OpenCV - Access to pixels along the curve/path

is there any way to access pixels along the specified c开发者_如何学Curve/path in OpenCV?

I've found LineIterator: http://opencv.willowgarage.com/documentation/cpp/core_drawing_functions.html?highlight=lineiterator#LineIterator but it's limited to lines. I would like to find something similar to LineIterator, but working with circles, since I need to read the pixels along the circle, or ellipse.

It is not builtin to opencv, but you can use http://en.wikipedia.org/wiki/Midpoint_circle_algorithm for circles, the article also mentions a paper that describes an extention to ellipses.