Doxygen tutorials: warnings cleared
This commit is contained in:
@@ -10,7 +10,7 @@ In this tutorial you will learn how to:
|
||||
- To calculate histograms of arrays of images by using the OpenCV function @ref cv::calcHist
|
||||
- To normalize an array by using the function @ref cv::normalize
|
||||
|
||||
@note In the last tutorial (@ref histogram_equalization) we talked about a particular kind of
|
||||
@note In the last tutorial (@ref tutorial_histogram_equalization) we talked about a particular kind of
|
||||
histogram called *Image histogram*. Now we will considerate it in its more general concept. Read on!
|
||||
|
||||
### What are histograms?
|
||||
@@ -42,10 +42,10 @@ histogram called *Image histogram*. Now we will considerate it in its more gener
|
||||
keep count not only of color intensities, but of whatever image features that we want to measure
|
||||
(i.e. gradients, directions, etc).
|
||||
- Let's identify some parts of the histogram:
|
||||
a. **dims**: The number of parameters you want to collect data of. In our example, **dims = 1**
|
||||
-# **dims**: The number of parameters you want to collect data of. In our example, **dims = 1**
|
||||
because we are only counting the intensity values of each pixel (in a greyscale image).
|
||||
b. **bins**: It is the number of **subdivisions** in each dim. In our example, **bins = 16**
|
||||
c. **range**: The limits for the values to be measured. In this case: **range = [0,255]**
|
||||
-# **bins**: It is the number of **subdivisions** in each dim. In our example, **bins = 16**
|
||||
-# **range**: The limits for the values to be measured. In this case: **range = [0,255]**
|
||||
- What if you want to count two features? In this case your resulting histogram would be a 3D plot
|
||||
(in which x and y would be \f$bin_{x}\f$ and \f$bin_{y}\f$ for each feature and z would be the number of
|
||||
counts for each combination of \f$(bin_{x}, bin_{y})\f$. The same would apply for more features (of
|
||||
@@ -68,82 +68,8 @@ Code
|
||||
- **Downloadable code**: Click
|
||||
[here](https://github.com/Itseez/opencv/tree/master/samples/cpp/tutorial_code/Histograms_Matching/calcHist_Demo.cpp)
|
||||
- **Code at glance:**
|
||||
@code{.cpp}
|
||||
#include "opencv2/highgui.hpp"
|
||||
#include "opencv2/imgproc.hpp"
|
||||
#include <iostream>
|
||||
#include <stdio.h>
|
||||
@includelineno samples/cpp/tutorial_code/Histograms_Matching/calcHist_Demo.cpp
|
||||
|
||||
using namespace std;
|
||||
using namespace cv;
|
||||
|
||||
/*
|
||||
* @function main
|
||||
*/
|
||||
int main( int argc, char** argv )
|
||||
{
|
||||
Mat src, dst;
|
||||
|
||||
/// Load image
|
||||
src = imread( argv[1], 1 );
|
||||
|
||||
if( !src.data )
|
||||
{ return -1; }
|
||||
|
||||
/// Separate the image in 3 places ( B, G and R )
|
||||
vector<Mat> bgr_planes;
|
||||
split( src, bgr_planes );
|
||||
|
||||
/// Establish the number of bins
|
||||
int histSize = 256;
|
||||
|
||||
/// Set the ranges ( for B,G,R) )
|
||||
float range[] = { 0, 256 } ;
|
||||
const float* histRange = { range };
|
||||
|
||||
bool uniform = true; bool accumulate = false;
|
||||
|
||||
Mat b_hist, g_hist, r_hist;
|
||||
|
||||
/// Compute the histograms:
|
||||
calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate );
|
||||
calcHist( &bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate );
|
||||
calcHist( &bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate );
|
||||
|
||||
// Draw the histograms for B, G and R
|
||||
int hist_w = 512; int hist_h = 400;
|
||||
int bin_w = cvRound( (double) hist_w/histSize );
|
||||
|
||||
Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) );
