confusion about monitor calibration and profiling

When you buy a monitor calibration software/spyder, what happens after it
finished running?

(1) it adds a startup software to modify the monitor's display
characteristic -- this affects everything that is displayed, so any software
that displays photo will display them more accurately. Specifically, it
makes the monitor into the sRGB colorspace.

or

(2) no startup software to change the monitor's display characteristic; but
a monitor ICC profile is created so that application that uses ICC profiles
like photoshop can use it to make photos display more accurately. software
that doesn't use the profile will continue to display photos the same old
way

Which of the above is correct? There seems to be conflicting evidence to
support both scenerios.

peter wrote:
When you buy a monitor calibration software/spyder, what happens after it
finished running?

(1) it adds a startup software to modify the monitor's display
characteristic -- this affects everything that is displayed, so any software
that displays photo will display them more accurately. Specifically, it
makes the monitor into the sRGB colorspace.

or

(2) no startup software to change the monitor's display characteristic; but
a monitor ICC profile is created so that application that uses ICC profiles
like photoshop can use it to make photos display more accurately. software
that doesn't use the profile will continue to display photos the same old
way

Which of the above is correct? There seems to be conflicting evidence to
support both scenerios.


There is startup software that simply verifies that the ICC profile is loaded
and up-to-date. The Spyder2 software creates a customer ICC profile and
the OS loads it at boot or login.

--
Thomas T. Veldhouse
Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0

"Thomas T. Veldhouse" wrote:

There is startup software that simply verifies that the ICC profile is
loaded and up-to-date. The Spyder2 software creates a customer ICC
profile and the OS loads it at boot or login.
Thomas T. Veldhouse

Yes, BUT...

The Win XP OS cannot handle loading separate colour profiles into the
separate LUTs of dual-head video cards. In this situation, the OS loads
the same profile into both LUTs on boot-up and the user must manually Run
the "Profile Chooser" software that comes with the Spyder2 in order to get
the proper profile loaded into the LUT for the second display.

Mardon wrote:

Yes, BUT...

The Win XP OS cannot handle loading separate colour profiles into the
separate LUTs of dual-head video cards. In this situation, the OS loads
the same profile into both LUTs on boot-up and the user must manually Run
the "Profile Chooser" software that comes with the Spyder2 in order to get
the proper profile loaded into the LUT for the second display.

Correct. I run a Dual-Headed display so I feel this pain. However, it is not
that big of a deal as I only preview images on one monitor and the other is
used strictly for menus and other "off desktop" applications. So, I really
see little need to calibrate the second monitor [which is a pain to
recalibrate anyway to a reasonably timely schedule].

--
Thomas T. Veldhouse
Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0

"Mardon" wrote in message
. 130...
"Thomas T. Veldhouse" wrote:

There is startup software that simply verifies that the ICC profile is
loaded and up-to-date. The Spyder2 software creates a customer ICC
profile and the OS loads it at boot or login.
Thomas T. Veldhouse

Yes, BUT...

The Win XP OS cannot handle loading separate colour profiles into the
separate LUTs of dual-head video cards. In this situation, the OS loads
the same profile into both LUTs on boot-up and the user must manually Run
the "Profile Chooser" software that comes with the Spyder2 in order to get
the proper profile loaded into the LUT for the second display.

Hi.

And the Spyder 2 instructions make that fact very clear.

Roy G

Yes, it is confusing. Color management continues to get more complex, and
the products reflect this complexity. The result is confusing and
conflicting beliefs and practices on the part of customers, and
manufacturers. There are several components to monitor profiling software,
and they are generally the same for all manufacturers.

1) The profiling software uses the associated hardware device (Spyder, Eye
One, Huey, or other colorimeter) to measure the brightness and color of
various colored patches on the screen.

2) A look up table (LUT) is created to bring the monitor to a specified
gamma and color temperature. This LUT is loaded after calibration, and at
system startup time, and changes the appearance of the display. If you
specified a gamma of 2.2 and a color temperature of 6500K, your display will
be a close approximation the sRGB color space. This is normally the
default.

3) A profile is created that specifies the appearance of RGB values on the
screen, based on the color measurements taken in step 1. This profile is
used by color aware applications, such as Photoshop, to display more
accurate colors. If your display is set to a different gamma or color
temperature than sRGB, images will display significantly differently using
the display profile.

4) A reminder application may be installed that runs at system startup time,
and tells you when you should recalibrate.

There are additional features provided by the "pro" versions of the
calibration software. With the slightly more elaborate versions of these
products, you may separately measure and/or change the overall brightness or
color temperature of your display. Some manufacturers allow you to plot a
graph over time of your display performance, so that you can monitor the
aging of your display.

It is not hard to learn to adjust your monitor manually to get good color,
and this is not a bad way to start to learn the finer points of adjusting
color appearance. The Apple Cinema display, for example, has a manual
procedure for adjusting brightness, gamma, and color. Even so, many people
lack the confidence or desire to calibrate their own monitors, and monitor
calibration devices are becoming more popular as they become higher quality,
and less expensive.

Manufacturers understandibly promote the virtues of their products, but
calibration is not a universal solution for consistent color quality. It's
important to do a sanity check after any monitor calibration. Verify that
you can distinguish all the squares of a 11 step step wedge, that all the
steps are close to neutral, and that skin tones and other important colors
from known good images look as they should. Otherwise you are buying a
false sense of security.
--
Mike Russell
www.curvemeister.com/forum/

"Mike Russell" -MOVE wrote in message
et...
2) A look up table (LUT) is created to bring the monitor to a specified
gamma and color temperature. This LUT is loaded after calibration, and at
system startup time, and changes the appearance of the display. If you
specified a gamma of 2.2 and a color temperature of 6500K, your display
will be a close approximation the sRGB color space. This is normally the
default.

