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Re: creating elliptically shaped images [message #37182 is a reply to message #37099]

Wed, 03 December 2003 09:24

condor
Messages: 35
Registered: January 2002

Member

mruschin@hotmail.com (mark) wrote in message news:<a9116224.0311240712.618f4088@posting.google.com>...
> I'd like to form an image which has an elliptical shape and where all
> the pixels within this ellipse have values corresponding to any given
> function that I would specify, the simplest example being a uniform
> image (i.e. a value of 1 for all the pixels in the ellipse). Is there
> any nice way to do this in IDL or MATLAB other than looping through
> all the pixels and determining whether any given one lies within the
> ellipse?

In IDL at least, you can send raw strings to your output device.
Depending on the device, you could use that to send clipping
instructions.

If you were plotting into a PostScript file for example, this might
look vaguely like this:

;; Some random dots to plot:
x=randomu(seed,5000)
y=randomu(seed,5000)

set_plot,'PS'
device,/landscape

;; plot without clipping to show where the dots are:

plot,x,y,psym=3

;; PS clipping path -- here vaguely elliptical, but could be anything:

clipstring='currentpoint 37 rotate 1 .5 scale '+$
'newpath 15000 5000 5000 0 360 arc clip '+$
'1 2 scale -37 rotate newpath moveto'

device,output=clipstring

;; plot again with different psym to illustrate clipping:

oplot,x,y,psym=4

device,/close
set_plot,'X'

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[Message index]

		creating elliptically shaped images By: mruschin on Mon, 24 November 2003 07:12
		Re: creating elliptically shaped images By: Paul Sorenson on Wed, 03 December 2003 15:03
		Re: creating elliptically shaped images By: condor on Wed, 03 December 2003 09:24

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