Overview of the use of SXT_PREP Ver 1.0 (MDM) 20-Mar-95 This note is intended as a quick reference reminder of the calling sequence options for SXT_PREP. It is broken into three parts. 1. A series of sample SXT_PREP calls 2. The list of keywords available for SXT_PREP 3. A list of the /ydb databases that should be on-line Other documents that could be useful /ys/sxt/doc/sxt_prep.txt - This document /ys/sxt/doc/coor_systems.txt - Describes the relation between Pixel (P), angle(A), heliocentric (H), and HXT coordinates /ys/sxt/doc/pointing_suncen.txt - Describes the SXT coordinate system and how the coordinates are saved internally -------------------------------------------------------------------------------- Sample SXT_PREP Calls -------------------------------------------------------------------------------- sxt_prep, infil, ss, index2, data2, $ /reg ;perform sub-pixel registration sxt_prep, infil, ss, index2, data2, $ /reg, $ ;perform sub-pixel registration /roll ;correct the roll so solar north is straight up sxt_prep, infil, ss, index2, data2, $ /fast ;perform whole pixel registration sxt_prep, infil, ss, index2, data2, $ /reg, $ ;perform sub-pixel registration uncert, $ ;return an array with the uncertainty per pixel satpix ;return an array showing saturated pixels sxt_prep, infil, ss, index2, data2, $ helio=[-9.8,-20.3], $ ;specify the E-W, N-S heliocentric center date_helio='14-JUN-92 02:37:41' ;the date of the heliocentric coord ;/REG is implied because of HELIO sxt_prep, infil, ss, index2, data2, $ outsiz=[100,200], $ ;output data will be [100,200] suncoord=[0,0] ;center the field of view the center of the sun ;resolution is FULL since not specified sxt_prep, infil, ss, index2, data2, $ suncoord=[0,-125] ;to maintain the normal FFI sun position ;resolution is FULL since not specified sxt_prep, index, data, index2, data2, $ /reg ;perform sub-pixel registration ref_image=index(55), $ ;align all images to this reference image outsiz=100 ;output size shall be [100,100] sxt_prep, index, data, index2, data2, $ ref_image=index(55), $ ;align all images to this reference image /helio ;adjust the registration for solar rotation sxt_prep, infil, $ ;a list of input file names ss, $ ;the list of images to process (datasets) index2, data2, $ ;the output /reg, $ ;perform sub-pixel registration /sfd, $ ;input is SFD compressed outres=1 ;make the output Half Resolution sxt_prep, infil, ss, $ ;input file and dataset list outfil=outfil, $ ;write the results to this output file /normalize ;exposure normalize the image sxt_prep, index_in, data_in, index_out, data_out, $ /dc_interpolate, $ ;dark current interpolation /normalize, $ ;exposure normalize /register, $ ;register for S/C jitter despike=5, $ ;despike (using default parameters) /vignette, $ ;correct for vignette outres=max(gt_res(index_in)) ;stay at lowest resolution available -------------------------------------------------------------------------------- Full List of SXT_PREP Parameters -------------------------------------------------------------------------------- The following is directly extracted from the SXT_PREP document header. You can access this header by using the following command from within IDL: doc_library, 'sxt_prep ; -------------------- Calibration Parameters -------------------- ; dc_scalar- If set, then a simple scalar value is used for dark current ; subtraction. Default is to take the image closest in exposure. ; dc_interpolate - If set, then perform interpolation on the dark frame ; images to get a better backround subtraction. Deafult is to ; take the image closest in exposure. ; upper_only - If set, only flag +1 pixels above (in a column) the ; saturated area (not the -1 pixels) [see call to sxt_satpix]. ; sfd_corr - If set, then the input image is an SFD image. Use the ; SFD decompression, perform the registration, and recompress ; using the SFD compression. ; ; -------------------- Alignment Parameters -------------------- ; register - If set, then perform the registration and correct only for ; the S/C jitter. See the /FAST option if you do not want ; to have sub-pixel registration performed. ; fast - If set, then perform the registration in "FAST" mode which ; is simple full pixel shifts instead of POLY2D. ; ; ref_image - A single roadmap or index structure which will be used ; to define the sun or heliocentric coordinates for alignment. ; It can be the image number (subscript) of the images being ; extracted which should be used (not the absolute dataset ; number within the images listed in "infil") ; ; helio - the reference latitude and longitude for the alignment. ; This should be the position of the active region at some ; time, preferably near the time it crossed closest to the ; center of the disk. If a sub-image is to be extracted, ; HELIO specifies the center of the sub-image. ; helio(0) = longitude E/W (E is negative) ; helio(1) = latitude N/S (S is negative) ; It can be a non-zero scalar value if REF_IMAGE is passed in. ; In this case, the heliocentric coordinates are derived ; from "REF_IMAGE". ; DO NOT USE WITH SUNCOORD AND CCDCOORD. ; date_helio - the reference date/time for the heliocentric input. ; ; suncoord - The coordinates of the center of the portion to extract ; in angular arcseconds relative to sun center. ; suncoord(0) = E-W coordinate (E is negative) ; suncoord(1) = N-S coordinate (S is negative) ; DO NOT USE WITH HELIO AND CCDCOORD. ; ; ccdcoord - The FRE (full resolution CCD pixel equivalent) of the ; center of the portion to extract ; DO NOT USE WITH SUNCOORD AND HELIO ; ; outres- The resolution of the output image (0=FR, 1=HR, 2=QR). ; If not set, and the input is not all FFI, then convert all ; to