[216.168.3.50]>, isw
<isw@witzend.com> wrote:

> > > > > it also doesn't work very well since there's no hardware puck.
> > >
> > > Do you have any hard evidence of that? I looked and could find none.
> > > Folks *who understand it* say it gives results very close to what
> > > hardware calibrators provide.

> >
> > what folks are those? everything i've seen is that at best, it might be
> > close, if you know what to look for when eyeballing it.

>
> People who are not skilled at something, or don't understand how it's
> supposed to work, should not be surprised if the performance they get
> from it is less than optimum ...


which is for all intents, just about everyone. most people don't
understand colour management and are not going to get good results by
calibrating by eye. those who are skilled at eyeballing it know the
limitations of human vision. they'll get better results, but not as
good as hardware.

in any event, you didn't answer my question. what folks say eyeballing
it is just as good? name some. i'm curious to see who they are and what
they have to say.

here's one who agrees with me:
<http://www.colorwiki.com/wiki/Monito...using_hardware
_better.3F_Why_use_it_instead_of_software_alone.3F >

Is using hardware better? Why use it instead of software alone?

When only software is used, you are left to guess at the phosphor
colors the monitor displays. With a hardware instrument the red,
green and blue phosphor colors, as well as the white points, are all
accurately measured and this builds a much more accurate profile. It
also takes into consideration the aging of your monitor.

> > worst case it's
> > not close at all, especially on a display that varies with viewing
> > angle (i.e., most laptops).

>
> I hope you're not claiming that a hardware calibrator can somehow make
> the angle dependency go away.


it does for the calibration procedure because the puck is placed
directly on the screen, it does not move and is always at the same
angle every time the calibration is done. you'll get consistent and
accurate results.

obviously, the angle dependency doesn't go away for the user, which
makes eyeballing it and getting consistent results effectively
impossible.

nospam 03-23-2011 03:33 PM

Re: Tweaking monitor calibration
 
In article <isw-B0F2CE.10152023032011@[216.168.3.50]>, isw
<isw@witzend.com> wrote:

> > in any event, you didn't answer my question. what folks say eyeballing
> > it is just as good? name some. i'm curious to see who they are and what
> > they have to say.

>
> I didn't keep a list -- it was the result of googling around for
> information.


ok, so no proof.

> But since I *do* understand how Apple's method works, I do
> expect to get pretty good results from it. As good as a hardware
> calibrator? No,


exactly.

> but good enough that the difference would be not (or
> nearly not) perceivable by eye. And there's not much reason to get any
> better than that.


nearly not?

> > here's one who agrees with me:
> > <http://www.colorwiki.com/wiki/Monito...using_hardware
> > _better.3F_Why_use_it_instead_of_software_alone.3F >
> >
> > Is using hardware better? Why use it instead of software alone?
> >
> > When only software is used, you are left to guess at the phosphor
> > colors the monitor displays. With a hardware instrument the red,
> > green and blue phosphor colors, as well as the white points, are all
> > accurately measured and this builds a much more accurate profile. It
> > also takes into consideration the aging of your monitor.

>
> Based on my knowledge as a physicist and my experience designing
> high-accuracy color film printers, I think his explanation is not
> correct. Basically, the things he mentions -- phosphor colorimetry and aging --
> are no more controllable by the calibrator than by eye -- they are what
> they are, and the calibration process has to do the best it can with
> what it has.


a puck can accurately measure it, the eye can't.

> And eyes can do it nearly as well as machinery -- *to the
> extent that eyes can perceive the difference*. IOW, a more precise
> calibration that produces no human-perceivable difference in the image
> is simply not necessary.


but it is perceivable, if for no other reason, consistent between
calibration runs.

> > > > worst case it's
> > > > not close at all, especially on a display that varies with viewing
> > > > angle (i.e., most laptops).
> > >
> > > I hope you're not claiming that a hardware calibrator can somehow make
> > > the angle dependency go away.

> >
> > it does for the calibration procedure because the puck is placed
> > directly on the screen, it does not move and is always at the same
> > angle every time the calibration is done. you'll get consistent and
> > accurate results.
> >
> > obviously, the angle dependency doesn't go away for the user, which
> > makes eyeballing it and getting consistent results effectively
> > impossible.

>
> But the dependency does *not* go away for your eyes, so the problem
> cannot be calibrated away in any case.


it's not that it is calibrated away, it's to get consistent results.

> OTOH, if you necessarily must view a monitor obliquely, I expect an
> eyeball calibration *at that angle* might be more useful than a head-on
> one done with a puck ...


only if your head is always at that angle. move it a little and things
change. with a puck in a known consistent position, you get consistent
results.


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