Headers for LASCO IDL Library: EXPOSURE

This page was created by IDL lasco_mk_html_help.pro on Wed Aug 17 12:21:55 2005.


List of Routines


Routine Descriptions

CC0

[List of Routines] (See ./cc0.pro)

 CC0 - cross correlation at zero offset of 2 images.


FIND_MODE

[List of Routines] (See ./find_mode.pro)

 FIND_MODE
	Make an estimate of the mode of a dataset.

 Usage:
	mode=find_mode(data[, plotit=plotit])

 Return value:
	mode	float	An estimate of the mode of the dataset.

 Argument:
	data	(float)	input	The data whose mode is needed.

 Keyword:
	plotit	??	input	If set then make a plot of the data &
				the fit.

 Method:
	2-step process:
	1) - Find the maximum of a coarse histogram of the data (100
            bins) other than the "zero" point (this is to deal with
            missing blocks)
       2) - make a finer histogram around the value from step 1 and
            fit a gaussian to it. The peak of the gaussian is then
            the mode returned.

 Restrictions:
	Conceptually this was developed to fix up the exposures on
	LASCO ratio images where the mode should ideally be 1 and
	where the histogram of the image is sharply peaked. It does
	however appear to work OK for "raw" images.

 History:
	Original: 7/1/96; SJT


FRACTILE

[List of Routines] (See ./fractile.pro)

 FRACTILE
	Return the requested fractile of the input data.

 Usage:
	fr = fractile(x, frac)

 Return:
	fr		The requested fractile.

 Arguments:
	x	most	input	The array whose fractile(s) are to be
				returned 
	frac	float	input	The fractile(s) to return.

 Restrictions:
	The input data must be a SORTable array (i.e. not complex,
	string or structure).

 Example:
	To find the interquartile range of a data set, try:
	q = fractile(data, [.25,.75])
	iqr = q(1)-q(0)
	
 History:
	Original: 26/9/95; SJT


GAUSSFIT

[List of Routines] (See ./las_fit_gauss.pro)

 NAME:
	GAUSSFIT

 PURPOSE:
 	Fit the equation y=f(x) where:

 		F(x) = A0*EXP(-z^2/2) + A3
 			and
		z=(x-A1)/A2

	A0 = height of exp, A1 = center of exp, A2 = sigma (the width).
	A3 = constant term
 	The parameters A0, A1, A2, A3 are estimated and then CURVEFIT is 
	called.

 CATEGORY:
	?? - fitting

 CALLING SEQUENCE:
	Result = GAUSSFIT(X, Y [, A])

 INPUTS:
	X:	The independent variable.  X must be a vector.
	Y:	The dependent variable.  Y must have the same number of points
		as X.

 OUTPUTS:
	The fitted function is returned.

 OPTIONAL OUTPUT PARAMETERS:
	A:	The coefficients of the fit.  A is a six-element vector as 
		described under PURPOSE.

 COMMON BLOCKS:
	None.

 SIDE EFFECTS:
	None.

 RESTRICTIONS:
	The peak or minimum of the Gaussian must be the largest
	or smallest point in the Y vector.

 PROCEDURE:
	If the (MAX-AVG) of Y is larger than (AVG-MIN) then it is assumed
	that the line is an emission line, otherwise it is assumed there
	is an absorbtion line.  The estimated center is the MAX or MIN
	element.  The height is (MAX-AVG) or (AVG-MIN) respectively.
	The width is found by searching out from the extrema until
	a point is found less than the 1/e value.

 MODIFICATION HISTORY:
	DMS, RSI, Dec, 1983.


LAS_AUTO_EXP

[List of Routines] (See ./las_auto_exp.pro)

 LAS_AUTO_EXP
	Do a "bootstrap" exposure correction to the currently selected
	images.

 Usage:
	las_auto_exp

 Arguments & Keywords: None

 Method:
	This routine make use of the 64x64 block in the centre of the
	occulting disk which is now normally transmitted. It is
	assumed that this retains a constant brightness. It is further
	assumed that the exposures are correct on average.

 Restrictions:
 	It is assumed that the images have been corrected for offset
 	bias and nominal exposure and that this is a fine adjustment.

