OpenGL and OpenCV not matching up

Using OPENCV to show an image (jpg etc)

Using OPENGL to draw on this image. Specifically drawing trace lines around the edges of the drawing.

When i scroll left/right and up/down my OpenGL draws offset.

Im not sure how to get these to align without hard coding.

I hard coded some numbers that eventually work so when I use the scroll bars everything lines up. However, i am having to use differnt numbers for differnt computers. To make matters worse, when i remote destop i noticed my image is scretched about 5% in the X axis. This means, a 10 x 10 box will draw about 10.5 x 10 but only remote desktop. Without Remote Desktop the same PC i remote into does not have the 5% issues but, i am still having to hard code the numbers in to work.

So in short, i need to find out how to calculate the following numbers that i had to hard code.

          m_image = cvLoadImage(pDoc->m_sImageFilePath)

if(true)///Work PC screen
	xPixels = .2825; ///(???)
	yPixels = xPixels;
else if(false)//Remote Desktop screen
	xPixels = .4;
	yPixels = .3336;

GLfloat x = (-m_image->width / 2) - (pDoc->m_pWindowOrg.x) * xPixels;
GLfloat y = (m_image->height / 2) - (pDoc->m_pWindowOrg.y) * yPixels;


glBitmap(NULL,NULL,m_image->width,m_image->height,pDoc->m_fZoomScale * x,pDoc->m_fZoomScale * y,NULL);