jpd00964@uxa.cso.uiuc.edu (08/25/89)
/* Written 8:26 am Aug 23, 1989 by kk@mcnc.org in uxa.cso.uiuc.edu:comp.sys.mac.programmer */ /* ---------- "Re: Meaning of visRgn in offscreen" ---------- */ >>BitMaps are slow because they are sent as Hex data as required by PostScript. > >I've just looked it up in the Adobe manuals: Hex or binary turns out to be >the same bits (unless LW driver tries to do some fancy data compression >while sending it over). hex is just encoded binary. However, this is not what the original meant. It is sent as hex data as opposed to a tokenized image. >The way Ifigure it out, it should take about 3 seconds to print a full-page >bitmap at 25% reduction with 'exact bimap image' turned ON. (this is assuming >transfer rate about .5Mbytes per second - I seem to recall this value from >somewhere in the IM). Can anybody tell me why it ain't so? The transfer rate is no where near that. That would be on an empty appletalk network with no overhead. Appletalk packets have overhead, and there are always people talking over the network at least saying I am still alive. Also the rate is roughly half that. But even so, data transmission is not the limiting factor here. The imaging rate is. Even though you are sending a bitmap, that bitmap is not going to be represented at the same resolution, or rather, postscript encoding will not gaurentee that it is identical. That means it must be re-rendered, and all those pixels must be turned either on or off accordingly. That is why it is so slow. It must convert your bit-map into its own bitmap. Michael Rutman