rick@soma.bcm.tmc.edu (Rick Gray) (12/15/87)
We are currently investigating ways to obtain high-quality color slides
from our Masscomp displays. Most of our graphics uses GPS format
(created with either Masscomp Data Presentation or Creare mcplot
software, or ged output) although we occasionally would like slides or
prints from images created with Doug Logan's Masspaint program or
possibly future images obtained with a scanner. With GPS files we have
the option of making a high resolution hardcopy, then photographing
that, but that isn't possible with bitmap files (at least we don't know
how to do it). We already have the ability to get good-quality black &
white plots of GPS files using either:
1) a pen plotter and drafting pens; or
2) a filter we wrote using the Masscomp-supplied gpsras filter and a
simplified version of their ACT color printer driver to output GPS
files to a HP Laserjet II at 300 dpi.
We would like to minimize the amount of darkroom work required to make
color slides, since we aren't set up for color processing in our lab. The
options we are working on now are:
1) Directly photographing the screen of an Aurora (1152x910) with a 35 mm
camera, using either Ektachrome or Polaroid Polachrome film. This
provides pretty good slides, but it's tricky to get even brightness
across the slide, and the image has to be reduced to ~75% to reduce
visible curvature. We also have 19" (832x600) and 12" (640x480) color
graphics tubes, but the lower resolution only makes things worse.
2) We are working on a GPS to BGL (Business Graphics Language) filter so
we can send files to our Medical Illustration Department's
high-resolution slide maker system. This looks promising, but since
they support many different fonts, some hand editing of the BGL file
will be necessary to get exactly what we want. We also have to wait
for them to make the slide and pay a healthy price for it (~$5/slide).
3) We have a Polaroid Freeze-frame Video Image Recorder as part of an
image analysis system, but it expects either 15.75 KHz NTSC color
composite or 15.75 KHz RGB input. All of our Masscomp color tubes have
a much higher horizontal scan frequency (30.86 KHz on the 12"; 32.4 KHz
on the 19"; and 63.34 KHz on the Aurora).
So, here are our questions:
1) Is there any way, preferably through software, to slow down the
horizontal scan rate on any of the graphics processors so we can use the
Polaroid Freeze-frame with our Masscomps? If that's not possible, is
there any way we can build a circuit to make the output compatible
with the Polaroid unit? [We can build practically any circuit, but
buying a $10K+ film recorder is not an option for us.]
2) How do other folks make high-quality color slides or illustrations of
data collected with their Masscomps (or any other graphics workstation)
for presentation?
--
Rick Gray uucp: {rice,shell}!soma!rick
Program in Neuroscience arpa: rick%soma.uucp@tmc.edu
Baylor Col. Med., Houston, Tx 77030dave@onfcanim.UUCP (Dave Martindale) (12/23/87)
In article <3286@soma.bcm.tmc.edu> rick@soma.bcm.tmc.edu (Rick Gray) writes: >We are currently investigating ways to obtain high-quality color slides >from our Masscomp displays. [ ..... ] >The options we are working on now are: > >1) Directly photographing the screen of an Aurora (1152x910) with a 35 mm > camera, using either Ektachrome or Polaroid Polachrome film. This > provides pretty good slides, but it's tricky to get even brightness > across the slide, and the image has to be reduced to ~75% to reduce > visible curvature. If the brightness change across the image is due to the monitor (measure with a spotmeter, or use a reflected light meter up close), look for a better monitor if you can. However, light falloff at the edges is also produced when you use a camera lens wide open. Closing the aperture a couple of stops will help considerably. If the image on the screen itself has curved sides, try to adjust the monitor's pincushion correction to fix it. If the curvature appears only on your photographs, it's because the CRT face itself is curved and the camera lens is designed to image a flat plane onto the film with minimal distortion. To reduce this, use as long a focal length of lens on the camera as you can manage in the space available. (This may help edge darkening problems too). >1) Is there any way, preferably through software, to slow down the > horizontal scan rate on any of the graphics processors so we can use the > Polaroid Freeze-frame with our Masscomps? If that's not possible, is > there any way we can build a circuit to make the output compatible > with the Polaroid unit? [We can build practically any circuit, but > buying a $10K+ film recorder is not an option for us.] I don't know about the Masscomp hardware, but you might not want to do it anyway, since you will then be limited to about 640x480 at best in resolution. If you can live with the reduced resolution, and the Masscomp frame buffer can't put out NTSC timings, there are scan conversion boxes around to convert the video signal to NTSC. However, they cost more than $10K, and suffer from the same resolution limitation. For more info on generating standard video, see "The Usable Intersection of PC Graphics and NTSC Video Recording", Tom DeFanti and Don Sandin, IEEE Computer Graphics and Applications, Vol 7 #10 (Oct 1987). Dave Martindale