 History:
	Original: 1/10/96; SJT


LAS_EXP_NORM

[List of Routines] (See ./las_exp_norm.pro)

 LAS_EXP_NORM
	Normalize images based on the integrated image intensities
	
 Usage:
	las_exp_norm, calib[, /store, /use_in_mem]

 Arguments:
	calib	input	string	The name of the file with the
				calibration image; at present this
				must be a full path.

 Keywords:
	store	??	input	If set, then add the calibration image
				to the set of loaded images -- useful
                               if you want to form differences
                               from the calibration image.
	all	??	input	If set, then normalize ALL images, by
				default only the currently selected
				images are normalized.
	use_in_mem ?	input	If set, then use the specified image
				from the currently loaded images.

 Restrictions:
	The STORE key is ignored if USE_IN_MEM is specified.

 Side Effect:
	Changes the values of the images.

 History:
	Original: Mar 96; SJT


MASK_OUT

[List of Routines] (See ./mask_out.pro)

 MASK_OUT
	Determine missing telemetry blocks.

 Usage:
	mask=mask_out(img,hdr)

 Return value:
	mask	byte	A 2-d byte array with the same size as the
			input image with zeroes in the telemetry holes
			and ones elsewhere.

 Arguments:
	img	any	input	The image to be analysed
	hdr	string	input	The FITS header associated with the
				image.

 Method:
	The size of a telemetry block in the image is determined from
	the SUMCOL or LEBYSUM, R?COL and the actual image size. The image is
	rebinned to a 4-d array its minimum value is subtracted and
	the resulting array is summed over the telemetry
	blocks. Zeroes in the summed array are assumed to be missing
	blocks. This is justified as (a) real data are +ve definite
	and (b) the probability of getting the whole of a telemetry
	block having the same value if there are real data present is
	vanishingly small. This algorithm has the advantage of not
	being dependent on whether the exposures have been normalized
	or whether the camera bias has been subtracted.


MIN_NZ

[List of Routines] (See ./min_nz.pro)

 MIN_NZ
	Extract the smallest positive element of an array.

 Call:
	val = min_nz(array[, mindex, max=max])

 Return Value:
	val	any	The smallest positive value or -1 if no positive
			values.

 Argument:
	array	any	input	The array whose min is needed
	mindex	long	output	The (first) location in the array at
				which the min value is found.

 Keyword:
	max	any	output	The maximum value in the array.

 History:
	Prototype: 24/1/91; SJT
	Improve and changes to smallest >0: 22/2/91; SJT
	Add MAX keyword: 31/3/92; SJT
	Add optional second argument for location of min value:
							20/8/93; SJT
	Add "finite" condition: 6/12/93; SJT


MK_LIST

[List of Routines] (See ./mk_list.pro)

 MK_LIST
	Form a "Standard" mask image from a list or more usually from
	a set of parameters to be matched.

 Usage:
	list=mk_list(  )


 Keywords: (all input)
	coronagraph	int	- Which coronagraph (1, 2 or 3)
	exposure	float	- 1-elements use exposures */10%,
				2-elements use exposures in given
				range, absent: use any exposure.
	filter		string	- Specify the filter or FP setting
				required (default "Clear")
	polarizer	string	- Specify the polarizer setting to be
				used (default clear)
	pixels		int	- Specify the size of image to use
                                 2-element array (default [1024,
                                 1024]).
	dir_pattern	string	- Specify a restricted set of
                                 directories in which to find the
                                 images (if used, this must be in a
                                 form acceptable as an argument to
                                 "find")
	upper_left	int	- Specify the location of the
                                 upper-left corner of the image
                                 (useful to distingush (say)
                                 half-resolution-whole-field images
                                 from full-resolution-quarter-field
                                 images, 2-element array (default [20,1]).

 Effects:
	A list of files matching the specified properties is
	generated.

 WARNING:
	It is the responsibility of the user to ensure that the image
	set being used is homogeneous.

 History:
	Original (modified from mk_stdim_list): 15/5/96, SJT
	Substantially improved: 14/5/96; SJT


MK_MINIM

[List of Routines] (See ./mk_minim.pro)

 MK_MINIM
	Form a "Standard" mask image from a list or more usually from
	a set of parameters to be matched.

