Xref: utzoo alt.next:84 comp.graphics:3368 Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!labrea!agate!violet.berkeley.edu!edmoy From: edmoy@violet.berkeley.edu Newsgroups: alt.next,comp.graphics Subject: Re: NeXT Message-ID: <15522@agate.BERKELEY.EDU> Date: 15 Oct 88 18:37:19 GMT References: <4431@polya.Stanford.EDU> <3686@peora.ccur.com> Sender: usenet@agate.BERKELEY.EDU Organization: University of California, Berkeley Lines: 27 In article , gaynor@porthos.rutgers.edu (Silver) writes: > rokicki@polya.stanford.edu writes: > >17" monochrome monitor, providing 1120x832 pixels at two bits per pixel. > >(Two bits/pixel implies four gray levels, rather than two, and allows for > >richer graphics.) Monitor includes 8 bit codec for voice input and 16 bit > > Would one of you more studly graphics folks tell me the advantage to doing > things thus, as opposed to providing one-bit pixels at somewhat finer > resolution? Sufficient response will be answered in summarization. I thing the main reason for having 2 bit planes is to be able to do highlighting of objects on the display, such as buttons and text in menus. Since PostScript is an imaging model, it can't do bit manipulation of the image, such as using XOR for highlighting. The Display PostScript in the NeXT machine has enhancements to regular PostScript, but to handle highlighting they have implemented something called "Alpha Channel" which I don't understand very well. Anyways, when they want to highlight black text on a white background, they change the white to light or dark gray, and then back to white when they are done. Edward Moy Principal Programmer - Macintosh & Unix Workstation Support Services Workstation Software Support Group University of California Berkeley, CA 94720 edmoy@violet.Berkeley.EDU ucbvax!violet!edmoy