gnuplot-beta

Outputing image fields

[V. <gae...@en...>]

   Hi,

  Is there a way to output a pm3d plot to an bitmap image where the image
would be, pixel by bixel, a height field of the data. That would be
feasily feasable with the png output driver with option "crop", if one=20
could control precisely the size of the bitmap comming out.

  If this is not possible, is there a simple aglorithme to determine the
size of the area that gets cropped ?

  Ga=EBl

Re: Outputing image fields

[Petr M. <mi...@ph...>]

>   Is there a way to output a pm3d plot to an bitmap image where the image
> would be, pixel by bixel, a height field of the data.

No, gnuplot scales the image, in both "with pm3d" and "with image":
  * you probably want to switch on "set pm3d corners2color c1", see
    demo/pm3d.dem
  * "splot ... with image" from the current development version


For exact 1:1 mapping, use the "zimg" program, zimg.sf.net.

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PM

Re: Outputing image fields

[Hans-Bernhard B. <br...@ph...>]

Ga=EBl Varoquaux wrote:

>   Is there a way to output a pm3d plot to an bitmap image where the ima=
ge
> would be, pixel by bixel, a height field of the data.=20

I'm completely confused by that sentence.  You refer to some "image" two =

times, but I fail to see whether it's supposed to be the same image both =

times and, if not, what is the difference between the two.  If it is the =

same image, how would this differ from the new 4.1 plot style "with=20
image"?  Or even from pm3d itself, for that matter?

 > That would be
> feasily feasable with the png output driver with option "crop", if one =

> could control precisely the size of the bitmap comming out.

What is feasible with a single output driver is, ultimately, irrelevant.
For it to make a useful gnuplot feature, it really should be feasible on =

a multitude of drivers.

>   If this is not possible, is there a simple aglorithme to determine th=
e
> size of the area that gets cropped ?

I'm not sure what "cropping" step you're referring to here, either.

Re: Outputing image fields

[V. <gae...@en...>]

  Yes, I am very unclear, I must admit it. Petr understood quite clearly
whit I meant, it is basicaly wath the zimg program does (thank for the
tip, by the way, Petr, it is very usefull).
  I am trying to create a 1:1 mapping between data and pixel in an splot
(or a with image, I must admit I had not looked at the CVS version).

  I understand that I am probablly trying to do something that gnuplot is
not meant for, as it deals with much more then a height field. I think I
will use zimg to do that, though I must admit I really like gnuplot's way
of dealing with colormap.

  Thank for the answer,
         Ga=EBl

Re: Outputing image fields

[Petr M. <mi...@ph...>]

>   I understand that I am probablly trying to do something that gnuplot is
> not meant for, as it deals with much more then a height field. I think I
> will use zimg to do that, though I must admit I really like gnuplot's way
> of dealing with colormap.

zimg uses exactly the same "traditional" colormap formulae.

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PM