mat2gray.m

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function a = mat2gray(x,limits)
%MAT2GRAY Convert matrix to intensity image.
%   I = MAT2GRAY(A,[AMIN AMAX]) converts the matrix A to the
%   intensity image I.  The returned matrix I contains values in 
%   the range 0.0 (black) to 1.0 (full intensity or white).
%   AMIN and AMAX are the values in A that correspond to 0.0 and
%   1.0 in I.
%
%   I = MAT2GRAY(A) sets the values of AMIN and AMAX to the
%   minimum and maximum values in A.
%
%   Class Support
%   -------------
%   The input array A and the output image I are of class
%   double.
%
%   Example
%   -------
%       I = imread('rice.tif');
%       J = filter2(fspecial('sobel'), I);
%       K = mat2gray(J);
%       imshow(I), figure, imshow(K)
%
%   See also GRAY2IND.

%   Clay M. Thompson 10-5-92
%   Copyright 1993-1998 The MathWorks, Inc.  All Rights Reserved.
%   $Revision: 5.6 $  $Date: 1997/11/24 15:35:52 $

if (~isa(x,'double'))
   error('A must be double');
end

if nargin==1,
   limits = [min(x(:)) max(x(:))];
end

if limits(2)==limits(1)   % Constant Image
   a = max(0,min(x,1));
else                      
   a = max(0,min((x-limits(1))/(limits(2)-limits(1)),1));
end