| Re: Diplay 2D data [message #57089 is a reply to message #57085] |
Tue, 04 December 2007 06:43  |
Vince Hradil
Messages: 574
Registered: December 1999
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Senior Member |
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On Dec 4, 4:26 am, Lasse Clausen <la...@lbnc.de> wrote:
> Hi there,
>
> in one of the recent posts there was a link to Brian Larsen's homepage
> and in particular his imagesc.pro. This reminded me that I wanted to
> ask a question related to the matter of image display with axes:
>
> What's the best way to display 2D colour-coded data with axes and what-
> not? Or rather, what do people out there use?
>
> For a long time I used a routine called IMDISP which I downloaded
> somewhere. It seems to be the same approach as Brian's, getting a 2D
> array, using one of the TV commands to display it at a certain
> position and the overplotting axes. I am not happy with that approach
> because axes and image are completely unconnected, if I change the
> axes ranges then I (or the display routine) needs to chop of bits of
> the image array, otherwise the same image is displayed just with
> different axes. More importantly, both mentioned routines cannot pad
> zeros to the image such that the axis range is extended over the
> extends of the image. This is important for me because I am anal and I
> want my dynamic spectra plots to start at round times - but the data
> doesn't. And also, since the pixels have finite dimensions, I really
> also need to change the axes values to the exact position at the end
> of the pixel.
>
> This then led me to write my own routine which uses POLYFILL. So
> basically every pixel is drawn as a filled polygon with a certain
> colour. This allows me to easily (in my mind) change the ranges
> without having to fiddle with the data.
>
> However, not only is a FOR loop with POLYFILL slow but also a page of
> three dynamic spectra with 8000x128 points now easily makes a 40MB
> PostScript - not surprisingly, really.
>
> So to get back to the original question: How do other people display
> 2D data?
>
> Cheers
> Lasse Clausen
I use tvim (http://www.astro.washington.edu/deutsch/idl/htmlhelp/
library28.html#TVIM) mostly out of habit, though. David has a nice tv/
tvscl replacement on his website, too http://www.dfanning.com/programs/tvimage.pro
. I don't think either of these handle the axes the way you want them
to, though. I always just extrac(t) the appropriate range and use
that.
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