statxture.m

冈萨雷斯的经典教材数字图像处理的matlab版源代码

function t = statxture(f, scale)
%STATXTURE Computes statistical measures of texture in an image.
%   T = STATXURE(F, SCALE) computes six measures of texture from an
%   image (region) F. Parameter SCALE is a 6-dim row vector whose
%   elements multiply the 6 corresponding elements of T for scaling
%   purposes. If SCALE is not provided it defaults to all 1s.  The
%   output T is 6-by-1 vector with the following elements:
%     T(1) = Average gray level
%     T(2) = Average contrast
%     T(3) = Measure of smoothness
%     T(4) = Third moment
%     T(5) = Measure of uniformity
%     T(6) = Entropy

%   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins
%   Digital Image Processing Using MATLAB, Prentice-Hall, 2004
%   $Revision: 1.5 $  $Date: 2004/11/04 22:33:43 $

if nargin == 1
   scale(1:6) = 1;
else % Make sure it's a row vector.
   scale = scale(:)';
end

% Obtain histogram and normalize it.
p = imhist(f);
p = p./numel(f);
L = length(p);

% Compute the three moments. We need the unnormalized ones
% from function statmoments. These are in vector mu.
[v, mu] = statmoments(p, 3);

% Compute the six texture measures:
% Average gray level.
t(1) = mu(1);
% Standard deviation.
t(2) = mu(2).^0.5;
% Smoothness.
% First normalize the variance to [0 1] by
% dividing it by (L-1)^2.
varn = mu(2)/(L - 1)^2;
t(3) = 1 - 1/(1 + varn);
% Third moment (normalized by (L - 1)^2 also).
t(4) = mu(3)/(L - 1)^2;
% Uniformity.
t(5) = sum(p.^2);
% Entropy.
t(6) = -sum(p.*(log2(p + eps)));

% Scale the values.
t = t.*scale;