pun@cui.UUCP (PUN Thierry) (03/02/88)
Hello !
Does anyone have experience (directly or indirectly) concerning
* the thermal transfer color printer Tektronix 4693D
(claimed at a full 16.7 million colors);
* the Parallax Graphics Processor Series 1280, which allows
display of a live video image in a workstation window.
More particularily, these two devices can be hooked-up to a Sun.
Has anyone tried it ?
Thanks in advance for any reply !!
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@cgeuge51jru@etn-rad.UUCP (John Unekis) (03/05/88)
In article <105@cui.UUCP> pun@cui.UUCP (PUN Thierry) writes: >Hello ! > >Does anyone have experience (directly or indirectly) concerning > * the thermal transfer color printer Tektronix 4693D > (claimed at a full 16.7 million colors); > * the Parallax Graphics Processor Series 1280, which allows > display of a live video image in a workstation window. >More particularily, these two devices can be hooked-up to a Sun. >Has anyone tried it ? Yes, we have both of these devices hooked up and working. We have Parallax graphics boards in an IBM PC/AT, a microvax II, and a SUN3. The parallax boards are well designed and function as advertised. You will need a SUN3 that has 2 or 3 spare VME slots. The parallax will indeed display a continously digitized NTSC video frame within a window on the 1280x1024 display. The video window is 640x480 in size, and can be placed anywhere on the screen(on an even 16 pixel boundary). Be advised that you must write some code in C to call the library functions which drive the parallax. The only drawbacks to the parallax are that they run HOT (I mean physical temperature) and they are power hogs. As long as you have adequate power supply in your system and enough cooling fans this will be no problem. NOTE: The parallax has two data modes for the display memory, one is 8 bits per pixel, with a separate 8x8 Look up table for each color, giving 256 out of 16.7M colors. The other mode is HSI (hue, saturation,and intensity) which uses blocks of four pixels , the 5 lowest bits are intensity, the next two bits of all four pixels are hue(sort of color) , and the upper bit of the four pixels has saturation(I think I am reporting this accurately). The video display window uses HSI format, so If you stop digitizing and copy the video window to somewhere else in memory, the display will be quite bizarre, ask parallax about conversion from HSI to normal display if you need it. As to the Tektronix 4693D, we have had one working for several months now, It accepts data and instructions over a centronics parallel interface. The documentation for the format of header information for the printer is very poor. If you do not purchase an existing software package to drive the printer you will need help getting the format correct. If this is a problem, send e-mail to me and I will explain in detail. Also, the Tektronix manuals exaggerate about the resolution of the printer. They claim that it will print at 300 dpi (12 dots per mm) and will produce 256 shades of grey or 16.7 M colors. This is very misleading. The resolution is indeed 300 dpi, but the monochrome and color shades are produced by an adaptive dithering algorithm. The printer is really a SHARP (of Japan) printing engine to which Tek adds a MC68020 processor and 4Meg of ram. The Tek enhancements allow the printer to receive an image as 8 bits per color per pixel, then perform a very intelligent adaptive dithering process before printing. But in order to produce a full 256 shades of grey or 16.7 M colors, the printer must use a 16x16 pixel box, so in full color the real resolution is about 19dpi (1 dot per mm). On most images the dithering is done so well that you will hardly notice, but if the image has lots of fine detail you will either lose detail or color accuracy. The printer is still a fine product, and we use it extensively to demonstrate our imaging system, but you must be aware of its limitations. --------The above are my opinions, not those of my employer-----------