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Author Topic: A method for setting your LCD brightness to the correct level using a light meter  (Read 5017 times)
craigwashburn
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« on: May 10, 2009, 03:01:31 PM »
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Like many here I'm sure, I've struggled with finding the correct brightness value to set my LCD display to for post production.  

The manufacturers of calibration equipment will recommend anywhere from 90 cd/m2 to 140 cd/m2, and then many non-graphics LCDs today can't even go below 200 at their minimum brightness setting.  The correct brightness depends on your viewing environment - a bright office requires a brighter screen.  A dark studio will want a lower level.  Therefore the correct answer to the question is it depends on your viewing environment.

Some calibration equipment have the ability to measure ambient light and then adjust your display (or instructs you to adjust) accordingly.  But I've found this ability often doesn't work very well.  The colormunki, in my experience, is terrible for determining LCD brightness based on ambient light level.  Worse yet, the software doesn't display the cd/m2 it reads with which to experiment with.

So to match my LCD to my ambient viewing environment, I tried this with my Sekonic L-358 light meter, and it seems to work pretty well.  It's not entirely scientific, but it seems to work well enough.

1.  Display a completely uniform screen on your adequately warmed up monitor.  I've been using white for this, but perhaps light gray would be better?

2.  Set your light meter to EV mode (on the L-358, dipswitch 1 under the battery cover should be set to "ON"), and then set it take Ambient light readings.

3.  With the dome extended, take several readings of the area where you view prints.  Note these values.  My studio averages 4.6 EV during a partly cloudy day.

4.  Retract the dome.  Then hold the meter in front of your face from exactly where you normally sit to work and take several readings of the display.  The distance is important here.  

5.  Adjust the brightness of your monitor until the EV reading is close to those measured in your print viewing area.

6.  For future reference, make note of what your calibration software declares this to be in cd/m2.

One note - it's impossible to convert your light meter reading directly to the cd/m2 that monitor calibrators use as there is a distance variable involved - the distance from the monitor to your eyes.  Remember light falls off with the inverse square.

You might do this at several times during the day to acquire a decent average brightness for your display.  Evening illumination provided by artificial light is going to be different than daylight through windows.


Any thoughts?  Am I crazy or going about this the entirely wrong way?  
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tho_mas
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« Reply #1 on: May 10, 2009, 04:04:53 PM »
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Quote from: craigwashburn
The colormunki, in my experience, is terrible for determining LCD brightness based on ambient light level.
Actually for the luminance level of the display manual adjustement is the best way... no measurment device knows what you are seeing...

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Am I crazy or going about this the entirely wrong way?
well, why not... if you have no other measurment device.
To adjust the luminance level of the display to about 120cd/qm set the light meter to spot, set ISO200, f8 (1/2) and 1/15'' and measure 10cm in front of the display. Adjust the luminance of the display to match the light meter. Better than nothing maybe. But again... the luminance level should be "pleasant" to you not to the device. If you have a viewing booth with some ISO standard lights to eye up prints you should try to match the luminance level accurate (but again manually).
« Last Edit: May 10, 2009, 04:05:50 PM by tho_mas » Logged
Wayne Fox
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« Reply #2 on: May 11, 2009, 06:21:21 PM »
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I agree, to me the correct setting isn't number based.  They are good starting points but don't guarantee a good display to print match.

The real goal is to match the brightness of your viewing station, and the best way to do this is comparing a piece of unprinted paper in the viewing station with a white document on the display.  Adjust the brightness of the display for a visual "match".  Whatever Luminance you end up is the "correct" luminance for your conditions.

If the two can't be compared visually then it may be more from trial and error.  If your prints are always a little dark or light, adjust the display luminance until you find the balance.

I make a note of my Luminance when creating a profile, but that value is just for future reference ... I already have what I feel is the correct setting without any measuring devices.
« Last Edit: May 11, 2009, 06:22:16 PM by Wayne Fox » Logged

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