Monitor Aspect Ratio versus Resolution
There once was a time, all monitors were CRT displays. But be they big or small, CRTs all had the same shape. Now that many of us are moving to LCD displays for photo editing, we have choices. And choices can lead to confusion.
VGA resolution is defined as 640 pixels wide by 480 pixels high. It's hard to believe, but back in the mid 1980s, that was considered high resolution. Then came SVGA at 800 x 600, followed in 1990 by XGA at 1024 x 768. For a fair while, this is where the state of the art remained unless you were willing to shell out the big bucks for UXGA ("Ultra XGA") at 1600 x 1200. But as resolution increased, aspect ratio remained constant. Each of these seemingly random pairings of numbers is exactly four- thirds as wide as it is tall. That's just the way they build both CRT monitors and television sets. As we entered the new century, movie theaters may have been projecting on ever wider screens, but CRTs just didn't lend themselves all that much to following this same trend.
The emergence of affordable LCD technology removed the design constraints that prevented monitors from getting wider. This ushered in a whole new range of designations for monitor resolution with one a common theme: whether it be WXGA, WSXGA or one of the other variations, most included the letter "W" for "wide." Rather than being the standard 4:3 aspect ratio, these new displays were commonly 16:9 or occasionally 5:4 ratio. A few CRT monitors featured nonstandard aspect ratios such as SXGA ("Super XGA") at 5:4 ratio, but this was mainly an LCD phenomenon.
None of this mattered much all that much though until the past few years when LCD monitors capable of the same color range and accuracy as CRTs had dropped in price to where most of us switched to using them. Of course, we basically had to switch to using LCD monitors since it was becoming almost impossible to even find CRT monitors. Most companies simply stopped making them as the market moved to LCD.
But as photographers gained back the huge chunk of space their old CRT occupied, some photographers got tripped up setting the resolution on their svelte new LCD display. It's no longer enough to pick the resolution that makes icons on your desktop look the size you expect them to. Now you also had to pick an available option that didn't stretch things to be the wrong shape. If you had a 5:4 ratio monitor and set the resolution to 1024 x 768 or one of the other "traditional" 4:3 resolutions things would look slightly stretched out side to side. If you had a 16:9 monitor and chose a 5:4 resolution you would experience a similar problem. While many would realize something was amiss and pick a different resolution I have talked to at least a few that didn't or at least didn't understand why the problem existed at all.
As wide screen displays become ever more popular, it is estimated that around forty percent of computer users still use XGA or SXGA monitors. As such, the issue of picking a screen resolution that matches the physical aspect ratio of your display will likely be with us for some time.
Generally, LCD displays are best run at their native resolution, whatever that may be. This provides for a one to one mapping between the pixels generated by your display driver and those on your monitor. Doing this isn't always practical though if your eyesight isn't up to the challenge, but if you do pick a resolution less than the native hardware one, be careful to pick one with the same aspect ratio to keep things from looking squished or stretched out.