This is what I thought. Thanks for confirming.

3) A profile is created that specifies the appearance of RGB values on the
screen, based on the color measurements taken in step 1. This profile is
used by color aware applications, such as Photoshop, to display more
accurate colors. If your display is set to a different gamma or color
temperature than sRGB, images will display significantly differently using
the display profile.

If after calibration the monitor approximates the sRGB color space, is there
any need to load a monitor profile into photoshop? Why not just turn off
color management in photoshop or use a standard sRGB colorspace. Most
digital cameras assumes a sRGB colorspace anyway.

Are inkjets pre-calibrated to match sRGB colorspace, or do we need to load a
printer specific ICC profile in photoshop in order to print correctly? It
seems that some printer driver also has a place to set ICC profile. Is it
better to turn off the printer ICC in photoshop and use the one in printer
driver, or the other way around?

"peter" wrote in message
news:GPTxh.4330$_d4.1623@trndny05...

[re monitor calibration]
If after calibration the monitor approximates the sRGB color space, is
there any need to load a monitor profile into photoshop? Why not just turn
off color management in photoshop or use a standard sRGB colorspace. Most
digital cameras assumes a sRGB colorspace anyway.

Theoretically, yes, but there are two factors at work he calibration,
which determines monitor appearance and characterization, which measures it.

Calibration brings the monitor to a known color temperature, gamma, and
overall brightness. This information is stored in the LUT that is loaded at
system startup, and also reflected in manual adjustment of brightness and
contrast, as guided by the calibration software. Keep in mind, though, that
the LUT is a limited adjustment, affecting each of the red, green, and blue
channels in isolation. You cannot use the LUT to, for example, change the
amount of green in response to amount of red or blue.

Characterization means measuring the actual performance of the display,
generally after it has been calibrated. Since the absolute colors of the
red, green, and blue phosphors or LCD filters will generally vary from those
of the sRGB standard, the monitor profile is needed to characterize the
display colors. This generally involves varying the amount of one color,
depending on the values of the other colors, either using a 3x3 matrix, or a
more complex multidimensional function table that allows all three colors to
vary arbitrarily. This complex function table is called, what else, a LUT,
LOL!

Are inkjets pre-calibrated to match sRGB colorspace, or do we need to load
a printer specific ICC profile in photoshop in order to print correctly?
It seems that some printer driver also has a place to set ICC profile.

All of these combinations work. Most inkjets have an sRGB setting, and
printing an sRGB image will generally give good results, provided the
manufacturer's paper and ink are being used. I usually advise people to try
this to see if the results are acceptable. Epson printers have another
setting, in addition to sRGB, called PhotoEnhance, which I find gives
slightly better results than sRGB.

Is it better to turn off the printer ICC in photoshop and use the one in
printer driver, or the other way around?

When using a profile, both ways work perfectly well. I generally specify
the profile in Photoshop, because I want to be positive that I've selected
the correct paper profile for the printer. If you use the same paper all
the time, there is no advantage to doing it this way, but I feel better if I
can convert in Photoshop, and see the name of the profile at the time I
print.

You've touched on an important subject, though, and that is printing. Most
people who calibrate their monitors are motivated by a desire to match their
printer output. This is often a fruitless waste of time, because it only
addresses half the problem. There are generally good quality "canned"
profiles available for Epson printers - beware of the older ones for the
1280 and earlier at the Epson site.

Printer calibration equipment is expensive - though there are software
solutions that use your scanner to (attempt to) generate a profile. It's
probably better to spend the same money on a profiling service create a
profile for your printer paper combination. Calibrating your printer
manually is capable of excellent results, provided you use a systematic
procedure, and are willing to be responsible for the end result.
http://www.curvemeister.com/download...test_strip.htm
--
Mike Russell
www.curvemeister.com/forum/

peter wrote:
When you buy a monitor calibration software/spyder, what happens after it
finished running?

(1) it adds a startup software to modify the monitor's display
characteristic -- this affects everything that is displayed, so any software
that displays photo will display them more accurately. Specifically, it
makes the monitor into the sRGB colorspace.

or

(2) no startup software to change the monitor's display characteristic; but
a monitor ICC profile is created so that application that uses ICC profiles
like photoshop can use it to make photos display more accurately. software
that doesn't use the profile will continue to display photos the same old
way

Which of the above is correct? There seems to be conflicting evidence to
support both scenerios.

Both; the current state of the art is not mature enough
is have a single solid working practice.

Some software wants to do its own profiling, some software
has never heard of color profiling, some software
wants to (correctly) allow the OS to do color profiling
on the apps behalf.

So getting color correction to work "nicely"
end-to-end involves careful reading of manuals
and careful configuration of each and every
software component.

Sorry.

BugBear

Thanks to all the response, I am ready to buy a calibrator. Does anyone have
a pointer to a review of more than one device, like this article but more
up-to-date:
http://www.drycreekphoto.com/Learn/m...tion_tools.htm

I want to buy one that would let me calibrate several monitors (LCD and
CRT). If all it does is spits out an ICC profile, then I can install the
software on a computer, calibrate, load the ICC into the display driver,
uninstall the software, and move on to the next computer. However, I read
that at least some package (e.g. huey) require the color sensor to be
attached to sense ambient light -- I would gladly give up this feature in
exchange for the ability to calibrate multiple monitors.