dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi) (12/09/90)
Let's just clarify a few things here. The crispness and detail visible on a display (which is what the eye cares about) depends on three things: (a) the sharpness of the electron beam, (b) the number of scan lines, and (c) the screen. The electron beam must be sharp, and I mean "sharp" in both a static and a dynamic sense. In the static sense, the size of the electron beam must be small when it hits the screen. This is a function of how well it's focussed. In the dynamic sense, the brightness (modulation) of the electron beam must vary quickly and precisely as it scans horizontally. This is a function of the video bandwidth. The sharper the electron beam, the better the resolution in the horizontal direction. The greater the number of scan lines, the better the resolution in the horizontal direction. The screen must respond properly to the video beam. This is more critical on a color display, in which case the smaller the dot pitch, the better the sharpness of the screen. Also, when the electron beam hits the phosphor, the light generated scatters in many directions. A good screen phosphor suppresses excessive scatter, so the eye sees a tiny point and not a fuzzy circle. Once the beam hits the phosphor, the phosphor should remain lit for long enough but not too long. If it's lit for not long enough, you may see flicker. (This flicker can be suppressed by a higher vertical scan rate. Around 60 to 70 Hz is good, but 100 Hz is better.) If it's lit for too long, changing images will be mushy. Claims like "1000 x 9000 resolution" have no meaning. Claims like "1000 x 9000 screen pixels" do have some meaning, but the meaning is not necessarily related to resolution. Ideally you need to specify video bandwidth, number of pixels in both directions, and dot pitch. -- Rahul Dhesi <dhesi%cirrusl@oliveb.ATC.olivetti.com> UUCP: oliveb!cirrusl!dhesi
sdawalt@cs.wright.edu (Shane Dawalt) (01/07/91)
From article <2788@cirrusl.UUCP>, by dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi): > Let's just clarify a few things here. The crispness and detail visible > on a display (which is what the eye cares about) depends on three > things: (a) the sharpness of the electron beam, (b) the number > of scan lines, and (c) the screen. > <lotsa interesting stuff deleted> > > Ideally you need to specify > video bandwidth, number of pixels in both directions, and dot pitch. I understood everything except "dot pitch". I have never been able to figure out what exactly "dot pitch" means. All I know is that .28 is suppose to be good!?!?! Care to elaborate? If this has been addressed before then I'm sorry. Obviously, I haven't seen it. Shane(); +--------------------------------------------------------------------------+ | Shane A. Dawalt (sdawalt@cs.wright.edu) | +--------------------------------------------------------------------------+ -- +--------------------------------------------------------------------------+ | Shane A. Dawalt (sdawalt@cs.wright.edu) |