 Usage:
	mk_minim[, stdim, {list|}]

 Arguments:
	filename string	input	The name to give to the image. If
				unset, then use "stdim.fts"
	list	string	input	An array with a list of filenames to
				be used in forming the average image.

 Keywords: (all input)
	coronagraph	int	- Which coronagraph (1, 2 or 3)
	exposure	float	- 1-elements use exposures */10%,
				2-elements use exposures in given
				range, absent: use any exposure.
	filter		string	- Specify the filter or FP setting
				required (default "Clear")
	polarizer	string	- Specify the polarizer setting to be
				used (default clear)
	pixels		int	- Specify the size of image to use
                                 2-element array (default [1024,
                                 1024]).
	dir_pattern	string	- Specify a restricted set of
                                 directories in which to find the
                                 images (if used, this must be in a
                                 form acceptable as an argument to
                                 "find")
	dark		int	- Specify the dark current (defaults
                                 c1:322, c2:470, c3:319 eit:0).
	interact	??	- If set, then display each image
                                 (reduced by a factor 2 if the larger
                                 dimansion is > 512) and ask the user
                                 whether to include it - tedious but
                                                         sometimes
                                                         needed.
	upper_left	int	- Specify the location of the
                                 upper-left corner of the image
                                 (useful to distingush (say)
                                 half-resolution-whole-field images
                                 from full-resolution-quarter-field
                                 images, 2-element array (default [20,1]).
	save		??	- If set, then save the generated image
				to disk
	clevel		float	- Specify the minimum correlation with
                                 the first image for the image to be
                                 used. When this is specified the
                                 first image is displayed as in
                                 INTERACT and you are prompted whther
                                 to use it; this continues until an
                                 image is accepted. Thereafter all
                                 images better correlated with the
                                 initial image than the given value
                                 are accepted - a typical level might
                                                be in the range .98
                                                to .99.
	centre_pick	??	- If set, then determine a Sun-centre
                                 and radius manually.
	maxc		int	- Set the maximum number of counts to
                                 show in a display of the image.

 Effects:
	A "standard" average image is generated and added to the end
	of the list of loaded images. Most of its header information
	is derived from the first image of the set. N.B. The image is
	NOT saved to disk, use one of the SAVE options in DISPLAY to
	do this.

 WARNING:
	It is the responsibility of the user to ensure that the image
	set being used is homogeneous.

 History:
	Original (modified from mk_stdim_list): 30/7/96, SJT


MK_STDIM

[List of Routines] (See ./mk_stdim.pro)

 MK_STDIM
	Form a "Standard" mask image from the current image set

 Usage:
	mk_stdim[, stdim, stexp=stexp, filename=filename]

 Arguments:
	filename string	input	The name to give to the image. If
				unset, then use "stdim.fts"

 Keywords:
	stexp	float	output	The integrated exposures of each
				pixel.
	save	??	input	If set, then save the generated image
				to disk

 Effects:
	A "standard" average image is generated and added to the end
	of the list of loaded images. Most of its header information
	is derived from the first image of the set. N.B. The image is
	NOT saved to disk, use one of the SAVE options in DISPLAY to
	do this.

 WARNING:
	It is the responsibility of the user to ensure that the image
	set being used is homogeneous.

 History:
	Original: Mar 96, SJT
	Reduce number of arrays to try to speed it up: 4/4/96; SJT
	Use NO_COPY handle extraction instead of GHANDLE for the same
	reason: 22/4/96; SJT


MK_STDIM_HDR

[List of Routines] (See ./mk_stdim_hdr.pro)

 MK_STDIM_HDR
	Make the fits header for a standard image.

 Usage:
	mk_stdim_hdr, head, last_head

 Arguments:
	head	string	in/out	The header to be updated - must be
                                                          derived
                                                          from the
                                                          first image
                                                          of the set
                                                          if it is to
                                                          work
                                                          properly
	last_head str	input	The header of the last image of the
				set.
	image	float	input	The standard image to be described by
				the header
	filename string	input	The name of the file to include in the
				header.
	nim	int	input	The number of images incorporated.

