; docformat = 'rst'

;+
; Convert RGB coordinates of colors to the 
;
; :Returns:
;    lonarr
;
; :Params:
;    rgb : in, required, type=bytarr
;       either bytarr(3) or bytarr(n, 3) array of RGB coordinates of colors
;-
function mg_rgb2index, rgb
  compile_opt strictarr
  on_error, 2
  
  if (n_elements(rgb) lt 3L) then message, 'not enough elements in RGB array'
  
  ndims = size(rgb, /n_dimensions)
  
  case ndims of
    1: return, rgb[0] + rgb[1] * 2L^8 + rgb[2] * 2L^16
    2: return, rgb[*, 0] + rgb[*, 1] * 2L^8 + rgb[*, 2] * 2L^16
    else: message, 'invalid number of dimensions for RGB array'
  endcase
end