14 Replies Latest reply: Dec 10, 2009 2:42 AM by littlesnow
miflo Level 1 Level 1 (10 points)
I am using an external LCD monitor (24", 1920x1200, connected via DVI) on my MacBook and I am wondering why the font rendering looks so terribly bad in most OS X applications. Especially in Apple Mail it is really hard to read mails, because the fonts are blurry and slushy. Curiously the fonts are looking quite well in Finder and Safari. Even when I select the same font type in Mail - the appearance of the fonts in Mail is completely different from Safari and Finder.

When I look at the internal 13" monitor, the font rendering is way better compared to the external monitor (even in Apple Mail). So, what can I do?


MacBook White 13", Mac OS X (10.6.1)
  • K T Level 7 Level 7 (23,700 points)
    Have you used the LCD font smoothing option in System Preferences/Appearance...?

    Also, this may be a good time to ask if you've checked/validated any of the problematic fonts with Apple's Font Book (look in the Applications folder). Find and remove duplicates also.

    Start there to be sure all fonts that are in play come out with a clean bill of health.

    And don't hesisate to perform wholesale deletion of old and/or little used fonts - be skeptical of anything that has come from Office 2008, including those related to an Equation Editor installation.
  • miflo Level 1 Level 1 (10 points)
    Thanks for the answer.

    My fonts are ok I think. It's the font rendering that simply is not optimal for the external LCD. The fonts look ok on the internal display. It doesn't matter which font I select in Mail (in font settings) - every font is "over-smoothed" and looks "edged" and slushy.

    What I do not understand is the fact that especially the Finder seems to do a completely different font rendering. If you have the possibility, please compare the characters in Finder with the same characters in Mail. I am quite sure that you will realize the same big difference.
  • Jazzmaniac Level 2 Level 2 (425 points)
    Font antialiasing and subpixel rendering depends a lot on the calibration of the screen. Unknown intensity responses make the whole idea of antialiasing nonsensical. So go ahead and calibrate your external screen and follow the instructions precisely.


  • miflo Level 1 Level 1 (10 points)
    I now made two screenshots of Mail: The first one while the external display was disconnected, the second one when it was connected (and Mail moved to the external display). I opened both screenshots in Photoshop and there was a clear difference between the font renderings: On the screenshot of the internal display, the fonts are smoothed with black and grey pixels only, while on the screenshot from the external display they are smoothed with colored pixels. This is the reason why the text looks so bad on the external one. Therefore, it is definitely a problem of the font rendering. In Photoshop, the difference of font rendering is clearly visible!

    See here:


    The first line is internal display, the second line external display. That's unbelievable.

    Another thing: I found out that it's not only Mail that has the problem - it is any application that was started after the external display had been connected. It seems that OS X applies the font rendering setting at the moment a application is starts. When I disconnect the display, start Finder, Mail, Safari and so on, and then connect the display, then all the applications look great even on the external display. When I quit the apps and then restart, the font rendering is broken again
  • Jazzmaniac Level 2 Level 2 (425 points)
    you actually DO want the colored pixels. That's subpixel rendering and enhances the contrast and clearness of the font rendering. What is confusing however is that your main display doesn't use it. Reasons for subpixel rendering failing are: running your display at non-native resolutions, wrong subpixel order selection, wrong monitor profile.

    So, the question is, what did you change and what is non-standard about your setup?


  • K T Level 7 Level 7 (23,700 points)
    My fonts are ok I think

    Be sure to double check. Fonts are behaving in a new manner w/SL, and it is critical to perform housekeeping if you have issues such as you describe. Don't let past assumptions distract you from getting things right with your new OS. Get rid of duplicates as well as any that throw errors...don't be shy about getting rid of ones that simply display warnings too.

    If you delay confirming your font health, you'll risk chasing the proverbial ghost in the machine
  • miflo Level 1 Level 1 (10 points)
    Thanks for your further answers.

