VNC request

Kenneth Albanowski kjahds "at"
Sun, 11 Oct 1998 21:31:51 +0000

On Mon, 12 Oct 1998, kandalva wrote:

> Dear Sirs,
> I use beta version of VNC for Macintosh,and works fine. :)
> But I want to suggest to add this feature to VNC.
> On server side,convert color screen to Black&White with
> dither and send to client as B/W graphic. It will boost-up 
> network performance about 8 times faster than 8 bit mode.

I expect this will not help, for two reasons. First, the VNC protocol has
no ability to transmit pixels in less then a byte, so 8-bits per pixel is
the minimum. (If I'm wrong, I'd like to hear about it.) 

Also, even if VNC could send 1-bit data, any dithering will undoubtedly
reduce the compressibility of the information, compared to chunks of solid
color on a normal color display. This would be especially acute if you
tool an actual color Mac screen and algorithmically dithered it to B&W. 

However, you should be able to use this already, though without most of
the speed gain: just go in to the Mac's Screen control panel, and switch
the display to 1-bit B&W. Assuming the VNC server understands this (I'm
not sure), you'll get mostly undithered B&W, which should compress quite

> It is not good for looking graphic(and color) depended
> work,but it is still enough to look whether server works fine,
> or see server for programming or writing and so on. 
> And it is useful for slow connection,such as ISDN,telephone.
> How about do you think this idea?

Very sensible, and very useful with a Mac (which still, to this day,
understands how to draw applications on a 1-bit screen.) It won't be
nearly as useful with a PC server, unfortunately. (With the coming of
multi-head, multi-depth versions of Windows, we might just see support for
1-bit B&W, since the technique the Mac uses to let a window sit across two
screens of different depths is also the technique that lets a window
display properly at 1-bit B&W as well as 24-bit color on a single head. I
wouldn't bet on MS getting this right, though.) 

I believe the X server should also understand 1-bit B&W, but I'm not sure
how well the common widget libraries cope with this. 

Kenneth Albanowski (kjahds "at", CIS: 70705,126)

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