freqspace (Image Processing Toolbox)

Determine frequency spacing for two-dimensional frequency response

Syntax

[f1,f2] = freqspace(n)
[f1,f2] = freqspace([m n])
[x1,y1] = freqspace(...,'meshgrid')
f = freqspace(N)
f = freqspace(N,'whole')

Description

freqspace returns the implied frequency range for equally spaced frequency responses. freqspace is useful when creating desired frequency responses for fsamp2, fwind1, and fwind2, as well as for various one-dimensional applications.

[f1,f2] = freqspace(n) returns the two-dimensional frequency vectors f1 and f2 for an n-by-n matrix.

For n odd, both f1 and f2 are [-n+1:2:n-1]/n.

For n even, both f1 and f2 are [-n:2:n-2]/n.

[f1,f2] = freqspace([m n]) returns the two-dimensional frequency vectors f1 and f2 for an m-by-n matrix.

[x1,y1] = freqspace(...,'meshgrid') is equivalent to

[f1,f2] = freqspace(...);
[x1,y1] = meshgrid(f1,f2);

f = freqspace(N) returns the one-dimensional frequency vector f assuming N evenly spaced points around the unit circle. For N even or odd, f is (0:2/N:1). For N even, freqspace therefore returns (N+2)/2 points. For N odd, it returns (N+1)/2 points.

f = freqspace(N,'whole') returns N evenly spaced points around the whole unit circle. In this case, f is 0:2/N:2*(N-1)/N.

Remarks

freqspace is a function in MATLAB.