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authorbsdnoobz <nash@bsd-noobz.com>2012-12-04 20:47:51 +0700
committerbsdnoobz <nash@bsd-noobz.com>2012-12-04 20:47:51 +0700
commit9fab7231cc5a2ed31f2e78f16263d26b094e6ea4 (patch)
tree0a64f481ad01f4203ddc57ba7e5279356c464504
parent57fc3d64ce3b7859a9f6cbe35cf2ab2a97c7ddc3 (diff)
improve display-histogram.cpp
-rw-r--r--display-histogram.cpp16
1 files changed, 11 insertions, 5 deletions
diff --git a/display-histogram.cpp b/display-histogram.cpp
index c4295e9..17f5a14 100644
--- a/display-histogram.cpp
+++ b/display-histogram.cpp
@@ -1,3 +1,6 @@
+/**
+ * Code sample for displaying image histogram in OpenCV.
+ */
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
@@ -9,11 +12,14 @@ void showHistogram(Mat& img)
{
int bins = 256; // number of bins
int nc = img.channels(); // number of channels
- vector<Mat> hist(nc);
+ vector<Mat> hist(nc); // histogram arrays
+
+ // Initalize histogram arrays
for (int i = 0; i < hist.size(); i++)
hist[i] = Mat::zeros(1, bins, CV_32SC1);
+ // Calculate the histogram of the image
for (int i = 0; i < img.rows; i++)
{
for (int j = 0; j < img.cols; j++)
@@ -26,6 +32,8 @@ void showHistogram(Mat& img)
}
}
+ // For each histogram arrays, obtain the maximum (peak) value
+ // Needed to normalize the display later
int hmax[3] = {0,0,0};
for (int i = 0; i < nc; i++)
{
@@ -38,6 +46,7 @@ void showHistogram(Mat& img)
vector<Mat> canvas(nc);
+ // Display each histogram in a canvas
for (int i = 0; i < nc; i++)
{
canvas[i] = Mat::ones(125, bins, CV_8UC3);
@@ -57,18 +66,15 @@ void showHistogram(Mat& img)
}
}
+// Test the `showHistogram()` function above
int main()
{
Mat src = imread("c:/users/nash/desktop/assets/lena.jpg");
-
if (src.empty())
return -1;
-
showHistogram(src);
-
imshow("src", src);
waitKey(0);
-
return 0;
}