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lasco_mk_html_help.pro
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CC0 - cross correlation at zero offset of 2 images.
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 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
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 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 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 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 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 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 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 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 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 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 Confirm the QUIT operation. Usage: iquit=norm_warn() Arguments and keywords: none: History: original: 19/1/95; SJT
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 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
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 WIdget interface for LAS_EXP_NORM History: Original: 26/3/96; SJT
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 Widget interface for POLY_DIFFIM History: Original: 26/3/96; SJT
W_STDIM_LIST A widget interface for MK_STDIM_LIST
lasco_mk_html_help.pro
on
Wed Aug 17 12:21:55 2005.