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Parameters of calcHist are hard to understand

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<std::initializer_list<float>> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = std::begin( *(std::begin(ranges) + i) );
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

Parameters of calcHist are hard to understand

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<std::initializer_list<float>> std::initializer_list<float[2]> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = std::begin( *(std::begin(ranges) + i) );
i);
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

I call it like this

cv::Mat hsv;
cv::MatND results; 
//.....do somthing
calc_histogram({hsv}, results, {0, 1}, {180, 256}, { {0, 180}, {0, 256} });

I don't know my assumptions correct or not.If you know another way to encapsulate it, please shed me some lights(I try to use std::array<float[2], n=""> to replace ranges, but this api need to specify nontype template parameter, although it could save the price of memory allocation).

Parameters of calcHist are hard to understand

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<float[2]> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = *(std::begin(ranges) + i);
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

I call it like thisthis(make it close to the api like python).

cv::Mat hsv;
cv::MatND results; 
//.....do somthing
calc_histogram({hsv}, results, {0, 1}, {180, 256}, { {0, 180}, {0, 256} });

I don't know my assumptions correct or not.If you know another way to encapsulate it, please shed me some lights(I try to use std::array<float[2], n=""> to replace ranges, but this api need to specify nontype template parameter, although it could save the price of memory allocation).

Parameters Understanding parameters of calcHist are hard to understandand encapsulate this api

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<float[2]> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = *(std::begin(ranges) + i);
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

I call it like this(make it close to the api like python).

cv::Mat hsv;
cv::MatND results; 
//.....do somthing
calc_histogram({hsv}, results, {0, 1}, {180, 256}, { {0, 180}, {0, 256} });

I don't know my assumptions correct or not.If you know another way to encapsulate it, please shed me some lights(I try to use std::array<float[2], n=""> to replace ranges, but this api need to specify nontype template parameter, although it could save the price of memory allocation).

click to hide/show revision 5
hope, you don't mind, if i remove the hash signs from your tags ( as it only adds anoying duplicates ) and again, apologies for getting your approach wrong in the first place !

updated 2013-09-03 15:35:35 -0500

berak gravatar image

Understanding parameters of calcHist and encapsulate this api

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<float[2]> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = *(std::begin(ranges) + i);
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

I call it like this(make it close to the api like python).

cv::Mat hsv;
cv::MatND results; 
//.....do somthing
calc_histogram({hsv}, results, {0, 1}, {180, 256}, { {0, 180}, {0, 256} });

I don't know my assumptions correct or not.If you know another way to encapsulate it, please shed me some lights(I try to use std::array<float[2], n=""> to replace ranges, but this api need to specify nontype template parameter, although it could save the price of memory allocation).

Understanding parameters of calcHist and encapsulate this api

Try to encapsulate the api of calcHist because it is too complicated for me. I've read the documentation for calcHist() many times, but I think my inexperience precluding me from understanding all of the parameters of this api.

void calcHist(const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false )

(1)nimages : Number of source images-->is it always same as the number of images point to? ex :

cv::Mat a, b, c;
cv::Mat images[] = {a, b, c};
int nimages = sizeof(images) / sizeof(cv::Mat);

(2)channels : List of the dims The channels used to compute the histogram-->is it always same as the number of dims? ex : int channels[] = {0, 1}; int dims = sizeof(channels)/ sizeof(int);

(3)histSizes && ranges: Are they always have the same elements numbers as channels?

(4)channels, histSize and ranges always have same number of elements? ex :

int channels[] = {0, 1}; //two elements
int histSize[] = {180, 256}; //two elements
float hue[] = {0, 180};
float sat[] = {0, 255};
float const *ranges[] = {hue, sat}; //two elements

(5)if (1)~(4) are correct, that means we could deduce nimages from images;deduce dims from channels, histSize or ranges?

encapsulation base on the assumption from (1)~(4)

void calc_histogram(std::initializer_list<cv::Mat> images, cv::OutputArray &output, std::initializer_list<int> channels,
                    std::initializer_list<int> hist_sizes, std::initializer_list<float[2]> ranges,
                    cv::InputArray const &mask = cv::Mat(), bool uniform = true, bool accumulate = false)
{        
    size_t const sizes = ranges.size();
    std::vector<float const*> d_ranges(sizes);
    for(size_t i = 0; i != sizes; ++i){
        d_ranges[i] = *(std::begin(ranges) + i);
    }

    cv::calcHist(std::begin(images), images.size(), std::begin(channels), mask, output,
                 channels.size(), std::begin(hist_sizes), &d_ranges[0], uniform ,accumulate);
}

I call it like this(make it close to the api like python).

cv::Mat hsv;
cv::MatND results; 
//.....do somthing
calc_histogram({hsv}, results, {0, 1}, {180, 256}, { {0, 180}, {0, 256} });

I don't know my assumptions correct or not.If you know another way to encapsulate it, please shed me some lights(I try to use std::array<float[2], n=""> to replace ranges, but this api need to specify nontype template parameter, although it could save the price of memory allocation).