Black color object detection HSV range in opencv

Question

What is the range of Black color object detection?

i tried following code

cvInRangeS(imgHSV, cvScalar(0, 0, 0, 0), cvScalar(0, 255, 255, 0), imgThreshold);

but its not working.

Answer 1

For black and white colors in HSV range you have to set hue at maximum range (0 to 180), and saturation at maximum range (0 to 255). You can play with the value, for example, 0 to 30 or 40 for black, and 200 to 255 for white.

// for black
cvInRangeS(imgHSV, cvScalar(0, 0, 0, 0), cvScalar(180, 255, 30, 0), imgThreshold);

// for white
cvInRangeS(imgHSV, cvScalar(0, 0, 200, 0), cvScalar(180, 255, 255, 0), imgThreshold);

Or you can use the C++ interface:

// for black
cv::inRange(imgHSV, cv::Scalar(0, 0, 0, 0), cv::Scalar(180, 255, 30, 0), imgThreshold);

// for white   
cv::inRange(imgHSV, cv::Scalar(0, 0, 200, 0), cv::Scalar(180, 255, 255, 0), imgThreshold);

Answer 2

Black colour in HSV and HSL colour space, is detected with low Value (or Lightness in HSL).

White colour in HSL detected with high Value. White colour is HSV detected with high Lightness and Low Saturation.

for white

cv::inRange(imgHSL, cv::Scalar(0, 0, 200, 0), cv::Scalar(180, 255, 255, 0), imgThreshold);

or

cv::inRange(imgHSV, cv::Scalar(0, 0, 200, 0), cv::Scalar(180, 20, 255, 0), imgThreshold);