This function creates an analysis in time of illumination level in some points 
  in the datpack. 
  A set of M points (pixels) randomly are selected in the datapack, 
  and through DATA(:,:,k) for all k value. These points can be selected with
  uniform distribution or a gaussian distribution.

  [YMEAN YSTD POINTS]=get_lux_level(DATA,M);
  [YMEAN YSTD POINTS]=get_lux_level(DATA,M,'on');
  [YMEAN YSTD POINTS]=get_lux_level(DATA,M,Sigma);
  [YMEAN YSTD POINTS]=get_lux_level(DATA,M,Sigma,'on');
  
  Input:
  DATA    is the speckle data pack. Where DATA is a 3D matrix created grouping NTIMES 
          intensity matrices with NLIN lines and NCOL columns. When N=size(DATA), then
          N(1,1) represents NLIN and
          N(1,2) represents NCOL and
          N(1,3) represents NTIMES.
  M       is the number of points in analysis.
  Sigma   [Optional]is the standard deviation in pixels. If this variable is used
          then the points are selected using a gaussian distribution. 
  Show    [Optional] can be used in the last position of input, and its function 
          is used to enable a graphic output of the selected points that formed the
          THSP. Show='on', Show='on-red', Show='on-red-filled', Show='on-green', 
          Show='on-green-filled', Show='on-blue' , Show='on-blue-filled'
          Show='on-cyan', Show='on-cyan-filled', Show='on-magenta', 
          Show='on-magenta-filled', Show='on-yellow', Show='on-yellow-filled',
          Show='on-black', Show='on-black-filled', Show='on-gray' or  
          Show='on-gray-filled', Show='on-white' or  
          Show='on-white-filled' to enable. 
          It is disabled in other cases, by default Show='off'.
          Show='on' plot the points in the color red, in other cases are used the
          specified colors.

  Output:
  YMEAN  is the mean illumination level in M points.
  YSTD   is the standard deviation value (arround) of illumination level in M points.
  POINTS [Optional] is a matrix with two columns and 
         M lines. Thus, each line represents one point in study, (line,column).


  For help, bug reports and feature suggestions, please visit:
  http://nongnu.org/bsltl/

Package: bsltl