comp.lang.idl-pvwave archive: archive » Re: Uneven background removal

Home » Public Forums » archive » Re: Uneven background removal

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Uneven background removal [message #79826 is a reply to message #79815]

Mon, 09 April 2012 06:04

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

On Monday, April 9, 2012 3:19:15 AM UTC-4, arun wrote:
> Hi there,
> I am having difficulty while removing the dark patch of the H-alpha image. I wish to remove that. The dirty image is put for reference on the link:
>
> www.prl.res.in/~awasthi/Files/5_9_1.jpg

It's unclear if you are trying to remove a dark patch like the one near (X,Y) = (110,85)? or do you mean the dark horizontal band? Since your (probable) signal and (probable) background are of comparable amplitudes, the job will be quite difficult. I don't think there will be a fool-proof receipe that anybody could give to you on a newsgroup.

If you want to remove the band, I think you could retrieve an average of each row, and then subtract that value from each row. Unfortunately, that may subtract some of the signal.

If you want to get more sophisticated, then it might be better to look for step-function jumps in the row averages (i.e. discontinuities), and then remove those.

Even better, try to find out if your instrument has calibration dark frames which you could use for subtraction.

Best wishes,
Craig Markwardt

Report message to a moderator

[Message index]

		Re: Uneven background removal By: Mats Löfdahl on Tue, 10 April 2012 12:16
		Re: Uneven background removal By: arun on Tue, 10 April 2012 08:15
		Re: Uneven background removal By: Craig Markwardt on Mon, 09 April 2012 06:04

Previous Topic:	Re: Minimization: Determine a constant across data sets
Next Topic:	interpolation of angular data (interpolation in a circle)

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 19:27:20 PDT 2025

Total time taken to generate the page: 0.00390 seconds