HSV Thresholding Difference between ImageJ and OpenCV

edit

I use ImageJ before using OpenCV functions because in ImageJ I can use their interactive HSV thresholding tool to get the HSV parameters I want to threshold using OpenCV functions. After using ImageJ and after converting a pic from BGR to HSV, I use the parameters from ImageJ in the cv2.thresholding function with cv2.THRESH_BINARY. However, when I look at my mask derived from the thresholding using OpenCV, it is close, but not the same as the one I obtained with ImageJ.

1. Is there a reason for this? Am I doing something wrong?

2. Is there an interactive thresholding script in Python that uses OpenCV functions?