pun@cui.UUCP (PUN Thierry) (01/04/88)
In article <3286@soma.bcm.tmc.edu> rick@soma.bcm.tmc.edu (Rick Gray) writes: >We are currently investigating ways to obtain high-quality color slides >from our Masscomp displays. Most of our graphics uses GPS format > .... > >So, here are our questions: > >1) Is there any way, preferably through software, to slow down the > horizontal scan rate on any of the graphics processors so we can use the > Polaroid Freeze-frame with our Masscomps? If that's not possible, is > there any way we can build a circuit to make the output compatible > with the Polaroid unit? [We can build practically any circuit, but > buying a $10K+ film recorder is not an option for us.] > >2) How do other folks make high-quality color slides or illustrations of > data collected with their Masscomps (or any other graphics workstation) > for presentation? > >-- >Rick Gray uucp: {rice,shell}!soma!rick >Program in Neuroscience arpa: rick%soma.uucp@tmc.edu >Baylor Col. Med., Houston, Tx 77030 Answer to 1) : none that I know of. Answer to 2) : we bought a $10K film recorder, namely the Dunn 638 Ultra-High scan line rate. At the time, it was the only device we found who was able to accept the video signal from our Suns. We are rather satisfied with it, although we still have some (hopefully minor) problems with it. Dunn is in California, 415-957-1600. We can use 35mm or Polaroid films. Good luck Thierry Pun Centre Universitaire d'Informatique, University of Geneva 12, rue du Lac CH-1207 Geneva SWITZERLAND Phone : (22) 87 65 82 EAN : pun@cui.unige.ch UUCP : seismo!mcvax!cernvax!cui!pun BITNET : pun@cgeuge51
dave@onfcanim.UUCP (Dave Martindale) (01/11/88)
In article <3286@soma.bcm.tmc.edu> rick@soma.bcm.tmc.edu (Rick Gray) writes: > >2) How do other folks make high-quality color slides or illustrations of > data collected with their Masscomps (or any other graphics workstation) > for presentation? A very flexible method, but one that requires writing some software, is this: Display whatever image you want on your workstation. Then run a program that grabs the contents of the screen frame buffer and writes it into a file. You now have an image file that is the same resolution as your screen, but in digital form, so you no longer care about the video sweep rates used by your workstation. Now, pick an image recording device. If you have a digital film recorder (i.e. one that is fed with a stream of numbers, not a video signal) which directly supports the resolution of the file you have, that's all you need. If it supports a different resolution (some digital film recorders have fixed 2048 or 4096 X-resolution) then you need to resize your image to fit the recorder. For best results, you'll probably want to use linear or cubic spline interpolation, though if the recorder's resolution is an integral multiple of the workstation's simple pixel and scanline replication will also work. If you don't have a digital film recorder, but do have a video-fed film recorder attached to some other workstation or frame buffer (you mentioned a Polaroid Freeze-Frame), then resize the image to fit this workstation or frame buffer and record it from there. Frame buffers supporting NTSC scan rates are typically 512 or 640 pixels in X by 480 or 485 in Y; you may have to deal with pixels that are not square during the resizing. This also allows recording directly to single-frame video equipment if you have it. The above discussion assumes that the original image was RGB. If, instead, it made use of the colour lookup table to set colours, you'll have to deal with that. Sometimes you can just pass the lookup table to the output device and have everything work, but generally you'll have to convert to RGB (particularly if you use interpolation when resizing, since that will produce colours that weren't in the original image). Although this method is slower than just buying the right video-fed film recorder for your workstation, it will work with any film or video output device and any number of different workstations, provided that: 1) You can grab the image from the workstation screen in raster form 2) You can record an arbitrary raster image on your recording device provided it is the correct resolution During the past few weeks, we transferred 60 seconds of animation (at 24 fps) from an IRIS workstation to video via the following process: 1) display each frame on the IRIS, grab screen contents and write to file 2) record each frame on film using a Celco digital film recorder (the Celco was set up for 1024 x 768 so no resizing was necessary) 3) process the film and get a print 4) transfer the film to video. All of the repetitive processes were controlled by scripts or file lists of some sort, so most of this proceeded unattended. (You can't expect a human operator to do anything correctly 1500 times in a row anyway.)