Gaussian sharpen

fgaussian.m

function h = fgaussian(S, sigma, normalize)
N = S(1);
if size(S, 2) == 2
    M = S(2);
else
    M = N;
end
if nargin < 3 
    normalize = 1;
end

Xind = -floor(M/2) : M-floor(M/2)-1;
Yind = -floor(N/2) : N-floor(N/2)-1;
[X, Y] = meshgrid(Xind, Yind);

%// Create Gaussian Mask
h = exp(-(X.^2 + Y.^2) / (2*sigma*sigma));

%// Normalize so that total area (sum of all weights) is 1
if normalize
    h = h / sum(h(:));
end

end

GaussianSharpen.m

function [O, invFG] = GaussianSharpen(M, sigma, lambda)
F = fft2(M);
G = fgaussian(size(M), sigma);
FG = fft2(G);
invFG = FG./(lambda + FG.^2);
% invFG = invFG/max(max(abs(invFG)));
F2 = F.*invFG;
O = fftshift(ifft2(F2));
end