How to generate a thermal picture using C++ and OpenCV? - c++

Question

I'm working on my school project. I use grid-eye to access the environment temperature. The data form is a 64 pixels array (8x8 2D-array). Now I want to use this array to generate a thermal picture. I can simply copy the value to Matlab, scale it, and use image (temperature) to output a picture like this
The more red and dark represent hotter.
But I build all program in C++. So I have to find a way to do the same thing in C++. The first thing I though is OpenCV. After some searching, I wrote a simple code for only gray-scale mat. But this image looks weird.
Here is my code:
void GridEye::showCV() {
// > threshold means this pixel contain heat object.
for (int i = 0; i < 64; ++i) {
if (temperature[i] > threshold) forimage[i] = 255;
else forimage[i] = 0;
}
Mat image(8, 8, CV_8UC1, forimage);
resize(image, image, Size(640, 640)); // to make picture larger
namedWindow("Display window", WINDOW_AUTOSIZE);
imshow("Display window", image);
waitKey(100);
}
Is there something wrong with my code? Or some suggestion for using other library because I am really not familiar to OpenCV.

Answer 1

Try something like:
Mat1f image(8, 8, temperature);
//threshold(image, image, your_threshold_value, 0, THRESH_TOZERO); // << Uncomment this line to apply a threshold
normalize(image, image, 0, 1, NORM_MINMAX);
imshow("original size", image);
Mat resized;
//resize(image, resized, Size(640, 640)); // << Apply bilinear interpolation
resize(image, resized, Size(640, 640), 0, 0, INTER_NEAREST);
imshow("resized", resized);
waitKey();