clipping.m

sfrmat is a Matlab function that provides a spatial frequency response* (SFR) from a digital image f

function [nlow, nhigh, status] = clipping(a, low, high, thresh1)
% [n, status] = clipping(a, low, high, thresh1) Checks for data clipping
% Function checks for clipping of data array
%  a       = array
%  low     = low clip value
%  high    = high clip value
%  thresh1 = threshhold fraction [0-1] used for warning, 
%            if thresh1 = 0, all clipping is reported
% Peter Burns 5 Aug. 2002
% Copyright (c) International Imaging Industry Association

status = 1;

[nlin npix ncol] = size(a);
n = nlin*npix;

nhigh = zeros(ncol, 1);
nlow =  zeros(ncol, 1);

for k = 1: ncol;
   for j = 1: npix;
      for i = 1: nlin;
if a(i, j, k) <= low;
   nlow(k) = nlow(k) + 1;
end;
if a(i, j, k) >= high;
   nhigh(k) = nhigh(k) + 1;
end;

end;
end;
end;

nhigh = nhigh./n;

for k =1: ncol;
 if nlow(k) > thresh1;
  disp([' *** Warning: low clipping in record ', num2str(k)]);
  status = 0;
  end;
 if nhigh(k) > thresh1;
  disp([' *** Warning: high clipping in record ', num2str(k)]);
  status = 0;
 end;
end;

nlow = nlow./n;
if status ~= 1
 warndlg('Data clipping errors detected','ClipCheck');
end;
return;