How to adjust iMac screen brightness?

[robert goldstein]

I am trying to calibrate a 24inch iMac using an Eye-One Display and Match 3 software. I would like to

have the luminance value at 120, but using on the screen brightness control in System Preferences, I

cannot get it below 145. This is with the White Point set at 6500. If I set it at Native, the minimum

luminance is even higher. Is there some other way to adjust display brightness? Unfortunately, the

display itself does not have brightness controls.

[ellis_vener_photography]

I have no problems getting my 20" iMac (intel Duo Core 2 @ 2.16Ghz) brightness down using

System Preferences > Display settings. I also use Eye One Match 3 for profiling. have you

pushed the brightness slider all the way over to the left?

[robert goldstein]

Ellis,

 

Yes, I have pushed it all the way to the left. I wonder if there is an internal adjustment that

can be made by a certified technician.

 

Rob

[serge c]

145 cd/m2 is not too bad for an LCD. Why, it feels too bright to you?

[robert goldstein]

<145 cd/m2 is not too bad for an LCD. Why, it feels too bright to you?>

 

No, it does not feel too bright, but it is brighter than the the standard luminance calibration

that will be used for printing my photos. Hence, there is every reason to believe that the

prints will be darker than what I see on my monitor.

[serge c]

"...standard luminance calibration that will be used for printing my photos... "

 

I have to admit I don't know what it means. A lab told you to do that?

 

145 is on the bright side, but it's not 350, you know. I doubt you would feel the difference. If prints don't come out right it's not because of luminance.

[Tim_Lookingbill]

Those cd/m2 luminance measurements are an averaged

calculation of the entire black to white brightness of the display.

You have such a high number for LCD's because the s-ips panel

backlight behavior built into most 20"plus mac displays lightens

the black along with the white.

 

This is why CRT's have a lower number because there black

points can go down as low as 0 and still render all 255 levels in

a grayramp. It's just their black point is denser looking than an

LCD's so the averaged number is lower.

 

The luminance number meaning was told to me by tech support

personel at GretagMacbeth's New York office. As to how the

luminance number is calculated to arrive at this average I didn't

ask.

 

What this means is you have to consider the brightness of the

entire screen by examining a grayramp spanning border to

border to get a good comparison to your viewing light. Also have

an image with a lot of white in it to compare to your a print under

your viewing light which should match in overall brightness. If it

doesn't you need to either lower the brightness of the LCD or

increase the brightness of your viewing light.

 

With LCD's you can't judge brightness by just looking at a white

sheet. They are bright right out of the box for a reason because

they take a hit in overall luminance after calibration. However if

the brightness is unmanageable you may have something

electronically wrong with your particular unit.

[kelly_flanigan1]

The old 233MHZ iMACS of 1998 also iMacs too; probably not so bright today!

[robert goldstein]

On the Apple iMac discussion forum, there are several posts about the 24 inch display

being excessively bright. There is a freeware program called "Brightness Control" that

lowers the brightness level beyond what can be accomplished with the iMac's own

controls. I downloaded it only to discover that it changes the color balance of the display

and also seems to be nullified during the calibration process.

 

I'm beginning to think that the 24 inch iMac may not be suitable for careful photo editing,

which is surprising and disappointing, given its otherwise splendid performance. Apple

obviously pegged this computer for the high end of the amatuer and low end of the

professional markets. One would think that they would have taken more care with

something as basic as display brightness.

[serge c]

But 145 is actually "better" than most monitors on the market. I don't understand why you are upset about it. There are LCDs out there that are 300 or 400 or whatever. So the imac is a little bit brighter than 120 - not such a big deal.

 

Of course a program that adjusts LUTs would conflict with calibration software that adjusts LUTs as well. Normally you'd want to keep LUT adjustments to a minimum anyway on an LCD.

