richard@pantor.UUCP (Richard Sargent) (05/02/90)
> From: ritter@versatc.versatec.COM (Jack Ritter) > Message-ID: <20674@versatc.versatec.COM> > > I am considering buying a digital film recorder. I've seen 1 for > about $5K. It is a desk top model, with 4K lines of resolution. > By digital I mean: it inputs a targa file (or similar image file), > NOT analog video. It's the Matrix Pro Color. (Matrix was recently > bought by Agfa). At 4K scan lines max, I can print an image sized > up to 3500 high by 4000 wide pixels. (35mm film). As with everything, you get what you pay for. I am not criticizing Matrix. In fact, I quite like their products. I have worked with their film recorders for many years now. However, claims of 3K x 4K, while true, are also misleading. Our experiences have been that addressability may be high, but resolvability is a lot lower. I have heard claims that low priced systems have a resolvability measure that is about half the claimed resolution. Usually, the spot size is considerably larger than 1/4000th of the screen inside the camera. Very high-priced cameras actually do have resolution and addressability match 1:1. What you need for your application is something that you will have to determine. Just don't get fooled by marketing sweet talk. Claimer: we sell graphics systems, including Matrix cameras as well as our own. Richard Sargent Internet: richard@pantor.UUCP Systems Analyst UUCP: ...!mnetor!becker!pantor!richard
dave@imax.com (Dave Martindale) (05/04/90)
In article <66.UUL1.3#5109@pantor.UUCP> richard@pantor.UUCP (Richard Sargent) writes: > >However, claims of 3K x 4K, while true, are >also misleading. Our experiences have been >that addressability may be high, but resolvability >is a lot lower. I have heard claims that >low priced systems have a resolvability measure >that is about half the claimed resolution. Usually, >the spot size is considerably larger than 1/4000th >of the screen inside the camera. Very high-priced >cameras actually do have resolution and addressability >match 1:1. Actually, that's no longer true. For example, the high-end Celco recorder used to be called the CFR-4000, even though it had a vertical addressability of 8192 lines, and horizontal addressability was whatever you wanted (set by an analog trimpot). A data buffer limitation prevented you from having more than 4096 pixels or 2048 runs per scanline, though. The spot size of this recorder is specified as .0008 inch, with a 7 inch CRT of which about 6 inches is usable, so a 4:3 aspect-ratio image would actually occupy an area of 4.8 by 3.6 inches on the CRT. Dividing spot size into image dimensions gives an estimate of 6000 by 4500 pixels as the maximum possible resolution. Then the Dunn "8000-line" digital recorder came out, which certainly had no better resolution than the Celco (electrostatic focus vs. magnetic focus CRT). Celco responded by renaming their top-of-the-line machine the CFR-8000, without changing anything. Then Management Graphics came along with their "Solitaire 16", with an addressability of 16384 pixels, although it uses a CRT with a spot size rated at .001 inch - certainly no better than the Celco. Still, lots of people thought that 16000 sounded twice as good as 8000. Celco responded by making their data buffer and vertical DAC bigger, and now they too have addressability of 16384. But the maximum resolution of any of these recorders is still limited by the CRT spot size and faceplate diameter - and is still no more than 6000 x 4500; probably worse in fact. The Dicomed family has always had 15 or 16 bits of addressability in X and Y, while using a spot size comparable to these other recorders and a 5 inch tube, so it's no better either. One way of looking at it is that, with a 16K-addressability recorder, you can position lines or edges in the image with an accuracy of about 1/3 of the minimum possible line width. I *suspect* it would allow you to plot things like text and bar charts and so on with no anti-aliasing whatsoever and still get excellent results. So the extra addressability is actually useful in some circumstances. It just means that you have to be aware of the difference between addressability and resolution, and the fact that there is often a *large* difference between them. On the other hand, this is not a criticism of vendors like Celco, Dicomed, and Management Graphics - they produce film recorders that can give excellent images, by CRT film recorder standards. But they are expensive. And you do often get what you pay for. I was once asked to look at a low-end video-fed film recorder that didn't give sharp images. We took it apart, and found that: - the CRT was an ordinary consumer-type small CRT with a rounded (bulging) face; there is no way that the centre and edge of the image would ever be in focus at the same time. - the lens was an enlarger lens, which would not have been corrected for use at the reproduction ratio it was being used at, and was further degraded by use of a common "close-up filter" to keep the optical path short. - it looked like the manufacturer just picked filters that were roughly red, green, and blue, rather than matching their characteristics to the phosphor and film. In general, buying a high-priced film recorder gets you a CRT that was designed for imaging, a lens that is at least roughly suited to the task at hand, and reasonable-quality filters. So, do lots of tests when comparing recorders! Dave Martindale
cfchiesa@bsu-cs.bsu.edu (Christopher Chiesa) (05/05/90)
In article <66.UUL1.3#5109@pantor.UUCP>, richard@pantor.UUCP (Richard Sargent) writes: > > From: ritter@versatc.versatec.COM (Jack Ritter) > > Message-ID: <20674@versatc.versatec.COM> > > > > I am considering buying a digital film recorder. I've seen 1 for > > about $5K. It is a desk top model, with 4K lines of resolution. > > By digital I mean: it inputs a targa file (or similar image file), > > NOT analog video. It's the Matrix Pro Color. (Matrix was recently > > bought by Agfa). At 4K scan lines max, I can print an image sized > > up to 3500 high by 4000 wide pixels. (35mm film). I work for Light Valve Technology, a Kodak company which makes a high-resolution Digital Image Recorder. Our box would be a bit too expensive (about $239K) and non-desktop (comes with a MicroVax III to drive it) for your particular application, but I mention it here for the benefit of others who may be looking for a very high quality output device. I won't go through the full commercial plug, but anyone reading these words can get FREE information by contacting us at Light Valve Technology 100 King's Highway, Suite 1400 Rochester, NY 14617 or (716) 724-7269 Include your name and mailing address. I can also answer particular questions via e-mail at this username or (mail here will bouce to) Chris_F_Chiesa@cup.portal.com. Chris Chiesa Software Engineer Light Valve Technology (back in town for a visit and posting this from my old University account) -- UUCP: <backbones>!{iuvax,pur-ee,uunet}!bsu-cs!cfchiesa cfchiesa@bsu-cs.UUCP