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;
; NAME:
;       LOAD_CTBL 
; PURPOSE:
;       Loads (and optionally displays) the specified Climsat ASCII color table.
; KEYWORD PARAMETERS:
;       Keywords:
;         FILENAME         Name of ASCII color table.  
;         NC               Number of colors to load (maximum 256). 
;         CMIN=cmin        Minimum color value (default 0). 
;         CMAX=cmax        Maximum color value (default 255).
;         DISPLAY=display  Display the loaded color table. 
; MODIFICATIONS:
;   Original author: Wesley Berg, CIRES/CDC, 1996(?)
;   Don Anderson, 2/17/99, Added display option. 
;
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PRO load_ctbl, filename, nc, cmin=cmn, cmax=cmx, display=display

; Initialize variables

 common colors, r_orig, g_orig, b_orig, r_curr, g_curr, b_curr
 if n_elements(cmn) eq 0 then cmn=0
 if n_elements(cmx) eq 0 then cmx=255

; Open and read the color table file
 print,'filename = ', filename
 openr, unit, filename, /get_lun, error=err
 print,'err = ', err
 if (err ne 0) then begin
   print, 'Error opening specified color table file, using default!'
   openr, unit, './rain.tbl', $
     /get_lun, error=err
   if (err ne 0) then begin
     print, 'Unable to open default color table, program exiting!'
     goto, stop
   endif
 endif
 readf, unit, ncolors

; Create R,G,B value arrays 

 a = bytarr (3, ncolors)
 r = bytarr (ncolors)
 g = bytarr (ncolors)
 b = bytarr (ncolors)

; Fill the R,G,B arrays with values in file

 readf, unit, a
 r = a (0,*)
 g = a (1,*)
 b = a (2,*)

; Adjust requested number of colors to available colors

 if n_elements(nc) EQ 0 then nc=!d.table_size
 if (nc GT ncolors) then nc=ncolors

; Interpolate if necessary 

 if (nc lt ncolors) then begin 
   p = lindgen(nc)
   p(cmn) = (lindgen(nc-cmn) * (cmx-cmn)) / (nc-1-cmn) + cmn
   r = r(p)
   g = g(p)
   b = b(p)
 endif

; Not sure what this does ...

 r_orig = r
 g_orig = g
 b_orig = b
 r_curr = r_orig
 g_curr = g_orig
 b_curr = b_orig

; Load the IDL display color translation tables from the specified variables

 tvlct, r, g, b
 if (nc GT cmx) then nc = cmx+1

; Display color table if requested 

 if keyword_set(display) then begin
   colorbar, /horizontal, /right, vmin=cmn, vmax=ncolors, cmin=cmn, cmax=ncolors 
 endif

; End of story

 close, unit
 free_lun, unit
 stop:
 end