Order of subpixels for font smoothing

cs02rm0

macrumors member
Original poster
Jul 31, 2013
94
31
I gather the order of subpixels in external monitors is normally RGB.

However the Seiki 4k, amongst others, I believe is BGR. Without the LCD font smoothing being aware of this ordering I gather font smoothing will be messed up - and given the fonts seem fuzzy and not as crisp as they should be I'm wondering if this is the issue I'm having.

Is there a way, short of finding how to rotate the desktop 180 and mount it upside down, that I can adjust this in OSX?
 

paulrbeers

macrumors 68040
Dec 17, 2009
3,960
120
I gather the order of subpixels in external monitors is normally RGB.

However the Seiki 4k, amongst others, I believe is BGR. Without the LCD font smoothing being aware of this ordering I gather font smoothing will be messed up - and given the fonts seem fuzzy and not as crisp as they should be I'm wondering if this is the issue I'm having.

Is there a way, short of finding how to rotate the desktop 180 and mount it upside down, that I can adjust this in OSX?
Are you sure OSX just isn't treating the Seiki as a TV and adding overscan?
 

cs02rm0

macrumors member
Original poster
Jul 31, 2013
94
31
Certain, as I understand overscan, I can see the full and height of the output and it matches that of the physical display.
 

musashiaharon

macrumors newbie
May 1, 2014
5
0
I'm also having subpixel issues. Turning off LCD font smoothing changes the display, but it actually makes things worse, to my eyes.

Also, it appears that the subpixel rendering changes every other pixel horizontally on my Seiki 4k display. To see this effect on your display, open the attached image and drag it horizontally across the monitor, pixel by pixel. The vertical lines will appear and disappear. I tried taking screenshots at different positions, but the image data is the same, whether the x-coordinate is even or odd. The only thing changing is how the TV displays it.

I thought that maybe the display has RGBGR ordering, or similar, but when magnified, the subpixels are clearly RGB (edit: see next post).

Relevant TV settings and info:
Sharpness: 0
Boot Ver: 001.0716.1017
Video Ver: 564869
Produce date: Aug 26 2013
 

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musashiaharon

macrumors newbie
May 1, 2014
5
0
BGR, not RGB

My image was inverted because I was further than the focal length of my lens. It's actually BGR. (Edit: added photo using a different lens.)
 

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musashiaharon

macrumors newbie
May 1, 2014
5
0
I found a partial solution to the disappearing lines.

Since the Mac detects the Seiki monitor as a TV, it tries to use the YCrPb color space when sending data to the TV. This leads to subpixel inaccuracies. By forcing the Mac to use the RGB color space even on the Seiki TV, you can improve text render quality.

After running this ruby script, moving the config folder into /System/Library/Displays/Overrides and restarting, the text render quality was much improved:

http://www.ireckon.net/2013/03/force-rgb-mode-in-mac-os-x-to-fix-the-picture-quality-of-an-external-monitor/comment-page-3#comment-9463

Unfortunately, the rendering still changes every other pixel, but it is still much more readable than before. Here's an image of what the Mac is sending to the TV now.
 

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edanuff

macrumors 6502
Oct 30, 2008
318
80
The monitor's EDID should tell OSX what the subpixel ordering is.

edit: assuming the EDID specifies it correctly