|
||||
|
||||
/// Normalize the result to [ 0, histImage.rows ]
|
||||
normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
|
||||
normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
|
||||
normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
|
||||
|
||||
/// Draw for each channel
|
||||
for( int i = 1; i < histSize; i++ )
|
||||
{
|
||||
line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at<float>(i-1)) ) ,
|
||||
Point( bin_w*(i), hist_h - cvRound(b_hist.at<float>(i)) ),
|
||||
Scalar( 255, 0, 0), 2, 8, 0 );
|
||||
line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at<float>(i-1)) ) ,
|
||||
Point( bin_w*(i), hist_h - cvRound(g_hist.at<float>(i)) ),
|
||||
Scalar( 0, 255, 0), 2, 8, 0 );
|
||||
line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at<float>(i-1)) ) ,
|
||||
Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ),
|
||||
Scalar( 0, 0, 255), 2, 8, 0 );
|
||||
}
|
||||
|
||||
/// Display
|
||||
namedWindow("calcHist Demo", WINDOW_AUTOSIZE );
|
||||
imshow("calcHist Demo", histImage );
|
||||
|
||||
waitKey(0);
|
||||
|
||||
return 0;
|
||||
}
|
||||
@endcode
|
||||
Explanation
|
||||
-----------
|
||||
|
||||
@@ -169,26 +95,26 @@ Explanation
|
||||
|
||||
4. Now we are ready to start configuring the **histograms** for each plane. Since we are working
|
||||
with the B, G and R planes, we know that our values will range in the interval \f$[0,255]\f$
|
||||
a. Establish number of bins (5, 10...):
|
||||
-# Establish number of bins (5, 10...):
|
||||
@code{.cpp}
|
||||
int histSize = 256; //from 0 to 255
|
||||
@endcode
|
||||
b. Set the range of values (as we said, between 0 and 255 )
|
||||
-# Set the range of values (as we said, between 0 and 255 )
|
||||
@code{.cpp}
|
||||
/// Set the ranges ( for B,G,R) )
|
||||
float range[] = { 0, 256 } ; //the upper boundary is exclusive
|
||||
const float* histRange = { range };
|
||||
@endcode
|
||||
c. We want our bins to have the same size (uniform) and to clear the histograms in the
|
||||
-# We want our bins to have the same size (uniform) and to clear the histograms in the
|
||||
beginning, so:
|
||||
@code{.cpp}
|
||||
bool uniform = true; bool accumulate = false;
|
||||
@endcode
|
||||
d. Finally, we create the Mat objects to save our histograms. Creating 3 (one for each plane):
|
||||
-# Finally, we create the Mat objects to save our histograms. Creating 3 (one for each plane):
|
||||
@code{.cpp}
|
||||
Mat b_hist, g_hist, r_hist;
|
||||
@endcode
|
||||
e. We proceed to calculate the histograms by using the OpenCV function @ref cv::calcHist :
|
||||
-# We proceed to calculate the histograms by using the OpenCV function @ref cv::calcHist :
|
||||
@code{.cpp}
|
||||
/// Compute the histograms:
|
||||
calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate );
|
||||
@@ -254,18 +180,15 @@ Explanation
|
||||
Scalar( 0, 0, 255), 2, 8, 0 );
|
||||
}
|
||||
@endcode
|
||||
|
||||
we use the expression:
|
||||
|
||||
@code{.cpp}
|
||||
b_hist.at<float>(i)
|
||||
@endcode
|
||||
|
||||
where \f$i\f$ indicates the dimension. If it were a 2D-histogram we would use something like:
|
||||
|
||||
@code{.cpp}
|
||||
b_hist.at<float>( i, j )
|
||||
@endcode
|
||||
|
||||
8. Finally we display our histograms and wait for the user to exit:
|
||||
@code{.cpp}
|
||||
namedWindow("calcHist Demo", WINDOW_AUTOSIZE );
|
||||
@@ -275,6 +198,7 @@ Explanation
|
||||
|
||||
return 0;
|
||||
@endcode
|
||||
|
||||
Result
|
||||
------
|
||||
|
||||
@@ -285,5 +209,3 @@ Result
|
||||
2. Produces the following histogram:
|
||||
|
||||

|
||||
|
||||
|
||||
|
Reference in New Issue
Block a user