picking pixel color from 320*240 image (of emgu opencv) as mouse click event occurs on the image.

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hi,
i am working on color detection on emgu opencv. i have 320*240 sized image and i want program to start detecting color same as a pixel in image selected by mouse click event. i have used MousePosition.X;(Y) but it returns coordinates with respect to screen but what i need is cursor location with respect to image i-e when it enters imagebox it sh return should return value as it were in 320*240 sized screen.

or in other word i need coordinates not greater than x:320 ,y:240. otherwise i am getting null exception error. please help.

Posted 3-Jan-12 20:48pm

ssattarr

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Sergey Alexandrovich Kryukov 4-Jan-12 2:55am

Not clear. Where is a problem? What's your code which is problematic? Could you make a short sample?
--SA

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lukeer · Answer 1 · 2012-01-03T21:11:00

Solution 1

You will most likely have to process something like this

C#

public System.Drawing.Point GetPositionInImage()
{
    int locationInImageX = locationOnScreen.X - imageUpperLeftCorner.X;
    if(locationInImageX < 0)
        locationInImageX = 0;
    if(locationInImageX >= imageLowerRightCorner.X)
        locationInImageX = imageLowerRightCorner.X - 1;

    return(new System.Drawing.Point(
        locationInImageX,
        locationInImageY    // Same processing as for x-value
    ));
}

Posted 3-Jan-12 21:11pm

lukeer

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ssattarr 4-Jan-12 11:23am

thanks lukeer , you got my problem. i did something similar to this and solved issue . what i am wondering if there is no direct way to do this? instead of calculations.

lukeer 5-Jan-12 8:19am

Actually, there is a method System.Windows.Forms.Control.PointToClient(), that does the translation part (use control co-ordinates instead of desktop co-ordinates).
The range check stays for you to do.