/usr/share/octave/site/m/vlfeat/toolbox/xtest/vl_test_imsmooth.m is in octave-vlfeat 0.9.17+dfsg0-6build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 | function results = vl_test_imsmooth(varargin)
% VL_TEST_IMSMOOTH
vl_test_init ;
function s = setup()
I = im2double(imread(fullfile(vl_root,'data','spots.jpg'))) ;
I = max(min(vl_imdown(I),1),0) ;
s.I = single(I) ;
function test_pad_by_continuity(s)
% Convolving a constant signal padded with continuity does not change
% the signal.
I = ones(3) ;
for ker = {'triangular', 'gaussian'}
ker = char(ker) ;
J = vl_imsmooth(I, 2, ...
'kernel', ker, ...
'padding', 'continuity') ;
vl_assert_almost_equal(J, I, 1e-4, ...
'padding by continutiy with kernel = %s', ker) ;
end
function test_kernels(s)
for ker = {'triangular', 'gaussian'}
ker = char(ker) ;
for type = {@single, @double}
for simd = [0 1]
for sigma = [1 2 7]
for step = [1 2 3]
vl_simdctrl(simd) ;
conv = type{1} ;
g = equivalent_kernel(ker, sigma) ;
J = vl_imsmooth(conv(s.I), sigma, ...
'kernel', ker, ...
'padding', 'zero', ...
'subsample', step) ;
J_ = conv(convolve(s.I, g, step)) ;
vl_assert_almost_equal(J, J_, 1e-4, ...
'kernel=%s sigma=%f step=%d simd=%d', ...
ker, sigma, step, simd) ;
end
end
end
end
end
function g = equivalent_kernel(ker, sigma)
switch ker
case 'gaussian'
W = ceil(4*sigma) ;
g = exp(-.5*((-W:W)/(sigma+eps)).^2) ;
case 'triangular'
W = max(round(sigma),1) ;
g = W - abs(-W+1:W-1) ;
end
g = g / sum(g) ;
function I = convolve(I, g, step)
if strcmp(class(I),'single')
g = single(g) ;
else
g = double(g) ;
end
for k=1:size(I,3)
I(:,:,k) = conv2(g,g,I(:,:,k),'same');
end
I = I(1:step:end,1:step:end,:) ;
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