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In a multi-monitor configuration, a number of web pages are appearing differently when the page is dragged to the other screen.

Example

The URL I'm testing is this one. http://www.lgsolutions.com/products/lcd-monitors/lg-cloud-monitors

Side by side example

The brighter monitor has Gamma, Brightness, and Contrast set so that the image should appear, but doesn't. By default, Gamma is way too bright on the LG E2411

enter image description here

Dell Monitor Close up

Note This image is dim because it reduces eye strain

enter image description here

LG E2411 Monitor Close up

(page is stretched across both screens)

enter image description here

Counter Example

If I use a Dell monitor in replacement for the LG monitor then the web page appears correctly. This occurs when the Dell monitor uses a different driver than the default windows one.

I just got off the phone with a CDW technician, and he has the same issue with a different brand of monitors. The only common configuration we both have is that we use the Microsoft PnP driver on Windows 7.

Question

Could it be that the PnP driver in Windows 7 has issues rendering web pages in a multi monitor configuration?

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1 Answer 1

up vote 6 down vote accepted

Different monitors will often display images differently even if you have the same brightness/contrast/gamma settings across both. This is especially true of monitors from different companies.

The reason for this is because, simply, no two LCD panels are equal (unless they're the exact same model/SKU, of course). Even if they both are rated for certain contrast ratios, color depths, etc, they still may have different colorspaces (aka color gamuts). At the most basic level, each pixel is assigned a color based on a set of three numbers: the red component, the green component, and the blue component. What changes based on the manufacturer is the question of what pure red looks like, pure green looks like, and pure blue looks like. Even though these three colors still may be combined to create 2^32 different color shades, the actual hue of the primary color itself can still differ depending on how the panel is manufactured. This means that the appearance of red, for example (#FF0000) on one monitor will not necessarily exactly match its appearance on the other monitor.

Each display has its own color gamut. A color gamut is basically a description of the colors that a monitor is physically capable of displaying. The gradients that appear as you sweep from one color to another is a part of how that's defined. Because of the way the human eye perceives color, the practice of designing a display that outputs color in a fashion that looks both complete and pleasing to the eye is a very researched one. Because of the inherent differences between displays themselves and between how we may perceive color and how we expect color to look, we have gamma correction. Gamma correction describes how we compensate for these differences.

You may be familiar with the gamma curve (example below). What this does is adjust the luminosity values for each shade in the scale such that it matches some desired appearance (for typical viewing, it may be an linear attenuation, or if you're in publishing, it may match the output of the printer you use).

For you, since you set your software gamma settings across both monitors, that accounts for some of it, but it will not cause both monitors to match. Because they have different color spaces, you will not likely find a way to get the images to match exactly. Next, I would try seeing if I could change the color temperature and brightness/contrast values of each monitor through its on-screen controls, but that will only go so far.

If you want both monitors to display the exact same image, the best solution is always and always will be to simply buy two of the exact same monitor.

Example gamma curve for CRT monitors

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Even the same monitor will not always show the same image over time. However, I think that you could have just said, check your contrast brightness settings on the monitor. Though, way to go the extra mile. :) –  kobaltz Jul 12 '12 at 16:45
    
That is true, possibly because of deterioration of the display panel itself, or the monitor cable (at least with VGA monitors). Differences in Windows' color settings could account for that too. All other things being equal, though, the same monitor should always produce the same image. –  Ben Richards Jul 12 '12 at 16:47
    
Correction: Windows 7 allows me to set Gamma settings specifically for each monitor –  makerofthings7 Jul 12 '12 at 18:44
    
Note that I did adjust contrast and brightness and am still unable to see the grey bar. Isn't there a level of quality that a monitor should adhere to? If I only had this one LG monitor editing a web page, I'd be going crazy trying to make the CSS work when my display is wrong. –  makerofthings7 Jul 12 '12 at 18:46
    
@makerofthings7 You can determine that the gray bar is actually there (and I see no reason why it wouldn't be) by screencapping and then using the color picker tool in an image editor tool. But, whatever standards there are, they aren't all geared towards those whose work is sensitive to displaying color with certain accuracy. People who are painters or photo editors often seek out a certain class of display (such as those with IPS panels), because they aren't all created equal. –  Ben Richards Jul 12 '12 at 19:15

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