 Keyword:
	rebin	???	input	If set & non-zero, then the image may
				have been rebinned if it was a
				low-resolution image.


 Effects:
	The FITS header is updated.

 History:
	Original: 4/6/96; SJT


MK_STDIM_LIST

[List of Routines] (See ./mk_stdim_list.pro)

 MK_STDIM_LIST
	Form a "Standard" mask image from a list or more usually from
	a set of parameters to be matched.

 Usage:
	mk_stdim[, stdim, {list|}]

 Arguments:
	filename string	input	The name to give to the image. If
				unset, then use "stdim.fts"
	list	string	input	An array with a list of filenames to
				be used in forming the average image.

 Keywords: (all input)
	coronagraph	int	- Which coronagraph (1, 2 or 3)
	exposure	float	- 1-elements use exposures */10%,
				2-elements use exposures in given
				range, absent: use any exposure.
	filter		string	- Specify the filter or FP setting
				required (default "Clear")
	polarizer	string	- Specify the polarizer setting to be
				used (default clear)
	pixels		int	- Specify the size of image to use
                                 2-element array (default [1024,
                                 1024]).
	dir_pattern	string	- Specify a restricted set of
                                 directories in which to find the
                                 images (if used, this must be in a
                                 form acceptable as an argument to
                                 "find")
	interact	??	- If set, then display each image
                                 (reduced by a factor 2 if the larger
                                 dimansion is > 512) and ask the user
                                 whether to include it - tedious but
                                                         sometimes
                                                         needed.
	upper_left	int	- Specify the location of the
                                 upper-left corner of the image
                                 (useful to distingush (say)
                                 half-resolution-whole-field images
                                 from full-resolution-quarter-field
                                 images, 2-element array (default [20,1]).
	save		??	- If set, then save the generated image
				to disk
	clevel		float	- Specify the minimum correlation with
                                 the first image for the image to be
                                 used. When this is specified the
                                 first image is displayed as in
                                 INTERACT and you are prompted whther
                                 to use it; this continues until an
                                 image is accepted. Thereafter all
                                 images better correlated with the
                                 initial image than the given value
                                 are accepted - a typical level might
                                                be in the range .98
                                                to .99.
	slevel		int	- Specify a pixel value to be
                                 considered as saturated (default
                                 16383). This is needed as some
                                 images show "soft saturation" at a
                                 level below 16383 counts.
	centre_pick	??	- If set, then determine a Sun-centre
                                 and radius, manually - else get a
                                 centre from OCCLTR_CNTR

 Effects:
	A "standard" average image is generated and added to the end
	of the list of loaded images. Most of its header information
	is derived from the first image of the set. N.B. The image is
	NOT saved to disk, use one of the SAVE options in DISPLAY to
	do this.

 WARNING:
	It is the responsibility of the user to ensure that the image
	set being used is homogeneous.

 History:
	Original (modified from mk_stdim): 26/4/96, SJT
	Substantially improved: 14/5/96; SJT


NORM_WARN

[List of Routines] (See ./norm_warn.pro)

 NORM_WARN
	Confirm the QUIT operation.

 Usage:
	iquit=norm_warn()

 Arguments and keywords: none:

 History:
	original: 19/1/95; SJT


OD_BRIGHT

[List of Routines] (See ./od_bright.pro)

 OD_BRIGHT
	Determine the brightness of the central block in the occulting
	disk, and also estimate whether the image has been bias
	subtracted and/or exposure corrected.

 Usage:
	od_bright, bright, bias, expc
	
 Arguments:
	bright	float	output	The relative brightness of the
				occulting disk block
	bias	byte	output	Estimate of whether the bias has been
				subtracted (Assumes that if the image
				has any part < 3/4 of the bias
				[corrected by exposure if needed] then
				the bias has been removed).
	expc	byte	output	Estimate of whether the image has been
				exposure corrected (assumes that if
				the maximum of the image multiplied
				by the exposure exceeds the saturation
				value of 16383 then the image has NOT
				been exposure-normalized).