full res. If all FFI, then set outres to the highest ; resolution of the input images (typically half resolution) ; Only relevant if registering the images. ; outsize- The dimention of the ouptut image [#col, #lin] ; If it is a scalar value, it will make the #lin = #col ; If not set, it will make it the largest size of the input ; field of views. If PFI and FFI are mixed, it will take ; the largest PFI. ; ; fill_gap - A gap can exist between two PFI strips for a single ; observing region because of a change in S/C pointing. ; If this variable is set, then the gap between the PFI ; strips is filled by interpolating the lines above and below ; trim_edge - Used with /FILL_GAP. If set, then replace the edge ; line of pixels as well as the gaps. Will set /FILL_GAP ; if /TRIM_EDG is set. ; noroll - If set, then do not perform roll corrections. Currently the ; default ; roll_do - If set, then perform the corrections for the roll offset ; interp - If set, roll correction uses bilinear interpolation ; (See Description in IDL poly_2D documentation header) ; cubic - If set, roll correction uses cubic convolution interpolation ; (See Description in IDL poly_2D documentation header) ; oride_pnt_chk - If set, then do not compare the ATT/GET_SUNCENTER ; results to the commanded values to see that they are ; truly valid points. This is useful for times when the ; commanded pointing history file is not updated properly ; or for real time applications when the commanded pointing ; history is not updated yet. ; align_unc - The uncertainties in alignment coordinates, a pair of ; (x,y) in FR pixels. If set to any scalar, this will use ; TEST_POLY to determine these values. TEST_POLY fits the ; corner coordinates obtained from ALIGN_PREP to a polynomial ; of degree bewteen 1 to 10, and estimates the mean uncertainty ; from the fluctuations of the pointing coordinates around the ; smoothed values. ; ; ; -------------------- Secondary Processing Parameters ---------- ; sum - Sum over SUM X SUM pixels. It must be a scalar value. ; exp_normalize- If set, perform exposure normalization ; normalize- Same as EXP_NORM ; ; vignette - If set, then apply the correction for the vignette ; loss in signal off axis. The function SXT_OFF_AXIS ; is called to peform the correction. For certain applications ; it is recommended to use /FLOAT with this /VIGNETTE option. ; ; -------------------- Image Filtering Parameters ---------- ; despike_thresh - Call DE_SPIKER to remove spikes from the image. ; This step is done before sub-pixel registration. ; The value set on the call is passed into the function ; DE_SPIKER as "threshold" (the first parameter) ; width - If DESPIKE_THRESH is set, then pass this value through ; to DE_SPIKER. If SIGMA_FILT is set, then pass this value ; through to the SIGMA_FILTER function. ; sigma_filt - Call the SIGMA_FILTER function with SIGMA_FILT as ; the "box_width" variable. ; n_sigma - If SIGMA_FILT is set, then pass this value through to ; the function SIGMA_FILTER ; sigma_iterate - If SIGMA_FILT is set, then pass this value through ; to the function SIGMA_FILTER as keyword input "iterate" ; ; -------------------- Miscellaneous Parameters ---------- ; float - If set, then make the output floating point (REAL*4) ; force_read - If set, read all datasets at once even if input was ; specified with INFIL/DSET. This is available because doing ; LEAK_SUB on all images at once if the input is PFI is more ; efficient ; outfil - If specified, the data will not be passed back in INDEX_OUT and ; DATA_OUT. Instead, it will be saved in an SDA file with the ; name specified by this parameter. ; If "uncert" and "satpix" are included in the procedure call, ; they will be saved with the same file name with a "_unc" ; and a "_sat" appended to the file name. ; qdebug - If set, display some diagnostic messages ; qstop - If set, stop execution inside this subroutine (for debugging) ; nocorrections- This keyword is intended for debugging purposes and should ; not be used. If set, then LEAK_SUB is not called. LEAK_SUB ; will automatically not be called if the input data is of ; non-byte type. -------------------------------------------------------------------------------- /ydb Databases Needed for SXT_PREP -------------------------------------------------------------------------------- Several databases are required for SXT_PREP to work properly. Several of them are listed below 1. SDC (SXT Dark Current): These images are required to perform dark current subtraction of cooled images. 99% of the images are taken at -21 C. 2. SDM (SXT Dark Current Mean): A new dark current database is being created which is the average of several dark images. This database will replace the SDC database. It should be available by Apr-1995. 3. SDW (SXT Warm Dark Current): If you are analyzing images taken with the CCD warm, then you will need this database. BE AWARE: It is extremely difficult to analyze warm images. 4. SFC (SXT Calibration Images): These are the leak images to calibrate the pin hole light leak which occured in Nov-1992. If any analysis is being performed on images after Nov-92, then this database is required. 5. ATT (Spacecraft Attitude): The spacecraft pointing information is stored approximately every 2 seconds in this file. The ATT database is required if any registration is being performed. See Appendix A.6 in the Yohkoh Analysis Guide (Ver 2.00) for more details on the sizes of these databases and on how to aquire them. For all databases except the SFC you only need the data for the week(s) you are analyzing. For the SFC you will need all images which are available. For SDC and SDW it is advisable to have +/- 2 or 3 week window of data files.