Get the median, added to mean and std value
I'm using : Core.meanStdDev(hist, mean, stdev);
Is there a possibility to have median in the result of meanStdDev ?
I'm using : Core.meanStdDev(hist, mean, stdev);
Is there a possibility to have median in the result of meanStdDev ?
I found a simple way to answer :
double getMedian(Mat hist) {
// binapprox algorithm
long n = hist.total();
int[] histBuff = new int[(int) n];
hist.get(0, 0, histBuff);
// Compute the mean and standard deviation
// int n = x.length;
double sum = 0;
// int i;
for (int i = 0; i < n; i++) {
sum += histBuff[i];
}
double mu = sum / n;
sum = 0;
for (int i = 0; i < n; i++) {
sum += (histBuff[i] - mu) * (histBuff[i] - mu);
}
double sigma = Math.sqrt(sum / n);
// Bin x across the interval [mu-sigma, mu+sigma]
int bottomcount = 0;
int[] bincounts = new int[1001];
for (int i = 0; i < 1001; i++) {
bincounts[i] = 0;
}
double scalefactor = 1000 / (2 * sigma);
double leftend = mu - sigma;
double rightend = mu + sigma;
int bin;
for (int i = 0; i < n; i++) {
if (histBuff[i] < leftend) {
bottomcount++;
} else if (histBuff[i] < rightend) {
bin = (int) ((histBuff[i] - leftend) * scalefactor);
bincounts[bin]++;
}
}
double median = 0;
// If n is odd
if ((n % 2) != 0) {
// Find the bin that contains the median
int k = (int) ((n + 1) / 2);
int count = bottomcount;
for (int i = 0; i < 1001; i++) {
count += bincounts[i];
if (count >= k) {
median = (i + 0.5) / scalefactor + leftend;
}
}
}
// If n is even
else {
// Find the bins that contains the medians
int k = (int) (n / 2);
int count = bottomcount;
for (int i = 0; i < 1001; i++) {
count += bincounts[i];
if (count >= k) {
int j = i;
while (count == k) {
j++;
count += bincounts[j];
}
median = (i + j + 1) / (2 * scalefactor) + leftend;
}
}
}
return median;
}
Asked: 2013-09-11 04:36:40 -0600
Seen: 11,873 times
Last updated: Sep 26 '13
How to get good matches from the ORB feature detection algorithm?
How to decrease the number of processed frames from a live video camera?
Unresolved inclusion in OpenCV+Android tutorial
build problems for android_binary_package - Eclipse Indigo, Ubuntu 12.04
Which values for window size and number of pyramids are reasonable for calcOpticalFlowPyrLK?
Errors running builder 'CDT Builder' when trying to build OpenCV for android samples
ndk-build deletes native OpenCV library
Installing Sample App / OpenCV Manager