I don’t even begin to know how to search for a solution to this problem, let alone fix it. Maybe just by forcing myself to describe it, I’ll see through to a solution. If not, then I hope there’s someone out there who might be able to point me in the right direction.
On my Lenovo X200 running an up to date install of Ubuntu’s Intrepid Ibex, I too see a smooth gradient—except on the far right, where it should be super dark gray just before the black, my screen breaks out in a case of adolescent 8-bit dithering.
I can tell you one thing, it makes editing photos with dark areas really really annoying.
Here’s my /etc/X11/xorg.conf file (minus the commented-out header bits at the top). It comes whole hog from ThinkWiki.
Section "Monitor" Identifier "Configured Monitor" EndSection Section "Monitor" Identifier "HDMI-1" Option "Ignore" "True" EndSection Section "Monitor" Identifier "HDMI-2" Option "Ignore" "True" EndSection Section "Screen" Identifier "Default Screen" Monitor "Configured Monitor" Device "Configured Video Device" DefaultDepth 24 SubSection "Display" Modes "1280x800" "1024x768" # The following line was an auto-configuration added by an external VGA projector; you might leave it out to try # letting the system detect dimensions appropriate for whatever display you happen to use. Virtual 2432 864 EndSubSection EndSection Section "Device" Identifier "Configured Video Device" Driver "intel" Option "monitor-HDMI-1" "HDMI-1" Option "monitor-HDMI-2" "HDMI-2" EndSection
Apparently this is my video card driver:
$ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
Is this the right driver? I have no idea. The X200 comes with an Intel Graphics Media Accelerator 4500MHD.
In an online forum I read:
if you see dithering in certain colors then it’s because notebooks use 6-bit displays and simply cannot reproduce all colors correctly. this phenomena is different than grain but will make a display look grainy under certain conditions.
Is that correct?
The comments in this official Lenovo blog post seem to confirm the above:
Over on Wikipedia I learn that TN stands for twisted nematic:
Also, panels that represent colors using 6 bits per color, instead of 8, are not able to display the 16.7 million color shades (24-bit truecolor) that are available from modern graphics cards. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use Frame Rate Control (FRC), which cycles pixels on and off to simulate a given shade. These color simulation methods are noticeable to most people and bothersome to some. FRC tends to be most noticeable in darker tones, while dithering appears to make the individual pixels of the LCD visible.
I’ve got your citation right here! But seriously, I have no idea if this 6-bit to 8-bit FRC translation is this really my problem. All I know is that the X200’s LCD panel is a 12.1″ WXGA. But is the dithering an innate hardware limitation, or a fixable software issue?
Wow, I feel like I’m getting a whole education on this. Especially when I read things like this: “There are no real 8-bit screens for notebooks at this point, it’s 6-bit like any other notebook panel.” When did the collective laptop industry go to shit?
Apparently a year ago Apple quietly settled a lawsuit over dithered laptop displays, this very issue. Apple? 6-bit per color displays. WTF? It’s like I’m in the twilight zone.
Note: I’ve removed “running Ubuntu” from the title, because it’s becoming clear to me that this is an innate AND AGGRAVATING hardware limitation, not a product of my running Ubuntu.