MATLAB: Undefined function or method ‘filter’

filter

hi i am getting an error in this code
   %  function y = filtdn(x, f, dim, extmod, shift)
  % FILTDN   Filter and downsample (by 2) along a dimension
  %



  %       y = filtdn(x, f, dim, extmod, shift)
  %
  % Input:
  %   x:      input signal
  %   f:      1-D filter
  %   dim:    the processing dimension
  %   extmod: extension mode (e.g. 'per' or 'sym')
  %   shift:  specifies the window over which filtering occurs
  %
  % Output:
  %   y:      filtered and dowsampled signal
  %
  % Note:
  %   The origin of the filter f is assumed to be floor(size(f)/2) + 1.
  %   Amount of shift should be no more than floor((size(f)-1)/2).
% Skip singleton dimension
if size(x, dim) == 1    
    y = x;
    return
end
% Cell array of indexes for each dimension
nd = ndims(x);
I = cell(1, nd);
for d = 1:nd
    I{d} = 1:size(x,d);
end
% Border extend
n = size(x, dim);
hlf = (length(f) - 1) / 2;
% Amount of extension at two ends
e1 = floor(hlf) + shift;
e2 = ceil(hlf) - shift;
switch extmod
    case 'per'
        I{dim} = [ly-e1+1:n , 1:n , 1:e2];
      case 'sym'
          I{dim} = [e1+1:-1:2 , 1:n , n-1:-1:e2];
      otherwise
          error('Invalid input for EXTMOD')
end
y = x(I{:});
% Filter, downsample, and return only the 'valid' part
y = filter(f, 1, y, [], dim);
I{dim} = (1:2:n) + length(f) - 1;
y = y(I{:});
and the error is ??? Undefined function or method 'filter' for input arguments of type 'uint8'.
Error in ==> filtdn at 54 y = filter(f, 1, y, [], dim);
Filter is an inbuilt function and i have image processing toolbox installed and set in my preferrence …
can anyone help me with this???

Best Answer

filter() does not accept arguments of datatype uint8(). You need to filter a single precision or double precision value.
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