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Author Topic: monitor calib: setting luminance numbers  (Read 9325 times)

FrankG

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monitor calib: setting luminance numbers
« on: May 15, 2007, 12:56:11 pm »

Hi

Calibrating a new monitor with an original Spyder and Optical.

PC setting gamma to 2.2

Any comment on setting theluminance  target numbers for Brightness (shadows) and Contrast (highlights) on a crt vs lcd ?
 
My 'guess' is that I should set the Brightness number as low as possible but still ensure seeing the difference between black and nearly black, between 95% to 100%, on a 21 step wedge. And vica versa on the Contrast.
Is this correct?

So far, it seems like the targets that maintain these steps are between .3 - .70 for Brightness/shadows  and  90 for Contrast/highlights

Thanks,
Frank
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Nill Toulme

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monitor calib: setting luminance numbers
« Reply #1 on: May 15, 2007, 01:08:25 pm »

"Correct" luminance depends in part on the ambient lighting in your work environment, and it will typically be a bit brighter for an LCD than a CRT in a given setting.  I calibrate my NEC 2090uxi to 95 cd/m², D65, 2.2.

Nill
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FrankG

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monitor calib: setting luminance numbers
« Reply #2 on: May 15, 2007, 01:28:39 pm »

Thank you Nill.
I also have 6500K, 2.2
but I wasnt sure about the high and low luminance points - you have 95...what is your low point ?
I am I correct in assuming the better the monitor (and the more ideal the viewing room/lighting)  the higher and lower you'd be able to set & 'stretch' the range between Bl(0) & Wh(100) while still differentiating all the % steps in a 21 step wedge ?

"Correct" luminance depends in part on the ambient lighting in your work environment, and it will typically be a bit brighter for an LCD than a CRT in a given setting.  I calibrate my NEC 2090uxi to 95 cd/m², D65, 2.2.

Nill
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Nill Toulme

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monitor calib: setting luminance numbers
« Reply #3 on: May 15, 2007, 03:26:06 pm »

No, not really.  Almost any LCD monitor will go much much brighter than you need or want.  In fact, a significant problem with many lower end LCDs is not being able to get them dim enough, not bright enough.  For this reason, contrast ratio is a fairly meaningless spec when it comes to monitors used for critical color work.

You want high point... the luminance setting... to be such that your monitor, in your particular working environment, more or less matches the overall brightness of your prints (assuming a fully color managed, calibrated workflow).  That's sort of a moving target, especially if your ambient lighting changes during the course of the day like mine does, and also because your prints look different when viewed under different light, so there's no 100% "correct" answer.

Black point, I dunno, my software just does the best it can with it — ideally black would be true black, 0,0,0, but that's not practically achievable.

Most people tend to set their LCDs too bright — even the often-recommended 120 cd/m² is probably only appropriate for typical bright office lighting, not the sort of lighting many of work in.

Try starting with 100 cd/m², profile and run some prints, look at them in whatever light they're most likely normally to viewed in, and see if they match your monitor reasonably well.  If they seem dark (or, less likely, overly light) in comparison, adjust in 5 cd/m² increments accordingly.

p.s.  I just recalibrated mine with the target settings I mentioned above.  On finishing it reported a black level of .39 and an intensity level of 94.4, amounting to a contrast ratio (also reported) of 244:1.

Nill
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« Last Edit: May 15, 2007, 05:47:35 pm by Nill Toulme »
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pfigen

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monitor calib: setting luminance numbers
« Reply #4 on: May 15, 2007, 07:11:48 pm »

Good quality CRTs are going to come in around .30 cd/m2 on the black point. I have my Artisans set to .31. LCD screens can get a black somewhere in the .50-.60 cd/m2 level or so. If you have your monitor in a darkened room like you would with a CRT, that level of black will seem only like a dark gray. An LCD needs to run at a higher luminence overall with a higher ambient light level than a CRT in order to have a similar on screen feel for contrast. It generally takes some trial and error to come to the optimum settings for your ambient an viewing conditions with your screen. You'll want the feeling of a good black without losing any black detail. Same on the highlight end. The play between black level, white level and ambient is very dynamic, but once you have it sorted it will work very well.
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Bill Koenig

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monitor calib: setting luminance numbers
« Reply #5 on: May 22, 2007, 06:28:33 pm »

Quote
Good quality CRTs are going to come in around .30 cd/m2 on the black point. I have my Artisans set to .31. LCD screens can get a black somewhere in the .50-.60 cd/m2 level or so. If you have your monitor in a darkened room like you would with a CRT, that level of black will seem only like a dark gray. An LCD needs to run at a higher luminence overall with a higher ambient light level than a CRT in order to have a similar on screen feel for contrast. It generally takes some trial and error to come to the optimum settings for your ambient an viewing conditions with your screen. You'll want the feeling of a good black without losing any black detail. Same on the highlight end. The play between black level, white level and ambient is very dynamic, but once you have it sorted it will work very well.
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I have a CRT (Sony GDM-F500R) I've had this monitor since 2000, paid big bucks for back then, still working just fine, has less than 4000 hours of use. (fingers crossed)
I use Monaco Optix XR Pro in the Expert mode. After calibration, my black luminance was set to 0.19 cd/m2, white luminance 96.2 cd/m2. The room is quite dark as I'm usually working at night, but I have night blinds that I can pull down during day light.
Depending how dark your room is, the black luminance could go as low as 0.16 cd/m2
Some day I'll have to switch to a LCD, the black luminance numbers that I'm seeing for those will mean a brighter room for sure, not looking foreword to that.
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Bill Koenig,
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