[robert goldstein]

Serge,

 

I use a service bureau (West Coast Imaging) for my best print enlargements. Their printer is

calibrated for luminance of about 120cd/m2. Unless I make a correct guess about how

bright the print will be, all of my prints will be off, either over or under. If I printed my own

photos, I would be able to make the correct adjustments, but this is not the case.

 

Rob

[christian_dallaire]

You have to use a freeware called Shades for dimming the screen on a 24 inchs iMac.

[neil_fiertel]

When one adjust the brighness using the OSX internal calibration, there is an adjust to

match minimally seen grey tone against a black square in YOUR standard light situation.

This is correct and with my several monitors, including a 30 Cinema Display, the

brightness of the screen is correct..The issue is not the screen brightness but rather the

reality that printing is much narrow in terms of gray range than the screen..As they say,

get used to it..One has to compress slightly the dynamic range to put what is seen on

the screen on paper..It is life. I have printed somewhere over 700 prints using an Epson

2200 and I noted exactly the issue of the print being darker than the screen. I tried

pretty much everything to produce an automatic compensation and gave up entirely on

the colorsync system. I now use the color controls available with Epson and perhaps

other printers. It allows me to set a series of default settings for gamma and so forth. As

well, one can choose a different gamma on the colour calabration using the OSX colour

calibraton as well. If you get the colour right on the screen using the many colour tests

within the system preferernces monitor colour and expert mode, believe me one can get

it spot on if you have excellent colour response in your eye and brain..I do and I can as it

wre get it right and lock it in. The iMac 24 in fabulous in terms of its screen brightness

and clarity. One does not need a particular screen brightness to get it right..one needs

to have the gamma and the range within the screen calibration from black to white,

correct and consider the limited range of the paper printing process when making a file

to print.

[Tim_Lookingbill]

On my 2004 G5 iMac it doesn't matter where I set the brightness slider, when the LUT is

cleared it reverts to native gamma which is how it looks (quite bright) at startup before the

profile is loaded.

 

You can see this using the Apple eyeball calibrator at which time you shouldn't touch the

brightness slider. It needs to be adjusted prior to opening the Apple utility. The Apple

eyeball calibrator will establish true native gamma based on the current brightness setting

by having you adjust 5 point luminance zones using raster targets. Afterward this you will

come to the section where you choose gamma which will have no affect on how bright 255

white looks on your screen but will make a noticeable difference in contrast.

 

Setting brightness may require different settings from one LCD model to the next because

some incorporate both contrast and brightness responses within one slider like my

particular model of iMac. The only accurate way of setting luminance for me is to adjust

first before calibration/profiling the brightness to match a white sheet of paper viewed

under my current lighting situation while having a white page fill the entire display screen.

 

Then I calibrate.

[a few images]

Just got the 24" iMac and was thinking to myself - Damn! This thing is bright! As in, hurting my eyes bright!

 

I stumbled across this thread looking for calibration tools to use with the LCD in general but now I see another issue - I may not be able to calibrate it because of too bright issue.. I'll keep reading and watching this thread..

[a few images]

bah.. just realized how freaking old this post is..

 

Anyway - a fix I found is to switch to Adobe RGB and adjust it then - it gets you much lower..

[Tim_Lookingbill]

Tom,

 

Have tried Universal Access settings within System Preferences? This slider has a

noticeable affect on contrast.

 

Not quite understanding what you did or where switching to AdobeRGB which is a working

space, not a monitor profile, and doesn't contain a gamma curve to download to the video

LUTs to affect contrast or brightness.

 

You need to calibrate regardless. Let me know what you think of the Apple eyeball

calibrator on your newer iMac. It takes a while to figure out what raster target adjusts

affect what area of the tonal scale. I load a 21step grayramp as my desktop pattern and it

helps a lot in nailing neutrality throughout the entire tonal scale going back and forth

tweaking the raster targets within the eyeball calibrator to perfection.

 

Apple really improved this little app especially when using it on the display/computer all in

ones.