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Re: Resolution [message #27648 is a reply to message #27647]

Mon, 29 October 2001 19:53

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

monache@met.sjsu.edu (Luca Delle Monache) writes:

> Hi there,
>
> I'm a beginer, so, sorry if the question is a low level question.
>
> I'm plotting an array using psym = 6 (square).
> On my scree, the squares do not look all the same! Also, printing a
> PNG file built with WRITE_PNG, I see the same problem.
>
> How I can avoid that problem? I mean, how I can create a better
> quality plot in PNG format?

I believe the answer to your question is that your plotting symbol is
actually not an integer number of pixels wide. Therefore, depending
on where the symbol appears in the data viewport, it might consume N
or N+1 real pixels, depending on the rounding error at that particular
position.

The easiest solution is to give your plot more resolution. This can
be accomplished by making the plot window bigger (more pixels per
plot), or by outputting to postscript (which has effectively infinite
resolution). Beyond that you could probably build your own symbol as
a bitmap and then use TV to put it on screen, but this might get ugly
with data-to-device coordinate conversions.

Good luck!
Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: Resolution By: David Fanning on Tue, 30 October 2001 15:16
		Re: Resolution By: Mark Hadfield on Tue, 30 October 2001 15:01
		Re: Resolution By: John-David T. Smith on Tue, 30 October 2001 14:55
		Re: Resolution By: Mark Hadfield on Tue, 30 October 2001 14:43
		Re: Resolution By: David Fanning on Tue, 30 October 2001 07:55
		Re: Resolution By: John-David T. Smith on Tue, 30 October 2001 07:48
		Re: Resolution By: David Fanning on Mon, 29 October 2001 20:47
		Re: Resolution By: Mark Hadfield on Mon, 29 October 2001 20:27
		Re: Resolution By: Craig Markwardt on Mon, 29 October 2001 19:53

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