OpenCV (C++) - Set HSV values of a pixel

Question

I have an RGB image that i converted to HSV and my goal is to set every pixel that doesn\'t meet a certain hue value (100) to black. So H = S = V = 0.

I have this code:

Answer 1

You can:

• build a mask where H channel equals 100, regardless the values of S,V channels (with inRange)
• set frame3 to zero according to the mask (with setTo)

Something like:

Mat frame3; // CV_8UC3, HSV image

Mat mask;
inRange(frame3, Scalar(100,0,0), Scalar(100, 255, 255), mask);

frame3.setTo(Scalar(0,0,0), mask);

---

To keep your code structure, you need to modify the actual value, not a copy of the value. You can do that keeping a reference to the value:

 Vec3b& hsv = frame3.at<Vec3b>(i, j);
 if (hsv[0] != hue) {
    hsv[0] = 0;
    hsv[1] = 0;
    hsv[2] = 0;
 }