INSTRUCTIONS

In order to use the EGSO cleaning code, the dynamic libraries for Gaussian Smoothing and Canny Edge Detection first have to be loaded into IDL. The libraries are loaded using the IDL linkimage procedure by the routine cleaning_startup.pro. This determines the current OS and architecture and loads the appropriate routine - those currently available are located in $SSW_EGSO/binaries/* 

To clean a full disk image the following list of actions can be performed:

- Fit an ellipse to the full disk image, using the limb_efit.pro IDL procedure.

- Correct irregularly shaped disk to a circle and resize the image, using  frclean_standardize.pro IDL function
	
- Evaluate Quiet Sun using qsmedian.pro and consequently, remove Quiet Sun contribution from the image using getcontrastimage.pro.


Procedure cleanimage.pro executes the above sequence with the parameters that were used for cleaning the images from Meudon Observatory.

Brief description of IDL procedures mentioned above is presented below. The rest of the files in the $SSW_EGSO/idl/efr_clean folder are auxilary.

Please, let us know of any bugs and problems you may encounter by sending an e-mail to fr-egso@brad.ac.uk


The cleaning software is described in detail in:

Zharkova V.V., Ipson S. S, Zharkov S. I, Benkhalil A. K, Aboudarham J.  and R.D. Bentley (2002): "A full disk image standardisation of the synoptic solar observations at the Meudon observatory", Solar Physics Journal, 214/1, pp.89-105, 2003

Other references???

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limb_efit.pro

limb_efit, image, xc, yc, r1, r2, theta, stdev, stdevGeo, algerr

Procedure to fit the ellipse to the Full Disk Solar Image (image). 
INPUT:
	image
Calculates/returns,
	ellipse center in pixel coordinates, (xc, yc)
	ellipse axis, 		(R1, R2)
	tilt angle				(theta)
	fit errors			(stdev, stdevGeo, algerr)
	
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frclean_standardize.pro

result=frclean_standardize(image, xc, yc, R1, R2, theta, N1, N2, Rad, xcn, ycn)	


Function standardizing the full disk to given parameters (ellipse 2 circle). 
INPUT:
	image,
	xc, yc, R1, R2, theta		- ellipse parameters
	N1, N2		- naxis1&naxis2 for the new image
	Rad			- new full disk radius
	xcn, ycn		- pixel coordinates for new disk center

RETURNs,
	N1 by N2 image with Full Disk of radius Rad centered at (xcn, ycn)


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qsmedian.pro

result=qsmedian(image, R, xc, yc)

Function, reconstructing quiet sun from the full disk image
INPUT:
	input image, disk radius, disk cenre (pixel coordinates)
	
Return:
	quiet sun disk with the above parameters( centre & radius )

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getcontrastimage.pro

result=getcontrastimage(image, QSImage, R, xc, yc, Inorm, /subtract)

FUNCTION producing the cleaned image by dividing/subtracting original by/from quiet sun

INPUT:
	input image, quiet sun image, disk center coordinates, radius
	
keywords:
	/subtract		use subtraction
	Inorm			normalising parameter for division (set to 				QuietSun maximum intensity, if not specified) 

Return:
	contrast image i.e. image with quiet sun contribution removed

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cleanimage.pro
cleanimage, image, result,  /subtract

Procedure correcting the shape of Solar disk, standardizing the image to given parameters and removing the limb darkening. 

INPUT
	image		full disk Solar Image

Keyword		subtract, if set, the code uses subtraction to 				remove limb darkening instead of division.

Returns, result