Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: XPutPixel
Message-ID: <8811151539.AA02975@EXPO.LCS.MIT.EDU>
Date: 15 Nov 88 15:39:56 GMT
References: <8811151509.AA07399@godot.radonc.unc.edu>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 36


    You seem to suggest it
    would be less efficient to have the server (which may have access to
    some specialized image munging hardware, and is in a much better
    position to make other hardware-specific optimizations) do this than
    to have clients do it.  Aside from the increased wire traffic I don't
    see how that can be.

The tradeoff isn't absolute, but decreasing server processing time
increases overall throughput when there are distributed clients
that can do the conversions concurrently (quite possibly on
separate processors), and decreasing the server time also improves
the perceived responsiveness (yes, some nice pre-emptive scheduling
in the server would help this, but ...).

    If your position is that always sending images as (unsigned long)
    *REQUIRES* XPutPixel-like handling of every pixel on the server side -
    handling which cannot be sidestepped - then I do see some rational for
    retaining the current model.

It will require conversion for most hardware that I am aware of.

    But, again, it is not clear that
    building conversions into the server *necessarily* removes a client's
    option to make non-portable assumptions in the name of speed.

I didn't argue against this point.  I *did* argue that a more reasonable
implementation of XPutPixel in Xlib, taking advantage of the mechanisms
that are there, could remove the need for much client code to have to
make performance assumptions.

   Yes, I know they're important, but then so are 12-bit CT images.

Sure.  It's also good to keep in mind that XImages were not designed
to handle real image processing needs (which is not to say that it
shouldn't do what it does a whole lot faster).