    I double checked with my other (new) MacBook (15" Unibody). The font rendering on the external 24" monitor is exactly the same, it looks very blurry and text can hardly be read. And be sure: I use the native resolution and even tried to calibrate the display with Apple's calibrating tool in system settings. The used profile is the right one, it is named like the monitor model. The same for the internal display: It uses Apple's own LCD profile.
    I also started Windows 7 in VMWare and the result was a pretty good picture with perfect font rendering on the external monitor. Therefore I am sure that there is a problem with the font rendering setting in OS X.

    The interesting thing is that the picture of the internal display of the 15" MBP looks great, although it is using the colored subpixels as well. I don't think that the colors make any disadvantage ingeneral, but it seems that the kind of font rendering is simply wrong for the external 24" monitor on both MacBooks. I think that OS X for sure does adapt the font rendering dependent on the monitor profile. What I would need is the possibility to change the kind of font rendering manually.

    Tomorrow I will try to use another profile that OS X offers. Maybe this safes the problem.
  • Jazzmaniac Level 2 Level 2 (425 points)
    that sounds a lot like the subpixel geometry of your external display is not standard and not taken into account by the OS. What display are you using?


  • miflo Level 1 Level 1 (10 points)
    It's a new Fujitsu Siemens 24" 1920*1200. Don't know the exact model number, but it is a business display - has not the best color quality. But with windows (even in VMWare), the font rendering is perfect. And as already mentioned, when I start an application in OS X before I connect the display, then the fonts are also rendered perfectly. OS X changes the font rendering especially for the display and I don't know how I can come around this annoying problem.
  • MarioGrgic Level 1 Level 1 (40 points)
    This is a known problem (to users I don't know if Apple actually knows about it) and it has to do with anti-aliasing settings not being applied if you attach a third party (non Apple) display. But there is a fix to bring it back:

    Open Terminal and enter the follwing command:

    defaults -currentHost write -globalDomain AppleFontSmoothing -int 2

    and then log out and back in.
  • miflo Level 1 Level 1 (10 points)
    At first I have to correct my post above: I was wrong with the pictures: the first line (with the grey subpixels) was the external monitor, and the second line with the colored subpixels was the internal one. I have access to the monitor again tomorrow, so I can do a final check not until this time. But I already compared what happens to the font rendering on my internal display when I enable and disable the "LCD font rendering" in System Preferences: Indeed, when I deselect the LCD rendering, the fonts have grey subpixels, and the text looks similar blurry than the picture on my external display (although it's not that bad, but this may be due to the big screen and maybe the matt surface of the Fujitsu display). LCD enabled brings colored subpixels for my internal display. On the external display, the rendering was grey although LCD rendering was selected. Therefore I am sure that this will solve the problem. Will see tomorrow and let you know! Thanks a lot!

    One question: Is this a permanent setting? If yes, how can I undo this setting?
  • MarioGrgic Level 1 Level 1 (40 points)
    Yes, the deault value for the setting you set with the above terminal command is permanent in the sense that it will remain there until you change it.

    If you want to restore the value to previous setting, then do the

    defaults -currentHost read -globalDomain AppleFontSmoothing

    This will either read and display the previous value, or issue a message that the setting has no value at all (which is the case for me).

    If the setting didn't have a value, and you want to restore it, then you simply delete the value

    defaults -currentHost delete -globalDomain AppleFontSmoothing

    or if you got the previous value, then restore it

    defaults -currentHost write -globalDomain AppleFontSmoothing -int x

    where x is the value that you got before you changed it.

    By the way, the valid values are:

    * 0 – is the setting for CRT rendering (looks horrible on LCD)
    * 1 – is the setting for Light
    * 2 – is the setting for Medium (Best for Flat Panel)
    * 3 – is the setting for Strong
  • miflo Level 1 Level 1 (10 points)

    thanks a lot for your help. I tried the external monitor again and the picture is great. Yes, that solved it.
  • littlesnow Level 1 Level 1 (0 points)
    When I do the
    defaults -currentHost write -globalDomain AppleFontSmoothing -int 2

    in OSX 10.6.2

    My System Preferences modul where you can set the LCD smoothing option does not start anymore.

    I have to delete the above setting with...then it starts?!!!

    defaults -currentHost delete -globalDomain AppleFontSmoothing