I have a Samsung DLP TV (HL50A650) and I had a difficult time getting it to display 1920×1080 resolution over the D-sub connector(VGA). In Windows XP I was eventually able to accomplish this, but later when I upgraded to Windows 7 64bit I was no longer able to get the ATI driver to run my TV at a 1920×1080 resolution at the required 60hz. As a matter of fact the manual indicates that resolution is supported over HDMI, and not over D-sub.
I was able to get the resolution from my computer at 1920×1080 with an HDMI cable, but the text was very blurry and jagged. It was nearly unreadable and very hard on the eyes. Other normally crisp graphics were also effected. In actuality the problem was a Sharpness setting on the TV that needed to be turned down to around zero or close to it. The extra sharpness post-processing was making the text and graphics jagged along the edge, and the mixing of adjacent colors made it appear blurry and jagged at the same time. Note that this Sharpness setting is specific to the selected video source, so make sure you change your input source to the computer’s HDMI3/DVI input source(you did plug it into HDMI 3 right?) , and then hit Menu on your Samsung remote and turn the Sharpness all the way down. Once I turned it down to 2, my image was perfect. I actually first switched the Mode setting on that same first Menu screen to Movie, as I liked the colors there the most, but it will look really horrible until you turn the Sharpness setting down. So it was really difficult to figure the problem out because there were multiple problems working against me when I first began. I now sit about 5′ from my 50″ TV and enjoy a huge space for my applications, games, and movies at a 1920×1080 HD resolution.
What everyone was saying on the forums regarding the Samsung DLP models was that it wasn’t producing the graphics in a one to one pixel mapping. Thus some pixels were being interpolated between a straddled pixel causing poor graphics quality. This is not true however, at least for my model. What was happening actually was the DLP TV was doing image processing based on it’s settings, and one of those settings was the Sharpness setting was jacked way up by default. Note, the settings you get when you press the Menu button on the Samsung remote are specific to the currently selected source. So normally Sharpness might be way down, but when I switched to the HDMI source, I found the Sharpness setting was jacked half way up to 50. Normally Sharpness should be all the way down or very close to zero. You would think, “Oh sharpness would make the image sharper and better, so that’s not the problem.” But it is the problem! The sharpness setting determines how much post-processing takes place, and normally if you have a quality image, you need no post processing, which is the case with an incoming computer signal. When you add more sharpness to an already sharp image, then it starts turning smooth curves into jagged steps and it messes up the colors to add contrast to adjacent colors. In a nutshell, use the Tools or Menu buttons on your Samsung remote to access the TV’s sharpness setting, and turn it all the way down(from 50 down to 1) and hopefully that will fix your blurriness problem.
Also see my article on troubleshooting Windows 7 display resolutions and the EDID setting, since it may be helpful if you have a similar TV hooked up to your computer.