VNC request

kandalva kandalva "at" ppp.bekkoame.or.jp
Wed, 14 Oct 1998 17:50:02 +0000



>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.) 

It may be realized by packing 8 B/W pixels into 1 byte(8 bit) and send
as 8 bit mode,and client may extract it and draw B/W graphics on screen.

>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
>well.

Nops,recent Macintosh have no B&W color mode. ;-) I have Power Macintosh
and it had no B&W color mode. Anyone can try on B&W mode?

>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

I think PC server can perform B&W operation.
     1.First make two offscreen,one is the same depth of screen,the other
          is the B&W
     2.When the screen update occurred,convert only updated region to B&W
          with dither algorism
     3.Pack these B&W bits into 8 bit packet and send it.

The algorithm of conversion any depth color mode to B&W mode  with dither
is popular,so it's equipment is not so tough.
 
Actually the source code that sort of argorhism is included in XV
(unix graphic application),NIH Image(Macintosh application) and 
these applications make their surce code in public.

----------------------------------------------------
Eizen Kimura
kandalva "at" med.hokudai.ac.jp
Medical School of Hokkaido Univ. Medical 4th Student
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