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Differences in calibrating two monitors

Differences in calibrating two monitors

2006-06-02 by randy

Hello, I have a 6 year old sony 21" crt and a several month old SGI 21" 
crt on a sony chasis. I have eyeballed in the white/black points using 
the contrast brightness controls with 30 step wedges in PS till I am 
happy with the luminance match.

I am also using 1.8 6500.  I realize 2.2 is recomended, but I like the 
shadow detail of 1.8.

Problem is the old monitor is more yellow than the new one.  Just a little.

I have the RGB adjustments to with in .12 in spyder 2 pro on both 
monitors. Well under .5 required.

I have large hoods over the monitors.

Is this something I can adjust?

Thanks

Randy Laskody

www.laskodyphotography.com

Re: [colorvision_group] Differences in calibrating two monitors

2006-06-03 by CDTobie@aol.com


In a message dated 6/2/06 3:19:11 PM, rlphoto@... writes:


Hello, I have a 6 year old sony 21" crt and a several month old SGI 21"
crt on a sony chasis. I have eyeballed in the white/black points using
the contrast brightness controls with 30 step wedges in PS till I am
happy with the luminance match.

I am also using 1.8 6500. I realize 2.2 is recomended, but I like the
shadow detail of 1.8.

Problem is the old monitor is more yellow than the new one. Just a little.

I have the RGB adjustments to with in .12 in spyder 2 pro on both
monitors. Well under .5 required.

I have large hoods over the monitors.

Is this something I can adjust?


A six year old monitor... wow, I hope its only seen intermittant use! You say you have "eyeballed" the black and whitepoints. I assume you would match black and white luminances using the Spyder and the Spyder2PRO software to match these, by determining which has the higher black, which has the lower white, and targeting these values on both.

You are choosing gamma 1.8, which is indeed yellower, unless you are working in the dark. But other than the color of white, that gets cancelled out by Photoshop, so I can't imagine you actually get more shadow detail by throwing away levels then you do by using a gamma closer to CRT native, and throwing away a lot fewer levels.

If, in the end you can't quite match the two, and wish to hand tweak the difference, you would create a custom curve for the older monitor, and increase the blue curve slightly, to reduce yellow.

C. David Tobie
Product Technology Manager
ColorVision Business Division
DataColor Inc.
CDTobie@colorvision.com
www.colorvision.com

Re: [colorvision_group] Differences in calibrating two monitors

2006-06-03 by randy

Hello CD,

First off, I am running version 2.1-7  is this the latest?
Show quoted textHide quoted text
>
> A six year old monitor... wow, I hope its only seen intermittant use! 
> You say you have "eyeballed" the black and whitepoints. I assume you 
> would match black and white luminances using the Spyder and the 
> Spyder2PRO software to match these, by determining which has the 
> higher black, which has the lower white, and targeting these values on 
> both.
>
> You are choosing gamma 1.8, which is indeed yellower, unless you are 
> working in the dark. But other than the color of white, that gets 
> cancelled out by Photoshop, so I can't imagine you actually get more 
> shadow detail by throwing away levels then you do by using a gamma 
> closer to CRT native, and throwing away a lot fewer levels.
>
> If, in the end you can't quite match the two, and wish to hand tweak 
> the difference, you would create a custom curve for the older monitor, 
> and increase the blue curve slightly, to reduce yellow.
>
> C. David Tobie
> Product Technology Manager
> ColorVision Business Division
> DataColor Inc.
> CDTobie@...
> www.colorvision.com
>
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Re: [colorvision_group] Differences in calibrating two monitors

2006-06-03 by CDTobie@aol.com


In a message dated 6/2/06 9:19:22 PM, rlphoto@... writes:


First off, I am running version 2.1-7 is this the latest?


Spyder2PRO v2.2 is available from the CV websites. It includes ambient light features that may be of interest to you...

C. David Tobie
Product Technology Manager
ColorVision Business Division
DataColor Inc.
CDTobie@colorvision.com
www.colorvision.com

Re: Differences in calibrating two monitors

2006-06-03 by sergecashman

I'll take a shot at this...

First print out reports for both monitors to see where you stand (run
File/Validat first, then File/Print Info). Compare the numbers and
look what the differences are. Most likely white point is the main
difference. If not then post the results here.

In my opinion the correct way of doing the white point matching is
looking at the "better" monitor x and y CIE numbers in the report and
then creating a New target (on the Select Target screen) for the other
monitor using CIE numbers (rather than the K number) for the white
point target (there's a Custom white point number in there). Select
same gamma. I'm not sure about the best compromise for Luminances, one
monitor being old and all that. 

Run calibration, run File/Validate, print results. See if they get closer.


A shortcut for lazy and careless people like myself is to load an ICC
profile created for the first monitor as a target for the second one
(File/Open target, navigate to the first icc profile)...

Re: [colorvision_group] Re: Differences in calibrating two monitors

2006-06-04 by CDTobie@aol.com


In a message dated 6/3/06 7:52:16 PM, sergecashman@... writes:


First print out reports for both monitors to see where you stand (run
File/Validat first, then File/Print Info). Compare the numbers and
look what the differences are. Most likely white point is the main
difference. If not then post the results here.

That would be a thorough way of doing it. But simply running a calbration on each, and checking the Info window on each will give the native white and black luminance of each monitor, so you can choose target white and black that both can reach.

In my opinion the correct way of doing the white point matching is
looking at the "better" monitor x and y CIE numbers in the report and
then creating a New target (on the Select Target screen) for the other
monitor using CIE numbers (rather than the K number) for the white
point target (there's a Custom white point number in there).

That would be the most comprehensive way of doing it, but simply choosing a K value for both would be more typical...


 Select
same gamma. I'm not sure about the best compromise for Luminances, one
monitor being old and all that.

There's no practical way of compromising... you set the target luminances for values both can hit.

Run calibration, run File/Validate, print results. See if they get closer.


A shortcut for lazy and careless people like myself is to load an ICC
profile created for the first monitor as a target for the second one
(File/Open target, navigate to the first icc profile)...


As long as you are sure the second monitor can hit the target values for the first, that will work fine. Typically starting with the older or more limited monitor is all that is needed to make this work...

C. David Tobie
Product Technology Manager
ColorVision Business Division
DataColor Inc.
CDTobie@...
www.colorvision.com

Re: Differences in calibrating two monitors

2006-06-04 by sergecashman

The reason I think it's better to target the second monitor's WP to
the first one's CIExy numbers:

When you target both to the same white point (6500K or D65 for
instance) the results may be on different sides of the target, so to
speak, increasing  the difference (Delta E) between the two. It is
better to get the actual numbers of one and try to get the other one
as close as you can.

Note:
You can't use the  K number (CCT) of the first monitor as a target for
the second monitor . You have to use CIExy. A white point target has
to be a defined chromaticity.

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.