Skip to content

Instantly share code, notes, and snippets.

@YaronBlinder

YaronBlinder/algstdfilt.m

Last active August 9, 2016 03:41
Show Gist options
  • Save YaronBlinder/01ffbbf65d0c9035b0279fb2acd91975 to your computer and use it in GitHub Desktop.
Save YaronBlinder/01ffbbf65d0c9035b0279fb2acd91975 to your computer and use it in GitHub Desktop.
Download ZIP
Raw
algstdfilt.m
%This is what stdfilt actually runs after checking the input - Y.B.
function J = algstdfilt(I,h)
% Main algorithm used by stdfilt function. See stdfilt for more
% details
% No input validation is done in this function.
% Copyright 2013-2015 The MathWorks, Inc.
n = sum(h(:));
% If n = 1 then return default J (all zeros).
% Otherwise, calculate standard deviation. The formula for standard deviation
% can be rewritten in terms of the theoretical definition of
% convolution. However, in practise, use correlation in IMFILTER to avoid a
% flipped answer when NHOOD is asymmetric.
% conv1 = imfilter(I.^2,h,'symmetric') / (n-1);
% conv2 = imfilter(I,h,'symmetric').^2 / (n*(n-1));
% std = sqrt(conv1-conv2).
% These equations can be further optimized for speed.
n1 = n - 1;
if n ~= 1
conv1 = imfilter(I.^2, h/n1 , 'symmetric');
conv2 = imfilter(I, h/sqrt(n*n1), 'symmetric').^2;
J = sqrt(max((conv1 - conv2),0));
else
J = zeros(size(I));
end
Raw
error
$ nosetests -sx test_calculateSC.py:test_std_filt_m
F
======================================================================
FAIL: test_calculateSC.test_std_filt_m
----------------------------------------------------------------------
Traceback (most recent call last):
File "C:\Users\mrbli_000\Desktop\Python\Anaconda\lib\site-packages\nose\case.py", line 198, in runTest
self.test(*self.arg)
File "C:\Users\mrbli_000\Desktop\f0cl\edenis-confidential\testrepo\edenis-v4msti\tests\calculateSC\test_calculateSC.py", line 70, in test_std_filt_m
return std_filt_m(test_file,std_filter)
File "<decorator-gen-2>", line 2, in std_filt_m
File "C:\Users\mrbli_000\Desktop\f0cl\edenis-confidential\testrepo\edenis-v4msti\tests\calculateSC\rt_insert.py", line 8, in _wrapper
return self.callback(wrapped, _args, _dargs, args, dargs)
File "C:\Users\mrbli_000\Desktop\f0cl\edenis-confidential\testrepo\edenis-v4msti\tests\calculateSC\test_calculateSC.py", line 38, in callback
assert np.allclose(mfunc_result, local_result), mfunc_name
AssertionError: stdfilt
----------------------------------------------------------------------
Ran 1 test in 0.158s
FAILED (failures=1)
stdfilt
octave:
[[ 1.67332005 2. 2.16794834 1.81659021 1. ]
[ 1.67332005 2. 2.16794834 1.81659021 1. ]
[ 1.67332005 2. 2.16794834 1.81659021 1. ]
[ 1.67332005 2. 2.16794834 1.81659021 1. ]
[ 1.67332005 2. 2.16794834 1.81659021 1. ]]
python:
[[ 0.83666003 1.30384048 1.58113883 1.30384048 0.83666003]
[ 0.83666003 1.30384048 1.58113883 1.30384048 0.83666003]
[ 0.83666003 1.30384048 1.58113883 1.30384048 0.83666003]
[ 0.83666003 1.30384048 1.58113883 1.30384048 0.83666003]
[ 0.83666003 1.30384048 1.58113883 1.30384048 0.83666003]]
octave/python:
[[ 2. 1.53392998 1.37113092 1.39326109 1.19522861]
[ 2. 1.53392998 1.37113092 1.39326109 1.19522861]
[ 2. 1.53392998 1.37113092 1.39326109 1.19522861]
[ 2. 1.53392998 1.37113092 1.39326109 1.19522861]
[ 2. 1.53392998 1.37113092 1.39326109 1.19522861]]
Raw
std_filt_m.py
@mimic('stdfilt')
def std_filt_m(img, kernel):
img = np.transpose(img)
n = kernel.sum()
n1 = n - 1
c1 = filter2D(img**2, -1, kernel/n1, borderType = BORDER_REFLECT)
c2 = filter2D(img, -1, kernel/np.sqrt(n*n1), borderType = BORDER_REFLECT)**2
J = np.sqrt(np.maximum(c1-c2, 0))
return np.transpose(J)
Raw
test_std_filt_m.py
def test_std_filt_m():
window_size = 5
std_filter = np.ones(window_size)
test_file = (np.arange(25.)).reshape(5,5)
return std_filt_m(test_file,std_filter)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment