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Diffstat (limited to 'silx/math/medianfilter/include/median_filter.hpp')
-rw-r--r-- | silx/math/medianfilter/include/median_filter.hpp | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/silx/math/medianfilter/include/median_filter.hpp b/silx/math/medianfilter/include/median_filter.hpp new file mode 100644 index 0000000..78d6c5a --- /dev/null +++ b/silx/math/medianfilter/include/median_filter.hpp @@ -0,0 +1,229 @@ +/*########################################################################## +# +# Copyright (c) 2017 European Synchrotron Radiation Facility +# +# Permission is hereby granted, free of charge, to any person obtaining a copy +# of this software and associated documentation files (the "Software"), to deal +# in the Software without restriction, including without limitation the rights +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +# copies of the Software, and to permit persons to whom the Software is +# furnished to do so, subject to the following conditions: +# +# The above copyright notice and this permission notice shall be included in +# all copies or substantial portions of the Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +# THE SOFTWARE. +# +# ###########################################################################*/ +// __authors__ = ["H. Payno"] +// __license__ = "MIT" +// __date__ = "10/02/2017" + +#ifndef MEDIAN_FILTER +#define MEDIAN_FILTER + +#include <vector> +#include <assert.h> +#include <algorithm> +#include <signal.h> +#include <iostream> + +// Modes for the median filter +enum MODE{ + NEAREST=0, + REFLECT=1, + MIRROR=2, + SHRINK=3 +}; + +// Simple function browsing a deque and registring the min and max values +// and if those values are unique or not +template<typename T> +void getMinMax(std::vector<const T*>& v, T& min, T&max, + typename std::vector<const T*>::const_iterator end){ + // init min and max values + typename std::vector<const T*>::const_iterator it = v.begin(); + if (v.size() == 0){ + raise(SIGINT); + }else{ + min = max = *(*it); + } + it++; + + // Browse all the deque + while(it!=end){ + // check if repeated (should always be before min/max setting) + if(*(*it) > max) max = *(*it); + if(*(*it) < min) min = *(*it); + + it++; + } +} + +template<typename T> +bool cmp(const T* a, const T* b){ + return *a < *b; +} + +// apply the median filter only on limited part of the vector +template<typename T> +const T* median(std::vector<const T*>& v, int window_size) { + std::nth_element(v.begin(), v.begin() + window_size/2, v.begin()+window_size, cmp<T>); + return v[window_size/2]; +} + +template<typename T> +void print_window(std::vector<const T*>& v, + typename std::vector<const T*>::const_iterator end){ + typename std::vector<const T*>::const_iterator it; + for(it = v.begin(); it != end; ++it){ + std::cout << *(*it) << " "; + } + std::cout << std::endl; +} + +// return the index into 0, (length_max - 1) in reflect mode +int reflect(int index, int length_max){ + int res = index; + // if the index is negative get the positive symetrical value + if(res < 0){ + res += 1; + res = -res; + } + // then apply the reflect algorithm. Frequence is 2 max length + res = res % (2*length_max); + if(res >= length_max){ + res = 2*length_max - res -1; + res = res % length_max; + } + return res; +} + +// return the index into 0, (length_max - 1) in mirror mode +int mirror(int index, int length_max){ + int res = index; + // if the index is negative get the positive symetrical value + if(res < 0){ + res = -res; + } + + int rightLimit = length_max -1; + // apply the redundancy each two right limit + res = res % (2*rightLimit); + if(res >= length_max){ + int distToRedundancy = (2*rightLimit) - res; + res = distToRedundancy; + } + return res; +} + +// Browse the column of pixel_x +template<typename T> +void median_filter( + const T* input, + T* output, + int* kernel_dim, // two values : 0:width, 1:height + int* image_dim, // two values : 0:width, 1:height + int y_pixel, // the x pixel to process + int x_pixel_range_min, + int x_pixel_range_max, + bool conditional, + int pMode){ + + assert(kernel_dim[0] > 0); + assert(kernel_dim[1] > 0); + assert(y_pixel >= 0); + assert(image_dim[0] > 0); + assert(image_dim[1] > 0); + assert(y_pixel >= 0); + assert(y_pixel < image_dim[0]); + assert(x_pixel_range_max < image_dim[1]); + assert(x_pixel_range_min <= x_pixel_range_max); + // kernel odd assertion + assert((kernel_dim[0] - 1)%2 == 0); + assert((kernel_dim[1] - 1)%2 == 0); + + // # this should be move up to avoid calculation each time + int halfKernel_x = (kernel_dim[1] - 1) / 2; + int halfKernel_y = (kernel_dim[0] - 1) / 2; + + MODE mode = static_cast<MODE>(pMode); + + // init buffer + std::vector<const T*> window_values(kernel_dim[0]*kernel_dim[1]); + + for(int x_pixel=x_pixel_range_min; x_pixel <= x_pixel_range_max; x_pixel ++ ){ + typename std::vector<const T*>::iterator it = window_values.begin(); + // fill the vector + for(int win_y=y_pixel-halfKernel_y; win_y<= y_pixel+halfKernel_y; win_y++) + { + for(int win_x = x_pixel-halfKernel_x; win_x <= x_pixel+halfKernel_x; win_x++) + { + int index_x = win_x; + int index_y = win_y; + switch(mode){ + case NEAREST: + index_x = std::min(std::max(win_x, 0), image_dim[1] - 1); + index_y = std::min(std::max(win_y, 0), image_dim[0] - 1); + break; + + case REFLECT: + index_x = reflect(win_x, image_dim[1]); + index_y = reflect(win_y, image_dim[0]); + break; + + case MIRROR: + index_x = mirror(win_x, image_dim[1]); + index_y = mirror(win_y, image_dim[0]); + break; + case SHRINK: + if((index_x < 0) || (index_x > image_dim[1] -1)){ + continue; + } + if((index_y < 0) || (index_y > image_dim[0] -1)){ + continue; + } + break; + } + *it = (&input[index_y*image_dim[1] + index_x]); + ++it; + } + } + + // get end of the windows. This is needed since in shrink mode we are + // not sure to fill the entire window. + typename std::vector<const T*>::iterator window_end; + int window_size = kernel_dim[0]*kernel_dim[1]; + if(mode == SHRINK){ + int x_shrink_ker_dim = std::min(x_pixel+halfKernel_x, image_dim[1]-1) - std::max(0, x_pixel-halfKernel_x)+1; + int y_shrink_ker_dim = std::min(y_pixel+halfKernel_y, image_dim[0]-1) - std::max(0, y_pixel-halfKernel_y)+1; + window_size = x_shrink_ker_dim*y_shrink_ker_dim; + window_end = window_values.begin() + window_size; + }else{ + window_end = window_values.end(); + } + + // apply the median value if needed for this pixel + const T* currentPixelValue = &input[image_dim[1]*y_pixel + x_pixel]; + if (conditional == true){ + T min = 0; + T max = 0; + getMinMax(window_values, min, max, window_end); + if ((*currentPixelValue == max) || (*currentPixelValue == min)){ + output[image_dim[1]*y_pixel + x_pixel] = *(median<T>(window_values, window_size)); + }else{ + output[image_dim[1]*y_pixel + x_pixel] = *currentPixelValue; + } + }else{ + output[image_dim[1]*y_pixel + x_pixel] = *(median<T>(window_values, window_size)); + } + } +} + +#endif // MEDIAN_FILTER |