Groups > comp.graphics.apps.gnuplot > #3700

Re: A couple of questions

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From	Ethan A Merritt <EAMerritt@gmail.com>
Newsgroups	comp.graphics.apps.gnuplot
Subject	Re: A couple of questions
Date	Tue, 25 Jul 2017 18:59:17 -0700
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layzarc@aol.com wrote:

> In most cases the data is on uniform grid and as I said, I get the
> expected image so "binary matrix with image" does work.  I just get
> the extra message which were not present in earlier versions.  Anyway
> its not a big deal.  I was just wondering what changed in later
> versions to generate the messages.

Earlier versions deferred interpretation of image data until the
first few pixels were about to be rendered.  The on-screen coordinates
of those pixels were inspected and some empirical rules were applied to
[figure out/guess] what the image dimensions were supposed to be.
These empirical rules were not always right and, worse, they were
reapplied each time the image was rendered.  That meant that if you
rotated a 3D plot  containing image data it could flip around and
distort as you dragged the mouse.

Starting with version 5, image data is instead inspected at the time
it is read in to determine the dimensions from the input data itself
rather than from the rendered coordinates on the screen.  The dimensions
are then stored with the image and not re-determined when the image
is later rendered.

If the image dimensions are ambiguous when read in, as in your case,
gnuplot will make a guess and issue a warning.  That's probably what
you are seeing.  In some cases you can fix this by describing the
data as "binary array=(dim1,dim2)" rather than as "binary matrix",
but  if I understand your earlier description that is not the case for
your data format.  

	Ethan

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A couple of questions layzarc@aol.com - 2017-07-24 12:50 -0700
  Re: A couple of questions Ethan A Merritt <EAMerritt@gmail.com> - 2017-07-24 21:16 -0700
    Re: A couple of questions layzarc@aol.com - 2017-07-25 07:02 -0700
      Re: A couple of questions Ethan A Merritt <EAMerritt@gmail.com> - 2017-07-25 08:33 -0700
        Re: A couple of questions layzarc@aol.com - 2017-07-25 14:34 -0700
          Re: A couple of questions Ethan A Merritt <EAMerritt@gmail.com> - 2017-07-25 18:59 -0700

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