Imstat on circular region

prajwel wrote on Apr 04, 2015

Hi,

I want to know the standard deviation of pixel values in a circular region. I tried in this manner, but failed.

cl> type expr ((sqrt((I-256)**2) + (J-256)**2) >= 5) ? -1 : a)
cl> imexpr @expr statimg a=M13refim.fits
cl> imstat statimg 

I obtained the above idea from a forum post >> http://iraf.net/forum/viewtopic.php?showtopic=109273

Any help or suggestion would be greatly appreciated. Thank you in advance for your help.

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prajwel wrote on Apr 05, 2015

I am quiet glad to say that I figured it out on my own. Thanks anyway.

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prajwel wrote on Apr 05, 2015

For anyone curious, I did it in this manner.

1. create a file, in my case "expr", with this inside

 ((sqrt((I-256)**2 + (J-256)**2) <= 50) ? a : -1) 

2. then, I ran this

 imexpr @expr statimg M13Irefnew1.fits 

3. finally,

 imstat statimg.fits lower=0 

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Last post on Apr 05, 2015