 Restrictions:
	It is possible that "on-board summed" images may confuse the
	EXPC determination.

 History:
	Original: 1/10/96; SJT
	Try median instead of masked mean: 7/11/96; SJT


POLY_DIFFIM

[List of Routines] (See ./poly_diffim.pro)

 POLY_DIFFIM
	Multiple image differencer.

 Usage:
	poly_diffim, {dindex | dname=dname}

 Argument:
	dindex	int	input	The number of the subtrahend image.

 Keyword:
	dname	string	input	The name of the subtrahend image
				(which must be loaded).
	in_place ??	input	If set, then do the subtraction in
				place and overwrite the old image in
				memory.
	divide	int	input	Whether to subtract images (divide=0
				or unset), divide images (1) or divide
				and subtract 1 (2).
	cr_mask	??	input	If set, then attempt to use
				SIGMA_FILTER to remove cosmic rays.
	fix_sum	??	input	If set, then divide the input image by
				the onboard summing.

 Restrictions:
	The DINDEX argument and the DNAME keyword are exclusive. Only
	the currently selected images are processed (the subtrahend
	isn't processed whether or not it is selected).

 Effects:
	A set of difference images is generated and selected (the
	previously selected images are deselected.

 History:
	Original: 21/3/96; SJT
	Modify to cope with assorted summings: Nov 96; SJT


SIGMA_MASK

[List of Routines] (See ./sigma_mask.pro)

 NAME:
	sigma_mask
 PURPOSE:
	Computes the mean and standard deviation of pixels in a box
	centered at  
	each pixel of the image, but excluding the center pixel. If the center 
	pixel value exceeds some # of standard deviations from the mean, it is 
	flagged. Note option to process pixels on
	the edges.
	
 CALLING SEQUENCE:
	Result = sigma_mask( image, box_width, N_sigma=(#), /ALL,/MON )
 INPUTS:
	image = 2-D image (matrix)
	box_width = width of square filter box, in # pixels (default = 3)
 KEYWORDS:
	N_sigma - # standard deviations to define outliers, floating point,
			recommend > 2, default = 3. For gaussian statistics:
			N_sigma = 1 flags 35% of pixels, 2 = 5%, 3 = 1%.
	RADIUS - alternative to specify box radius, so box_width = 2*radius+1.
      /ALL_PIXELS causes computation to include edges of image,
      /MONITOR prints information about % pixels replaced.
 Optional Outputs:
	N_CHANGE - # of pixels flagged (mask = 0)
	VARIANCE - image of pixel neighborhood variances * (N_sigma)^2,
	DEVIATION - image of pixel deviations from neighborhood means,
	squared.
	OUTBOX - Size of box to return flagged around any marked pixel
                (default 1)
 CALLS:
	function filter_image( )
 PROCEDURE:
	Compute mean over moving box-cars using smooth, subtract center values,
	compute variance using smooth on deviations from mean,
	check where pixel deviation from mean is within variance of
	box.
	Return a mask array with ones where the deviation is less than
	the specified amount and zeros for the points outside the range.
	
 MODIFICATION HISTORY:
	Derived from Frank Varosi's SIGMA_FILTER routine. Mar 1996, SJT.


W_LAS_EXP_NORM

[List of Routines] (See ./w_las_exp_norm.pro)

 W_LAS_EXP_NORM
	WIdget interface for LAS_EXP_NORM

 History:
	Original: 26/3/96; SJT


W_MK_STDIM

[List of Routines] (See ./w_mk_stdim.pro)

 W_MK_STDIM
	Widget interface for MK_STDIM

 Keywords:
	group	long	input	Group leader for the heirarchy.

 History:
	Original: 26/3/96; SJT


W_POLY_DIFFIM

[List of Routines] (See ./w_poly_diffim.pro)

 W_POLY_DIFFIM
	Widget interface for POLY_DIFFIM

 History:
	Original: 26/3/96; SJT


W_STDIM_LIST

[List of Routines] (See ./w_stdim_list.pro)

 W_STDIM_LIST
	A widget interface for MK_STDIM_LIST


This page was created by IDL lasco_mk_html_help.pro on Wed Aug 17 12:21:55 2005.