Write OpenCV Mat in 16Bit one channel - c++

Question

I'm stuck on writing a OpenCV Mat in 16 Bit. Whatever I try the result is always an 8 Bit (0-255) image. I checked for relating questions on SO but nothig here solved this issue.
The Mat contains 0-65535 greyscale values before writing it to disk. I already tried the following (and many more approaches):
cv::Mat depth;
depth.convertTo(depth, CV_16UC1);
imwrite("depth.png", depth);
as in the documentation for imwrite() they say, that it is possible to save a Mat with imwrite() when it is in CV_16U
What is wrong with the code? Anybody knows how to solve this?

Answer 1

Both the following work:
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace cv;
int main( int, char** argv )
{
// Start with unsigned shorts and write to PNG
unsigned short data[4] = {0,12000,24000,65535};
Mat src = Mat(1,4,CV_16UC1,data);
imwrite("depth.png",src);
// Start with floats and convert to 16-bit then write to PNG
float dataf[4]={0.0,12000.0,25000.0,65000.0};
Mat a = Mat(1,4,CV_32FC1,dataf);
a.convertTo(a,CV_16UC1);
imwrite("d2.png",a);
}
I can check them with ImageMagick as follows, and both are 16-bit greyscale PNGs:
convert depth.png txt:
# ImageMagick pixel enumeration: 4,1,65535,gray
0,0: (0) #000000000000 gray(0)
1,0: (12000) #2EE02EE02EE0 gray(18.3108%)
2,0: (24000) #5DC05DC05DC0 gray(36.6217%)
3,0: (65535) #FFFFFFFFFFFF gray(255)
and
convert d2.png txt:
# ImageMagick pixel enumeration: 4,1,65535,gray
0,0: (0) #000000000000 gray(0)
1,0: (12000) #2EE02EE02EE0 gray(18.3108%)
2,0: (25000) #61A861A861A8 gray(38.1476%)
3,0: (65000) #FDE8FDE8FDE8 gray(99.1836%)
I suggest your problem is elsewhere. Please provide an MCVE.
Also, maybe try writing it to FileStorage or PGM format instead of PNG and look at the file in a normal editor to see if it really looks like 16-bit data - and if it works at all.