function frebin,image,nsout,nlout,total=total ;+ ; NAME: ; FREBIN ; ; PURPOSE: ; Shrink or expand the size of an array an arbitrary amount using interpolation ; ; EXPLANATION: ; FREBIN is an alternative to CONGRID or REBIN. Like CONGRID it ; allows expansion or contraction by an arbitrary amount. ( REBIN requires ; integral factors of the original image size.) Like REBIN it conserves ; flux by ensuring that each input pixel is equally represented in the output ; array. ; ; CALLING SEQUENCE: ; result = FREBIN( image, nsout, nlout, [ /TOTAL] ) ; ; INPUTS: ; image - input image, 1-d or 2-d numeric array ; nsout - number of samples in the output image, numeric scalar ; ; OPTIONAL INPUT: ; nlout - number of lines in the output image, numeric scalar ; If not supplied, then set equal to 1 ; ; OPTIONAL KEYWORD INPUTS: ; /total - if set, the output pixels will be the sum of pixels within ; the appropriate box of the input image. Otherwise they will ; be the average. Use of the /TOTAL keyword conserves total counts. ; ; OUTPUTS: ; The resized image is returned as the function result. If the input ; image is of type DOUBLE or FLOAT then the resized image is of the same ; type. If the input image is BYTE, INTEGER or LONG then the output ; image is usually of type FLOAT. The one exception is expansion by ; integral amount (pixel duplication), when the output image is the same ; type as the input image. ; ; EXAMPLE: ; Suppose one has an 800 x 800 image array, im, that must be expanded to ; a size 850 x 900 while conserving the total counts: ; ; IDL> im1 = frebin(im,850,900,/total) ; ; im1 will be a 850 x 900 array, and total(im1) = total(im) ; NOTES: ; If the input image sizes are a multiple of the output image sizes ; then FREBIN is equivalent to the IDL REBIN function for compression, ; and simple pixel duplication on expansion. ; ; If the number of output pixels are not integers, the output image ; size will be truncated to an integer. The platescale, however, will ; reflect the non-integer number of pixels. For example, if you want to ; bin a 100 x 100 integer image such that each output pixel is 3.1 ; input pixels in each direction use: ; n = 100/3.1 ; 32.2581 ; image_out = frebin(image,n,n) ; ; The output image will be 32 x 32 and a small portion at the trailing ; edges of the input image will be ignored. ; ; PROCEDURE CALLS: ; None. ; HISTORY: ; Adapted from May 1998 STIS version, written D. Lindler, ACC ; Added /NOZERO, use INTERPOLATE instead of CONGRID, June 98 W. Landsman ; Fixed for nsout non-integral but a multiple of image size Aug 98 D.Lindler ; DJL, Oct 20, 1998, Modified to work for floating point image sizes when ; expanding the image. ; Improve speed by addressing arrays in memory order W.Landsman Dec/Jan 2001 ;- ;---------------------------------------------------------------------------- On_error,2 compile_opt idl2 if N_params() LT 1 then begin print,'Syntax = newimage = FREBIN(image, nsout, nlout, [/TOTAL])' return,-1 endif if n_elements(nlout) eq 0 then nlout=1 ; ; determine size of input image ; ns = n_elements(image[*,0]) nl = n_elements(image)/ns ; ; determine if we can use the standard rebin function ; dtype = size(image,/TNAME) if dtype EQ 'DOUBLE' then begin sbox = ns/double(nsout) lbox = nl/double(nlout) end else begin sbox = ns/float(nsout) lbox = nl/float(nlout) end ; Contraction by an integral amount if (nsout eq long(nsout)) && (nlout eq long(nlout)) then begin if ((ns mod nsout) EQ 0) && ((nl mod nlout) EQ 0) then \$ if (dtype EQ 'DOUBLE') || (dtype EQ 'FLOAT') then begin if keyword_set(total) then \$ return,rebin(image,nsout,nlout)*sbox*lbox else \$ return,rebin(image,nsout,nlout) endif else begin if keyword_set(total) then \$ return,rebin(float(image),nsout,nlout)*sbox*lbox else \$ return,rebin(float(image),nsout,nlout) endelse ; Expansion by an integral amount if ((nsout mod ns) EQ 0) && ((nlout mod nl) EQ 0) then begin xindex = long(lindgen(nsout)/(nsout/ns)) if nl EQ 1 then begin if keyword_set(total) then \$ return,interpolate(image,xindex)*sbox else \$ return,interpolate(image,xindex) endif yindex = long(lindgen(nlout)/(nlout/nl)) if keyword_set(total) then \$ return,interpolate(image,xindex,yindex,/grid)*sbox*lbox else \$ return,interpolate(image,xindex,yindex,/grid) endif endif ns1 = ns-1 nl1 = nl-1 ; Do 1-d case separately if nl EQ 1 then begin if dtype eq 'DOUBLE' then result = dblarr(nsout,/NOZERO) \$ else result = fltarr(nsout,/NOZERO) for i=0L,nsout-1 do begin rstart = i*sbox ;starting position for each box istart = long(rstart) rstop = rstart + sbox ;ending position for each box istop = long(rstop)