eli@spdcc.COM (Steve Elias) (01/09/89)
eli@ursa-major.spdcc.COM (Steve Elias) writes: > > for greyscale you will need group 4. nobody has > these for PCs yet... or much else... big $$$. this isn't exactly right... there are some group 3 machines which support a proprietary greyscale system. (it won't transmit to another vendors fax machine)... CCITT is going to come out with a standard for group 3 greyscale soon -- if they haven't already... by the way -- is someone going to get in trouble for not naming this newsgroup alt.weemba.fax ? -- Steve Elias (eli@spdcc.com) ((617 239 9406)) (((617 890 6844))) ()
domo@riddle.UUCP (Dominic Dunlop) (01/11/89)
In article <2388@spdcc.SPDCC.COM> eli@ursa-major.spdcc.COM (Steve Elias) writes: (apparently replying to himself!) > eli@ursa-major.spdcc.COM (Steve Elias) writes: >> >> for greyscale you will need group 4. nobody has >> these for PCs yet... or much else... big $$$. [My understanding is that group 4 goes at 64 kbit/sec, and requires a digital circuit (such as an ISDN connection). Right or wrong, anybody? (Group 3 goes at 9600 bits/sec over a voice connection.)] > > this isn't exactly right... there are some group 3 > machines which support a proprietary greyscale system. > (it won't transmit to another vendors fax machine)... > CCITT is going to come out with a standard for group 3 > greyscale soon -- if they haven't already... My company has a Canon group 3 (ie mass-market standard) fax machine which does a greyscale which can be recieved by any other group 3 fax machine, whether made by Canon or not. It works by doing a half-tone analysis of the image, in much the same way that one must do to get greys from standard printing processes -- or from laser printers. As the resulting image is simply made up of little black dots, of course any receiving fax machine can handle it. What's the catch? Images take A G E S to transmit: group 3 embodies a compression algorithm which relies on the presence of runs of black (or white) pixels. Such runs are absent in the grey areas of a half-tone image, so no compression is possible. We hardly ever use the facility. I don't even think that our operator knows how to select it... Scrabbling madly around for a PC connection, does anybody know if the PC (and Macintosh) fax connections now available can handle greyscales and/or half-tones? How? -- Dominic Dunlop domo@sphinx.co.uk domo@riddle.uucp