bobp@amiga.UUCP (Robert S. Pariseau) (04/17/86)
TITLE: Long Persistence Color Monitors I strongly suggest you look into the possibility of using a "long-persistence" analog RGB color monitor with your Amiga computer. Use of such a monitor allows you to use your Amiga at 640x400 resolution without regard to choice of colors or contrast and the effect they may have on flicker. In a simple static image, this means that you can have true 16-color displays where each color is choosen out of the Amiga palette of 4096. NOT JUST MONOCHROME! Given the screen and COPPER software already in your Amiga, you can, of course, have many more than just 16 colors simultaneously displayed on your hi-res display -- mixed with even more colors from your low-res screens simultaneously displayed! Need I point out the advantage of having to use only one monitor for both low-res and glorious, multi-color hi-res? There are already Amiga application programs available which take advantage of the Amiga's full-color hi-res displays. For instance Deluxe Paint from Electronic Arts. At a recent IEEE conference, all of the technical slides we presented about the Amiga were constructed ON an Amiga, in hi-res, using Deluxe Paint. Needless to say, the (er...) competition couldn't make such a claim due to an unfortunate lack of sufficient color in THEIR hi-res. In addition, the V1.2 system software will support standardized Workbench display at 640x400 resolution as a Preferences selectable option. The limiting factor, up to now, in getting people to use hi-res on the Amiga has been annoying display flicker. The physiology of flicker perception is pretty well understood. The eye's ability to perceive flicker goes up as the contrast between adjacent horizontal lines goes up and, also, as the overall illumination (screen plus room lighting) goes up. Back when the current TV standards were designed, the engineers realized that the physics of TV cameras would keep the contrast down -- so they took the cheap way out and choose a 30Hz interlaced frame rate. It turns out the eye can perceive flicker at anything under about a 50Hz rate if the contrast is high enough. That's why you don't see flicker on your TV screen until someone puts up a good contrasty image such as the computer generated graphics they put on during football games. The Amiga computer is designed to be compatible with the NTSC standard (which defines broadcast quality TV). That means we update our 320x200 and 640x200 displays at a 60Hz rate and we update our 320x400 and 640x400 displays at a 30Hz rate (actually, every other line is displayed in one pass and then the skipped lines are displayed in a second pass -- each pass takes a 60th of a second, so the whole picture takes a 30th of a second to redisplay -- this is, in essence, what "interlace" is all about). Because of that, if you have a sufficiently contrasty image (such as alternating black and white horizontal lines (cringe!)) you will see flicker on a regular persistence monitor -- such as the Amiga 1080. Many people already use the x400 displays on the Amiga by dint of adjusting the display colors, the room lighting, and the brightness of their monitor display to the point where they, personally, do not see an objectionable amount of flicker. The other way to do it is to use a different style of monitor. The competition does it by using a monitor (and the corresponding display hardware inside the computer) that receives all 400 lines in one pass and, thus, updates at a rate faster than the eye can follow. That works fine, but requires so much data to come out of the computer each 60th of a second that they don't have sufficient memory bandwidth to put out lots of colors. We suggest you use a long persistence monitor. This is a monitor that uses color phosphers on the display tube that retain the image of one display frame just long enough for the computer to come around and put up another display frame. Effectively this eliminates flicker. There are two commonly heard objections to long persistence monitors. First is the objection that they "smear" a moving image. This is certainly true to an annoying degree on MONOCHROME long persistence monitors where the "real" image is the same color (usually green) as the "smeared" image left behind when it is moved. On a COLOR long persistence monitor there are 3 color phosphers in use. The green phospher retains the image longer than the other two so that whatever smear is produced is, basically, green. But in a color image, most if not all of the "real" image is NOT green. Thus the brain readily rejects the smear and perceives only the moving real image. My personal experience with these monitors is that you don't "see" the smear unless you are "looking" for it -- something which I didn't believe until I tried it myself. We've now got enough people using these beasties on Amigas that I'm happy to report that everybody agrees. You only see smearing on really active animations such as the "Fields" graphics demo. In practical applications it is no problem. The other common objection is that long persistence color monitors are too expensive. This is true now, but not likely to be true for long. Basically the pricing on these monitors is about where the pricing on regular persistence analog RGB monitors was early last year -- AND FOR THE SAME REASON -- namely that volume sales are just starting. There is NOTHING inherent in the long persistence monitor which should increase the price over a comparably featured regular persistence monitor -- it's the same electronics, just a different phospher painted on the tube. I predict that by the end of this year there will be no significant difference in price between the two types of monitors. Of course you have the PRICE ADVANTAGE of being able to use JUST ONE monitor for both hi-res and low-res images. With both resolutions in beautiful full color. ----------------- For those of you who'd like to try out a long persistence monitor, here is info on two such monitors you can buy right now and use with your Amiga computer. Note that both of them are a little spendy, but that's because both of them (particularly the Electrohome) are lab-grade high end monitors. Electrohome model #ECM1301, High Resolution Color Monitor. Be sure to order the RS170 RGB Module as well. We recently purchased such a combination for $1360 (plus tax) from Videomedia, 211 Weddell Drive, Sunnyvale, Ca. 94089, phone (408)745-1700. If you're out of the area, you might try getting in touch with Electrohome directly in Kitchener, Ontario, Canada. This monitor is truly a high end monitor with all the goodies built-in, and thus the price. Mitsubishi model #c-3479LPAG-WC, High Resolution Color Display Monitor. The WC in that model number means "with cabinet" -- otherwise you get something that looks like the inside of your TV set. We recently purchased one of these for $1000 (plus tax) from Computer Modules, Inc., 1190 Miraloma Way Suite Y, Sunnyvale Ca. 94086, phone (408)737-7727. If that doesn't do it for you, I'm not sure how you can find your local Mitsubishi rep. There are undoubtedly other such monitors around -- if you lobby with your friends in the biz there will be even more (and cheaper ones) soon! If you find another one you like, let me know and I'll spread the word. Enjoy!