How can I make my threshold window only work for half my image?

Question

I am using Visual Basic 2010 Express, and opencv in c++, and while this line already limits my color to track in the threshold window,

inRange(HSV,Scalar(0,1,170),Scalar(196,137,256),thresholdL);

I am trying to figure out how to also say 'only show pixels(I don't know the proper terminology for it) that lie somewhere from 320 to 640 on the x axis in this threshold window.'

I do have a variable that i use to check the x position, called

int xPos;

but I'm not sure how to take that and funnel the info into my threshold window. Do I modify the line shown? is there a function for this that I just haven't found and can insert underneath? Will I have to set up a whole new class or something?

Thank you in advance.

Answer 1

If you want to work on some specific part of the image OpenCV ROI may help you

You can have something like

Mat HSV; //your source image for inrange
Mat thresholdL//destination image
int xPos= x_starting_point;
int yPos=HSV.rows
width=HSV.cols-xPos;
height=HSV.rows;

cv::Rect roi(xPos, yPos, width, height); // Your ROI rectangle
//Set image ROI
cv::Mat image_roi = HSV(roi);// note: this assignment does not copy data,HSV and image_roi now share data
//Perform your operation
inRange(image_roi,Scalar(0,1,170),Scalar(196,137,256),thresholdL);

// Now dislpay
imshow("out",HSV);

Hope these helpful for you...